用点分割线串并在 R 中分配新的线段 ID
Split linestring with points and assign new segment ID in R
我正在尝试使用水坝（点）将河流（线）分割成水坝之间的连接段。
答案 最接近我想要达到的目标。问题是 st_split 使用多边形边界作为 'blade' 从而将一条线分成三条而不是两条。我还想为每个点之间的线段分配一个公共 ID。
期望的输出
这是我试过的方法。对于这个例子，结果应该有 9 个特征。
library(tidyverse)
library(sf)
library(lwgeom)
buf_all <- st_buffer(pt, 0.001)
parts <- st_collection_extract(lwgeom::st_split(ln$geometry, buf_all), "LINESTRING")
parts_all <- st_as_sf(
data.frame(
id = 1:length(parts),
geometry = parts
)
)
但结果并不如预期。
>nrow(parts_all)
[1] 13 2
数据
ln <- structure(list(River_ID = c(159, 160, 161, 186, 196), geometry = structure(list(
structure(c(289924.625, 289924.5313, 289922.9688, 289920.0625,
289915.7499, 289912.7188, 289907.4375, 289905.3438, 289901.1251,
289889, 289888.5, 289887.5938, 289886.5, 289886.4063, 289885.3124,
289884.0938, 289884.0001, 289882.8125, 289881.625, 289878.6875,
289877.9688, 289876.25, 289874.5625, 289874.25, 289872.7188,
289871.2813, 289871.1875, 289870.0313, 289869, 289868.5939,
289867.8436, 289865.8438, 289864.0625, 289862.5939, 289862.375,
289861.5, 289860.7812, 289860.5625, 289859.5313, 289858.375,
289857.7813, 289855.4063, 289854.25, 289850.8749, 289846.4376,
289841.9064, 289836.0625, 289828.1562, 289822.8438, 289816.625,
289812.4376, 289807.9064, 289798.75, 289793.125, 289786.2188,
289781.375, 289777.3124, 289770.0313, 289765.4375, 289762.2188,
289759.25, 289755.5938, 289753.0625, 289747.9687, 289743.7499,
289741.5938, 289739.5, 289736.1874, 289732.75, 289727, 289723.7499,
289719.625, 289715.5626, 289713.7499, 202817.531300001, 202817.2031,
202815.1094, 202812.468699999, 202809.3906, 202806.7656,
202799.7969, 202797.906300001, 202794.093800001, 202783.515699999,
202783.125, 202782.4844, 202781.906300001, 202781.8125, 202781.3594,
202781.093800001, 202780.9999, 202780.5469, 202780, 202777.625,
202777.0469, 202775.718800001, 202774.1875, 202773.906300001,
202772.1875, 202770.4531, 202770.25, 202768.5156, 202766.6719,
202766, 202764.0469, 202759.6719, 202755.8749, 202752.781300001,
202752.1875, 202749.953199999, 202748.297, 202747.906300001,
202746.0625, 202744.2344, 202743.5625, 202740.4375, 202738.8125,
202734.5, 202727.9844, 202723.5625, 202719.1875, 202714.9845,
202713.031300001, 202710.6875, 202710.0469, 202711.406300001,
202714.5626, 202716.9845, 202718.718900001, 202719.5469,
202718.734300001, 202716.4531, 202715.125, 202713.7344, 202712.093800001,
202709.8749, 202708.875, 202709.2655, 202710.7031, 202712.375,
202712.375, 202712.2344, 202711.0469, 202707.906300001, 202705.406300001,
202703.0469, 202701.468800001, 202700.7656), .Dim = c(74L,
2L), class = c("XY", "LINESTRING", "sfg")), structure(c(289954.375,
289953.5, 289950.6562, 289949.7499, 289949, 289948.125, 289946.0625,
289945.9688, 289944.5313, 289943.4063, 289941.3438, 289939.4375,
289937.4375, 289935.1875, 289932.75, 289930.625, 289928.8125,
289928.25, 289926.7188, 289925.5313, 289925.7813, 289925.625,
289925.4063, 289925.1251, 289924.625, 202872.75, 202872.031400001,
202868.7031, 202867.343699999, 202864.906199999, 202861.515699999,
202858.297, 202854.406300001, 202851.9375, 202849.468800001,
202847.703, 202846.75, 202845.4531, 202843.6719, 202843.0625,
202841.593900001, 202839.7344, 202839.2344, 202838, 202835.9375,
202832.875, 202825.7344, 202822.9531, 202819.4531, 202817.531300001
), .Dim = c(25L, 2L), class = c("XY", "LINESTRING", "sfg"
)), structure(c(290042.6563, 290042.3437, 290041.5313, 290038.4376,
290037.625, 290036.5313, 290035.5313, 290034.8438, 290034.5313,
290033.7188, 290032.9375, 290032.125, 290030.3437, 290030.0313,
290028.625, 290027.5626, 290027.3438, 290026.7188, 290024.5313,
290023.625, 290020.625, 290018.0001, 290014.9375, 290012.0938,
290008.5625, 290004.375, 290000.0001, 289999.875, 289997.625,
289993.7188, 289990.5, 289987.1562, 289985.4063, 289980.375,
289973.3124, 289966.375, 289961.8438, 289959, 289954.375,
202884.0625, 202884.25, 202884.843800001, 202888.4531, 202889.75,
202891.0469, 202892.0469, 202892.656300001, 202892.843800001,
202893.2501, 202893.5469, 202893.656300001, 202893.4531,
202893.4531, 202893.343699999, 202893.093800001, 202893.0469,
202892.843800001, 202891.953199999, 202891.5469, 202889.843800001,
202888.218800001, 202885.1094, 202880.9219, 202877.5625,
202873.968800001, 202872.5469, 202872.5156, 202872.625, 202874.5469,
202876.734300001, 202878.1719, 202877.953199999, 202876.3125,
202873.468800001, 202872.031400001, 202872.906199999, 202873.0781,
202872.75), .Dim = c(39L, 2L), class = c("XY", "LINESTRING",
"sfg")), structure(c(290054.125, 290053.4375, 290052.5313,
290051.625, 290050.0313, 290048.125, 290044.125, 290040.4376,
290039.4375, 290036.9688, 290031.4375, 290027.5312, 290024.8125,
290021.7499, 290020.9688, 290018.3437, 290015, 290010.25,
290006.0313, 290002.4376, 290000.0001, 289999.2187, 289996.6875,
289995.3438, 289994.125, 289991.1875, 289989.2187, 289987.9688,
289986.125, 289980.5313, 289975.0314, 289970.9063, 289968.5625,
289961.0312, 289948.0001, 289939.625, 289933.1563, 289928.3125,
289926.5313, 289924.625, 202835.953199999, 202835.656300001,
202835.4531, 202835.343699999, 202835.5469, 202835.7656,
202836.25, 202836.4531, 202836.5469, 202836.5469, 202835.953199999,
202836.031400001, 202836.625, 202837.7969, 202838.4844, 202839.343699999,
202836.25, 202832.7656, 202832.3125, 202833.4844, 202834.4844,
202834.8125, 202834.2344, 202832.625, 202830.625, 202828.593800001,
202828.968800001, 202831.0625, 202833.2655, 202835.5781,
202838, 202838.906199999, 202839.125, 202836.4531, 202830.781300001,
202827.093800001, 202823.625, 202818.5, 202817.5625, 202817.531300001
), .Dim = c(40L, 2L), class = c("XY", "LINESTRING", "sfg"
)), structure(c(290042.625, 290042.0313, 290041.2187, 290040.3125,
290038.4063, 290037.7188, 290035.8125, 290033.7188, 290030.9063,
290028.2187, 290021.5313, 290021.2187, 290014.2188, 290013.4063,
290012.3125, 290010.0625, 290007.9375, 290005.9688, 290004.125,
290000.0001, 289999.4063, 289998.3125, 289997.5312, 289996.8438,
289993.625, 289993.0314, 289989.7188, 289989.3438, 289987.625,
289987.2187, 289984.0313, 289978.125, 289977.9375, 289974.3437,
289972.7188, 289970.9375, 289967.9375, 289965.2187, 289965.1563,
289962.3437, 289960.5313, 289959.1251, 289959.0314, 289959.3438,
289959.4375, 289959.4375, 289959.3438, 289959.2187, 289958.9375,
289958.5313, 289956.125, 289954.375, 202953.781300001, 202952.4844,
202951.281300001, 202950.0781, 202948.1875, 202947.5781,
202945.8749, 202944.281300001, 202941.781300001, 202940.1875,
202936.375, 202936.1875, 202931.968800001, 202931.4844, 202930.875,
202929.093800001, 202927.1094, 202925.031300001, 202922.734300001,
202917.2031, 202916.4375, 202915.2031, 202914.5469, 202914.4531,
202911.4531, 202910.843800001, 202908.0469, 202907.75, 202906.75,
202906.5469, 202904.843800001, 202901.843800001, 202901.75,
202900.0469, 202899.156400001, 202898.0469, 202894.656300001,
202892.0469, 202891.9844, 202889.343699999, 202887.656300001,
202885.75, 202884.5469, 202883.343699999, 202882.5469, 202881.343699999,
202880.0469, 202879.343699999, 202877.656300001, 202876.25,
202874.25, 202872.75), .Dim = c(52L, 2L), class = c("XY",
"LINESTRING", "sfg"))), n_empty = 0L, crs = structure(list(
input = "OSGB 1936 / British National Grid", wkt = "PROJCRS[\"OSGB 1936 / British National Grid\",\n BASEGEOGCRS[\"OSGB 1936\",\n DATUM[\"OSGB 1936\",\n ELLIPSOID[\"Airy 1830\",6377563.396,299.3249646,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4277]],\n CONVERSION[\"British National Grid\",\n METHOD[\"Transverse Mercator\",\n ID[\"EPSG\",9807]],\n PARAMETER[\"Latitude of natural origin\",49,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",-2,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"Scale factor at natural origin\",0.9996012717,\n SCALEUNIT[\"unity\",1],\n ID[\"EPSG\",8805]],\n PARAMETER[\"False easting\",400000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",-100000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"unknown\"],\n AREA[\"UK - Britain and UKCS 49°46'N to 61°01'N, 7°33'W to 3°33'E\"],\n BBOX[49.75,-9.2,61.14,2.88]],\n ID[\"EPSG\",27700]]"), class = "crs"), class = c("sfc_LINESTRING",
"sfc"), precision = 0, bbox = structure(c(xmin = 289713.7499,
ymin = 202700.7656, xmax = 290054.125, ymax = 202953.781300001
), class = "bbox"))), row.names = c(NA, -5L), class = c("sf",
"data.frame"), sf_column = "geometry", agr = structure(c(River_ID = NA_integer_), .Label = c("constant",
"aggregate", "identity"), class = "factor"))
pt <- structure(list(lat = c(202805.8942, 202836.136, 202872.9487,
202905.3284), lng = c(289912.0584, 290014.8446, 290001.2364,
289984.9382), id = 1:4, geometry = structure(list(structure(c(289912.058400425,
202805.894199679), class = c("XY", "POINT", "sfg")), structure(c(290014.844597566,
202836.136003318), class = c("XY", "POINT", "sfg")), structure(c(290001.236395958,
202872.948712436), class = c("XY", "POINT", "sfg")), structure(c(289984.938209474,
202905.32838227), class = c("XY", "POINT", "sfg"))), n_empty = 0L, crs = structure(list(
input = "OSGB 1936 / British National Grid", wkt = "PROJCRS[\"OSGB 1936 / British National Grid\",\n BASEGEOGCRS[\"OSGB 1936\",\n DATUM[\"OSGB 1936\",\n ELLIPSOID[\"Airy 1830\",6377563.396,299.3249646,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4277]],\n CONVERSION[\"British National Grid\",\n METHOD[\"Transverse Mercator\",\n ID[\"EPSG\",9807]],\n PARAMETER[\"Latitude of natural origin\",49,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",-2,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"Scale factor at natural origin\",0.9996012717,\n SCALEUNIT[\"unity\",1],\n ID[\"EPSG\",8805]],\n PARAMETER[\"False easting\",400000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",-100000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"unknown\"],\n AREA[\"UK - Britain and UKCS 49°46'N to 61°01'N, 7°33'W to 3°33'E\"],\n BBOX[49.75,-9.2,61.14,2.88]],\n ID[\"EPSG\",27700]]"), class = "crs"), class = c("sfc_POINT",
"sfc"), precision = 0, bbox = structure(c(xmin = 289912.058400425,
ymin = 202805.894199679, xmax = 290014.844597566, ymax = 202905.32838227
), class = "bbox"))), row.names = c(NA, 4L), class = c("sf",
"data.frame"), sf_column = "geometry", agr = structure(c(lat = NA_integer_,
lng = NA_integer_, id = NA_integer_), .Label = c("constant",
"aggregate", "identity"), class = "factor"))
我将提出一个基于名为 sfnetworks 的新 R 包的解决方案。目前，它不在 CRAN 上，但您可以按如下方式安装它：
install.packages("remotes"); library("remotes")
install_github("luukvdmeer/sfnetworks")
最后一步不是很理想，因为它涉及手动操作。它适用于此示例，但要将其推广到更大的网络并不容易。
无论如何，第一步，我加载包和数据。
library(sf)
library(sfnetworks)
library(dplyr)
library(tmap)
ln <- structure(list(River_ID = c(159, 160, 161, 186, 196), geometry = structure(list(
structure(c(
289924.625, 289924.5313, 289922.9688, 289920.0625,
289915.7499, 289912.7188, 289907.4375, 289905.3438, 289901.1251,
289889, 289888.5, 289887.5938, 289886.5, 289886.4063, 289885.3124,
289884.0938, 289884.0001, 289882.8125, 289881.625, 289878.6875,
289877.9688, 289876.25, 289874.5625, 289874.25, 289872.7188,
289871.2813, 289871.1875, 289870.0313, 289869, 289868.5939,
289867.8436, 289865.8438, 289864.0625, 289862.5939, 289862.375,
289861.5, 289860.7812, 289860.5625, 289859.5313, 289858.375,
289857.7813, 289855.4063, 289854.25, 289850.8749, 289846.4376,
289841.9064, 289836.0625, 289828.1562, 289822.8438, 289816.625,
289812.4376, 289807.9064, 289798.75, 289793.125, 289786.2188,
289781.375, 289777.3124, 289770.0313, 289765.4375, 289762.2188,
289759.25, 289755.5938, 289753.0625, 289747.9687, 289743.7499,
289741.5938, 289739.5, 289736.1874, 289732.75, 289727, 289723.7499,
289719.625, 289715.5626, 289713.7499, 202817.531300001, 202817.2031,
202815.1094, 202812.468699999, 202809.3906, 202806.7656,
202799.7969, 202797.906300001, 202794.093800001, 202783.515699999,
202783.125, 202782.4844, 202781.906300001, 202781.8125, 202781.3594,
202781.093800001, 202780.9999, 202780.5469, 202780, 202777.625,
202777.0469, 202775.718800001, 202774.1875, 202773.906300001,
202772.1875, 202770.4531, 202770.25, 202768.5156, 202766.6719,
202766, 202764.0469, 202759.6719, 202755.8749, 202752.781300001,
202752.1875, 202749.953199999, 202748.297, 202747.906300001,
202746.0625, 202744.2344, 202743.5625, 202740.4375, 202738.8125,
202734.5, 202727.9844, 202723.5625, 202719.1875, 202714.9845,
202713.031300001, 202710.6875, 202710.0469, 202711.406300001,
202714.5626, 202716.9845, 202718.718900001, 202719.5469,
202718.734300001, 202716.4531, 202715.125, 202713.7344, 202712.093800001,
202709.8749, 202708.875, 202709.2655, 202710.7031, 202712.375,
202712.375, 202712.2344, 202711.0469, 202707.906300001, 202705.406300001,
202703.0469, 202701.468800001, 202700.7656
), .Dim = c(
74L,
2L
), class = c("XY", "LINESTRING", "sfg")), structure(c(
289954.375,
289953.5, 289950.6562, 289949.7499, 289949, 289948.125, 289946.0625,
289945.9688, 289944.5313, 289943.4063, 289941.3438, 289939.4375,
289937.4375, 289935.1875, 289932.75, 289930.625, 289928.8125,
289928.25, 289926.7188, 289925.5313, 289925.7813, 289925.625,
289925.4063, 289925.1251, 289924.625, 202872.75, 202872.031400001,
202868.7031, 202867.343699999, 202864.906199999, 202861.515699999,
202858.297, 202854.406300001, 202851.9375, 202849.468800001,
202847.703, 202846.75, 202845.4531, 202843.6719, 202843.0625,
202841.593900001, 202839.7344, 202839.2344, 202838, 202835.9375,
202832.875, 202825.7344, 202822.9531, 202819.4531, 202817.531300001
), .Dim = c(25L, 2L), class = c("XY", "LINESTRING", "sfg")), structure(c(
290042.6563, 290042.3437, 290041.5313, 290038.4376,
290037.625, 290036.5313, 290035.5313, 290034.8438, 290034.5313,
290033.7188, 290032.9375, 290032.125, 290030.3437, 290030.0313,
290028.625, 290027.5626, 290027.3438, 290026.7188, 290024.5313,
290023.625, 290020.625, 290018.0001, 290014.9375, 290012.0938,
290008.5625, 290004.375, 290000.0001, 289999.875, 289997.625,
289993.7188, 289990.5, 289987.1562, 289985.4063, 289980.375,
289973.3124, 289966.375, 289961.8438, 289959, 289954.375,
202884.0625, 202884.25, 202884.843800001, 202888.4531, 202889.75,
202891.0469, 202892.0469, 202892.656300001, 202892.843800001,
202893.2501, 202893.5469, 202893.656300001, 202893.4531,
202893.4531, 202893.343699999, 202893.093800001, 202893.0469,
202892.843800001, 202891.953199999, 202891.5469, 202889.843800001,
202888.218800001, 202885.1094, 202880.9219, 202877.5625,
202873.968800001, 202872.5469, 202872.5156, 202872.625, 202874.5469,
202876.734300001, 202878.1719, 202877.953199999, 202876.3125,
202873.468800001, 202872.031400001, 202872.906199999, 202873.0781,
202872.75
), .Dim = c(39L, 2L), class = c(
"XY", "LINESTRING",
"sfg"
)), structure(c(
290054.125, 290053.4375, 290052.5313,
290051.625, 290050.0313, 290048.125, 290044.125, 290040.4376,
290039.4375, 290036.9688, 290031.4375, 290027.5312, 290024.8125,
290021.7499, 290020.9688, 290018.3437, 290015, 290010.25,
290006.0313, 290002.4376, 290000.0001, 289999.2187, 289996.6875,
289995.3438, 289994.125, 289991.1875, 289989.2187, 289987.9688,
289986.125, 289980.5313, 289975.0314, 289970.9063, 289968.5625,
289961.0312, 289948.0001, 289939.625, 289933.1563, 289928.3125,
289926.5313, 289924.625, 202835.953199999, 202835.656300001,
202835.4531, 202835.343699999, 202835.5469, 202835.7656,
202836.25, 202836.4531, 202836.5469, 202836.5469, 202835.953199999,
202836.031400001, 202836.625, 202837.7969, 202838.4844, 202839.343699999,
202836.25, 202832.7656, 202832.3125, 202833.4844, 202834.4844,
202834.8125, 202834.2344, 202832.625, 202830.625, 202828.593800001,
202828.968800001, 202831.0625, 202833.2655, 202835.5781,
202838, 202838.906199999, 202839.125, 202836.4531, 202830.781300001,
202827.093800001, 202823.625, 202818.5, 202817.5625, 202817.531300001
), .Dim = c(40L, 2L), class = c("XY", "LINESTRING", "sfg")), structure(c(
290042.625, 290042.0313, 290041.2187, 290040.3125,
290038.4063, 290037.7188, 290035.8125, 290033.7188, 290030.9063,
290028.2187, 290021.5313, 290021.2187, 290014.2188, 290013.4063,
290012.3125, 290010.0625, 290007.9375, 290005.9688, 290004.125,
290000.0001, 289999.4063, 289998.3125, 289997.5312, 289996.8438,
289993.625, 289993.0314, 289989.7188, 289989.3438, 289987.625,
289987.2187, 289984.0313, 289978.125, 289977.9375, 289974.3437,
289972.7188, 289970.9375, 289967.9375, 289965.2187, 289965.1563,
289962.3437, 289960.5313, 289959.1251, 289959.0314, 289959.3438,
289959.4375, 289959.4375, 289959.3438, 289959.2187, 289958.9375,
289958.5313, 289956.125, 289954.375, 202953.781300001, 202952.4844,
202951.281300001, 202950.0781, 202948.1875, 202947.5781,
202945.8749, 202944.281300001, 202941.781300001, 202940.1875,
202936.375, 202936.1875, 202931.968800001, 202931.4844, 202930.875,
202929.093800001, 202927.1094, 202925.031300001, 202922.734300001,
202917.2031, 202916.4375, 202915.2031, 202914.5469, 202914.4531,
202911.4531, 202910.843800001, 202908.0469, 202907.75, 202906.75,
202906.5469, 202904.843800001, 202901.843800001, 202901.75,
202900.0469, 202899.156400001, 202898.0469, 202894.656300001,
202892.0469, 202891.9844, 202889.343699999, 202887.656300001,
202885.75, 202884.5469, 202883.343699999, 202882.5469, 202881.343699999,
202880.0469, 202879.343699999, 202877.656300001, 202876.25,
202874.25, 202872.75
), .Dim = c(52L, 2L), class = c(
"XY",
"LINESTRING", "sfg"
))
), n_empty = 0L, crs = structure(list(
input = "OSGB 1936 / British National Grid", wkt = "PROJCRS[\"OSGB 1936 / British National Grid\",\n BASEGEOGCRS[\"OSGB 1936\",\n DATUM[\"OSGB 1936\",\n ELLIPSOID[\"Airy 1830\",6377563.396,299.3249646,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4277]],\n CONVERSION[\"British National Grid\",\n METHOD[\"Transverse Mercator\",\n ID[\"EPSG\",9807]],\n PARAMETER[\"Latitude of natural origin\",49,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",-2,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"Scale factor at natural origin\",0.9996012717,\n SCALEUNIT[\"unity\",1],\n ID[\"EPSG\",8805]],\n PARAMETER[\"False easting\",400000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",-100000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"unknown\"],\n AREA[\"UK - Britain and UKCS 49°46'N to 61°01'N, 7°33'W to 3°33'E\"],\n BBOX[49.75,-9.2,61.14,2.88]],\n ID[\"EPSG\",27700]]"
), class = "crs"), class = c(
"sfc_LINESTRING",
"sfc"
), precision = 0, bbox = structure(c(
xmin = 289713.7499,
ymin = 202700.7656, xmax = 290054.125, ymax = 202953.781300001
), class = "bbox"))), row.names = c(NA, -5L), class = c(
"sf",
"data.frame"
), sf_column = "geometry", agr = structure(c(River_ID = NA_integer_), .Label = c(
"constant",
"aggregate", "identity"
), class = "factor"))
pt <- structure(list(lat = c(
202805.8942, 202836.136, 202872.9487,
202905.3284
), lng = c(
289912.0584, 290014.8446, 290001.2364,
289984.9382
), id = 1:4, geometry = structure(list(structure(c(
289912.058400425,
202805.894199679
), class = c("XY", "POINT", "sfg")), structure(c(
290014.844597566,
202836.136003318
), class = c("XY", "POINT", "sfg")), structure(c(
290001.236395958,
202872.948712436
), class = c("XY", "POINT", "sfg")), structure(c(
289984.938209474,
202905.32838227
), class = c("XY", "POINT", "sfg"))), n_empty = 0L, crs = structure(list(
input = "OSGB 1936 / British National Grid", wkt = "PROJCRS[\"OSGB 1936 / British National Grid\",\n BASEGEOGCRS[\"OSGB 1936\",\n DATUM[\"OSGB 1936\",\n ELLIPSOID[\"Airy 1830\",6377563.396,299.3249646,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4277]],\n CONVERSION[\"British National Grid\",\n METHOD[\"Transverse Mercator\",\n ID[\"EPSG\",9807]],\n PARAMETER[\"Latitude of natural origin\",49,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",-2,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"Scale factor at natural origin\",0.9996012717,\n SCALEUNIT[\"unity\",1],\n ID[\"EPSG\",8805]],\n PARAMETER[\"False easting\",400000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",-100000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"unknown\"],\n AREA[\"UK - Britain and UKCS 49°46'N to 61°01'N, 7°33'W to 3°33'E\"],\n BBOX[49.75,-9.2,61.14,2.88]],\n ID[\"EPSG\",27700]]"
), class = "crs"), class = c(
"sfc_POINT",
"sfc"
), precision = 0, bbox = structure(c(
xmin = 289912.058400425,
ymin = 202805.894199679, xmax = 290014.844597566, ymax = 202905.32838227
), class = "bbox"))), row.names = c(NA, 4L), class = c(
"sf",
"data.frame"
), sf_column = "geometry", agr = structure(c(
lat = NA_integer_,
lng = NA_integer_,
id = NA_integer_
), .Label = c(
"constant",
"aggregate", "identity"
), class = "factor"))
然后，我需要从 ln 对象开始构建一个 sfnetwork 结构。我需要一个 sfnetwork 对象用于后续步骤（特别是 st_network_blend() 函数）
ln_sfnetwork <- as_sfnetwork(ln)
这是结果
ln_sfnetwork
#> # A sfnetwork with 6 nodes and 5 edges
#> #
#> # CRS: OSGB 1936 / British National Grid
#> #
#> # A rooted tree with spatially explicit edges
#> #
#> # Node Data: 6 x 1 (active)
#> # Geometry type: POINT
#> # Dimension: XY
#> # Bounding box: xmin: 289713.7 ymin: 202700.8 xmax: 290054.1 ymax: 202953.8
#> geometry
#> <POINT [m]>
#> 1 (289924.6 202817.5)
#> 2 (289713.7 202700.8)
#> 3 (289954.4 202872.8)
#> 4 (290042.7 202884.1)
#> 5 (290054.1 202836)
#> 6 (290042.6 202953.8)
#> #
#> # Edge Data: 5 x 4
#> # Geometry type: LINESTRING
#> # Dimension: XY
#> # Bounding box: xmin: 289713.7 ymin: 202700.8 xmax: 290054.1 ymax: 202953.8
#> from to River_ID geometry
#> <int> <int> <dbl> <LINESTRING [m]>
#> 1 1 2 159 (289924.6 202817.5, 289924.5 202817.2, 289923 202815.1, ~
#> 2 3 1 160 (289954.4 202872.8, 289953.5 202872, 289950.7 202868.7, ~
#> 3 4 3 161 (290042.7 202884.1, 290042.3 202884.2, 290041.5 202884.8~
#> # ... with 2 more rows
这是图形输出
par(mar = rep(0.1, 4))
plot(ln_sfnetwork)
下一步是从 pt 对象中的点开始，将几个新节点定义到网络结构中。这个过程可以使用函数st_network_blend()来完成。有关详细信息，请参阅 here：
ln_sfnetwork <- st_network_blend(ln_sfnetwork, st_geometry(pt))
#> Warning: st_network_blend assumes attributes are constant over geometries
这是图形输出，您可以看到新节点
par(mar = rep(0.1, 4))
plot(ln_sfnetwork)
现在我可以为每条边定义一个唯一的 ID 并恢复 LINESTRING 结构
ln_sf <- ln_sfnetwork %>%
activate("edges") %>%
mutate(new_river_id = as.character(1:n())) %>%
st_as_sf()
同样，这是图形输出
tm_shape(ln_sf) +
tm_lines(col = "new_river_id", lwd = 3)
我看到你要合并ID 1,3,7,5,9，所以我会修改ID
ln_sf[["new_river_id"]][2] <- "1"
ln_sf[["new_river_id"]][c(1, 3, 7, 5, 9)] <- "2"
ln_sf[["new_river_id"]][6] <- "3"
ln_sf[["new_river_id"]][4] <- "4"
ln_sf[["new_river_id"]][8] <- "5"
最后，我可以将 LINESTRING(s) 合并到同一组中
ln_sf_merged <- ln_sf %>%
group_by(new_river_id) %>%
summarise()
#> `summarise()` ungrouping output (override with `.groups` argument)
这是结果
ln_sf_merged
#> Simple feature collection with 5 features and 1 field
#> geometry type: GEOMETRY
#> dimension: XY
#> bbox: xmin: 289713.7 ymin: 202700.8 xmax: 290054.1 ymax: 202953.8
#> projected CRS: OSGB 1936 / British National Grid
#> # A tibble: 5 x 2
#> new_river_id geometry
#> <chr> <GEOMETRY [m]>
#> 1 1 LINESTRING (289912.1 202805.9, 289907.4 202799.8, 289905.3 20279~
#> 2 2 MULTILINESTRING ((289924.6 202817.5, 289924.5 202817.2, 289923 2~
#> 3 3 LINESTRING (290054.1 202836, 290053.4 202835.7, 290052.5 202835.~
#> 4 4 LINESTRING (290042.7 202884.1, 290042.3 202884.2, 290041.5 20288~
#> 5 5 LINESTRING (290042.6 202953.8, 290042 202952.5, 290041.2 202951.~
这是图形输出
tm_shape(ln_sf_merged) +
tm_lines(col = "new_river_id", lwd = 3)
由 reprex package (v0.3.0)
于 2021 年 1 月 18 日创建
正如我提到的，最后一步对于较大的网络可能会有问题，但这取决于您的用例。如果您想阅读有关 sfnetworks 的更多详细信息，请查看 website and the vignettes.
我正在尝试使用水坝（点）将河流（线）分割成水坝之间的连接段。
答案 st_split 使用多边形边界作为 'blade' 从而将一条线分成三条而不是两条。我还想为每个点之间的线段分配一个公共 ID。
期望的输出
这是我试过的方法。对于这个例子，结果应该有 9 个特征。
library(tidyverse)
library(sf)
library(lwgeom)
buf_all <- st_buffer(pt, 0.001)
parts <- st_collection_extract(lwgeom::st_split(ln$geometry, buf_all), "LINESTRING")
parts_all <- st_as_sf(
data.frame(
id = 1:length(parts),
geometry = parts
)
)
但结果并不如预期。
>nrow(parts_all)
[1] 13 2
数据
ln <- structure(list(River_ID = c(159, 160, 161, 186, 196), geometry = structure(list(
structure(c(289924.625, 289924.5313, 289922.9688, 289920.0625,
289915.7499, 289912.7188, 289907.4375, 289905.3438, 289901.1251,
289889, 289888.5, 289887.5938, 289886.5, 289886.4063, 289885.3124,
289884.0938, 289884.0001, 289882.8125, 289881.625, 289878.6875,
289877.9688, 289876.25, 289874.5625, 289874.25, 289872.7188,
289871.2813, 289871.1875, 289870.0313, 289869, 289868.5939,
289867.8436, 289865.8438, 289864.0625, 289862.5939, 289862.375,
289861.5, 289860.7812, 289860.5625, 289859.5313, 289858.375,
289857.7813, 289855.4063, 289854.25, 289850.8749, 289846.4376,
289841.9064, 289836.0625, 289828.1562, 289822.8438, 289816.625,
289812.4376, 289807.9064, 289798.75, 289793.125, 289786.2188,
289781.375, 289777.3124, 289770.0313, 289765.4375, 289762.2188,
289759.25, 289755.5938, 289753.0625, 289747.9687, 289743.7499,
289741.5938, 289739.5, 289736.1874, 289732.75, 289727, 289723.7499,
289719.625, 289715.5626, 289713.7499, 202817.531300001, 202817.2031,
202815.1094, 202812.468699999, 202809.3906, 202806.7656,
202799.7969, 202797.906300001, 202794.093800001, 202783.515699999,
202783.125, 202782.4844, 202781.906300001, 202781.8125, 202781.3594,
202781.093800001, 202780.9999, 202780.5469, 202780, 202777.625,
202777.0469, 202775.718800001, 202774.1875, 202773.906300001,
202772.1875, 202770.4531, 202770.25, 202768.5156, 202766.6719,
202766, 202764.0469, 202759.6719, 202755.8749, 202752.781300001,
202752.1875, 202749.953199999, 202748.297, 202747.906300001,
202746.0625, 202744.2344, 202743.5625, 202740.4375, 202738.8125,
202734.5, 202727.9844, 202723.5625, 202719.1875, 202714.9845,
202713.031300001, 202710.6875, 202710.0469, 202711.406300001,
202714.5626, 202716.9845, 202718.718900001, 202719.5469,
202718.734300001, 202716.4531, 202715.125, 202713.7344, 202712.093800001,
202709.8749, 202708.875, 202709.2655, 202710.7031, 202712.375,
202712.375, 202712.2344, 202711.0469, 202707.906300001, 202705.406300001,
202703.0469, 202701.468800001, 202700.7656), .Dim = c(74L,
2L), class = c("XY", "LINESTRING", "sfg")), structure(c(289954.375,
289953.5, 289950.6562, 289949.7499, 289949, 289948.125, 289946.0625,
289945.9688, 289944.5313, 289943.4063, 289941.3438, 289939.4375,
289937.4375, 289935.1875, 289932.75, 289930.625, 289928.8125,
289928.25, 289926.7188, 289925.5313, 289925.7813, 289925.625,
289925.4063, 289925.1251, 289924.625, 202872.75, 202872.031400001,
202868.7031, 202867.343699999, 202864.906199999, 202861.515699999,
202858.297, 202854.406300001, 202851.9375, 202849.468800001,
202847.703, 202846.75, 202845.4531, 202843.6719, 202843.0625,
202841.593900001, 202839.7344, 202839.2344, 202838, 202835.9375,
202832.875, 202825.7344, 202822.9531, 202819.4531, 202817.531300001
), .Dim = c(25L, 2L), class = c("XY", "LINESTRING", "sfg"
)), structure(c(290042.6563, 290042.3437, 290041.5313, 290038.4376,
290037.625, 290036.5313, 290035.5313, 290034.8438, 290034.5313,
290033.7188, 290032.9375, 290032.125, 290030.3437, 290030.0313,
290028.625, 290027.5626, 290027.3438, 290026.7188, 290024.5313,
290023.625, 290020.625, 290018.0001, 290014.9375, 290012.0938,
290008.5625, 290004.375, 290000.0001, 289999.875, 289997.625,
289993.7188, 289990.5, 289987.1562, 289985.4063, 289980.375,
289973.3124, 289966.375, 289961.8438, 289959, 289954.375,
202884.0625, 202884.25, 202884.843800001, 202888.4531, 202889.75,
202891.0469, 202892.0469, 202892.656300001, 202892.843800001,
202893.2501, 202893.5469, 202893.656300001, 202893.4531,
202893.4531, 202893.343699999, 202893.093800001, 202893.0469,
202892.843800001, 202891.953199999, 202891.5469, 202889.843800001,
202888.218800001, 202885.1094, 202880.9219, 202877.5625,
202873.968800001, 202872.5469, 202872.5156, 202872.625, 202874.5469,
202876.734300001, 202878.1719, 202877.953199999, 202876.3125,
202873.468800001, 202872.031400001, 202872.906199999, 202873.0781,
202872.75), .Dim = c(39L, 2L), class = c("XY", "LINESTRING",
"sfg")), structure(c(290054.125, 290053.4375, 290052.5313,
290051.625, 290050.0313, 290048.125, 290044.125, 290040.4376,
290039.4375, 290036.9688, 290031.4375, 290027.5312, 290024.8125,
290021.7499, 290020.9688, 290018.3437, 290015, 290010.25,
290006.0313, 290002.4376, 290000.0001, 289999.2187, 289996.6875,
289995.3438, 289994.125, 289991.1875, 289989.2187, 289987.9688,
289986.125, 289980.5313, 289975.0314, 289970.9063, 289968.5625,
289961.0312, 289948.0001, 289939.625, 289933.1563, 289928.3125,
289926.5313, 289924.625, 202835.953199999, 202835.656300001,
202835.4531, 202835.343699999, 202835.5469, 202835.7656,
202836.25, 202836.4531, 202836.5469, 202836.5469, 202835.953199999,
202836.031400001, 202836.625, 202837.7969, 202838.4844, 202839.343699999,
202836.25, 202832.7656, 202832.3125, 202833.4844, 202834.4844,
202834.8125, 202834.2344, 202832.625, 202830.625, 202828.593800001,
202828.968800001, 202831.0625, 202833.2655, 202835.5781,
202838, 202838.906199999, 202839.125, 202836.4531, 202830.781300001,
202827.093800001, 202823.625, 202818.5, 202817.5625, 202817.531300001
), .Dim = c(40L, 2L), class = c("XY", "LINESTRING", "sfg"
)), structure(c(290042.625, 290042.0313, 290041.2187, 290040.3125,
290038.4063, 290037.7188, 290035.8125, 290033.7188, 290030.9063,
290028.2187, 290021.5313, 290021.2187, 290014.2188, 290013.4063,
290012.3125, 290010.0625, 290007.9375, 290005.9688, 290004.125,
290000.0001, 289999.4063, 289998.3125, 289997.5312, 289996.8438,
289993.625, 289993.0314, 289989.7188, 289989.3438, 289987.625,
289987.2187, 289984.0313, 289978.125, 289977.9375, 289974.3437,
289972.7188, 289970.9375, 289967.9375, 289965.2187, 289965.1563,
289962.3437, 289960.5313, 289959.1251, 289959.0314, 289959.3438,
289959.4375, 289959.4375, 289959.3438, 289959.2187, 289958.9375,
289958.5313, 289956.125, 289954.375, 202953.781300001, 202952.4844,
202951.281300001, 202950.0781, 202948.1875, 202947.5781,
202945.8749, 202944.281300001, 202941.781300001, 202940.1875,
202936.375, 202936.1875, 202931.968800001, 202931.4844, 202930.875,
202929.093800001, 202927.1094, 202925.031300001, 202922.734300001,
202917.2031, 202916.4375, 202915.2031, 202914.5469, 202914.4531,
202911.4531, 202910.843800001, 202908.0469, 202907.75, 202906.75,
202906.5469, 202904.843800001, 202901.843800001, 202901.75,
202900.0469, 202899.156400001, 202898.0469, 202894.656300001,
202892.0469, 202891.9844, 202889.343699999, 202887.656300001,
202885.75, 202884.5469, 202883.343699999, 202882.5469, 202881.343699999,
202880.0469, 202879.343699999, 202877.656300001, 202876.25,
202874.25, 202872.75), .Dim = c(52L, 2L), class = c("XY",
"LINESTRING", "sfg"))), n_empty = 0L, crs = structure(list(
input = "OSGB 1936 / British National Grid", wkt = "PROJCRS[\"OSGB 1936 / British National Grid\",\n BASEGEOGCRS[\"OSGB 1936\",\n DATUM[\"OSGB 1936\",\n ELLIPSOID[\"Airy 1830\",6377563.396,299.3249646,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4277]],\n CONVERSION[\"British National Grid\",\n METHOD[\"Transverse Mercator\",\n ID[\"EPSG\",9807]],\n PARAMETER[\"Latitude of natural origin\",49,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",-2,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"Scale factor at natural origin\",0.9996012717,\n SCALEUNIT[\"unity\",1],\n ID[\"EPSG\",8805]],\n PARAMETER[\"False easting\",400000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",-100000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"unknown\"],\n AREA[\"UK - Britain and UKCS 49°46'N to 61°01'N, 7°33'W to 3°33'E\"],\n BBOX[49.75,-9.2,61.14,2.88]],\n ID[\"EPSG\",27700]]"), class = "crs"), class = c("sfc_LINESTRING",
"sfc"), precision = 0, bbox = structure(c(xmin = 289713.7499,
ymin = 202700.7656, xmax = 290054.125, ymax = 202953.781300001
), class = "bbox"))), row.names = c(NA, -5L), class = c("sf",
"data.frame"), sf_column = "geometry", agr = structure(c(River_ID = NA_integer_), .Label = c("constant",
"aggregate", "identity"), class = "factor"))
pt <- structure(list(lat = c(202805.8942, 202836.136, 202872.9487,
202905.3284), lng = c(289912.0584, 290014.8446, 290001.2364,
289984.9382), id = 1:4, geometry = structure(list(structure(c(289912.058400425,
202805.894199679), class = c("XY", "POINT", "sfg")), structure(c(290014.844597566,
202836.136003318), class = c("XY", "POINT", "sfg")), structure(c(290001.236395958,
202872.948712436), class = c("XY", "POINT", "sfg")), structure(c(289984.938209474,
202905.32838227), class = c("XY", "POINT", "sfg"))), n_empty = 0L, crs = structure(list(
input = "OSGB 1936 / British National Grid", wkt = "PROJCRS[\"OSGB 1936 / British National Grid\",\n BASEGEOGCRS[\"OSGB 1936\",\n DATUM[\"OSGB 1936\",\n ELLIPSOID[\"Airy 1830\",6377563.396,299.3249646,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4277]],\n CONVERSION[\"British National Grid\",\n METHOD[\"Transverse Mercator\",\n ID[\"EPSG\",9807]],\n PARAMETER[\"Latitude of natural origin\",49,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",-2,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"Scale factor at natural origin\",0.9996012717,\n SCALEUNIT[\"unity\",1],\n ID[\"EPSG\",8805]],\n PARAMETER[\"False easting\",400000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",-100000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"unknown\"],\n AREA[\"UK - Britain and UKCS 49°46'N to 61°01'N, 7°33'W to 3°33'E\"],\n BBOX[49.75,-9.2,61.14,2.88]],\n ID[\"EPSG\",27700]]"), class = "crs"), class = c("sfc_POINT",
"sfc"), precision = 0, bbox = structure(c(xmin = 289912.058400425,
ymin = 202805.894199679, xmax = 290014.844597566, ymax = 202905.32838227
), class = "bbox"))), row.names = c(NA, 4L), class = c("sf",
"data.frame"), sf_column = "geometry", agr = structure(c(lat = NA_integer_,
lng = NA_integer_, id = NA_integer_), .Label = c("constant",
"aggregate", "identity"), class = "factor"))
我将提出一个基于名为 sfnetworks 的新 R 包的解决方案。目前，它不在 CRAN 上，但您可以按如下方式安装它：
install.packages("remotes"); library("remotes")
install_github("luukvdmeer/sfnetworks")
最后一步不是很理想，因为它涉及手动操作。它适用于此示例，但要将其推广到更大的网络并不容易。
无论如何，第一步，我加载包和数据。
library(sf)
library(sfnetworks)
library(dplyr)
library(tmap)
ln <- structure(list(River_ID = c(159, 160, 161, 186, 196), geometry = structure(list(
structure(c(
289924.625, 289924.5313, 289922.9688, 289920.0625,
289915.7499, 289912.7188, 289907.4375, 289905.3438, 289901.1251,
289889, 289888.5, 289887.5938, 289886.5, 289886.4063, 289885.3124,
289884.0938, 289884.0001, 289882.8125, 289881.625, 289878.6875,
289877.9688, 289876.25, 289874.5625, 289874.25, 289872.7188,
289871.2813, 289871.1875, 289870.0313, 289869, 289868.5939,
289867.8436, 289865.8438, 289864.0625, 289862.5939, 289862.375,
289861.5, 289860.7812, 289860.5625, 289859.5313, 289858.375,
289857.7813, 289855.4063, 289854.25, 289850.8749, 289846.4376,
289841.9064, 289836.0625, 289828.1562, 289822.8438, 289816.625,
289812.4376, 289807.9064, 289798.75, 289793.125, 289786.2188,
289781.375, 289777.3124, 289770.0313, 289765.4375, 289762.2188,
289759.25, 289755.5938, 289753.0625, 289747.9687, 289743.7499,
289741.5938, 289739.5, 289736.1874, 289732.75, 289727, 289723.7499,
289719.625, 289715.5626, 289713.7499, 202817.531300001, 202817.2031,
202815.1094, 202812.468699999, 202809.3906, 202806.7656,
202799.7969, 202797.906300001, 202794.093800001, 202783.515699999,
202783.125, 202782.4844, 202781.906300001, 202781.8125, 202781.3594,
202781.093800001, 202780.9999, 202780.5469, 202780, 202777.625,
202777.0469, 202775.718800001, 202774.1875, 202773.906300001,
202772.1875, 202770.4531, 202770.25, 202768.5156, 202766.6719,
202766, 202764.0469, 202759.6719, 202755.8749, 202752.781300001,
202752.1875, 202749.953199999, 202748.297, 202747.906300001,
202746.0625, 202744.2344, 202743.5625, 202740.4375, 202738.8125,
202734.5, 202727.9844, 202723.5625, 202719.1875, 202714.9845,
202713.031300001, 202710.6875, 202710.0469, 202711.406300001,
202714.5626, 202716.9845, 202718.718900001, 202719.5469,
202718.734300001, 202716.4531, 202715.125, 202713.7344, 202712.093800001,
202709.8749, 202708.875, 202709.2655, 202710.7031, 202712.375,
202712.375, 202712.2344, 202711.0469, 202707.906300001, 202705.406300001,
202703.0469, 202701.468800001, 202700.7656
), .Dim = c(
74L,
2L
), class = c("XY", "LINESTRING", "sfg")), structure(c(
289954.375,
289953.5, 289950.6562, 289949.7499, 289949, 289948.125, 289946.0625,
289945.9688, 289944.5313, 289943.4063, 289941.3438, 289939.4375,
289937.4375, 289935.1875, 289932.75, 289930.625, 289928.8125,
289928.25, 289926.7188, 289925.5313, 289925.7813, 289925.625,
289925.4063, 289925.1251, 289924.625, 202872.75, 202872.031400001,
202868.7031, 202867.343699999, 202864.906199999, 202861.515699999,
202858.297, 202854.406300001, 202851.9375, 202849.468800001,
202847.703, 202846.75, 202845.4531, 202843.6719, 202843.0625,
202841.593900001, 202839.7344, 202839.2344, 202838, 202835.9375,
202832.875, 202825.7344, 202822.9531, 202819.4531, 202817.531300001
), .Dim = c(25L, 2L), class = c("XY", "LINESTRING", "sfg")), structure(c(
290042.6563, 290042.3437, 290041.5313, 290038.4376,
290037.625, 290036.5313, 290035.5313, 290034.8438, 290034.5313,
290033.7188, 290032.9375, 290032.125, 290030.3437, 290030.0313,
290028.625, 290027.5626, 290027.3438, 290026.7188, 290024.5313,
290023.625, 290020.625, 290018.0001, 290014.9375, 290012.0938,
290008.5625, 290004.375, 290000.0001, 289999.875, 289997.625,
289993.7188, 289990.5, 289987.1562, 289985.4063, 289980.375,
289973.3124, 289966.375, 289961.8438, 289959, 289954.375,
202884.0625, 202884.25, 202884.843800001, 202888.4531, 202889.75,
202891.0469, 202892.0469, 202892.656300001, 202892.843800001,
202893.2501, 202893.5469, 202893.656300001, 202893.4531,
202893.4531, 202893.343699999, 202893.093800001, 202893.0469,
202892.843800001, 202891.953199999, 202891.5469, 202889.843800001,
202888.218800001, 202885.1094, 202880.9219, 202877.5625,
202873.968800001, 202872.5469, 202872.5156, 202872.625, 202874.5469,
202876.734300001, 202878.1719, 202877.953199999, 202876.3125,
202873.468800001, 202872.031400001, 202872.906199999, 202873.0781,
202872.75
), .Dim = c(39L, 2L), class = c(
"XY", "LINESTRING",
"sfg"
)), structure(c(
290054.125, 290053.4375, 290052.5313,
290051.625, 290050.0313, 290048.125, 290044.125, 290040.4376,
290039.4375, 290036.9688, 290031.4375, 290027.5312, 290024.8125,
290021.7499, 290020.9688, 290018.3437, 290015, 290010.25,
290006.0313, 290002.4376, 290000.0001, 289999.2187, 289996.6875,
289995.3438, 289994.125, 289991.1875, 289989.2187, 289987.9688,
289986.125, 289980.5313, 289975.0314, 289970.9063, 289968.5625,
289961.0312, 289948.0001, 289939.625, 289933.1563, 289928.3125,
289926.5313, 289924.625, 202835.953199999, 202835.656300001,
202835.4531, 202835.343699999, 202835.5469, 202835.7656,
202836.25, 202836.4531, 202836.5469, 202836.5469, 202835.953199999,
202836.031400001, 202836.625, 202837.7969, 202838.4844, 202839.343699999,
202836.25, 202832.7656, 202832.3125, 202833.4844, 202834.4844,
202834.8125, 202834.2344, 202832.625, 202830.625, 202828.593800001,
202828.968800001, 202831.0625, 202833.2655, 202835.5781,
202838, 202838.906199999, 202839.125, 202836.4531, 202830.781300001,
202827.093800001, 202823.625, 202818.5, 202817.5625, 202817.531300001
), .Dim = c(40L, 2L), class = c("XY", "LINESTRING", "sfg")), structure(c(
290042.625, 290042.0313, 290041.2187, 290040.3125,
290038.4063, 290037.7188, 290035.8125, 290033.7188, 290030.9063,
290028.2187, 290021.5313, 290021.2187, 290014.2188, 290013.4063,
290012.3125, 290010.0625, 290007.9375, 290005.9688, 290004.125,
290000.0001, 289999.4063, 289998.3125, 289997.5312, 289996.8438,
289993.625, 289993.0314, 289989.7188, 289989.3438, 289987.625,
289987.2187, 289984.0313, 289978.125, 289977.9375, 289974.3437,
289972.7188, 289970.9375, 289967.9375, 289965.2187, 289965.1563,
289962.3437, 289960.5313, 289959.1251, 289959.0314, 289959.3438,
289959.4375, 289959.4375, 289959.3438, 289959.2187, 289958.9375,
289958.5313, 289956.125, 289954.375, 202953.781300001, 202952.4844,
202951.281300001, 202950.0781, 202948.1875, 202947.5781,
202945.8749, 202944.281300001, 202941.781300001, 202940.1875,
202936.375, 202936.1875, 202931.968800001, 202931.4844, 202930.875,
202929.093800001, 202927.1094, 202925.031300001, 202922.734300001,
202917.2031, 202916.4375, 202915.2031, 202914.5469, 202914.4531,
202911.4531, 202910.843800001, 202908.0469, 202907.75, 202906.75,
202906.5469, 202904.843800001, 202901.843800001, 202901.75,
202900.0469, 202899.156400001, 202898.0469, 202894.656300001,
202892.0469, 202891.9844, 202889.343699999, 202887.656300001,
202885.75, 202884.5469, 202883.343699999, 202882.5469, 202881.343699999,
202880.0469, 202879.343699999, 202877.656300001, 202876.25,
202874.25, 202872.75
), .Dim = c(52L, 2L), class = c(
"XY",
"LINESTRING", "sfg"
))
), n_empty = 0L, crs = structure(list(
input = "OSGB 1936 / British National Grid", wkt = "PROJCRS[\"OSGB 1936 / British National Grid\",\n BASEGEOGCRS[\"OSGB 1936\",\n DATUM[\"OSGB 1936\",\n ELLIPSOID[\"Airy 1830\",6377563.396,299.3249646,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4277]],\n CONVERSION[\"British National Grid\",\n METHOD[\"Transverse Mercator\",\n ID[\"EPSG\",9807]],\n PARAMETER[\"Latitude of natural origin\",49,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",-2,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"Scale factor at natural origin\",0.9996012717,\n SCALEUNIT[\"unity\",1],\n ID[\"EPSG\",8805]],\n PARAMETER[\"False easting\",400000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",-100000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"unknown\"],\n AREA[\"UK - Britain and UKCS 49°46'N to 61°01'N, 7°33'W to 3°33'E\"],\n BBOX[49.75,-9.2,61.14,2.88]],\n ID[\"EPSG\",27700]]"
), class = "crs"), class = c(
"sfc_LINESTRING",
"sfc"
), precision = 0, bbox = structure(c(
xmin = 289713.7499,
ymin = 202700.7656, xmax = 290054.125, ymax = 202953.781300001
), class = "bbox"))), row.names = c(NA, -5L), class = c(
"sf",
"data.frame"
), sf_column = "geometry", agr = structure(c(River_ID = NA_integer_), .Label = c(
"constant",
"aggregate", "identity"
), class = "factor"))
pt <- structure(list(lat = c(
202805.8942, 202836.136, 202872.9487,
202905.3284
), lng = c(
289912.0584, 290014.8446, 290001.2364,
289984.9382
), id = 1:4, geometry = structure(list(structure(c(
289912.058400425,
202805.894199679
), class = c("XY", "POINT", "sfg")), structure(c(
290014.844597566,
202836.136003318
), class = c("XY", "POINT", "sfg")), structure(c(
290001.236395958,
202872.948712436
), class = c("XY", "POINT", "sfg")), structure(c(
289984.938209474,
202905.32838227
), class = c("XY", "POINT", "sfg"))), n_empty = 0L, crs = structure(list(
input = "OSGB 1936 / British National Grid", wkt = "PROJCRS[\"OSGB 1936 / British National Grid\",\n BASEGEOGCRS[\"OSGB 1936\",\n DATUM[\"OSGB 1936\",\n ELLIPSOID[\"Airy 1830\",6377563.396,299.3249646,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4277]],\n CONVERSION[\"British National Grid\",\n METHOD[\"Transverse Mercator\",\n ID[\"EPSG\",9807]],\n PARAMETER[\"Latitude of natural origin\",49,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",-2,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"Scale factor at natural origin\",0.9996012717,\n SCALEUNIT[\"unity\",1],\n ID[\"EPSG\",8805]],\n PARAMETER[\"False easting\",400000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",-100000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"unknown\"],\n AREA[\"UK - Britain and UKCS 49°46'N to 61°01'N, 7°33'W to 3°33'E\"],\n BBOX[49.75,-9.2,61.14,2.88]],\n ID[\"EPSG\",27700]]"
), class = "crs"), class = c(
"sfc_POINT",
"sfc"
), precision = 0, bbox = structure(c(
xmin = 289912.058400425,
ymin = 202805.894199679, xmax = 290014.844597566, ymax = 202905.32838227
), class = "bbox"))), row.names = c(NA, 4L), class = c(
"sf",
"data.frame"
), sf_column = "geometry", agr = structure(c(
lat = NA_integer_,
lng = NA_integer_,
id = NA_integer_
), .Label = c(
"constant",
"aggregate", "identity"
), class = "factor"))
然后，我需要从 ln 对象开始构建一个 sfnetwork 结构。我需要一个 sfnetwork 对象用于后续步骤（特别是 st_network_blend() 函数）
ln_sfnetwork <- as_sfnetwork(ln)
这是结果
ln_sfnetwork
#> # A sfnetwork with 6 nodes and 5 edges
#> #
#> # CRS: OSGB 1936 / British National Grid
#> #
#> # A rooted tree with spatially explicit edges
#> #
#> # Node Data: 6 x 1 (active)
#> # Geometry type: POINT
#> # Dimension: XY
#> # Bounding box: xmin: 289713.7 ymin: 202700.8 xmax: 290054.1 ymax: 202953.8
#> geometry
#> <POINT [m]>
#> 1 (289924.6 202817.5)
#> 2 (289713.7 202700.8)
#> 3 (289954.4 202872.8)
#> 4 (290042.7 202884.1)
#> 5 (290054.1 202836)
#> 6 (290042.6 202953.8)
#> #
#> # Edge Data: 5 x 4
#> # Geometry type: LINESTRING
#> # Dimension: XY
#> # Bounding box: xmin: 289713.7 ymin: 202700.8 xmax: 290054.1 ymax: 202953.8
#> from to River_ID geometry
#> <int> <int> <dbl> <LINESTRING [m]>
#> 1 1 2 159 (289924.6 202817.5, 289924.5 202817.2, 289923 202815.1, ~
#> 2 3 1 160 (289954.4 202872.8, 289953.5 202872, 289950.7 202868.7, ~
#> 3 4 3 161 (290042.7 202884.1, 290042.3 202884.2, 290041.5 202884.8~
#> # ... with 2 more rows
这是图形输出
par(mar = rep(0.1, 4))
plot(ln_sfnetwork)
下一步是从 pt 对象中的点开始，将几个新节点定义到网络结构中。这个过程可以使用函数st_network_blend()来完成。有关详细信息，请参阅 here：
ln_sfnetwork <- st_network_blend(ln_sfnetwork, st_geometry(pt))
#> Warning: st_network_blend assumes attributes are constant over geometries
这是图形输出，您可以看到新节点
par(mar = rep(0.1, 4))
plot(ln_sfnetwork)
现在我可以为每条边定义一个唯一的 ID 并恢复 LINESTRING 结构
ln_sf <- ln_sfnetwork %>%
activate("edges") %>%
mutate(new_river_id = as.character(1:n())) %>%
st_as_sf()
同样，这是图形输出
tm_shape(ln_sf) +
tm_lines(col = "new_river_id", lwd = 3)
我看到你要合并ID 1,3,7,5,9，所以我会修改ID
ln_sf[["new_river_id"]][2] <- "1"
ln_sf[["new_river_id"]][c(1, 3, 7, 5, 9)] <- "2"
ln_sf[["new_river_id"]][6] <- "3"
ln_sf[["new_river_id"]][4] <- "4"
ln_sf[["new_river_id"]][8] <- "5"
最后，我可以将 LINESTRING(s) 合并到同一组中
ln_sf_merged <- ln_sf %>%
group_by(new_river_id) %>%
summarise()
#> `summarise()` ungrouping output (override with `.groups` argument)
这是结果
ln_sf_merged
#> Simple feature collection with 5 features and 1 field
#> geometry type: GEOMETRY
#> dimension: XY
#> bbox: xmin: 289713.7 ymin: 202700.8 xmax: 290054.1 ymax: 202953.8
#> projected CRS: OSGB 1936 / British National Grid
#> # A tibble: 5 x 2
#> new_river_id geometry
#> <chr> <GEOMETRY [m]>
#> 1 1 LINESTRING (289912.1 202805.9, 289907.4 202799.8, 289905.3 20279~
#> 2 2 MULTILINESTRING ((289924.6 202817.5, 289924.5 202817.2, 289923 2~
#> 3 3 LINESTRING (290054.1 202836, 290053.4 202835.7, 290052.5 202835.~
#> 4 4 LINESTRING (290042.7 202884.1, 290042.3 202884.2, 290041.5 20288~
#> 5 5 LINESTRING (290042.6 202953.8, 290042 202952.5, 290041.2 202951.~
这是图形输出
tm_shape(ln_sf_merged) +
tm_lines(col = "new_river_id", lwd = 3)
由 reprex package (v0.3.0)
于 2021 年 1 月 18 日创建正如我提到的，最后一步对于较大的网络可能会有问题，但这取决于您的用例。如果您想阅读有关 sfnetworks 的更多详细信息，请查看 website and the vignettes.