如何找出哪些管道朝向错误的方向
How to find out which pipes are facing wrong direction
我正在尝试计算区域供暖系统。我从 shapefile 中获取信息——对于管道，我有一个带有开始和结束坐标的线串几何形状。我创建了一个 geopandas 数据框：
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| ID | geometry |
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| 0 | LINESTRING (1679896.423 5802688.586, 1679896.034 5802688.745) |
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| 1 | LINESTRING (1679896.034 5802688.745, 1679892.419 5802689.660) |
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| 2 | LINESTRING (1679908.185 5802692.533, 1679911.830 5802691.936, 1679927.258 5802689.562, 1679945.682 5802686.042) |
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| 3 | LINESTRING (1679945.667 5802685.478, 1679945.653 5802685.247) |
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| 4 | …. |
+-------+----------------------------------------------------------------------------------------------------------------------+
对于计算，我必须确定线之间的所有连接（当前管道必须定义上一个管道和下一个管道）。我这样做的方式是创建线串的起点和终点，并将数据框与其自身合并（终点与起点成对）。问题是，一些线串（大约 1/5）朝向错误的方向，所以我只是为它们得到 NaN 结果（因为现在当前管道的终点没有触及下一个管道的起点，而只是另一个终点点）。
+-------+-------------+-----------------+------------------------------------+------------------------------------+--------------------------------------------------------------------+
| | | | | | |
| ID | PipeNext | PipePrevious | StartPoint | EndPoint | Geometry |
+-------+-------------+-----------------+------------------------------------+------------------------------------+--------------------------------------------------------------------+
| | | | | | |
| 1 | 2 | 477 | POINT (1679896.423 5802688.586) | POINT (1679896.034 5802688.745) | LINESTRING (1679896.423 5802688.586, 1679896.034 5802688.745) |
| | | | | | |
| | | | | | |
+-------+-------------+-----------------+------------------------------------+------------------------------------+--------------------------------------------------------------------+
| | | | | | |
| 7 | 8 | 477 | POINT (1679896.423 5802688.586) | POINT (1679898.491 5802694.799) | LINESTRING (1679896.423 5802688.586, 1679898.491 5802694.799) |
| | | | | | |
| | | | | | |
+-------+-------------+-----------------+------------------------------------+------------------------------------+--------------------------------------------------------------------+
| | | | | | |
| 3 | 467, 468 | Nan | POINT (1679077.671 5802691.617) | POINT (1679060.406 5802674.810) | LINESTRING (1679077.671 5802691.617, 1679060.406 5802674.810) |
| | | | | | |
| | | | | | |
+-------+-------------+-----------------+------------------------------------+------------------------------------+--------------------------------------------------------------------+
另一个问题是，有 10 个管道连续面对错误方向的示例（所以在它们之间，我实际上得到了结果，但它们是错误的）——另一个问题是，有时 PipeNext 是 NaN 仅仅是因为当前行是结束行。
有什么方法可以确定管道朝向错误的方向吗？如果不是，是否可以使线条的方向在绘图上可见？
编辑 - 添加当前代码：
import pandas as pd
import geopandas as gpd
import folium
import shapefile
import matplotlib.pyplot as plt
from geopandas import GeoDataFrame
import contextily as ctx
df_pipes=gpd.read_file("DO_Hrastnik_odsek.shp")
df_user=gpd.read_file("DO_Hrastnik_objekt.shp")
df_pipes.crs = {'init': 'epsg:3912'}
df_pipes=df_pipes.to_crs("EPSG:3857")
df_user.crs = {'init': 'epsg:3912'}
df_user=df_user.to_crs("EPSG:3857")
df_pipes["ID"] = df_pipes.index + 1
df_pipes['ID']=df_pipes['ID'].astype(str)
df_pipes=df_pipes[["geometry","ID","LENGTH_3D"]].copy()
from shapely.geometry import Point, LineString
df_pipes["node_ups"] = gpd.GeoSeries([Point(list(pt['geometry'].coords)[0]) for i,pt in df_pipes.iterrows()])
df_pipes["node_dws"] = gpd.GeoSeries([Point(list(pt['geometry'].coords)[-1]) for i,pt in df_pipes.iterrows()])
tmp = df_pipes[['ID', 'node_dws', 'node_ups']]
df_connections=pd.merge(tmp, tmp, left_on='node_dws', right_on='node_ups',how="outer")
df_connections=pd.merge(df_connections, tmp, left_on='node_ups_x', right_on='node_dws',how="outer")
df_connections.drop(['node_dws_y', 'node_ups_y','node_dws', 'node_ups'], axis=1, inplace=True)
df_connections = df_connections[df_connections['ID_x'].notna()]
df_connections = df_connections.rename(columns={'ID_x': 'ID_pipe', 'node_dws_x': 'node_dws','node_ups_x': 'node_ups', 'ID_y': 'pipeNext','ID': 'pipePrevious'})
tmp = df_connections[['ID_pipe', 'pipeNext', 'pipePrevious']]
df_connections=pd.merge(tmp, df_pipes, left_on='ID_pipe', right_on='ID',how="outer")
您根据评论提出的检查端点相交位置的想法是可行的方法，它并不像您说的那么复杂。从网络的起始管道开始（所有水都来自这里——我假设那是一根管道）并使用递归函数沿着网络向下移动：
from shapely.geometry import Point, LineString # You can delete your own code after this line.
# df.apply is faster than iterrows, so I rewrote the following two lines
df_pipes['node_ups'] = df_pipes.geometry.apply(lambda linestring: Point(list(linestring.coords)[0])
df_pipes['node_dws'] = df_pipes.geometry.apply(lambda linestring: Point(list(linestring.coords)[-1])
def check_downstream(pipe_id, pipes):
"""Set next and previous pipe ID for all downstream pipes"""
endpoint = pipes.loc[pipe_id, 'node_dws']
next_ids = list(pipes['node_ups' == endpoint]['ID'])
reversed_ids = list(pipes[(pipes['node_dws'] == endpoint) & (pipes['ID'] != pipe_id)]['ID'])
for rev_id in reversed_ids:
pipes.loc[rev_id, 'node_ups'], pipes.loc[rev_id, 'node_dws'] = pipes.loc[rev_id, 'node_dws'], pipes.loc[rev_id, 'node_ups']
next_ids = next_ids + reversed_ids
for nxt_id in next_ids:
pipes.loc[pipe_id, 'pipeNext'] = nxt_id
pipes.loc[nxt_id, 'pipePrevious'] = pipe_id
check_downstream(nxt_id, pipes) # This is the recursive function call.
df_connections = df_pipes.copy()
df_connections['pipePrevious'] = 'undetermined'
df_connections['pipeNext'] = 'undetermined'
first_id = 99 # or whatever it is
check_downstream(first_id, df_connections)
请注意，这不会反转线串本身，但如果需要，您也可以这样做。
我正在尝试计算区域供暖系统。我从 shapefile 中获取信息——对于管道，我有一个带有开始和结束坐标的线串几何形状。我创建了一个 geopandas 数据框：
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| ID | geometry |
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| 0 | LINESTRING (1679896.423 5802688.586, 1679896.034 5802688.745) |
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| 1 | LINESTRING (1679896.034 5802688.745, 1679892.419 5802689.660) |
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| 2 | LINESTRING (1679908.185 5802692.533, 1679911.830 5802691.936, 1679927.258 5802689.562, 1679945.682 5802686.042) |
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| 3 | LINESTRING (1679945.667 5802685.478, 1679945.653 5802685.247) |
+-------+----------------------------------------------------------------------------------------------------------------------+
| | |
| 4 | …. |
+-------+----------------------------------------------------------------------------------------------------------------------+
对于计算，我必须确定线之间的所有连接（当前管道必须定义上一个管道和下一个管道）。我这样做的方式是创建线串的起点和终点，并将数据框与其自身合并（终点与起点成对）。问题是，一些线串（大约 1/5）朝向错误的方向，所以我只是为它们得到 NaN 结果（因为现在当前管道的终点没有触及下一个管道的起点，而只是另一个终点点）。
+-------+-------------+-----------------+------------------------------------+------------------------------------+--------------------------------------------------------------------+
| | | | | | |
| ID | PipeNext | PipePrevious | StartPoint | EndPoint | Geometry |
+-------+-------------+-----------------+------------------------------------+------------------------------------+--------------------------------------------------------------------+
| | | | | | |
| 1 | 2 | 477 | POINT (1679896.423 5802688.586) | POINT (1679896.034 5802688.745) | LINESTRING (1679896.423 5802688.586, 1679896.034 5802688.745) |
| | | | | | |
| | | | | | |
+-------+-------------+-----------------+------------------------------------+------------------------------------+--------------------------------------------------------------------+
| | | | | | |
| 7 | 8 | 477 | POINT (1679896.423 5802688.586) | POINT (1679898.491 5802694.799) | LINESTRING (1679896.423 5802688.586, 1679898.491 5802694.799) |
| | | | | | |
| | | | | | |
+-------+-------------+-----------------+------------------------------------+------------------------------------+--------------------------------------------------------------------+
| | | | | | |
| 3 | 467, 468 | Nan | POINT (1679077.671 5802691.617) | POINT (1679060.406 5802674.810) | LINESTRING (1679077.671 5802691.617, 1679060.406 5802674.810) |
| | | | | | |
| | | | | | |
+-------+-------------+-----------------+------------------------------------+------------------------------------+--------------------------------------------------------------------+
另一个问题是，有 10 个管道连续面对错误方向的示例（所以在它们之间，我实际上得到了结果，但它们是错误的）——另一个问题是，有时 PipeNext 是 NaN 仅仅是因为当前行是结束行。 有什么方法可以确定管道朝向错误的方向吗？如果不是，是否可以使线条的方向在绘图上可见？
编辑 - 添加当前代码：
import pandas as pd
import geopandas as gpd
import folium
import shapefile
import matplotlib.pyplot as plt
from geopandas import GeoDataFrame
import contextily as ctx
df_pipes=gpd.read_file("DO_Hrastnik_odsek.shp")
df_user=gpd.read_file("DO_Hrastnik_objekt.shp")
df_pipes.crs = {'init': 'epsg:3912'}
df_pipes=df_pipes.to_crs("EPSG:3857")
df_user.crs = {'init': 'epsg:3912'}
df_user=df_user.to_crs("EPSG:3857")
df_pipes["ID"] = df_pipes.index + 1
df_pipes['ID']=df_pipes['ID'].astype(str)
df_pipes=df_pipes[["geometry","ID","LENGTH_3D"]].copy()
from shapely.geometry import Point, LineString
df_pipes["node_ups"] = gpd.GeoSeries([Point(list(pt['geometry'].coords)[0]) for i,pt in df_pipes.iterrows()])
df_pipes["node_dws"] = gpd.GeoSeries([Point(list(pt['geometry'].coords)[-1]) for i,pt in df_pipes.iterrows()])
tmp = df_pipes[['ID', 'node_dws', 'node_ups']]
df_connections=pd.merge(tmp, tmp, left_on='node_dws', right_on='node_ups',how="outer")
df_connections=pd.merge(df_connections, tmp, left_on='node_ups_x', right_on='node_dws',how="outer")
df_connections.drop(['node_dws_y', 'node_ups_y','node_dws', 'node_ups'], axis=1, inplace=True)
df_connections = df_connections[df_connections['ID_x'].notna()]
df_connections = df_connections.rename(columns={'ID_x': 'ID_pipe', 'node_dws_x': 'node_dws','node_ups_x': 'node_ups', 'ID_y': 'pipeNext','ID': 'pipePrevious'})
tmp = df_connections[['ID_pipe', 'pipeNext', 'pipePrevious']]
df_connections=pd.merge(tmp, df_pipes, left_on='ID_pipe', right_on='ID',how="outer")
您根据评论提出的检查端点相交位置的想法是可行的方法，它并不像您说的那么复杂。从网络的起始管道开始（所有水都来自这里——我假设那是一根管道）并使用递归函数沿着网络向下移动：
from shapely.geometry import Point, LineString # You can delete your own code after this line.
# df.apply is faster than iterrows, so I rewrote the following two lines
df_pipes['node_ups'] = df_pipes.geometry.apply(lambda linestring: Point(list(linestring.coords)[0])
df_pipes['node_dws'] = df_pipes.geometry.apply(lambda linestring: Point(list(linestring.coords)[-1])
def check_downstream(pipe_id, pipes):
"""Set next and previous pipe ID for all downstream pipes"""
endpoint = pipes.loc[pipe_id, 'node_dws']
next_ids = list(pipes['node_ups' == endpoint]['ID'])
reversed_ids = list(pipes[(pipes['node_dws'] == endpoint) & (pipes['ID'] != pipe_id)]['ID'])
for rev_id in reversed_ids:
pipes.loc[rev_id, 'node_ups'], pipes.loc[rev_id, 'node_dws'] = pipes.loc[rev_id, 'node_dws'], pipes.loc[rev_id, 'node_ups']
next_ids = next_ids + reversed_ids
for nxt_id in next_ids:
pipes.loc[pipe_id, 'pipeNext'] = nxt_id
pipes.loc[nxt_id, 'pipePrevious'] = pipe_id
check_downstream(nxt_id, pipes) # This is the recursive function call.
df_connections = df_pipes.copy()
df_connections['pipePrevious'] = 'undetermined'
df_connections['pipeNext'] = 'undetermined'
first_id = 99 # or whatever it is
check_downstream(first_id, df_connections)
请注意，这不会反转线串本身，但如果需要，您也可以这样做。