如何在 R 中正确读取 KML 文件，或将集中变量分离到列中

Question

我使用以下内容读入了 KML 文件：

clinics = st_read(dsn = "Data/clinics-kml.kml","CLINICS")

但是，我的所有变量（坐标除外）都集中在 Description 下的 1 列中（见下文 link）。

分离变量的最佳方法是什么？或者，有没有办法正确导入 KML 文件来避免此问题？ You may view the screenshot of the problem here.

Answer 1

想出了一个替代方法，即使用 QGIS 将 KML 转换为 SHP。然后将其作为 SHP 读入 R.

Answer 2

问题（或可能不是）是 Description 列有一个 html table 作为每个观察的字符串。如果您想解析 html 字符串并获得一个漂亮的 table 就可以了，例如在创建交互式网络地图时。但如果你只是想要里面的数据，这可能会让人头疼。

因此，只需按照以下步骤即可在 R 中完成所有过程：

从互联网下载 KML 文件
解压缩下载的文件
将 KML 文件作为空间对象读取
获取每个观察的属性
将属性绑定到每个观察作为新列

所有代码都有注释，见下：

library(tidyverse)
library(sf)
library(mapview)
library(rvest)
library(httr)

# 1) Download the kml file
moh_chas_clinics <- GET("https://data.gov.sg/dataset/31e92629-980d-4672-af33-cec147c18102/download",
                        write_disk(here::here("moh_chas_clinics.zip"), overwrite = TRUE))

# 2) Unzip the downloaded zip file 
unzip(here::here("moh_chas_clinics.zip"))

# 3) Read the KML file as a Spatial object
moh_chas_clinics <- read_sf(here::here("chas-clinics-kml.kml"))

# Watch data
moh_chas_clinics %>%
  glimpse()

# See map
mapview(moh_chas_clinics)

# 4) Get the attributes for each observation

# Option a) Using a simple lapply
attributes <- lapply(X = 1:nrow(moh_chas_clinics), 
                     FUN = function(x) {

                       moh_chas_clinics %>% 
                         slice(x) %>%
                         pull(Description) %>%
                         read_html() %>%
                         html_node("table") %>%
                         html_table(header = TRUE, trim = TRUE, dec = ".", fill = TRUE) %>%
                         as_tibble(.name_repair = ~ make.names(c("Attribute", "Value"))) %>% 
                         pivot_wider(names_from = Attribute, values_from = Value)

                     })

# Option b) Using a Parallel lapply (faster)
future::plan("multisession")

attributes <- future.apply::future_lapply(X = 1:nrow(moh_chas_clinics), 
                                          FUN = function(x) {

                                            moh_chas_clinics %>% 
                                              slice(x) %>%
                                              pull(Description) %>%
                                              read_html() %>%
                                              html_node("table") %>%
                                              html_table(header = TRUE, trim = TRUE, dec = ".", fill = TRUE) %>%
                                              as_tibble(.name_repair = ~ make.names(c("Attribute", "Value"))) %>% 
                                              pivot_wider(names_from = Attribute, values_from = Value)

                                          })

# 5) Bind the attributes to each observation as new columns
moh_chas_clinics_attr <- 
  moh_chas_clinics %>%
  bind_cols(bind_rows(attributes)) %>%
  select(-Description)

# Watch new data
moh_chas_clinics_attr %>%
  glimpse()

# New map
mapview(moh_chas_clinics_attr, 
        zcol = "CLINIC_PROGRAMME_CODE", 
        layer.name = "Clinic Programme Code")

以最终地图为例，显示了一个点的所有属性并按 "Clinic Programme Code":

着色

如何在 R 中正确读取 KML 文件，或将集中变量分离到列中

How to read in KML file properly in R, or separate out lumped variables into columns

r

kml

sf