计算居住在距医院一定距离之内或之外的人数 [英] Calculating the number of people who live within or outside a certain distance from hospitals

问题描述

我是地理空间统计的新手，无法解决一个简单的问题:

I'm new to geospatial stats and can't figure out a simple question:

我有两个具有空间坐标的数据集.一个人在特定地区拥有医院和诊所的坐标.另一个具有该地区所有家庭的坐标.

I have two datasets with spatial coordinates. One has coordinates of hospitals and clinics in a particular district. The other has coordinates of all households in that district.

这里有一些模拟数据

hospital_coord <-data.frame(longitude = c(80.15998, 72.89125, 77.65032, 77.60599), 
                latitude = c(12.90524, 19.08120, 12.97238, 12.90927))    

people_coord <-data.frame(longitude = c(72.89537, 77.65094, 73.95325, 72.96746, 
                              77.65058, 77.66715, 77.64214, 77.58415,
                              77.76180, 76.65470, 76.65480, 76.65490, 76.65500, 76.65560, 76.65560), 
                latitude = c(19.07726, 13.03902, 18.50330, 19.16764, 
                             12.90871, 13.01693, 13.00954, 12.92079,
                             13.02212, 12.81447, 12.81457, 12.81467, 12.81477, 12.81487, 12.81497))

我想计算以下内容:

• 距离最近的诊所/医院超过2公里的家庭有多少百分比
• 在数据框中创建一列，指示哪些家庭在2公里范围之内或之外

推荐答案

我认为这使用最新的sf软件包而不是链接的问题中的geosphere可以满足您的要求.方法如下:

I think this does what you want, using the more recent sf package rather than geosphere from the question linked. The approach is as follows:

1. 使用st_as_sf
将纬度/经度点转换为几何对象
2. 将坐标参考系统设置为标准的长/纬度，因为数据为长/纬度(这是WGS84)
3. 使用st_distance来计算每个人与每家医院之间的距离，作为units表，以米为单位.
4. 将这张units表格转换为常规tbl，因为这很麻烦，并检查哪些对之间的距离超过2公里
5. 使用mutate_at来检查每一行，以查看每个医院是否在2公里之内(T)或2公里以上(F)
6. 最后，使用pmap和any检查每一行，看看是否至少 一家医院在2公里之内！

1. Convert the latitude/longitude points into geometry objects using st_as_sf
2. Set the coordinate reference system to a standard long/lat one since the data is in long/lat (this is WGS84)
3. Use st_distance to compute the distance between each person and each hospital as a units table, in metres.
4. Convert that units table into a regular tbl because it is a pain to deal with, and check which pairs have more than 2km separation
5. Use mutate_at to check each row to see whether each hospital is less than 2km away (T) or more than 2km away (F)
6. Finally, use pmap and any to check each row and see if at least one hospital is within 2km!

看起来只有第一位病人在医院的2公里之内.

It looks like only the first patient is within 2km of a hospital.

library(tidyverse)
library(sf)
hospital <- tibble(
  longitude = c(80.15998, 72.89125, 77.65032, 77.60599),
  latitude = c(12.90524, 19.08120, 12.97238, 12.90927)
  )
people <- tibble(
  longitude = c(72.89537, 77.65094, 73.95325, 72.96746, 77.65058,
                77.66715, 77.64214, 77.58415, 77.76180, 76.65470,
                76.65480, 76.65490, 76.65500, 76.65560, 76.65560),
  latitude = c(19.07726, 13.03902, 18.50330, 19.16764, 12.90871,
               13.01693, 13.00954, 12.92079, 13.02212, 12.81447,
               12.81457, 12.81467, 12.81477, 12.81487, 12.81497)
  )

hospital_sf <- hospital %>%
  st_as_sf(coords = c("longitude", "latitude")) %>%
  st_set_crs(4326)

people_sf <- people %>%
  st_as_sf(coords = c("longitude", "latitude")) %>%
  st_set_crs(4326)

distances <- st_distance(people_sf, hospital_sf) %>%
  as_tibble() %>%
  mutate_at(vars(V1:V4), as.numeric) %>%
  mutate_at(vars(V1:V4), function (x) x > 2000) %>%
  mutate(within_2km = pmap_lgl(., function(V1, V2, V3, V4) any(V1, V2, V3, V4)))
# A tibble: 15 x 5
   V1    V2    V3    V4    within_2km
   <lgl> <lgl> <lgl> <lgl> <lgl>     
 1 T     F     T     T     T         
 2 T     T     T     T     F         
 3 T     T     T     T     F         
 4 T     T     T     T     F         
 5 T     T     T     T     F         
 6 T     T     T     T     F         
 7 T     T     T     T     F         
 8 T     T     T     T     F         
 9 T     T     T     T     F         
10 T     T     T     T     F         
11 T     T     T     T     F         
12 T     T     T     T     F         
13 T     T     T     T     F         
14 T     T     T     T     F         
15 T     T     T     T     F  

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