PROSAGA码农传奇-时空索引-dotsInPolys长度不匹配使用通过tidycensus下载的数据

<div class =“post-text”itemprop =“text”>
  <P>
    看起来你可能已经解决了这个问题，但我想分享另一种使用方法
    <a href="https://r-spatial.github.io/sf/reference/st_sample.html" rel="nofollow noreferrer">
       <code>
        sf::st_sample()
      </code>
    </A>
     代替
     <code>
      maptools::dotsInPolys()
    </code>
    。这样做的一个优点是你不需要转换
     <code>
      sf
    </code>
     你得到的对象
     <code>
      tidycensus
    </code>
     到了
     <code>
      sp
    </code>
     宾语。
  </p>
  <P>
    在以下示例中，我将人口普查数据按比赛分成三个列表
     <code>
      sf
    </code>
     对象然后执行
     <code>
      st_sample()
    </code>
     在列表的每个元素上（每个种族）。接下来，我将采样点重新组合成一个
     <code>
      sf
    </code>
     每个点都有一个新的种族变量的对象。最后，我用
     <code>
      tmap
    </code>
     制作地图，尽管你可以使用
     <code>
      ggplot2
    </code>
     要么
     <code>
      leaflet
    </code>
     也要映射。
  </p>
   <pre class="lang-r prettyprint-override">
    <code>
      library(tidyverse)
library(tidycensus)
library(sf)
library(tmap)

person.number.divider <- 1000

racevars <- c(White = "B02001_002", #"P005003" 
              Black = "B02001_003", #Black or African American alone
              Latinx = "B03001_003"
              )

# get acs data with geography in "tidy" form
nj.county <- get_acs(geography = "county", #tract
                     year = 2015,
                     variables = racevars,
                     state = "NJ", #county = "Harris County",
                     geometry = TRUE,
                     summary_var = "B02001_001"
                     )

# split by race
county.split <- nj.county %>% 
  split(.$variable)

# randomly sample points in polygons based on population
points.list <- map(county.split, ~ st_sample(., .$estimate / person.number.divider))

# combine points into sf collections and add race variable 
points <- imap(points.list, ~ st_sf(tibble(race = rep(.y, length(.x))), geometry = .x)) %>% 
  reduce(rbind)

# map!
tm_shape(nj.county) +
  tm_borders(col = "darkgray", lwd = 0.5) +
  tm_shape(points) +
  tm_dots(col = "race", size = 0.01, pal = "Set2")

</code>
  </pre>
  <P>
    我没有足够的代表直接发布地图图片，
    <a href="https://i.imgur.com/MMgRum3.png" rel="nofollow noreferrer">
      但在这里
    </A>
    。
  </p>
</DIV>