在R地图中使用FIPS代码对县进行着色

问题描述

我正在寻找一种在R中的美国地图上给县添加阴影的方法.我有一个数字/字符县FIPS代码列表，可以将其输入作为参数.我只需要突出显示这些县-所以只需要阴影它们，就没有与这些县相对应的值或变体.我试图查找

I am looking for a way to shade counties on the US maps in R. I have list of numeric/char county FIPS code that I can input as parameter. I just need to highlight these counties -- so would just need to shade them and there are no values or variations corresponding to the counties. I tried to look up

 library(choroplethr)
 library(maps)

和

county_choropleth(df_pop_county)

head(df_pop_county)
    region  value
 1   1001  54590
 2   1003 183226
 3   1005  27469
 4   1007  22769
 5   1009  57466
 6   1011  10779

但是这些需要一个区域，值对.例如，上面的fips代码和填充.有没有一种方法可以仅使用fipscode数据帧来调用county_choropleth函数而不必使用值.这样，我就可以用一种颜色来编码我的fips了.使用Choroplethr在R中完成此任务的有效方法是什么?

But these need a region, value pair. For e.g.,fips code and population in the above. Is there a way to call the county_choropleth function without having to use the values, just with the fipscode dataframe. In that way, I can my fips code with one color. What would be an efficient way to accomplish this in R using Choroplethr?

推荐答案

以下是使用maps库的示例:

library(maps)
library(dplyr)

data(county.fips)

## Set up fake df_pop_county data frame
df_pop_county <- data.frame(region=county.fips$fips)
df_pop_county$value <- county.fips$fips
y <- df_pop_county$value
df_pop_county$color <- gray(y / max(y))

## merge population data with county.fips to make sure color column is
## ordered correctly.
counties <- county.fips %>% left_join(df_pop_county, by=c('fips'='region'))
map("county", fill=TRUE, col=counties$color)

这是生成的地图:

请注意，FIPS较低的县较暗，而FIPS较高的县较亮.

Notice that counties with lower FIPS are darker, while counties with higher FIPS are lighter.

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