R code to Generating map of US states with specific colors

问题

I am trying to generate the map of U.S. in which each state can have one of the following colors:

EScolors <- c("#7aad42","#4a77bb","#f7931e","#d3dfbd","#787878")

I have created a data frame, states_info, to match each state with it's color.

head(states_info)
  State.Code   region St_Abbr Num_Estab  colors
1          1   alabama      AL     13123 #f7931e
3          4   arizona      AZ     18053 #f7931e
4          5   arkansas      AR      9154 #4a77bb
5          6   california      CA    143937 #787878
6          8   colorado      CO     21033 #d3dfbd
7          9   connecticut      CT     17176 #f7931e

I have tried various ways to get the colors for each state correct, but my code is not working. (btw, "colors" is a factor variable and contain the hex value of specific colors)

Approach 1:

map('state',fill=TRUE,col=states_info$colors)

I get a map, but the colors for the states are not correct. This approach probably requires matching, but I cannot figure it out.

Approach 2: I create a data frame by merging the latitudes and longitudes for each state with my state_info dataframe to draw the map

    states_location <- map_data("state")
    map.df <- merge(states_location,states_info,    by=intersect(states_location$region, states_info$region), all=TRUE)
    map.df <- map.df[order(map.df$order),]

   ggplot(map.df, aes(x=long,y=lat,group=group))+
     geom_polygon(aes(fill=region.x))+
       geom_path()+
        scale_color_hue(states_info$colors)

This approach generates a map using its own color gradient and not the colors I specified. What am I doing wrong? Thank you.

回答1:

Let ggplot2 do the hard work for you:

library(ggplot2)

read.table(text="State.Code   region St_Abbr Num_Estab  colors
1          1   alabama      AL     13123 #f7931e
3          4   arizona      AZ     18053 #f7931e
4          5   arkansas      AR      9154 #4a77bb
5          6   california      CA    143937 #787878
6          8   colorado      CO     21033 #d3dfbd
7          9   connecticut      CT     17176 #f7931e", 
           stringsAsFactors=FALSE, header=TRUE, comment.char="") -> df

usa_map <- map_data("state")

gg <- ggplot()
gg <- gg + geom_map(data=usa_map, map=usa_map,
                    aes(long, lat, map_id=region),
                    color="#2b2b2b", size=0.15, fill=NA)
gg <- gg + geom_map(data=df, map=usa_map,
                    aes(fill=colors, map_id=region),
                    color="#2b2b2b", size=0.15)
gg <- gg + scale_color_identity()
gg <- gg + coord_map("polyconic")
gg <- gg + ggthemes::theme_map()
gg

回答2:

Using the base maps package can be a little tricky. The order and the naming of the states is not standard, several states have more than one region, i.e. Manhattan island in New York. A little manipulation is required to properly label/color the map.
In this solution, I created a dataframe statelist to hold the state names, islands and an index. Then merge this with your dataframe, state_info, and then plotted.

#function to split strings an return a dataframe
strtodf<-function (list){
  slist<-strsplit(list, ":")
  x<-sapply(slist, FUN= function(x) {x[1]})
  y<-sapply(slist, FUN= function(x) {x[2]})
  df<-data.frame(state=x, island=y, stringsAsFactors = FALSE)
  return(df)
}

#user defined coloring scheme
#    Example data for to test solution
colors<- c("#7aad42","#4a77bb","#f7931e","#d3dfbd","#787878")
region<-c("washington", "new york", "virginia", "pennsylvania", "ohio")
states_info<-data.frame(region, colors)
#    End of example data

#dataframe to hold state names for mapping purposes
library(maps)
maplist<-map("state", namesonly = TRUE, plot=FALSE)
statelist<-strtodf(maplist)  #convert to dataframe
statelist$row<-as.numeric(rownames(statelist))  #index column

#merge the data from and resort into proper order
statelist<-merge(statelist, states_info, by.x = "state", by.y="region", sort=FALSE, all.x=TRUE)
statelist<-statelist[order(statelist$row),]

#plot the map
maplist<-map("state", fill=TRUE, col=statelist$colors)

来源：https://stackoverflow.com/questions/38777732/r-code-to-generating-map-of-us-states-with-specific-colors

标签

colors

maps

states