Question

I am trying to produce a choropleth map using geom_map in ggplot2. I want to outline the various regions in black or some other color to distinguish between areas that are similar in color on the gradient. Using the following code I ve tried to set the color to outline the areas. The code produces the map, but no borders. When I move the colour command into the aesthetic it produces the expected pink borders with a legend. Any ideas why setting the color won t produce borders, but mapping will? I saw a similar discussion on the ggplot2 Google Group.

ggplot(subset(df, as.character(variable) == "value"), aes(map_id = id)) +
  geom_map(aes(fill = pct), colour = "black", map = ggmap) +
  expand_limits(x = ggmap$long, y = ggmap$lat) +
  scale_fill_gradient(low = "antiquewhite", high = "darkred") +
  opts(title = "Title", panel.background = theme_rect(fill = "grey90"))

成就

Answer 1

你们需要使用地平线添加多角边界。在以下代码中,您需要填写每个多功能体的<代码>XXXX和(/data)和“t and long”(x和y。我通常从<代码>地图获取我的数据。一揽子计划并不确定这是你所做的。

ggplot(subset(df, as.character(variable) == "value"), aes(map_id = id)) +
  geom_map(aes(fill = pct), colour = "black", map = ggmap) +
  geom_polygon(data=XXXX, aes(x=XXXX, y=XXXX), colour= black , fill=NA) +
  expand_limits(x = ggmap$long, y = ggmap$lat) +
  scale_fill_gradient(low = "antiquewhite", high = "darkred") +
  opts(title = "Title", panel.background = theme_rect(fill = "grey90"))

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