添加一个点到基于纬度和经度的等值线图 - r

Question

我绘制了美国的等值线图和每个州的叠加数据。现在我正在尝试向某些纬度和经度坐标添加点，并认为将 geom_point 添加到我的 ggplot 中可以解决问题。我想我在输入 aes 时遇到了一些问题，并且在弄清楚如何解决这个问题时遇到了很多麻烦。这是代码：

library(ggplot2)
library(fiftystater)
library(colorplaner)
library(RColorBrewer)

# prepare data frame
data("fifty_states") 

df <- data.frame(state=tolower(rownames(USArrests)), USArrests)
names(df)[names(df)=='Murder'] <- 'Fake_Data'
names(df)[names(df)=='Assault'] <- 'Bucket'
df<-df[,-c(4:5)]

df$Fake_Data <- runif(nrow(df), 1,60)

df$Bucket = 0
for (i in 1:nrow(df)){
  if(df[i, 2] <= 10){
    df[i,3] = 1
  } else if(df[i,2] > 10 & df[i,2] <= 20){
    df[i,3] = 2
  } else if(df[i,2] > 20 & df[i,2] <= 30){
    df[i,3]= 3
  } else if(df[i,2] > 30 & df[i,2] <= 40){
    df[i,3] = 4
  } else if(df[i,2] > 40 & df[i,2] <= 50){
    df[i,3] = 5
  }
  else if(df[i,2] > 50)
    df[i,3]=6
}

p <- ggplot(df, aes(map_id = state)) + 
  # map points to the fifty_states shape data
  geom_map(aes(fill = factor(Bucket)), map = fifty_states, color = 'gray') + 
  expand_limits(x = fifty_states$long, y = fifty_states$lat) +
  coord_map() +
  scale_x_discrete(breaks = NULL) + 
  scale_y_discrete(breaks = NULL) +
  labs(x = "", y = "") +
  theme(legend.position = "right", 
        panel.background = element_blank())

labs <- data.frame(long = c(-122.064873,-122.306417), 
                   lat = c(36.951968,47.644855), 
                   names = c('lab', 'Seattle'), stringsAsFactors = FALSE)

p + fifty_states_inset_boxes()+ 
  scale_fill_manual('Fake Data Percentages',
                    values = c('#fef0d9', '#fdd49e', '#fdbb84', '#fc8d59', '#e34a33', 
                               '#b30000'), 
                    labels = c('0-10','10-20','20-30','30-40','40-50','50-60'))+
  geom_point(data = labs, aes(x=long, y=lat),
             color = 'black', size = 5) + 
  geom_point(data = labs, aes(x=long, y=lat),
             color = 'blue', size = 4)

我尝试用 map_id = state 和简单的 x=long, y=lat 替换 geom_point 中的 x 和 y 值。但没有运气。我得到的错误是：

Error in FUN(X[[i]], ...) : object 'state' not found

如有任何帮助，我们将不胜感激！

Answer 1

在绘图的全局选项中，您设置了：

ggplot(df, aes(map_id = state))

这会尝试将数据框 df 和美学 map_id state 传递给所有参数，除非在几何选项中被覆盖。这就是导致错误的原因。

要解决此问题，只需在 geom_map 调用中设置 map_id。这确保它只在本地为那个对象设置：

p <- ggplot(df) + 
  # map points to the fifty_states shape data
  geom_map(aes(fill = factor(Bucket), map_id = state), map = fifty_states, color = 'gray') + 
  expand_limits(x = fifty_states$long, y = fifty_states$lat) +
  coord_map() +
  scale_x_discrete(breaks = NULL) + 
  scale_y_discrete(breaks = NULL) +
  labs(x = "", y = "") +
  theme(legend.position = "right", 
        panel.background = element_blank())

labs <- data.frame(long = c(-122.064873,-122.306417), 
                   lat = c(36.951968,47.644855), 
                   names = c('lab', 'Seattle'), stringsAsFactors = FALSE)

p + fifty_states_inset_boxes() + 
  scale_fill_manual('Fake Data Percentages',
                    values = c('#fef0d9', '#fdd49e', '#fdbb84', '#fc8d59', '#e34a33', 
                               '#b30000'), 
                    labels = c('0-10','10-20','20-30','30-40','40-50','50-60'))+
  geom_point(data = labs, aes(x=long, y=lat),
             color = 'black', size = 5) + 
  geom_point(data = labs, aes(x=long, y=lat),
             color = 'blue', size = 4)

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