facet_grid中的免费色标

时间:2019-01-02 15:41:18

标签: r ggplot2 facet-grid

说我有以下数据框:

# Set seed for RNG
set.seed(33550336)

# Create toy data frame
loc_x <- c(a = 1, b = 2, c = 3)
loc_y <- c(a = 3, b = 2, c = 1)
scaling <- c(temp = 100, sal = 10, chl = 1) 

df <- expand.grid(loc_name = letters[1:3], 
                  variables = c("temp", "sal", "chl"), 
                  season = c("spring", "autumn")) %>% 
  mutate(loc_x = loc_x[loc_name],
         loc_y = loc_y[loc_name],
         value = runif(nrow(.)),
         value = value * scaling[variables])

看起来像

# > head(df)
#   loc_name variables season loc_x loc_y     value
# 1        a      temp spring     1     3 86.364697
# 2        b      temp spring     2     2 35.222573
# 3        c      temp spring     3     1 52.574082
# 4        a       sal spring     1     3  0.667227
# 5        b       sal spring     2     2  3.751383
# 6        c       sal spring     3     1  9.197086

我想使用variablesseason将这些数据绘制在构面网格中,以定义面板,如下所示:

g <- ggplot(df) + geom_point(aes(x = loc_name, y = value), size = 5)
g <- g + facet_grid(variables ~ season) 
g

enter image description here

如您所见,不同的variables具有不同的比例。因此,我使用scales = "free"来解决这个问题。

g <- ggplot(df) + geom_point(aes(x = loc_name, y = value), size = 5)
g <- g + facet_grid(variables ~ season, scales = "free") 
g

enter image description here

非常方便。现在,说我想这样做,但是用loc_xloc_y绘制点,并用颜色而不是y位置表示value

g <- ggplot(df) + geom_point(aes(x = loc_x, y = loc_y, colour = value), 
                             size = 5)
g <- g + facet_grid(variables ~ season, scales = "free") 
g <- g + scale_colour_gradient2(low = "#3366CC", 
                                mid = "white", 
                                high = "#FF3300", 
                                midpoint = 50) 
g

enter image description here

请注意,颜色刻度不是免费的,并且像第一个数字一样,salchl的值不易读取。

我的问题:是否可以做scales = "free"的等效项,但是要使用颜色,以便每一行(在这种情况下)都有单独的颜色条?或者,我是否必须绘制每个变量(即图中的行)并使用cowplot之类的变量将它们修补在一起?

1 个答案:

答案 0 :(得分:2)

使用dplyr的开发版本:

library(dplyr)
library(purrr)
library(ggplot2)
library(cowplot)

df %>% 
  group_split(variables, season) %>% 
  map(
    ~ggplot(., aes(loc_x, loc_y, color = value)) + 
      geom_point(size = 5) +
      scale_colour_gradient2(
        low = "#3366CC", 
        mid = "white", 
        high = "#FF3300", 
        midpoint = median(.$value)
      ) +
      facet_grid(~ variables + season, labeller = function(x) label_value(x, multi_line = FALSE))
  ) %>% 
  plot_grid(plotlist = ., align = 'hv', ncol = 2)

enter image description here