在ggplot的极坐标图中分别缩放轴? [英] Scaling the axes in a polar plot of ggplot individually?

问题描述

我的数据集是

cvar setting value
var1 min 20
var2 min 5
var3 min 140
var4 min 40
var5 min 600
var1 max 60
var2 max 15
var3 max 180
var4 max 80
var5 max 1200
var1 center 40
var2 center 10
var3 center 160
var4 center 60
var5 center 900
var1 upper 57
var2 upper 13
var3 upper 162
var4 upper 79
var5 upper 1250
var1 lower 20
var2 lower 6
var3 lower 153
var4 lower 40
var5 lower 620

使用

library(ggplot2)
ggplot(data=daten, aes(x=factor(cvar), y=value, group = setting, color = setting)) + 
  geom_line() + 
  coord_polar()

我得到的东西与我要找的东西很接近. 我希望每个轴分别缩放，从0到各自的最大值，或者每个轴都有各自的最小值和最大值.

I get something close to what I am looking for. I would like to have each of the axes scaled individually, either from 0 to the respective max or with individual min and max for each.

有人可以给我一个提示吗? 提前致谢 霍尔格

Could someone give me a hint, please? Thanks in advance Holger

推荐答案

如果您要对每个cvar的值范围进行缩放，则可以在将数据帧传递到ggplot之前执行以下操作:

If you mean you want the range of values to be scaled for each cvar, you can do that before passing the data frame to ggplot:

library(dplyr)

daten2 <- daten %>%
  group_by(cvar) %>%

  # option 1: this scales the values at each varX from 0 to max
  mutate(value.scaled = value / max(value)) %>% 

  # option 2: this scales the values at each varX from min to max
  mutate(value.scaled2 = (value - min(value)) / (max(value) - min(value))) %>%

  ungroup() %>%
  mutate(setting = factor(setting,
                          levels = c("max", "upper", "center", "lower", "min")))

p1 <- ggplot(data = daten2, 
       aes(x = factor(cvar), y = value.scaled, group = setting, color = setting)) + 
  geom_line(size = 1) + 
  expand_limits(y = 0) +
  coord_polar() +
  ggtitle("Scaled value range from 0 to max")

p2 <- ggplot(data = daten2, 
             aes(x = factor(cvar), y = value.scaled2, group = setting, color = setting)) + 
  geom_line(size = 1) + 
  coord_polar() +
  ggtitle("Scaled value range from min to max")

gridExtra::grid.arrange(p1, p2, nrow = 1)

编辑:如果要连接第一个和最后一个cvar值，可以在x轴的末端重复var1，并明确设置expand = c(0, 0)，以便最后一个expand = c(0, 0) c0>值与极坐标下的第一个:

Edit: If you want to join the first and last cvar values, you can repeat var1 at the end of the x-axis, and explicitly set expand = c(0, 0) so that the last cvar value joins up with the first under polar coordinates:

# I'm only demonstrating with one of the two cases above, 
# but the same principle applies in either case.

ggplot(data = daten2 %>%
         filter(cvar == "var1") %>% # make a copy of the dataset with only var1
         mutate(cvar = "var6") %>%
         rbind(daten2),             # append the copy to the full dataset
             aes(x = factor(cvar), y = value.scaled2, group = setting, color = setting)) + 
  geom_line(size = 1) + 
  scale_x_discrete(expand = c(0, 0),
                   breaks = c("var1", "var2", "var3", "var4", "var5")) +
  coord_polar() +
  ggtitle("Scaled value range from min to max")

如果您希望直线在极坐标下是直线，则答案

And if you want the lines to be straight under polar coordinates, the answer here describes an alternative:

coord_radar <- function (theta = "x", start = 0, direction = 1) {
  theta <- match.arg(theta, c("x", "y"))
  r <- if (theta == "x") "y" else "x"
  ggproto("CordRadar", CoordPolar, theta = theta, r = r, start = start, 
          direction = sign(direction),
          is_linear = function(coord) TRUE)
}

ggplot(data = daten2 %>%
         filter(cvar == "var1") %>%
         mutate(cvar = "var6") %>%
         rbind(daten2), 
             aes(x = factor(cvar), y = value.scaled2, group = setting, color = setting)) + 
  geom_line(size = 1) + 
  scale_x_discrete(expand = c(0, 0),
                   breaks = c("var1", "var2", "var3", "var4", "var5")) +
  coord_radar() +
  ggtitle("Scaled value range from min to max")

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