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在geom_bezier2(), 中是什么单位size，我可以将其指定为绘图坐标的函数吗？

library(ggplot2); library(ggforce)

beziers <- 
  data.frame(
    x = c(1, 2, 3, 4),
    y = c(1, 1, 0, 0),
    type = rep('quadratic', 4),
    point = c('end', 'control', 'control', 'end')
)

colfunc <- colorRampPalette(c("orange", "blue"))

ggplot() + 
  scale_y_continuous(limits = c(0, 1.5)) +
  geom_bezier2(aes(x = x, y = y, 
                   group = type),
               size = seq(35, 3, length.out = 100), # respecify as function of plot coordinates?
               color = colfunc(100),
               alpha = .4,
               data = beziers)
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1 回答 1

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据我所知和 ggplot2 的文档，单位size是mm，即“线的大小是它的宽度，以毫米为单位”。来源：这里。

是的。使用中after_stat介绍的函数，ggplot2 3.3.0您可以指定size绘图坐标的函数。

作为一个例子，为了澄清差异，我做了四个图。首先绘制代码的结果。第二个图在大小上映射了 x 的复杂函数，这对绘制的大小基本上没有影响。地块 3 和 4 使用after_stat. 图 3 映射由 on size 计算的插值 x 值，geom/stat_bezier2而图 4 应用对数变换。 

library(ggplot2); library(ggforce); library(patchwork)

beziers <- 
  data.frame(
    x = c(1, 2, 3, 4),
    y = c(1, 1, 0, 0),
    type = rep('quadratic', 4),
    point = c('end', 'control', 'control', 'end')
  )

colfunc <- colorRampPalette(c("orange", "blue"))

# Setting size and color as functions of x using after_stat
p1 <- ggplot() + 
  scale_y_continuous(limits = c(0, 1.5)) +
  geom_bezier2(aes(x = x, y = y, 
                   group = type),
               size = seq(35, 3, length.out = 100), # respecify as function of plot coordinates?
               color = colfunc(100),
               alpha = .4,
               data = beziers) + 
  labs(title = "Original plot")

p2 <- ggplot() + 
  scale_y_continuous(limits = c(0, 1.5)) +
  geom_bezier2(aes(x = x, y = y, 
                   group = type, 
                   size = exp(log(x)^2 + 10)),
               color = colfunc(100),
               alpha = .4,
               data = beziers) +
  scale_size(range = c(35, 3)) +
  guides(size = FALSE) + 
  labs(title = "exp(log(x)^2 + 10) mapped on size")

p3 <- ggplot() + 
  scale_y_continuous(limits = c(0, 1.5)) +
  geom_bezier2(aes(x = x, y = y, 
                   group = type, 
                   size = after_stat(x)),
               color = colfunc(100),
               alpha = .4,
               data = beziers) +
  scale_size(range = c(35, 3)) +
  guides(size = FALSE) + 
  labs(title = "x mapped on size using after stat")

p4 <- ggplot() + 
  scale_y_continuous(limits = c(0, 1.5)) +
  geom_bezier2(aes(x = x, y = y, 
                   group = type, 
                   size = after_stat(log(x))),
               color = colfunc(100),
               alpha = .4,
               data = beziers) +
  scale_size(range = c(35, 3)) +
  guides(size = FALSE)  + 
  labs(title = "log(x) mapped on size using after stat")

(p1 + p2) / (p3 + p4)

由reprex 包于 2020-03-29 创建(v0.3.0)

于 2020-03-29T09:43:02.087 回答