Question

如何在ggplot中不对称地调整限制的扩展？例如，

library(ggplot2)

ggplot(mtcars) + 
  geom_bar(aes(x = cyl), width = 1)

我希望条形图的底部与面板背景的底部齐平，但仍然希望顶部有空格。我可以使用空白注释来实现这一点：

ggplot(mtcars) + 
  geom_bar(aes(x = cyl), width = 1) +
  annotate("blank", x = 4, y = 16) +
  scale_y_continuous(expand = c(0.0,0))

在以前版本的ggplot中，我可以使用the solution provided by Rosen Matev：

library("scales")
scale_dimension.custom_expand <- function(scale, expand = ggplot2:::scale_expand(scale)) {
  expand_range(ggplot2:::scale_limits(scale), expand[[1]], expand[[2]])
}

scale_y_continuous <- function(...) {
  s <- ggplot2::scale_y_continuous(...)
  class(s) <- c('custom_expand', class(s))
  s
}

然后使用scale_y_continuous(expand = list(c(0,0.1), c(0,0)))，它会在图表顶部添加一致的附加内容。但是，在当前版本中，我收到错误

ggplot(mtcars) + 
  geom_bar(aes(x = cyl), width = 1) +
  scale_y_continuous(expand = list(c(0,0.1), c(0,0)))

# Error in diff(range) * mul : non-numeric argument to binary operator

ggplot2 2.0是否有效的解决方案？

解决方案应包括使用构面灵活工作的能力，以及free_xy缩放选项。例如，

ggplot(mtcars) + 
  geom_bar(aes(x = cyl, fill = factor(vs)), width = 1) + 
  facet_grid(vs ~ ., scales = "free_y")

解决方案应该提供如下内容：

ggplot(mtcars) + 
  geom_bar(aes(x = cyl, fill = factor(vs)), width = 1) + 
  facet_grid(vs ~ ., scales = "free_y") + 
  scale_y_continuous(expand = c(0,0)) + 
  geom_blank(data = data.frame(cyl = c(5,5), y = c(12, 16), vs = c(1,0)), aes(x = cyl, y = y))

Answer 1

2018年7月发布的

ggplot2 v3.0.0有expand_scale()选项（w / mult参数）来实现OP的目标

library(ggplot2)

ggplot(mtcars) + 
  geom_bar(aes(x = cyl, fill = factor(vs)), width = 1) + 
  facet_grid(vs ~ ., scales = "free_y") + 
  scale_y_continuous(expand = expand_scale(mult = c(0, .2)))

Answer 2

我现在尝试将此代码添加到ggplot2;见issue #1669和corresponding pull request。如果它被接受，expand参数的语法将从c(m, a)更改为c(m_lower, a_lower, m_uppper, a_upper)，以指定范围下限和上限的单独扩展值。（旧的语法仍将继续有效，因为如果缺少元素3和/或4，前两个元素将被重用。）

使用这种新语法，您可以使用

ggplot(mtcars) +
  geom_bar(aes(x = cyl), width = 1) +
  scale_y_continuous(expand = c(0, 0, 0.05, 0))

结果如下：

它也适用于分面：

ggplot(mtcars) +
  geom_bar(aes(x = cyl, fill = factor(vs)), width = 1) +
  facet_grid(vs ~ ., scales = "free_y") +
  scale_y_continuous(expand = c(0, 0, 0.05, 0))

Answer 3

我经常使用Rosen Matev的解决方案，当它与ggplot 2.0版打破时感到很失望。我提供了一个解决方案，虽然不像Rosen那样优雅，但是可以处理没有任何方面的情节，facet_wrap和facet_grid，以及单向和双向facet_grid。但是，它不适用于更复杂的构面网格，也不适用于coord_flip。有两个功能：一个用于沿y轴的不对称扩展，一个用于沿x轴的扩展。这些函数执行乘法和加法扩展。

函数从图中收集信息，计算y（或x）轴的新限制，然后使用geom_blank构建具有所需扩展因子的新图。

首先，沿y轴执行不对称扩展的功能。

# Function takes two parameters
#   'p' is the plot
#   'expand' is a list of two vectors:
#     First vector contains the multiplicative factors;
#     Second vector contains the additive parts.
#       First element in each vector refers to the lower boundary;
#       Second element refers to the upper boundary.

asymmY = function(p, expand = list(mult = c(0, .2), add = c(0, 0))) {

  np = p + coord_cartesian(expand = FALSE)  # No expand
  gb <- ggplot_build(np)

  limits <- sapply(gb$panel$ranges, "[[", "y.range")
  range = apply(limits, 2, function(x) max(x) - min(x))
  rangeU = range*expand[[1]][2]
  rangeL = range*expand[[1]][1]
  limits <- limits + rbind(-rangeL, rangeU)  # Multiplicative expand

  limits[1,] = limits[1,] - expand[[2]][1]   # Additive expand
  limits[2,] = limits[2,] + expand[[2]][2]   

  limits = as.vector(limits)

  df = facet_type(np, gb, "y", limits)  # df with new limits - depends on facet type

  np = np + geom_blank(data = df, inherit.aes = FALSE, aes(x = Inf, y = y)) # new plot

  # But the x axis expansions were set to false. Put back the default expand
  gb <- ggplot_build(np)

 if(any(grepl("Discrete", class(gb$panel$x_scale[[1]])))) {
    limits <- sapply(gb$panel$ranges, "[[", "x.range")
    limits[1,] = ceiling(limits[1,]) - .6
    limits[2,] = trunc(limits[2,]) + .6
    limits = as.vector(limits)
 } else {
    limits <- sapply(gb$panel$ranges, "[[", "x.range")
    range = apply(limits, 2, function(x) max(x) - min(x))
    rangeU = range*.05
    rangeL = range*.05
    limits <- limits + rbind(-rangeL, rangeU)
    limits = as.vector(limits)
 }

  df = facet_type(np, gb, "x", limits)

  np + geom_blank(data = df, inherit.aes = FALSE, aes(x = x, y = Inf))
}

# Function to determine type of facetting  
# and to get data frame of new limits.
facet_type = function(np, gb, axis, limits) {
    if(class(np$facet)[1] == "null") { 
      setNames(data.frame(y = limits), axis)
  } else 
    if(class(np$facet)[1] == "wrap") {
      facetvar <- as.character(np$facet$facets)
      facetlev <- gb$panel$layout[[facetvar]]
      setNames(data.frame(rep(facetlev, each = 2), limits), c(facetvar, axis))
  } else {
      facetvar <- as.character(np$facet$cols)
      if(length(facetvar) == 0) facetvar <- as.character(np$facet$rows)
      facetlev <- gb$panel$layout[[facetvar]]
      setNames(data.frame(rep(facetlev, each = 2), limits), c(facetvar, axis))
  }
}

尝试使用一些小平面包裹和小平面网格图。

# Try asymmetric expand along y-axis
library(ggplot2)

p1 <- ggplot(mtcars) + 
  geom_bar(aes(x = factor(cyl))) + 
  facet_grid(am  ~ vs , scales = "free_y")

p2 <- ggplot(mtcars) + 
  geom_bar(aes(x = factor(cyl), fill = factor(vs)), width = .5) + 
  facet_grid(vs ~ ., scales = "free_y") 

p3 <- ggplot(mtcars) + 
  geom_bar(aes(x = factor(cyl), fill = factor(vs)), width = .5) + 
  facet_grid(. ~ vs)

p4 <- ggplot(mtcars) + 
  geom_bar(aes(x = factor(cyl), fill = factor(vs)), width = .5) + 
  facet_wrap(~vs, scales = "free_y") 

asymmY(p1, list(c(0, 0.1), c(0, 0)))
asymmY(p2, list(c(0, 0.1), c(0, 0)))
asymmY(p3, list(c(0, 0.1), c(0, 0)))
asymmY(p4, list(c(0, 0.1), c(0, 0)))

第二，沿x轴执行不对称扩展的功能。

asymmX = function(p, expand = list(mult = c(0, .2), add = c(0, 0))) {

  np = p + coord_cartesian(expand = FALSE)  # No expand
  gb <- ggplot_build(np)

  limits <- sapply(gb$panel$ranges, "[[", "x.range")
  range = apply(limits, 2, function(x) max(x) - min(x))
  rangeU = range*expand[[1]][2]
  rangeL = range*expand[[1]][1]
  limits <- limits + rbind(-rangeL, rangeU)  # Mult expand

  limits[1,] = limits[1,] - expand[[2]][1]
  limits[2,] = limits[2,] + expand[[2]][2]   # Add expand

  limits = as.vector(limits)

  df = facet_type(np, gb, "x", limits)  # df with new limits - depends on facet type

  np = np + geom_blank(data = df, inherit.aes = FALSE, aes(x = x, y = Inf)) # new plot

  # But the y axis expansions were set to false. Put back the default expand
  gb <- ggplot_build(np)

 if(any(grepl("Discrete", class(gb$panel$y_scale[[1]])))) {
    limits <- sapply(gb$panel$ranges, "[[", "y.range")
    limits[1,] = ceiling(limits[1,]) - .6
    limits[2,] = trunc(limits[2,]) + .6
    limits = as.vector(limits)
 } else {
    limits <- sapply(gb$panel$ranges, "[[", "y.range")
    range = apply(limits, 2, function(x) max(x) - min(x))
    rangeU = range*.05
    rangeL = range*.05
    limits <- limits + rbind(-rangeL, rangeU)
    limits = as.vector(limits)
 }

  df = facet_type(np, gb, "y", limits)

  np + geom_blank(data = df, inherit.aes = FALSE, aes(x = Inf, y = y))
}

尝试一下。

# Try asymmetric expand along x-axis
df = data.frame(x = c(20, 15, 25, 23, 12, 14), 
                y = rep(c("a", "b", "c"), 2),
                z = rep(c("aaa", "bbb"), each = 3),
                w = rep(c("ccc", "ddd", "eee"), each = 2))

p1 = ggplot(df[,-4]) + geom_point(aes(x, y)) +
   geom_segment(aes(x = 0, xend = x, y = y, yend = y)) +
   geom_text(aes(x = x, y = y, label = x), hjust = -1) +
   facet_grid(. ~ z, scales = "free_x") 

p2 = ggplot(df[, -4]) + geom_point(aes(x, y)) +
   geom_segment(aes(x = 0, xend = x, y = y, yend = y)) +
   geom_text(aes(x = x, y = y, label = x), hjust = -1) +
   facet_grid(z ~ .)

p3 = ggplot(df) + geom_point(aes(x, y)) +
   geom_segment(aes(x = 0, xend = x, y = y, yend = y)) +
   geom_text(aes(x = x, y = y, label = x), hjust = -1) +
   facet_grid(w ~ z)

p4 = ggplot(df[,-4]) + geom_point(aes(x, y)) +
   geom_segment(aes(x = 0, xend = x, y = y, yend = y)) +
   geom_text(aes(x = x, y = y, label = x), hjust = -1) +
   facet_wrap(~ z)

asymmX(p1, list(c(0, .15), c(0, 0)))
asymmX(p2, list(c(0, 0), c(0, 5)))
asymmX(p3, list(c(0, .2), c(0, 0)))
asymmX(p4, list(c(0, 0), c(9, 5)))

ggplot轴的非对称扩展限制

3 个答案: