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使用ggplot2创建带有分面的华夫饼图

rggplot2waffle-chart
7

有没有一种简单的方法可以将瓦夫尔图与ggplot2中的分面组合使用，或者与waffle包进行组合？例如，将下面的每个条形图替换为100个正方形，以表示1%。

ggplot(mtcars, aes(x = factor(vs), y = hp, fill = as.factor(carb))) +
  geom_bar(stat = 'identity', position = 'fill') +
  facet_wrap('gear')
3个回答
12

我不确定我是否会用stat_waffle() / geom_waffle()，但是你可以使用该软件包中的逻辑来绕过长路做同样的事情：

library(hrbrthemes)
library(tidyverse)

我们需要弄清楚百分比，然后让每个组加起来总共达到100，因此我们需要一个在SO上已经存在一段时间的辅助函数：

smart_round <- function(x, digits = 0) { # somewhere on SO
  up <- 10 ^ digits
  x <- x * up
  y <- floor(x)
  indices <- tail(order(x-y), round(sum(x)) - sum(y))
  y[indices] <- y[indices] + 1
  y / up
}

Waffle包中有两个“魔法”比特。一个比特是算法的一部分，它只是将因子组件复制正确的次数。我们将按行应用以下函数到我们将要创建的数据框中：

waffleize <- function(xdf) {
  data_frame(
    gear_vs = rep(xdf$gear_vs, xdf$pct),
    carb = rep(xdf$carb, xdf$pct)
  )
}

现在我们需要：

  • 对于您的示例，执行与ggplot2相同的数学运算
  • 计算每个组的百分比
  • 将%转化为100份，并使每个组总共达到100
  • 由于我们不能在一个面板中有两个不同的geom_tile()，我们需要伪造一个可以实现相同功能的facet名称
  • 按所说的hack进行分组
  • 复制每行pct次
  • 确保正确排序
  • 连接10x10的x/y网格，因为我们将有多少个facet（在本例中为6）；这是waffle包的“魔术”的另一部分
  • 绘制瓷砖

^^ 翻译成：（这个管道链对我来说有点长，但是“它有效”）

count(mtcars, gear, vs, carb, wt=hp) %>% 
  group_by(gear, vs) %>% 
  mutate(pct = n/sum(n)) %>% 
  mutate(pct = (smart_round(pct, 1) * 100L) %>%  as.integer()) %>% 
  select(-n) %>% 
  ungroup() %>% 
  mutate(carb = as.character(carb))  %>% 
  mutate(gear_vs = sprintf("%s-%s", gear, vs)) %>% 
  select(gear_vs, carb, pct, -gear, -vs) %>% 
  rowwise() %>% 
  do(waffleize(.)) %>% 
  ungroup() %>% 
  arrange(gear_vs, carb) %>% 
  bind_cols(
    map_df(seq_len(length(unique(.$gear_vs))), ~expand.grid(y = 1:10, x = 1:10))
  ) %>% 
  ggplot(aes(x, y)) + 
  geom_tile(aes(fill=carb), color="white", size=0.5) +
  ggthemes::scale_fill_tableau() +
  facet_wrap(~gear_vs) +
  coord_equal() +
  labs(x=NULL, y = NULL) +
  hrbrthemes::theme_ipsum_rc(grid="") +
  theme(axis.text=element_blank())

enter image description here

3-0、4-1和5-0的百分比四舍五入有误吗？ - Mikko
3

对于@hrbrmstr的出色回答（感谢您制作此软件包并与我们分享代码！），我有一个小补充。我也曾努力制作这样的图表，因为我认为这是比饼状图更好的可视化数据比较的方式。我的华夫饼图哲学与现有解决方案（waffle和ggwaffle）有三个不同之处：

  1. 华夫饼图应始终以10x10％网格的1:1比例呈现，就像OP问题和@hrbrmstr回答所要求的那样。这使读取百分比更容易。
  2. 华夫饼图应从左到右（阅读方向）填充，并从下往上（就像杯子里的水一样，与现有解决方案不同）。这使我更自然地阅读百分比。
  3. 1％的单元格可以被划分以容纳小数百分比。当使用完整百分比时，贡献小于1％的组会消失，但在我使用这些图的应用程序中，缺失的组具有与（0,1）组不同的含义。
因为解决上述问题花了我相当长的时间，所以我在下面发布我的解决方案。代码背后的“魔法”（即方法）是从现有软件包中挖掘出来的。我希望这能帮助某些人并推动华夫饼图的发展。我真的认为这些图表在数据可视化方面有潜力。很好地实现函数作为ggplot2 proto对象将是不错的，但尝试后我不得不放弃。我对proto系统的理解还不够，无法编写相关代码。一旦我添加了所有我计划添加的功能（计划是使华夫饼图类似于scatterpie），我只需复制我打算包含在我的R包中的代码即可。请注意，下面大部分代码都是用来美化华夫饼图的。制作华夫饼图的部分并不那么复杂，并且在@hrbrmstr的答案中有很好的解释。
运行示例所需的函数：
library(dplyr)
library(ggplot2)

#' @title Convert line sizes measured as points to ggplot line sizes
#' @description Converts line sizes measured as points (as given by most programs such as Adobe Illustrator etc.) to ggplot font sizes
#' @param x numeric vector giving the lines sizes in points
#' @return Returns a numeric vector of lenght \code{x} of ggplot line sizes
#' @keywords internal
#' @export
#'
LS <- function(x) x/2.13

#' @title Round values preserving total sums
#' @description The function rounds values preserving total sums
#' @param x numeric vector of values to be rounded
#' @param digits integer indicating the number of decimal places. See \code{\link[base]{round}}.
#' @return Returns a numeric vector.
#' @author The function is written as a communal effort. Main authors are \href{https://dev59.com/hVwY5IYBdhLWcg3wgX-V and \href{https://www.r-bloggers.com/round-values-while-preserve-their-rounded-sum-in-r/}{BioStatMatt}.
#' @keywords internal
#' @family waffle
#' @export

round_preserve_sum <- function(x, digits = 0) {
  up <- 10 ^ digits
  x <- x * up
  y <- floor(x)
  indices <- tail(order(x-y), round(sum(x)) - sum(y))
  y[indices] <- y[indices] + 1
  y / up
}  # from https://www.r-bloggers.com/round-values-while-preserve-their-rounded-sum-in-r/

#' @title Prepare data for waffle plots
#' @description Manipulates a data frame ready for plotting with the \code{\link{waffle_chart}} function.
#' @param dt data frame containing the data which should be transformed
#' @param fill character specifying the column name which should be used as fill for the waffle plot.
#' @param value character specifying the column name which contains values of the \code{fill} variable.
#' @param composition logical indicating whether a compositional waffle (i.e. fill adds up to 100\%) should be created. If \code{FALSE}, waffle cells will be scaled to \code{max_value} and missing cells filled with an "empty" category.
#' @param max_value numerical giving the value to which waffle cells should be scaled to, if \code{composition = FALSE}.
#' @param digits integer indicating the number of decimal places to be used in rounding of the waffle cells. 
#' @return returns a \link[tibble]{tibble} data frame containing the minimum and maximum extent of each \code{fill} level.
#' @author Mikko Vihtakari 
#' @keywords internal
#' @family waffle
#' @import dplyr
#' @export

waffleize <- function(dt, fill, value, composition = TRUE, max_value = NULL, digits = 3) {

   x <- dt[c(fill, value)]
   names(x) <- c("variable", "value")

  if(composition) {
    x$value <- round_preserve_sum(10^digits*x$value/sum(x$value))
  } else {

    if(is.null(max_value)) stop("max_value has to be given, if composition = FALSE")
    if(max_value < sum(x$value)) stop("max_value has to be larger than the sum of 'value' column. Use composition = TRUE, if you want a compositional waffle chart")

    x <- rbind(x, data.frame(variable = "empty", value = max_value - sum(x$value)))
    x$value <- round_preserve_sum(10^digits*x$value/max_value)
  }

  if(!is.factor(x$variable)) x$variable <- factor(x$variable, levels = c(sort(unique(x$variable)[unique(x$variable) != "empty"]), "empty"))

  x <- x[order(x$variable),]

  #tmp <- data.frame(X = 1:100, ymin = rep(c(0, (1:9)*10), each = 100), ymax = rep((1:10)*10, each = 100), variable = rep(dt[[fill]], dt[[value]]))

  tmp <- data.frame(X = 1:10^(digits-1), ymin = rep(c(0, (1:9)*10^(digits-2)), each = 10^(digits-1)), ymax = rep((1:10)*10^(digits-2), each = 10^(digits-1)), variable = rep(x$variable, x$value))

  out <- tmp %>% group_by(variable, ymin, ymax) %>% summarise(xmin = min(X)-1, xmax = max(X))

  ## Remove the empty category

  out[out$variable != "empty",]

}

#' @title Plot waffle charts
#' @description The function uses \link[ggplot2]{ggplot2} to create waffle charts from data.
#' @param data data frame to be plotted
#' @param fill character specifying the column name which should be used as fill for the waffle plot.
#' @param value character specifying the column name which contains values of the \code{fill} variable. Will be used to fill the waffle cells.
#' @param facet character specifying the column name which should be used to \code{\link[ggplot2]{facet_wrap}} waffle charts.
#' @param ncol number of columns to be used in facetting. See \code{\link[ggplot2]{facet_wrap}}.
#' @param composition logical indicating whether a compositional waffle (i.e. fill adds up to 100\%) should be created. If \code{FALSE}, waffle cells will be scaled to \code{max_value} and missing cells filled with an "empty" category.
#' @param max_value numerical giving the value to which waffle cells should be scaled to, if \code{composition = FALSE}.
#' @param digits integer indicating the number of decimal places to be used in rounding of the waffle cells. The value 3 indicates percentages, while 4 permilles. 
#' @param fill_colors named character vector giving the colors for \code{fill} levels. See \code{\link[ggplot2]{scale_fill_manual}}.
#' @param fill_title character giving the title for the color legend.
#' @param base_size numeric giving the base size for the plot. See \code{\link[ggplot2]{theme_void}}.
#' @param legend.position character specifying the position of the legend. See \code{\link[ggplot2]{ggtheme}}.
#' @details The waffle charts are read from left to right (like text) and from bottom upwards (like water glass). The cells indicate 1\% of the maximum value (100% if \code{composition = TRUE} else \code{max_value}). The cells are divided vertically to fractions specifies by the \code{digits} argument. 
#' @return Returns a \link[ggplot2]{ggplot2} waffle plot
#' @import ggplot2 dplyr
#' @family waffle
#' @author Mikko Vihtakari with code ideas from \href{https://github.com/hrbrmstr/waffle}{hrbrmstr} and \href{https://github.com/liamgilbey/ggwaffle}{Liam Gilbey}
#' @export

# data = dt; fill = "variable"; value = "value"; facet = NULL; composition = TRUE; max_value = NULL; digits = 3; fill_colors = NULL; fill_title = NULL; ncol = NULL; base_size = 12; legend.position = "bottom"
waffle_chart <- function(data, fill, value = "value", facet = NULL, composition = TRUE, max_value = NULL, digits = 3, fill_colors = NULL, fill_title = NULL, ncol = NULL, base_size = 12, legend.position = "bottom") {

  ## White 1% grid

  grid_data <- data.frame(xmin = c(0,(1:9)*10^(digits-2)), xmax = (1:10)*10^(digits-2), ymin = rep(c(0,(1:9)*10^(digits-2)), each = 10^(digits-2)), ymax = rep((1:10)*10^(digits-2), each = 10^(digits-2)))

  if(is.null(facet)) { ## No facetting

    if(any(duplicated(data[[fill]]))) stop("data contains duplicated entries in fill column. Use the facet argument or summarize data before plotting.")

    waffle_data <- waffleize(dt = data, fill = fill, value = value, composition = composition, max_value = max_value, digits = digits)

    ## Plot ####
    p <- ggplot() + 
      geom_rect(data = waffle_data, aes(xmin = xmin, xmax = xmax, ymin = ymin, ymax = ymax, fill = variable)) + 
      geom_rect(data = grid_data, aes(xmin = xmin, xmax = xmax, ymin = ymin, ymax = ymax), fill = NA, color = "white") +
      coord_equal(expand = FALSE) + 
      theme_void()

    ## ####

  } else { ## Facetting

    waffle_data <- data %>% group_by_(facet) %>% do(waffleize(dt = ., fill = fill, value = value, composition = composition, max_value = max_value, digits = digits))

    ## Plot ####
    p <- ggplot() + 
      geom_rect(data = waffle_data, aes(xmin = xmin, xmax = xmax, ymin = ymin, ymax = ymax, fill = variable)) + 
      geom_rect(data = grid_data, aes(xmin = xmin, xmax = xmax, ymin = ymin, ymax = ymax), fill = NA, color = "white") +
      facet_wrap(facet, ncol = ncol) + 
      coord_equal(expand = FALSE) + 
      theme_void()

    ## ####

  }


  ## Fill colors ####

  if(is.null(fill_title)) fill_title <- "Variable"

  if(!is.null(fill_colors)) {
    p <- p + scale_fill_manual(name = fill_title, values = fill_colors)
  } else {
    p <- p + scale_fill_viridis_d(name = fill_title)
  }

  ## Final theme manipulation

  p <- p + theme(
    legend.position = legend.position,
      aspect.ratio = 1, 
      panel.border = element_rect(color = "black", size = LS(1), fill = NA),
      strip.background = element_rect(fill = alpha("white", 0.4), color = NA),
      strip.text.x = element_text(size = base_size*0.8, margin = margin(t = 2, r = 0, b = 3, l = 0, unit = "pt")),
      plot.title = element_text(size = base_size, hjust = 0.5, face = 2),
      legend.background = element_blank(),
      legend.box.background = element_blank(),
      legend.title = element_text(size = base_size),
      legend.text = element_text(size = base_size),
      plot.background = element_blank(),
      panel.spacing = unit(0.2, units = "line"),
      legend.box.margin = margin(t = 0, r = 0, b = 3, l = 0, unit = "pt"),
      plot.margin = unit(c(0.2, 0.5, 0.1, 0.1), units = "line")
  )

  ## Return the plot

  p

}

最后，我们可以制作图表：
# Manipulate the dataset first to make sure that there are no replicate 
# entries of factors used for the waffles

data("mtcars")

mtcars$gear_vs <- paste(mtcars$gear, mtcars$vs, sep = "-")
mtcars$carb <- factor(mtcars$carb)
x <- mtcars %>% group_by(gear_vs, carb) %>% summarise(value = sum(hp))

waffle_chart(x, fill = "carb", facet = "gear_vs", value = "value")

enter image description here

## You can also scale the waffles to a maximum hp in gear_vs

y <- x %>% group_by(gear_vs) %>% summarise(value = sum(value))

waffle_chart(x, fill = "carb", facet = "gear_vs", value = "value", composition = FALSE, max_value = max(y$value))

enter image description here

1

这里提供了一种替代方法，只使用tidyverse（即dplyr、tidyr和ggplot2）来创建waffle plot或square pie chart。它基于hrbrmstr's answer，但我试图使其更加通用; 任何频率表都可以作为输入，并且很容易调整华夫饼的尺寸（例如矩形而不是正方形）。

library(tidyverse)
freq_table = mtcars %>%
  count(gear, vs, carb, wt = hp) %>% 
  group_by(gear, vs) %>% 
  mutate(pct = n / sum(n)) %>% 
  select(gear, vs, carb, pct)

第二步创建坐标。使用tidyr::expand()而不是waffleize()。仍然使用smart_round()。
waffle.n = 100 # Number of blocks
waffle.cols = ceiling(sqrt(waffle.n)) # For square. Otherwise pick integer.
coordinates = freq_table %>% 
  group_by(gear, vs) %>%
  mutate(waffle.num = smart_round(pct,1) * waffle.n) %>%
  group_by(carb, gear, vs) %>%
  expand(count = seq(1:waffle.num)) %>% 
  select(-count) %>%
  group_by(gear, vs) %>%
  arrange(gear, vs) %>%
  mutate(
    waffle.x = rep_len(1:waffle.cols, waffle.n),
    waffle.y = floor((row_number() - 1) / waffle.cols)
  )

我将两个变量 (gear 和 vs) 进行分组，因此使用了 facet_grid()。如果您只需要按单个变量进行分组，则可以使用 facet_wrap()。您需要微调选项以获得最佳结果（例如设备大小、点的大小和笔画）。
fig = coordinates %>%
  ggplot(aes(x = waffle.x, y = waffle.y, fill = as.factor(carb))) +
    geom_point(size = 7, shape = 22, color = "white", stroke = 0.8) +
    #geom_raster() + # Alternative to geom_point() without gap between blocks.
    facet_grid(rows = vars(gear), cols = vars(vs)) +
    theme_void() +
    theme(legend.position = "bottom", plot.margin = margin(5.5, 5.5, 5.5, 5.5, "pt"), panel.spacing = unit(15, "pt"))
fig
#ggsave("fig.pdf", width = 13, height = 17.5, units = "cm", dpi = 150)

enter image description here

一个更有趣的例子，其中块数不均匀且份额不可被10整除。

将块/单元格分割以适应分数百分比，如Mikko建议的，可以通过增加waffle.n并使用类似于 geom_raster(hjust=0, vjust=0) + geom_vline(xintercept=seq(0,waffle.cols,by=2), color="white") + geom_hline(yintercept=seq(0,waffle.cols-1,by=1), color="white") 而不是 geom_point() 来实现。 - bonna
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