如何在ggplot geom_tile中正确使用构面，同时保持长宽比不变？

时间：2019-06-05 13:35:28

标签： r ggplot2 heatmap facet aspect-ratio

我正在尝试创建一个“相似度图”，以快速显示表中项目的相似度与其他项目。

一个简单的例子：

要使用的“ property_data.csv”文件：

"","Country","Town","Property","Property_value"
"1","UK","London","Road_quality","Bad"
"2","UK","London","Air_quality","Very bad"
"3","UK","London","House_quality","Average"
"4","UK","London","Library_quality","Good"
"5","UK","London","Pool_quality","Average"
"6","UK","London","Park_quality","Bad"
"7","UK","London","River_quality","Very good"
"8","UK","London","Water_quality","Decent"
"9","UK","London","School_quality","Bad"
"10","UK","Liverpool","Road_quality","Bad"
"11","UK","Liverpool","Air_quality","Very bad"
"12","UK","Liverpool","House_quality","Average"
"13","UK","Liverpool","Library_quality","Good"
"14","UK","Liverpool","Pool_quality","Average"
"15","UK","Liverpool","Park_quality","Bad"
"16","UK","Liverpool","River_quality","Very good"
"17","UK","Liverpool","Water_quality","Decent"
"18","UK","Liverpool","School_quality","Bad"
"19","USA","New York","Road_quality","Bad"
"20","USA","New York","Air_quality","Very bad"
"21","USA","New York","House_quality","Average"
"22","USA","New York","Library_quality","Good"
"23","USA","New York","Pool_quality","Average"
"24","USA","New York","Park_quality","Bad"
"25","USA","New York","River_quality","Very good"
"26","USA","New York","Water_quality","Decent"
"27","USA","New York","School_quality","Bad"

代码：

prop <- read.csv('property_data.csv')

Property_col_vector <- c("NA" = "#e6194b",
                "Very bad" = "#e6194B",
                "Bad" = "#ffe119",
                "Average" = "#bfef45",
                "Decent" = "#3cb44b",
                "Good" = "#42d4f4",
                "Very good" = "#4363d8")

plot_likeliness <- function(town_property_table){
    g <- ggplot(town_property_table, aes(Property, Town)) +
      geom_tile(aes(fill = Property_value, width=.9, height=.9)) +
      theme_classic() +
      theme(axis.text.x = element_text(angle = 90, hjust = 1, vjust=0.5),
            strip.text.y = element_text(angle = 0)) +
      scale_fill_manual(values = Property_col_vector) +
      coord_fixed()
    return(g)
}

summary_town_plot <- plot_likeliness(prop)

输出： Single_town_plot.png

这看起来很棒！ 现在，由于使用了coord_fixed（）函数，因此创建了一个看起来不错的图，但是现在我想创建一个由Country组成的图。

为此，我创建了以下函数：

plot_likeliness_facetted <- function(town_property_table){
  g <- ggplot(town_property_table, aes(Property, Town)) +
    geom_tile(aes(fill = Property_value, width=.9, height=.9)) +
    theme_classic() +
    theme(axis.text.x = element_text(angle = 90, hjust = 1, vjust=0.5),
          strip.text.y = element_text(angle = 0)) +
    scale_fill_manual(values = Property_col_vector) +
    facet_grid(Country ~ .,
               scale = 'free_y')
  return(g)
}

facetted_town_plot <- plot_likeliness_facetted(prop)
facetted_town_plot

结果： facetted_town_plot.png

但是，现在我的瓷砖已经拉伸了，如果我尝试使用'+ coords_fixed（）'，我会收到错误消息：

Error: coord_fixed doesn't support free scales

我如何才能使图面化，但要保持长宽比？请注意，我正在按顺序绘制这些图形，因此我不希望用手动值对图形的高度进行硬编码，这是我需要的解决方案，我需要一些可以随表中值的数量动态缩放的东西。

非常感谢您的帮助！

编辑：尽管在其他地方稍有不同的情况下问了同样的问题，但它有多个答案，没有一个被标记为解决问题。

2 个答案:

答案 0 :(得分：7)

rData[idx[-1] & idx[-length(idx)], , drop = FALSE] # Data #3 a #4 3 #5 3 #11 b #12 3 #13 3 #19 c #20 2 #21 3 和theme(aspect.ratio = 1)似乎有用。

space = 'free'

enter image description here

答案 1 :(得分：3)

这可能不是一个完美的答案，但是无论如何我都会尝试一下。基本上，使用基本ggplot很难做到这一点，因为-正如您提到的-coord_fixed()或theme(aspect.ratio = ...)不能很好地应用于构面。

我将建议的第一个解决方案是使用gtables以编程方式设置面板的宽度以匹配x轴上的变量数量：

plot_likeliness_gtable <- function(town_property_table){
  g <- ggplot(town_property_table, aes(Property, Town)) +
    geom_tile(aes(fill = Property_value, width=.9, height=.9)) +
    theme_classic() +
    theme(axis.text.x = element_text(angle = 90, hjust = 1, vjust=0.5),
          strip.text.y = element_text(angle = 0)) +
    scale_fill_manual(values = Property_col_vector) +
    facet_grid(Country ~ .,
               scale = 'free_y', space = "free_y")
  # Here be the gtable bits
  gt <- ggplotGrob(g)
  # Find out where the panel is stored in the x-direction
  panel_x <- unique(gt$layout$l[grepl("panel", gt$layout$name)])[1]
  # Set that width based on the number of x-axis variables, plus 0.2 because
  # of the expand arguments in the scales
  gt$widths[panel_x] <- unit(nlevels(droplevels(town_property_table$Property)) + 0.2, "null")
  # Respect needs to be true to have 'null' units match in x- and y-direction
  gt$respect <- TRUE
  return(gt)
}

可以通过以下方式工作：

library(grid)
x <- plot_likeliness_gtable(prop)
grid.newpage(); grid.draw(x)

并给出以下情节：

enter image description here

这一切都工作得很好，但是在这一点上，讨论使用gtables而不是ggplot对象的一些缺点可能是一件好事。首先，您无法再使用ggplot对其进行编辑，因此无法添加其他+ geom_myfavouriteshape()或类似的内容。您仍然可以在gtable / grid中编辑部分情节。其次，它具有古怪的grid.newpage(); grid.draw()语法，需要网格库。第三，我们有点依靠ggplot刻面来正确设置y方向面板的高度（在您的示例中为2.2和1.2 null-units），但这可能并不适合所有情况。从好的方面来看，您仍在以灵活的空单位定义尺寸，因此它可以在您使用的任何绘图设备上很好地缩放。

我将提出的第二种解决方案对于许多人来说可能有点笨拙，但是它消除了使用gtables的前两个缺点。不久前，我在刻面时遇到奇怪的面板尺寸问题，因此我写了these functions来设置面板尺寸。这些功能与我的个人休闲包的其余部分非常独立，因此您只需将它们复制粘贴到R会话中即可。这样做的本质是从正在制作的任何绘图中复制面板绘图功能，并将其包装在一个新功能中，该功能将面板尺寸设置为一些预定义的数字。但是，必须在任何构面函数之后调用它。它将像这样工作：

plot_likeliness_forcedsizes <- function(town_property_table){
  g <- ggplot(town_property_table, aes(Property, Town)) +
    geom_tile(aes(fill = Property_value, width=.9, height=.9)) +
    theme_classic() +
    theme(axis.text.x = element_text(angle = 90, hjust = 1, vjust=0.5),
          strip.text.y = element_text(angle = 0)) +
    scale_fill_manual(values = Property_col_vector) +
    facet_grid(Country ~ .,
               scale = 'free_y', space = "free_y") +
    force_panelsizes(cols = nlevels(droplevels(town_property_table$Property)) + 0.2,
                     respect = TRUE)
  return(g)
}

myplot <- plot_likeliness_forcedsizes(prop)
myplot

enter image description here

尽管它仍然依靠ggplot正确设置y方向的高度，但是如果出现问题，您可以在force_panelsizes()内覆盖它们。

希望这有帮助，祝您好运！

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