创建具有不同间隔宽度且图例级别之间没有间距的离散颜色条

Question

我想重现这个色标ggplot2: (来源)

在过去,我发现创建带有标签的离散色标ggplot2可能很棘手.

这可以完成吗？我最近提出的一个类似但不完全相同的问题就是这个问题.

Answer 1

由于Tjebo的答案,我设法创建绘制一个漂亮的彩条,通过使用被添加到地块的功能cowplot,patchwork或其他类似的包像他的榜样.

这里是:

plot_discrete_cbar = function(
    breaks, # Vector of breaks. If +-Inf are used, triangles will be added to the sides of the color bar
    palette = "Greys", # RColorBrewer palette to use
    colors = RColorBrewer::brewer.pal(length(breaks) - 1, palette), # Alternatively, manually set colors
    direction = 1, # Flip colors? Can be 1 or -1
    spacing = "natural", # Spacing between labels. Can be "natural" or "constant"
    border_color = NA, # NA = no border color
    legend_title = NULL,
    legend_direction = "horizontal", # Can be "horizontal" or "vertical"
    font_size = 5,
    expand_size = 1, # Controls spacing around legend plot
    spacing_scaling = 1, # Multiplicative factor for label and legend title spacing
    width = 0.1, # Thickness of color bar
    triangle_size = 0.1 # Relative width of +-Inf triangles
) {
    require(ggplot2)
    if (!(spacing %in% c("natural", "constant"))) stop("spacing must be either 'natural' or 'constant'")
    if (!(direction %in% c(1, -1))) stop("direction must be either 1 or -1")
    if (!(legend_direction %in% c("horizontal", "vertical"))) stop("legend_direction must be either 'horizontal' or 'vertical'")
    breaks = as.numeric(breaks)
    new_breaks = sort(unique(breaks))
    if (any(new_breaks != breaks)) warning("Wrong order or duplicated breaks")
    breaks = new_breaks
    if (class(colors) == "function") colors = colors(length(breaks) - 1)
    if (length(colors) != length(breaks) - 1) stop("Number of colors (", length(colors), ") must be equal to number of breaks (", length(breaks), ") minus 1")
    if (!missing(colors)) warning("Ignoring RColorBrewer palette '", palette, "', since colors were passed manually")

    if (direction == -1) colors = rev(colors)

    inf_breaks = which(is.infinite(breaks))
    if (length(inf_breaks) != 0) breaks = breaks[-inf_breaks]
    plotcolors = colors

    n_breaks = length(breaks)

    labels = breaks

    if (spacing == "constant") {
        breaks = 1:n_breaks
    }

    r_breaks = range(breaks)

    cbar_df = data.frame(stringsAsFactors = FALSE,
        y = breaks,
        yend = c(breaks[-1], NA),
        color = as.character(1:n_breaks)
    )[-n_breaks,]

    xmin = 1 - width/2
    xmax = 1 + width/2

    cbar_plot = ggplot(cbar_df, aes(xmin=xmin, xmax = xmax, ymin = y, ymax = yend, fill = factor(color, levels = 1:length(colors)))) +
        geom_rect(show.legend = FALSE,
                  color=border_color)

    if (any(inf_breaks == 1)) { # Add < arrow for -Inf
        firstv = breaks[1]
        polystart = data.frame(
            x = c(xmin, xmax, 1),
            y = c(rep(firstv, 2), firstv - diff(r_breaks) * triangle_size)
        )
        plotcolors = plotcolors[-1]
        cbar_plot = cbar_plot +
            geom_polygon(data=polystart, aes(x=x, y=y),
                        show.legend = FALSE,
                        inherit.aes = FALSE,
                        fill = colors[1],
                        color=border_color)
    }
    if (any(inf_breaks > 1)) { # Add > arrow for +Inf
        lastv = breaks[n_breaks]
        polyend = data.frame(
            x = c(xmin, xmax, 1),
            y = c(rep(lastv, 2), lastv + diff(r_breaks) * triangle_size)
        )
        plotcolors = plotcolors[-length(plotcolors)]
        cbar_plot = cbar_plot +
            geom_polygon(data=polyend, aes(x=x, y=y),
                        show.legend = FALSE,
                        inherit.aes = FALSE,
                        fill = colors[length(colors)],
                        color=border_color)
    }

    if (legend_direction == "horizontal") { #horizontal legend
        mul = 1
        x = xmin
        xend = xmax
        cbar_plot = cbar_plot + coord_flip()
        angle = 0
        legend_position = xmax + 0.1 * spacing_scaling
    } else { # vertical legend
        mul = -1
        x = xmax
        xend = xmin
        angle = -90
        legend_position = xmax + 0.2 * spacing_scaling
    }

    cbar_plot = cbar_plot +
        geom_segment(data=data.frame(y = breaks, yend = breaks),
            aes(y=y, yend=yend),
            x = x - 0.05 * mul * spacing_scaling, xend = xend,
            inherit.aes = FALSE) +
        annotate(geom = 'text', x = x - 0.1 * mul * spacing_scaling, y = breaks,
                label = labels,
                size = font_size) +
        scale_x_continuous(expand = c(expand_size,expand_size)) +
        scale_fill_manual(values=plotcolors) +
        theme_void()

    if (!is.null(legend_title)) { # Add legend title
        cbar_plot = cbar_plot +
            annotate(geom = 'text', x = legend_position, y = mean(r_breaks),
                label = legend_title,
                angle = angle,
                size = font_size)
    }

    cbar_plot
}

用法示例:

plot_discrete_cbar(c(1:10))

plot_discrete_cbar(c(0,2,5,10,20, Inf), palette="Reds")

plot_discrete_cbar(c(0,2,5,10,20, Inf), colors=rainbow, legend_direction="vertical", legend_title="A title! WOW!", border_color="red")

plot_discrete_cbar(c(-Inf, -8, -4, -2, -1, 1, 2, 4, 8, Inf), palette="BrBG", legend_title="Precipitation bias (mm/day)")

plot_discrete_cbar(c(-Inf, -8, -4, -2, -1, 1, 2, 4, 8, Inf), palette="BrBG", legend_title="Precipitation bias (mm/day)", spacing="constant")

Answer 2

受此问题中@Henrik的回答启发，一种可能的解决方法是制作一个看起来像图例的图：)

require(ggplot2)
require(cowplot)


values <- c(0,1,2,5,10) # this vector is needed not only for the data frame cbar, but also for plotting
group <- letters[1:5]
diff_values <- c(0, diff(values))
cbar_df <- data.frame(x = 1, y = values, diff_values,group,  stringsAsFactors = FALSE)
#that's for the fake legend

iris2 <- iris #don't want to mess with your iris data set
              #I used iris because you hadn't provided data
iris2$cuts <- cut(iris2$Petal.Length, values) #the already offered 'cut-approach' 


p1  <- ggplot(iris2, aes(Sepal.Length, y = Sepal.Width, color = cuts))+ 
          geom_point() +
          scale_color_brewer("", palette = "Reds")

cbar_plot <- ggplot(cbar_df, aes(x, y = diff_values, fill = c(NA, rev(group[2:5])))) + 
  # I had to do implement this 'fill=' workaround 
  # in creating a new vector introducing an NA, 
  # and I had to flip the fills in order to fit to the scale... 
    geom_col(width = 0.1, show.legend = FALSE)  +
    geom_segment(y = values, yend = values, x = 0.9, xend = 1.05) +
    annotate(geom = 'text', x = 0.85, y = values, label = values) +
  # the numbers are quasi-randomly chosen but define the length of your ticks, obviously
    scale_x_continuous(expand = c(1,1)) + 
  # you might need to play around with the expand argument for the width of your legend
    scale_fill_brewer("", palette = "Reds", direction = -1) +  
  # don't know why you have to flip this again... 
    coord_flip() +
    theme_void()

plot_grid(p1, cbar_plot, nrow = 2)

我的意思是-当然还有很多改进的空间（使图例的图更小等）。但是你觉得呢？

#P.S. 
sessionInfo() 
cowplot_0.9.2 ggplot2_2.2.1

Answer 3

我认为以下答案完全不同，值得第二个答案。ggplot2 在过去的 2 年里发生了巨大的变化（！），现在有了新的函数，例如scale_..._binned，以及特定的梯度创建函数，例如scale_..._fermenter

这使得离散渐变条的创建相当简单。

对于“完整分隔符”而不是刻度，请参阅用户 teunbrands post。

library(ggplot2)

ggplot(iris, aes(Sepal.Length, y = Sepal.Width, fill = Petal.Length))+
  geom_point(shape = 21) +
  scale_fill_fermenter(breaks = c(1:3,5,7), palette = "Reds") + 
  guides(fill = guide_colorbar(
    ticks = TRUE, 
    even.steps = FALSE,
    frame.linewidth = 0.55, 
    frame.colour = "black", 
    ticks.colour = "black",
    ticks.linewidth = 0.3)) +
  theme(legend.position = "bottom")

我今天早些时候发布的另一个选项是创建手动中断并计算颜色需要重复的频率，这涉及到一些代数。它还使用了 Claus Wilke 的修改函数。

library(ggplot2)
#importFrom RColorBrewer brewer.pal

mybreaks <- c(0,1,2,5,10) 

new_breaks <- seq(mybreaks[1], mybreaks[length(mybreaks)], sect_x(mybreaks))
my_lims <- c(mybreaks[1], mybreaks[length(mybreaks)])
rep_times <- (diff(mybreaks)[!is.na(diff(mybreaks))])/sect_x(mybreaks)
mycols <- rep(RColorBrewer::brewer.pal(length(mybreaks)-1, "Reds"), rep_times) 

ggplot(iris, aes(Sepal.Length, y = Sepal.Width, fill = Petal.Length))+
  geom_point(shape = 21) +
  scale_fill_discrete_gradient(limits = my_lims,
    breaks = mybreaks, colors = mycols, bins = length(mycols),
    guide = guide_colourbar(frame.colour = "black", 
                            ticks.colour = "black", # you can also remove the ticks with NA
                            barwidth=20)
  ) +
  theme(legend.position = "bottom")

选项 2 的功能

## from Claus Wilke
discrete_gradient_pal <- function(colours, bins = 5) {
  ramp <- scales::colour_ramp(colours)
  
  function(x) {
    if (length(x) == 0) return(character())
    
    i <- floor(x * bins)
    i <- ifelse(i > bins-1, bins-1, i)
    ramp(i/(bins-1))
  }
}
## modified to "fill" from Claus Wilke
scale_fill_discrete_gradient <- 
  function(..., colours, bins = 5, 
           na.value = "grey50", 
           guide = "colourbar", 
           aesthetics = "fill", colors)  {
    colours <- if (missing(colours)) 
      colors
    else colours
    continuous_scale(
      aesthetics,
      "discrete_gradient",
      discrete_gradient_pal(colours, bins),
      na.value = na.value,
      guide = guide,
      ...
    )
  } 

## /sf/answers/362173451/
decimalplaces <- function(x) {
    if ((x %% 1) != 0) {
      nchar(strsplit(sub('0+$', '', as.character(x)), ".", fixed=TRUE)[[1]][[2]])
    } else {
      return(0)
    }
  }

## find the number by which each element is divisible as an integer
# importFrom numbers divisors
sect_x <- function(x){
  diff_x <- diff(x)[!is.na(diff(x))]
  diff_x <- round(diff_x, 2)
  max_dec <-  max(sapply(diff_x, decimalplaces))
  ## https://math.stackexchange.com/a/3732661/662220
  m_int <- 10^(-1*max_dec)
  x_div <- as.integer(round(diff_x / m_int, 0))
  x_div <- x_div[x_div != 0]
  max_divisor <- max(Reduce(intersect, lapply(x_div, numbers::divisors)))
  fac_div <- m_int * max_divisor
  fac_div
}