R plot.default 中的 x 轴太短

Question

我的x轴太短了。

d <- data.frame(x = c(120,200,300), y = rep(1,3))

 plot(d$x, 
      d$y,
      xlim = c(min(d$x), max(d$x)),
      axes = FALSE,
      xlab = "",
      ylab = "")

axis(1, lwd = 2)

显然这并不理想。我知道有许多针对单个绘图实例的解决方案。但是，我以编程方式生成了许多具有不同 x 值的此类图表。因此，我需要一个通用且可直接适用于不同 x 值的解决方案。

下面是一些头脑风暴代码：

 #This works but the tick marks are ugly.  I also can't control lwd of axis
 plot(d$x, 
      d$y,
      yaxt="n",
      frame.plot = FALSE,
      xlab = "",
      ylab = "",
      xaxp = c(120, 300, 50)) 

 #this is the solution for this particular case, however, it would not work in general
 plot(d$x, 
      d$y,
      xlim = c(min(d$x)-20, max(d$x)),
      axes = FALSE,
      xlab = "",
      ylab = "")

axis(1, lwd = 2)

有什么想法吗？

Answer 1

这是一个使用 ggplot2 进行绘图的选项。下面的代码将 x 范围设置为数据范围下方和上方最接近的 50 的倍数，并在每 50 的倍数处放置刻度线。不同地块的数据范围。

library(ggplot2)
library(gridExtra)  # For grid.arrange function

xfun 计算最小和最大 x 限制。 tick.dist 设置图表中刻度线之间的距离。默认设置为 50。因此，默认情况下，当 which="min"、xfun returns 小于 value 的 50 的最大倍数时。当which="max"、xfun、returns大于value的50的大倍数时。

xfun = function(value, which, tick.dist=50) {

  # Calculate lower x-limit
  if(which=="min") {
    return(value - value %% tick.dist)
  }

  # Calculate upper x-limit
  if(which=="max") {
    return(value + (tick.dist - value %% tick.dist))
  }
}

现在我们创建一个自定义主题，仅绘制点标记和 x 轴：

my_theme = list(theme_bw(),
                theme(panel.border=element_blank(), 
                      axis.line=element_line(), 
                      axis.line.y=element_blank(),
                      panel.grid.major=element_blank(),
                      panel.grid.minor=element_blank(),
                      axis.ticks.y=element_blank(),
                      axis.text.y=element_blank()),
                labs(y="",x=""))

现在我们为四组不同的 x 值创建绘图，使用 xfun 设置 x 限制。

# Try out various ranges for the x-values
x_vals = c(-23, 56, 80, 123)

# Set distance between ticks and x-axis padding
tick.dist=50
pad = 5

# List to store the plots
p.list=list()

# Create a plot for each element of x_vals
for (i in 1:length(x_vals)) {

  # Create fake data
  d <- data.frame(x=runif(10, x_vals[i], x_vals[i] + 220), y = rep(3,10))  

  # Set x limits
  xmin = xfun(min(d$x), "min", tick.dist) 
  xmax = xfun(max(d$x), "max", tick.dist) 

  # Plot
  p.list[[i]] = ggplot(d, aes(x,y)) +
    geom_point() +
    # Set the exact x-axis range
    coord_cartesian(xlim=c(xmin - pad, xmax + pad)) + 
    # Set major tick values
    scale_x_continuous(breaks=seq(-1000,1000, tick.dist)) +
    my_theme
}

# Plot all the graphs on a single "page"
do.call(grid.arrange, p.list)

Answer 2

这是一种使用基本 R 图形的方法。逻辑类似于 ggplot2 答案。下面的代码将 x 范围设置为数据范围下方和上方最接近的 50 的倍数，并在每 50 的倍数处放置刻度线。不同地块的数据范围。

xfun 计算最小和最大 x 限制。 tick.dist 设置图表中刻度线之间的距离。默认设置为 50。因此，默认情况下，当 which="min"、xfun returns 小于 value 的 50 的最大倍数时。 which="max"、xfun、returns大于value的50的大倍数时。

xfun = function(value, which, tick.dist=50) {

  # Calculate minimum x-limit
  if(which=="min") {
    return(value - value %% tick.dist)
  }

  # Calculate maximum x-limit
  if(which=="max") {
    return(value + (tick.dist - value %% tick.dist))
  }
}

现在我们创建四个样本地块。

par(mfrow=c(2,2))

# Try out various ranges for the x-values
x_vals = c(-23, 56, 80, 123)

# Set distance between tick marks
tick.dist=50

for (i in 1:length(x_vals)) {
  # Create fake data
  d <- data.frame(x=runif(10, x_vals[i], x_vals[i] + 220), y = rep(3,10))  

  # Set x limits and number of tick marks
  xmin = xfun(min(d$x), "min", tick.dist) 
  xmax = xfun(max(d$x), "max", tick.dist) 
  nticks = as.integer((xmax - xmin)/tick.dist)

  # Plot
  plot(d$x, d$y, xaxt="n", yaxt="n", frame.plot = FALSE,
       xlab = "", ylab = "", xlim=c(xmin, xmax)) 

  # xaxp controls location of min and max x-axis tick marks
  #  as well as the total number of tick marks. 
  #  See ?par("xaxp") for more info.
  axis(1, lwd = 2, xaxp = c(xmin, xmax, nticks))
}

R plot.default 中的 x 轴太短

x axis is too short in R plot.default

r

plot

axis