减少 plot() R 中绘制点之间的空间

Question

我有一个看似非常简单的问题，但找不到答案。我已经创建了这个图，只是想让两个外部点更靠近中间。

#Sample code
    x=1:3
    y=c(-50,-70,-120)
plot(x,y)

我已经通过设置 par(mar=c(5.1,9,4.1,9)) 尝试了这个reducing the space between plotted points in plot( x, y) type=n，但这只会改变绘图的比例，但不会改变相对距离。我对 qplot 有同样的问题。请注意，我想使用axis() 设置我自己的刻度标签。

Answer 1

您可以在 x 轴点的任一侧添加一些填充。例如，这里有一个函数负责填充并控制轴中断的数量：

x=1:3
y=c(-50,-70,-120)

# Function to plot with padding on either side of x-axis points.
# Padding is set with pad parameter equal to a fraction of the range of the x values.
# The ... argument allows you to pass additional arguments to plot, such as
#  xlab, main, ylim, col, etc.
pad_plot = function(x, y, pad=0.4, n=5, ...) {

  # Get range of x values
  xrng = diff(range(x))

  # Plot, but don't include axis, so that we can directly control the axis labels.
  # Otherwise, plot will add axis breaks at 0, 4, and other values outside the 
  #  range of the data.
  plot(x,y, xlim = range(x) + c(-1,1)*pad*xrng, xaxt="n", ...)

  # Add axis breaks and labels
  axis(side=1, at=pretty(x, n))
}

par(mfrow=c(2,2))
pad_plot(x,y)
pad_plot(x,y, n=2, main="This is a title", pch=16, col="red")
pad_plot(x,y,pad=0.2, n=8)
pad_plot(x,y, pad=2)