如何在R语言plot()函数中调整轴标签至更靠近绘图区域？

问题场景 #

使用以下R代码绘制图形时，轴标签与轴的距离过远，甚至出现标签覆盖刻度数字的情况：

plot(x= T38$Variables,
     y= T38$Q5_E_38, type = "b", pch=16, col = "red", 
     xlab = "", ylab = "", yaxt = "n", 
     xaxt= "n", main="RMSE ")
title(xlab = "Variables", line =1.5, cex.lab = 1.5)
title(ylab = "RMSE"     , line =1.5, cex.lab = 1.5 )
axis(2, at= T38$Q5_E_38[37], col="red", cex.axis=0.6)
axis(1, cex.axis=0.6)

解决方案 #

有两种简单的调整方式：

1. 修改title()函数的line参数

line参数控制轴标签距离轴线的行数，数值越小，标签越靠近绘图区域。将原代码中line=1.5改为更小的数值（比如0.8或0.5）即可：

plot(x= T38$Variables,
     y= T38$Q5_E_38, type = "b", pch=16, col = "red", 
     xlab = "", ylab = "", yaxt = "n", 
     xaxt= "n", main="RMSE ")
title(xlab = "Variables", line = 0.8, cex.lab = 1.5)
title(ylab = "RMSE"     , line = 0.8, cex.lab = 1.5 )
axis(2, at= T38$Q5_E_38[37], col="red", cex.axis=0.6)
axis(1, cex.axis=0.6)

2. 在plot()中直接设置标签并调整mgp参数

mgp是一个长度为3的向量，分别控制轴标签、刻度标签、轴线的位置（默认值为c(3,1,0)）。调小第一个元素的值，就能让轴标签更靠近轴线：

plot(x= T38$Variables,
     y= T38$Q5_E_38, type = "b", pch=16, col = "red", 
     xlab = "Variables", ylab = "RMSE", yaxt = "n", 
     xaxt= "n", main="RMSE ",
     mgp = c(2, 1, 0), cex.lab = 1.5)
axis(2, at= T38$Q5_E_38[37], col="red", cex.axis=0.6)
axis(1, cex.axis=0.6)

这里mgp=c(2,1,0)表示轴标签距离轴线2行，刻度标签距离1行，轴线在0行位置，相比默认值大幅拉近了标签与绘图区域的距离。

内容的提问来源于stack exchange，提问作者BabakK