在一个条形图中设置轴标签和刻度线的不同位置

Question

我想重新排列/偏移一个条形图的x轴和相关的刻度线。这应该很简单，但我无法找到答案。以下是24个类别的一些示例数据。

xval = c(1:24) 
count = c(0.03,0.03,0.08,0.06,0.11,0.4,0.3,0.5,0.5,0.6,0.4,0.1,0.1,0.4,0.2,0.1,0.06,0.05,0.03,0.02,0.01,0.03,0.01,0.02) 
df = as.data.frame(cbind(xval, count)) 

我可以很容易地生产具有在使用下面的代码条的中点对准刻度标记一个barplot：

mp <- barplot(df$count, space=0, axes=FALSE) 
axis(side=2, pos=-0.2) 
axis(side=1, at =mp, labels=df$xval) 

我也可以移动整个x轴（标签和蜱）与对准的使用下面的杆的外侧（虽然这现在无法掺入最后扎入轴）：

axis(side=1, at =mp-0.5, labels=df$xval) 

虽然我想x轴和相关的刻度线与杆b被对准边界（即在酒吧的任一侧而不是中心的刻度线），我希望X轴标签保持在酒吧中点。有没有简单的方法来实现这一目标？

Answer 1

这是你在找什么？

# create positions for tick marks, one more than number of bars 
at_tick <- seq_len(length(count) + 1) 

# plot without axes 
barplot(count, space = 0, axes = FALSE) 

# add y-axis 
axis(side = 2, pos = -0.2) 

# add x-axis with offset positions, with ticks, but without labels. 
axis(side = 1, at = at_tick - 1, labels = FALSE) 

# add x-axis with centered position, with labels, but without ticks. 
axis(side = 1, at = seq_along(count) - 0.5, tick = FALSE, labels = xval)