r - 使用 ggplot2 的 geom_bar() 查询 - R

Question

我有一个类似的数据框如下：

mapDF <- structure(list(var = c(11L, 3L, 4L, 15L, 19L, 17L, 1L), approvals = c(10.5233545765422, 
67.9809421770218, 9.66394835013545, 2.93736399165075, 3.36787205222721, 
4.0168261757783, 1.50969267664431)), .Names = c("var", "approvals"
), row.names = c(NA, -7L), class = "data.frame")

当我尝试使用上面的数据框创建条形图时：

gplot <- ggplot(mapDF, aes(x= mapDF[1], y= mapDF[2])) + geom_bar()

..我收到以下消息，但RStudio 的“绘图”部分没有显示任何内容：

Don't know how to automatically pick scale for object of type data.frame. Defaulting to continuous
Don't know how to automatically pick scale for object of type data.frame. Defaulting to continuous
Error: stat_bin requires the following missing aesthetics: x

谁能指出我的错误？

Answer 1

将@joran 的评论转化为答案：

ggplot(mapDF, aes(x=var, y=approvals)) + geom_bar(stat="identity")