绘制分类变量

Question

我是 R 新手，我按照说明幻灯片进行绘图：

survey[["Program"]] 是数据框中的分类数据列。

> survey[["Program"]]  # returns the Program column as a vector
 [1] "PPM"   "PPM"   "PPM"   "Other" "PPM"   "PPM"   "PPM"   "Other" "PPM"   "Other" "MISM"  "PPM"   "MISM" 
[14] "Other" "PPM"   "PPM"   "PPM"   "PPM"   "PPM"   "Other" "PPM"   "MISM"  "PPM"   "PPM"   "PPM"   "MISM" 
[27] "PPM"   "Other" "Other" "PPM"   "Other"

但是，当我实现 plot(survey[["Program"]]) 时，我得到了错误：

Error in plot.window(...) : need finite 'ylim' values
In addition: Warning messages:
1: In xy.coords(x, y, xlabel, ylabel, log) : NAs introduced by coercion
2: In min(x) : no non-missing arguments to min; returning Inf
3: In max(x) : no non-missing arguments to max; returning -Inf

我不知道为什么我不能得到如图所示的结果。

Answer 1

该绘图命令仅适用于 factor 列。 （嗯，它适用于很多事情，但这里的混乱是因为变量不是一个因素。）比较例如

plot(c('a', 'a', 'b', 'b', 'c'))

Error in plot.window(...) : need finite 'ylim' values
In addition: Warning messages:
1: In xy.coords(x, y, xlabel, ylabel, log) : NAs introduced by coercion
2: In min(x) : no non-missing arguments to min; returning Inf
3: In max(x) : no non-missing arguments to max; returning -Inf

与

plot(factor(c('a', 'a', 'b', 'b', 'c')))

您可以通过调用str(survey) 来检查您的列的类别。您读取数据的方式可能与那些幻灯片所假设的不同。

你可以使用

plot(factor(survey[["Program"]]))

或许

barplot(table(survey[["Program"]]))

得到相同的结果。