使用ggplot2在r中绘制data.frame的列

Question

I have a data.frame 'test' that's similar to this:

names  mean
a        1   
b        2
c        3
d        4 

I want to draw a boxplot only for the 'mean' column. How can I do this using ggplot2?

I tried this but it won't work:

qplot(mean, data=test, geom="boxplot") + geom_jitter() 

Answer 1

The geom_boxplot requires variables for both axes. In your example you have only one variable and you have mapped it to the x variable, because that is the one named first in qplot . If you want to draw only one boxplot (all values belonging to the same group) you should create a variable in the test data.frame that has the same value for each row. This would give you what you are after.

test <- data.frame(
  names = letters[1:4],
  mean = 1:4,
  x = "group")

qplot(x, mean, data = test, geom = "boxplot")