R ggplot stat_summary Inconsistent Results

Question

I plot the average mpg in the mtcar data frame using ggplot. I get several points for each cylinder class denoting the mean value, categorized by the vs variable.

library(ggplot2)
ggplot(mtcars, aes(cyl, mpg)) + geom_point(aes(color = factor(vs)), stat = "summary", fun.y = "mean")

If I overlay these averages on top of the raw data by adding + geom_point (below) the averages differ from what they originally were above. What am I doing wrong? Why aren't the means consistent?

ggplot(mtcars, aes(cyl, mpg)) + geom_point() + geom_point(aes(color = factor(vs)), stat = "summary", fun.y = "mean")

They don't look different to me (although the range of the y scale differs between the two plots, which complicates the comparisons). Can you add plots that show what you're seeing? — aosmith

stackinator stackinator · Accepted Answer · 2017-11-07T16:25:48

How embarassing. I didn't even look at the scale of the Y-axis. Thank you aosmith. There is no inconsistency in stat_summary.

R ggplot stat_summary Inconsistent Results

1 Answers