ggplot2 : Plot mean with geom_bar

ggplot2 : Plot mean with geom_bar



I have the following data frame:


test2 <- data.frame(groups = c(rep("group1",4), rep("group2",4)),
X2 = c(rnorm(4), rnorm(4)) ,
label = c(rep(1,2),rep(2,2),rep(1,2),rep(2,2)))



and I am plotting the bar graphs for each label per group using:


ggplot(test2, aes(label, X2, fill=as.factor(groups))) +
geom_bar(position="dodge", stat="identity")



enter image description here



However, I am cannot seem to be able to find a stat="mean" so I can plot the means on each bar graph instead of the identity.


stat="mean"



Thanks for any help.






This tutorial provides a good description of how to achieve this: r-bloggers.com/using-r-barplot-with-ggplot2

– seaotternerd
May 12 '15 at 6:29






possible duplicate of Plotting the average values for each level in ggplot2

– seaotternerd
May 12 '15 at 6:32




3 Answers
3



simply use stat = "summary" and fun.y = "mean"


stat = "summary"


fun.y = "mean"


ggplot(test2) +
geom_bar(aes(label, X2, fill = as.factor(groups)),
position = "dodge", stat = "summary", fun.y = "mean")



enter image description here






Wow this is awesome and really elegant. Thanks! Do you happen to know how to get darker colors in a nice way?

– Cauchy
May 12 '15 at 7:00




ggplot2 likes 1 data point for 1 plot point. Create a new data frame with your summary statistics, then plot with stat="identity"


ggplot2


stat="identity"


require(reshape2)
plot.data <- melt(tapply(test2$X2, test2$groups,mean), varnames="group", value.name="mean")

ggplot(plot.data, aes(x=group,y=mean)) + geom_bar(position="dodge", stat="identity")



enter image description here



Try using ggpubr. It creates ggplot2-like charts.


library(ggpubr)

ggbarplot(test2, x = "label", y = "X2",
add = "mean", fill = "groups")



enter image description here



Alternatively, add a facet:


ggbarplot(test2, x = "label", y = "X2",
add = "mean", fill = "groups",
facet.by = "groups")



enter image description here



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