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Plotting grouped bar charts in R

Asked 2012-11-03T14:40:59.113
11

I am trying to plot this data in R:

column1  column2  column3
1-2       abc       10
1-2       def       15
1-2       ghi       20
2-3       abc       80
2-3       def       95
2-3       ghi       10
3-4       abc       30
3-4       def       55
3-4       ghi       80

The x axis would be column1 (so 1-2, 2-3 and 3-4 would be present as the x axis), and on y axis, the values in column3 should be plotted for each of the column2 elements. So this would be a "grouped" bar chart essentially.

I am not able to plot this grouped bar chart using R. The code snippet I am using is below:

dataset <- fetch(rs,n=-1)
plot_var <- table(dataset$percentage, dataset$age)
barplot(plot_var, names.arg,
        main="Title of Graph",
        xlab="Column1", col=c("darkblue","red"),
        legend = rownames(plot_var), beside=TRUE)

How do I get this grouped bar chart to display?

r plot bar-chart
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1 Answer

10

I like to use ggplot2 for this kind of task.

#Make the data reproducible:
column1 <- c(rep("1-2", 3), rep("2-3", 3), rep("3-4", 3))
column2 <- gl(3, 1, 9, labels=c("abc", "def", "ghi"))
column3 <- c(10, 15, 20, 80, 95, 10, 30, 55, 80)

d <- data.frame(column1=column1, column2=column2, column3=column3)

require(ggplot2)
ggplot(d, aes(x=column1, y=column3, fill=column2)) + geom_bar(position=position_dodge())

The reason I find this intuitive (after a bit of a learning period) is that you clearly stated what you want on the x and y axes, and we simply tell ggplot that (as well as which variable defines the 'fill' color, and which kind of plot - here, geom_bar - to use.

enter image description here

answered 2012-11-03T20:12:35.560

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