Create plots in a loop using ggplot2

Question

I have to generate 250 plots with the same view.

My example data set:

df <- data.frame(name = c("john","alex","mike","dennis","alex"),
             expenses = c("10","12","15","8","2"),
             type = c("food","rent","rent","food","food"))

I would like bar plots with the expenses for every name in a single plot. The plot for "alex" will look like:

selected.name <- "alex"
df1 <- subset(df, name == selected.name)
ggplot(data = df1, aes(type, expenses)) + geom_bar()

Now I want to use a loop that plots the same plot for every name in the df. I have tried to use a for loop that runs the plot code above as a source file. But I can't pass the name variable to the source file so that it plots the graph for every name. Now I only get one graph out of the for loop.

please specify your question a little more. is your problem that you only get 1 window with 1 graph? than x11() could be the solution. if you want to save pdfs then use pdf(file) print(ggplot(...) dev.off().... — Seb
– Seb, Commented Feb 2, 2012 at 11:52
Hi Seb, thanks for the reply. I want create a plot like the plot I created for the name alex for every other name in df. Without having to manually type in the names. Because in the real data there are 250 names. Hope this helps. — jeroen81
– jeroen81, Commented Feb 2, 2012 at 11:58

Paul Hiemstra · Accepted Answer · 2012-02-02 12:08:02Z

15

To answer your orignal question. To do this using standard R:

doPlot = function(sel_name) {
   dum = subset(df, name == sel_name)
   ggobj = ggplot(data = dum, aes(type, expenses)) + geom_bar()
   print(ggobj)
   ggsave(sprintf("%s.pdf", sel_name))
}
lapply(unique(df$name), doPlot)

In this way you end up with a large number of pdf files called Adam.pdf etc. You could then use pdftk (pdf tool kit) to cat the files together in one document. I would still prefer, a better solution using e.g. facetting or a different type of plot.

Wouldn't it be much better to use facetting? Given your example the code would be:

ggplot(data = df, aes(type, expenses)) + 
   geom_bar() + facet_wrap(~name)

which leads to the following plot:

enter image description here

Maybe for 250 names and more variables, this might be a problem. But I'd look at facetting nonetheless.

edited Feb 2, 2012 at 12:08

answered Feb 2, 2012 at 12:01

Paul Hiemstra

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4 Comments

jeroen81 Over a year ago

Thanks Paul, this is a nice feature. It handy to compare the plots. In the real df there are 250 names and 12 expenses variables. This will generate a very complex plot. I am building a reporting tool that generates all kind of KPIs per employee. And we don't make an comparisons in this report. That why I need all individual plots. The report in generated with Latex/R sweave.

Paul Hiemstra Over a year ago

I added a solution with individual plots in separate pdf files to my answer.

jeroen81 Over a year ago

Thanks Paul, this works perfect for me right now. I can adept the functions further to my needs.

Yu Shen Over a year ago

The key is to have print(ggobj) to get the side effect of plot being displayed, otherwise, there will be no plot displayed.

jeroen81 · Accepted Answer · 2013-12-21 02:00:43Z

2

A collegue just pointed out that using subset in a function is a very bad idea. See ?subset() for more info. So I adapted the anwser of Paul Hiemstra and replaced the subset.

doPlot = function(sel_name) {
   dum <- df[df$name == sel_name,]
   ggobj = ggplot(data = dum, aes(type, expenses)) + geom_bar()
   print(ggobj)
   ggsave(sprintf("%s.pdf", sel_name))
}
lapply(unique(df$name), doPlot)

answered Dec 21, 2013 at 2:00

jeroen81

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