[R] qplot and for loops

Joshua Wiley jwiley.psych at gmail.com
Tue Jul 12 22:43:33 CEST 2011


You actually did the loop correctly.  The problem is that the graphs
were created very quickly so you only see the last one.  One way
around this is to make R wait for user input.  You can turn this on
and off for a particular device using:

par(ask = TRUE)

See ?par for details on this.

To create the various files in a for loop, you actually do not need
this.  You should be able to get by with something like:

png(filename = "Graph%03d.png")
for(i in 1:4){

Hope this helps!


On Tue, Jul 12, 2011 at 12:21 PM, wwreith <reith_william at bah.com> wrote:
> I have 4 columns and 56 rows of made up data that I want to plot as a series
> of bar graphs. The idea is to create one bar graph for each of the 4 columns
> using a for loop. I tried the following command in RStudio and when I type x
> in the console I get just the 4th graph instead of all four graphs. I did
> not define what x is before hand. I was not sure what it would be. Any
> suggestions on how you would properly define x?
> for(i in 1:4){
> qplot(x[i]<-mydata[,i])
> }
> The headers of the columns are Trial.1 Trial.2 Trial.3 and Trial.4. Also
> note that I can easily make any of the four graphs by
> i=1 or i=2, etc.
> qplot(x<-mydata[,i])
> I just need to figure out how to make it loop correctly. The ultimate goal
> would also be to save these graphs to my computer with automatically
> generated file names. Something like test graph1.png, test graph2.png, etc.
> Thanks For The Help!
> --
> View this message in context: http://r.789695.n4.nabble.com/qplot-and-for-loops-tp3663292p3663292.html
> Sent from the R help mailing list archive at Nabble.com.
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Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles

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