[R] qplot and for loops

[David Winsemius]

On Jul 12, 2011, at 3:21 PM, wwreith 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?

Does this work

for(i in 1:4){
   png(file=paste("graph",i,".png". sep="")
   print(qplot(x<-mydata[,i]) )
   dev.off()
}


I'm not so sure about the x<-mydata[,i] part, but you say it's  
working. I would have guess that you should have had particular  
arguments. But then you didn't see fit to show either your data or str  
on data so you get a vague answer to a vague question.


> 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!
>
> --
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>
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David Winsemius, MD
West Hartford, CT