[R] problems subsetting

[Ivan Calandra]

Hi,

I got a bit lost with your explanation for your second problem. A 
reproducible example would DEFINITELY help to understand what you have 
and what you're trying to get.

For your first problem
subset1 <- summarystats[summarystats$Class == 1 & summarystats$Type == 1 
& summarystats$Category == 1, ]
should work.
If not, maybe looking at str(summarystats) could help you figure out 
what the problem is (or could be)

By the way in
summarystats<-as.data.frame(read.csv(file=f_summary))
as.data.frame() is useless since read.csv() outputs a data.frame

For your second problem, it's difficult for me to understand anything 
because I don't know what summarystats$Dataset is. Could there be a 
problem with factors here?

HTH,
Ivan



Le 11/18/2010 15:39, Martin Tomko a écrit :
> Dear all,
> I have searched the forums for an answer - and there is plenty of 
> questions along the same line - but none of the paproaches shown 
> worked to my problem:
>
> I have a data frame that I get from a csv:
>
> summarystats<-as.data.frame(read.csv(file=f_summary));
>
> where I have the columns Dataset, Class, Type, Category,..
> Problem1:  I want to find a subset of this frame, based on values in 
> multiple columns
> What I do currently is:
>
> subset1 <- summarystats
> subset1<-subset1[subset1$Class == 1,]
> subset1<-subset1[subset1$Type == 1,]
> subset1<-subset1[subset1$Category == 1,]
>
> Now, this works, but is UGLY! I tried using "&&" or "&" , for isntance 
> : subset1<-subset1[ (subset1$Class == 1)&& (subset1$Category == 1),]
> but it returns an empty data frame.
>
> Anyway, the main problem is
> Problem2:
> I have a second data frame - a square matrix (rownames == colnames), 
> distm:
>
> distm<-read.table(file=f_simmatrix, sep = ",");
> what I want is select ONLY the columns and rows entries matching the 
> above subset1:
>
> subset2<-distm[subset1$Dataset,subset1$Dataset] returns a matrix of 
> correct size, but with incorrect entries (established by visual 
> inspection).
>
> this is the same as:
> selectedrows<-as.vector(subset1$Dataset)
> subset2<-distm[selectedrows,selectedrows]
>
> also verified using:
> rownames(subset2)%in% selectedrows
>  [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE 
> FALSE
> [13] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE 
> FALSE
> [25] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE 
> FALSE
> [37] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
>
> What am I missing?
>
> Thanks
> Martin
>
> ______________________________________________
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> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. Säugetiere
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calandra at uni-hamburg.de

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