[R] Replace column values in R conditional on values from different column

[Pieter Schoonees]

Or have a look at tapply().

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
> On Behalf Of Pascal Oettli
> Sent: Saturday, October 13, 2012 22:16
> To: GradStudentDD
> Cc: r-help at r-project.org
> Subject: Re: [R] Replace column values in R conditional on values from
> different column
> 
> Hello,
> 
> No need for a loop. "else if" doesn't exist in R. And Health2$CohenM and
> Health2_CohenF have to be created first, in case of a loop
> 
> If Health2$q_5a only have 1 and 2 as possible values, just use "which"
> and "-". And I would suggest to not add new variables in your data frame,
> because you will include some NA. Create 2 new variables, then do your
> different calculations on.
> 
> CohenM <- Health2$CohenSum[w]
> CohenF <- Health2$CohenSum[-w]
> 
> Regards
> Pascal
> 
> 
> Le 12/10/13 20:59, GradStudentDD a écrit :
> > Dear List,
> >
> > I am working on a stats project and have been stumped by the issue of
> > replacing values in a column conditional on values from a different column.
> > I searched the forum and google in general, and was able to put some
> > code together, but it's not working the way it's supposed to... I
> > appreciate any help you can offer! A detailed description of the
> > issue, and the code I came up with, is below.
> >
> > I am trying to separate one variable (CohenSum) into separate values
> > for males and females, in two separate columns, so I can do
> > computations on them (i.e. mean, sd). I tried the code below, but the
> > values I got didn't make sense - the length of the M and F columns
> > should have been about half of the initial column length and NA for
> > the rest (I have about half men and half women in the sample) but
> > instead every cell has values in it, except for the initial NAs. I
> > think R somehow inserted 0 instead of NAs for the gender values which
> > were not supposed to be in that column (i.e. replaced values for females
> with 0 in the male column) but I don't know why.
> >
> > Thanks!!!!!
> >
> > for(i in 1:length(Health2$CohenSum)){
> >    if (Health2$q_5a[i]==1) Health2$CohenM[i] <- Health2$CohenSum[i]
> >    else if (Health2$q_5a[i]==2) Health2$CohenF[i] <- Health2$CohenSum[i]
> >    else Health2$CohenF[i] <- NA
> >    }
> >
> >
> >
> > --
> > View this message in context:
> > http://r.789695.n4.nabble.com/Replace-column-values-in-R-conditional-o
> > n-values-from-different-column-tp4646087.html
> > Sent from the R help mailing list archive at Nabble.com.
> >
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> >
> 
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