[R] changing column labels for data frames inside a list

[Sven E. Templer]

On 30 March 2015 at 17:19, Vikram Chhatre <crypticlineage at gmail.com> wrote:

> First of all, thank you for all the quick replies.  Here is a solution that
> worked for me.
>
> mylist2 <- lapply(mylist, function(e){colnames(e) <- paste0('pop',1:12);
> return(e)})
>
> > head(mylist2[[1]])
>         pop1  pop2  pop3  pop4  pop5  pop6  pop7  pop8  pop9 pop10 pop11
> pop12
> L0001.1 0.60 0.500 0.325 0.675 0.600 0.500 0.500 0.375 0.550 0.475 0.350
> 0.275
> L0001.2 0.40 0.500 0.675 0.325 0.400 0.500 0.500 0.625 0.450 0.525 0.650
> 0.725
>
> While we are at this, I wanted to create a 13th column in each data frame
> for average of each row.
>

For new problems you should use a new topic.


>
> # Calculate average
> myavg <- lapply(mylist2, function(e) rowSums(mylist2)/12)
>
> # Attach to the main data frame
> mylist3 <- cbind(mylist2, myavg)
>

> This does not work the way I imagined it would.  The myavg vector is
> attached directly to mylist2, not to individual dataframes within.
>
>
But it works as expected (read ?cbind).
You try to cbind two lists (myavg and mylist2).
You want to cbind each list object (the data.frames) with each rowSums
output.
So, use cbind within your first lapply.

p.s. Is it a standard convention to always copy the reply to the last
> person who responded?
>

I guess it depends on which answer you refer to.


>
> On Mon, Mar 30, 2015 at 10:56 AM, Sven E. Templer <sven.templer at gmail.com>
> wrote:
>
> > On 30 March 2015 at 16:47, Sarah Goslee <sarah.goslee at gmail.com> wrote:
> >
> > > colnames(e) <- paste0('pop',1:12)
> > >
> > > isn't a function and doesn't return anything.
> > >
> >
> > But
> > function(e){colnames(e) <- paste0('pop', 1:2)}
> > is a function and it returns something (the last evaluated expression! -
> > here the paste0 return):
> >
> > > mylist2 <- lapply(mylist, function(e){colnames(e) <- paste0('pop',
> 1:2)})
> > > mylist2
> > [[1]]
> > [1] "pop1" "pop2"
> >
> > [[2]]
> > [1] "pop1" "pop2"
> >
> > [[3]]
> > [1] "pop1" "pop2"
> >
> >  from ?return:
> >
> > If the end of a function is reached without calling return, the value of
> > the last evaluated expression is returned.
> >
> > >
> > > > mylist <- list(
> > > + data.frame(a = runif(10), b = runif(10)),
> > > + data.frame(c = runif(10), d = runif(10)),
> > > + data.frame(e = runif(10), f = runif(10)))
> > > > mylist2 <- lapply(mylist, function(e){colnames(e) <- paste0('pop',
> > 1:2);
> > > e})
> > > > colnames(mylist2[[1]])
> > > [1] "pop1" "pop2"
> > >
> > > Sarah
> > >
> > > On Mon, Mar 30, 2015 at 9:54 AM, Vikram Chhatre
> > > <crypticlineage at gmail.com> wrote:
> > > >> summary(mygenfreqt)
> > > >                   Length Class  Mode
> > > > dat1.str 59220  -none- numeric
> > > > dat2.str 59220  -none- numeric
> > > > dat3.str 59220  -none- numeric
> > > >
> > > >> head(mylist[[1]])
> > > >            1     2     3     4     5     6     7     8     9    10
> > 11
> > > >  12
> > > > L0001.1 0.60 0.500 0.325 0.675 0.600 0.500 0.500 0.375 0.550 0.475
> > 0.350
> > > > 0.275
> > > > L0001.2 0.40 0.500 0.675 0.325 0.400 0.500 0.500 0.625 0.450 0.525
> > 0.650
> > > > 0.725
> > > >
> > > > I want to change 1:12 to pop1:pop12
> > > >
> > > > mylist<- lapply(mylist, function(e) colnames(e) <-
> paste0('pop',1:12))
> > > >
> > > > What this is doing is replacing the data frames with just names
> > > > pop1:pop12.  I just want to replace the column labels.
> > > >
> > > > Thanks for any suggestions.
> > > >
> > >
> > > --
> > > Sarah Goslee
> > > http://www.functionaldiversity.org
> > >
> > > ______________________________________________
> > > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > > https://stat.ethz.ch/mailman/listinfo/r-help
> > > PLEASE do read the posting guide
> > > http://www.R-project.org/posting-guide.html
> > > and provide commented, minimal, self-contained, reproducible code.
> > >
> >
> >         [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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