[R] How to aggregate values in corresponding dataframes

[lily li]

Each dataframe is a gridded file, so I want to add the values at
corresponding grid cells from all the dataframes.

On Mon, Mar 25, 2019 at 6:22 PM Rui Barradas <ruipbarradas using sapo.pt> wrote:

> Sorry, I forgot to ask something.
>
> When you say you want to add the df's values, what exactly do you mean?
> All of the values, by row, by column, what?
>
> Rui Barradas
>
> Às 10:20 de 25/03/2019, Rui Barradas escreveu:
> > Hello,
> >
> > Maybe something like this?
> > Note that you *never* need to set header = FALSE, it already is the
> > default of read.table. You would have to with read.csv.
> >
> >
> > old_dir <- setwd("~/directory")
> > f1990 <- list.files(pattern = "^199.*\\.txt$")
> > r1990 <- lapply(f1990, read.table)
> > setwd(old_dir)
> >
> >
> > Hope this helps,
> >
> > Rui Barradas
> >
> >
> > Às 08:30 de 25/03/2019, lily li escreveu:
> >> Hi R users,
> >>
> >> I have multiple dataframes in a directory, and with the same postfix
> >> ".txt". Each dataframe is a gridded file with just values, but each
> value
> >> represents one grid cell. There are many years, and each year has 12
> >> months, so there are many such files. For each year, I want to read the
> >> corresponding year's files and add the values of the dataframes, but I
> >> don't know how to do that. For example, the file names are
> >> 1990_file01.txt
> >> 1990_file02.txt
> >> ...
> >> 1990_file12.txt
> >> 1991_file01.txt
> >> ...
> >> 1991_file12.txt
> >> ...
> >>
> >> And my code is like this:
> >> f1990 = list.files("~/directory", pattern = "^1990(.*).txt$")
> >> for(i in 1:length(f1990)){
> >> r1990 = read.table(paste('~/directory',f1990[i],sep='/'),head=F)
> >> }
> >>
> >> Could you provide some help on this? Thanks very much.
> >>
> >>     [[alternative HTML version deleted]]
> >>
> >> ______________________________________________
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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.
> >>
> >
> > ______________________________________________
> > R-help using 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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