[R] conditional filling of data.frame - improve code

Andrew Simmons @kw@|mmo @end|ng |rom gm@||@com
Thu Mar 10 17:15:17 CET 2022

I think what you're looking for is match.
It returns the indexes of the output where the inputs can be matched, and
has a nomatch argument incase no match is found, usually people would use
NA or 0 for nomatch.

On Thu, Mar 10, 2022, 10:51 Ivan Calandra <ivan.calandra using rgzm.de> wrote:

> Dear useRs,
> I would like to improve my ugly (though working) code, but I think I
> need a completely different approach and I just can't think out of my box!
> I have some external information about which sample(s) belong to which
> experiment. I need to get that manually into R (either typing directly
> in a script or read a CSV file, but that makes no difference):
> exp <- list(ex1 = c("sample1-1", "sample1-2"), ex2 = c("sample2-1",
> "sample2-2" , "sample2-3"))
> Then I have my data, only with the sample IDs:
> mydata <- data.frame(sample = c("sample2-2", "sample2-3", "sample1-1",
> "sample1-1", "sample1-1", "sample2-1"))
> Now I want to add a column to mydata with the experiment ID. The best I
> could find is that:
> for (i in names(exp)) mydata[mydata[["sample"]] %in% exp[[i]],
> "experiment"] <- i
> In this example, the experiment ID could be extracted from the sample
> IDs, but this is not the case with my real data so it really is a matter
> of matching. Of course I also have other columns with my real data.
> I'm pretty sure the last line (with the loop) can be improved in terms
> of readability (speed is not an issue here). I have close to no
> constraints on 'exp' (here I chose a list, but anything could do), the
> only thing that cannot change is the format of 'mydata'.
> Thank you in advance!
> Ivan
> --
> Dr. Ivan Calandra
> Imaging lab
> RGZM - MONREPOS Archaeological Research Centre
> Schloss Monrepos
> 56567 Neuwied, Germany
> +49 (0) 2631 9772-243
> https://www.researchgate.net/profile/Ivan_Calandra
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