conditional filling of data.frame - improve code

Thank you Jeff and Tim for your ideas. Indeed merge/join is probably the 
nicest way. Still, the code becomes much longer because I need more 
formatting of the input and output objects than with my ugly for loop :)

Cheers,
Ivan

--
Dr. Ivan Calandra
Imaging lab
RGZM - MONREPOS Archaeological Research Centre
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Le 10/03/2022 ? 18:58, Ebert,Timothy Aaron a ?crit?:

You could try some of the "join" commands from dplyr.
https://dplyr.tidyverse.org/reference/mutate-joins.html
https://statisticsglobe.com/r-dplyr-join-inner-left-right-full-semi-anti


Regards,
Tim
-----Original Message-----
From: R-help <r-help-bounces at r-project.org> On Behalf Of Jeff Newmiller
Sent: Thursday, March 10, 2022 11:25 AM
To: r-help at r-project.org; Ivan Calandra <ivan.calandra at rgzm.de>; R-help <r-help at r-project.org>
Subject: Re: [R] conditional filling of data.frame - improve code

[External Email]

Use merge.

expts <- read.csv( text =
"expt,sample
ex1,sample1-1
ex1,sample1-2
ex2,sample2-1
ex2,sample2-2
ex2,sample2-3
", header=TRUE, as.is=TRUE )

mydata <- data.frame(sample = c("sample2-2", "sample2-3", "sample1-1", "sample1-1", "sample1-1", "sample2-1"))

merge( mydata, expts, by="sample", all.x=TRUE )


On March 10, 2022 7:50:23 AM PST, Ivan Calandra <ivan.calandra at 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

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