[R] Using Partial Column Matching for Mutate

[Shawn Way]

Frankly, this is great.  I don’t really care if it base or tidy, I just need it to work.

Thank you kindly!

Shawn Way, PE

From: Eric Berger <ericjberger using gmail.com>
Sent: Tuesday, August 06, 2019 8:30 AM
To: Shawn Way <SWay using meco.com>
Cc: r-help using r-project.org
Subject: Re: [R] Using Partial Column Matching for Mutate

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Hi Shawn,
Here is a solution using base R (no dplyr). The only regex appears in the statement to get the common prefixes.

colsPrefixes <- sub("_Planned$","",colnames(gross_test)[ grep("_Planned$",colnames(gross_test))])
f <- function(s) {
  gross_test[,paste(s,"Diff",sep="_")] <<- gross_test[,paste(s,"Actual",sep="_")] - gross_test[,paste(s,"Planned",sep="_")]
}
tmpOut <- sapply(colsPrefixes,f)

HTH,
Eric


On Tue, Aug 6, 2019 at 3:34 PM Shawn Way <SWay using meco.com<mailto:SWay using meco.com>> wrote:
I have a tibble that has a large number of variables and because I'm partial lazy (and I really want to know how to do this), I would like find out if it possible to partial column matching with the mutate function in the tidyverse.

I have a tibble with the following

> gross_test  <- gross_df %>%
+     select(Job,Mfg_Labor_Hrs_Planned,Mfg_Labor_Hrs_Actual,Eng_Labor_Hrs_Planned,Eng_Labor_Hrs_Actual)
> gross_test
# A tibble: 6 x 5
    Job Mfg_Labor_Hrs_Pla~ Mfg_Labor_Hrs_Ac~ Eng_Labor_Hrs_Pl~ Eng_Labor_Hrs_Ac~
* <dbl>              <dbl>             <dbl>             <dbl>             <dbl>
1  9892               950.             1082.               133              302.
2  9893               950.             1082.               133              302.
3  9652               950.             1082.               133              302.
4  9894               950.             1082.               133              302.
5  9652               950.             1082.               133              302.
6  9894               950.             1082.               133              302.
>

The column names follow a pattern of (.+)_Planned and (.+)_Actual and there are a large number of them.  What I would like to do is the following:

mutate(Mfg_Labor_Hrs_Diff= Mfg_Labor_Hrs_Actual- Mfg_Labor_Hrs_Planned)

using a regex.  Something like the following

mutate( $1_Diff = $1_Actual - $1_Planned)

Where $1 was Mfg_Labor_Hrs.  This would iterate over the entire set of columns doing Mfg_Labor_Hrs and then Eng_Labor_Hrs, etc.

Is this even possible or will I need to explicitly write out the mutate for each combination?

Thanks for looking at this.

Shawn Way, P.E.



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