CODEWITHSUNDEEP
rfunctiondataframesubset
rnorouzian
rnorouzian

Reputation: 7517

Automatic addition of columns to a data.frame in an R function

In function foo below, argument long accepts a vector of binary T/F input. Given the data.frame called out in my function, I want my function to add a column named "long" and populate it with Ts for the T inputs and F for the F inputs from "long" argument. Also, I want my function to add a column named "short" and populate it with Fs for the T inputs, and T for the F inputs from "long" argument.

Here is what I have tried with no success:

foo <- function(d, long){

nm <- if(!missing(long) & long) "long" else if(!missing(long) & !long) "short" # problematic

out <- data.frame(d)

if(!missing(long))out[nm] <- long  ## problematic

return(out)
}

 foo(d = 1:3, long = c(T, F,T))

Upvotes: 1

Views: 36

Answers (1)

Ronak Shah
Ronak Shah

Reputation: 389175

You could do

foo <- function(d, long){
  data.frame(d, long = long, short = !long)
}

foo(d = 1:3, long = c(T, F,T))

#  d  long short
#1 1  TRUE FALSE
#2 2 FALSE  TRUE
#3 3  TRUE FALSE

Or if you want output as "T" and "F" only 

foo <- function(d, long){
   out <- data.frame(d, long = long, short = !long)
   transform(out, long = substr(long, 1, 1), short = substr(short, 1, 1))
}

foo(d = 1:3, long = c(T, F,T))
#  d long short
#1 1    T     F
#2 2    F     T
#3 3    T     F

Upvotes: 1

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