CODEWITHSUNDEEP
rlist
kin182
kin182

Reputation: 403

How to do subtractions in a list in R?

I have a list of 25 data frames. My goal is to do a subtraction of one column from another in each list. For example:

a1 <- list(mtcars[1:5,], mtcars[6:10,])

I have to calculate drat - wt and make a new column to show to results. Like this:

[[1]]
                 mpg cyl disp  hp drat    wt  qsec vs am gear carb Results
Mazda RX4       21.0   6  160 110 3.90 2.620 16.46  0  1    4    4    1.28
Mazda RX4 Wag   21.0   6  160 110 3.90 2.875 17.02  0  1    4    4   1.025

[[2]]
              mpg cyl  disp  hp drat   wt  qsec vs am gear carb Results
Valiant      18.1   6 225.0 105 2.76 3.46 20.22  1  0    3    1   -0.70
Duster 360   14.3   8 360.0 245 3.21 3.57 15.84  0  0    3    4   -0.36

I could not figure it out. Could someone help? Thanks!

Upvotes: 0

Views: 32

Answers (1)

www
www

Reputation: 39154

a2 is a list with all the same data frame in a1 except that one column Results is updated.

a1 <- list(mtcars[1:5,], mtcars[6:10,])

a2 <- lapply(a1, function(dt){
  dt$Results <- dt$drat - dt$wt
  return(dt)})

Upvotes: 1

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