rapply to nested list of data frames in R

Question

i have a nested list whose fundamental element is data frames, and i want to traverse this list recursively to do some computation of each data frame, finally to get a neste

Answer 1

Update June 2020:

You can now also use rrapply in the rrapply-package, (an extended version of base rapply). rrapply includes an additional argument dfaslist, which if set to FALSE does not treat data.frames as list-like objects by recursing into their individual columns:

library(rrapply)

L <- list(a = BOD, b = BOD)

## apply f to data.frames 
rrapply(L, f = colSums, dfaslist = FALSE)
#> $a
#>   Time demand 
#>     22     89 
#> 
#> $b
#>   Time demand 
#>     22     89

## apply f to individual columns of data.frames
rrapply(L, f = function(x, .xname) if(.xname == "demand") scale(x) else x)
#> $a
#>   Time     demand
#> 1    1 -1.4108974
#> 2    2 -0.9789900
#> 3    3  0.8998070
#> 4    4  0.2519460
#> 5    5  0.1655645
#> 6    7  1.0725699
#> 
#> $b
#>   Time     demand
#> 1    1 -1.4108974
#> 2    2 -0.9789900
#> 3    3  0.8998070
#> 4    4  0.2519460
#> 5    5  0.1655645
#> 6    7  1.0725699