Recursively Apply a Function to a List of Data Objects

rapply2d is a recursive version of lapply with three differences to rapply:

  1. data frames (or other list-based objects specified in classes) are considered as atomic, not as (sub-)lists

  2. FUN is applied to all 'atomic' objects in the nested list

  3. the result is not simplified / unlisted.

rapply2d(l, FUN, ..., classes = "data.frame")

Arguments

l

a list.

FUN

a function that can be applied to all 'atomic' elements in l.

...

additional elements passed to FUN.

classes

character. Classes of list-based objects inside l that should be considered as atomic.

Value

A list of the same structure as l, where FUN was applied to all atomic elements and list-based objects of a class included in classes.

Note

The main reason rapply2d exists is to have a recursive function that out-of-the-box applies a function to a nested list of data frames.

For most other purposes rapply, or by extension the excellent rrapply function / package, provide more advanced functionality and greater performance.

Examples

l <- list(mtcars, list(mtcars, as.matrix(mtcars)))
rapply2d(l, fmean)
#> [[1]]
#>        mpg        cyl       disp         hp       drat         wt       qsec 
#>  20.090625   6.187500 230.721875 146.687500   3.596562   3.217250  17.848750 
#>         vs         am       gear       carb 
#>   0.437500   0.406250   3.687500   2.812500 
#> 
#> [[2]]
#> [[2]][[1]]
#>        mpg        cyl       disp         hp       drat         wt       qsec 
#>  20.090625   6.187500 230.721875 146.687500   3.596562   3.217250  17.848750 
#>         vs         am       gear       carb 
#>   0.437500   0.406250   3.687500   2.812500 
#> 
#> [[2]][[2]]
#>        mpg        cyl       disp         hp       drat         wt       qsec 
#>  20.090625   6.187500 230.721875 146.687500   3.596562   3.217250  17.848750 
#>         vs         am       gear       carb 
#>   0.437500   0.406250   3.687500   2.812500 
#> 
#> 
unlist2d(rapply2d(l, fmean))
#>   .id.1 .id.2      mpg    cyl     disp       hp     drat      wt     qsec
#> 1     1    NA 20.09062 6.1875 230.7219 146.6875 3.596562 3.21725 17.84875
#> 2     2     1 20.09062 6.1875 230.7219 146.6875 3.596562 3.21725 17.84875
#> 3     2     2 20.09062 6.1875 230.7219 146.6875 3.596562 3.21725 17.84875
#>       vs      am   gear   carb
#> 1 0.4375 0.40625 3.6875 2.8125
#> 2 0.4375 0.40625 3.6875 2.8125
#> 3 0.4375 0.40625 3.6875 2.8125