Closed DyfanJones closed 3 weeks ago
I came across a bug in paws.common that does something similar to list_transpose. https://github.com/paws-r/paws/issues/791#issuecomment-2202681892.
list_transpose
When transposing a list the first element is taken to create the template (if one isn't already provided) https://github.com/tidyverse/purrr/blob/870696c7d9f3208298ea84a36d813ffd28e59e49/R/list-transpose.R#L78 If the first element is empty then list_transpose will return an empty list. Would taking the maximum length be more appropriate to avoid this?
# paws.common original implementation: transpose_orig <- function (x) { if (any(found <- lengths(x) == 0)) { x[found] <- list(rep(list(), length.out = length(x[[1]]))) } .mapply(list, x, NULL) } # paws.common new implementation: transpose_new <- function (x) { lens <- lengths(x) if (any(found <- lens == 0)) { x[found] <- list(rep(list(), length.out = max(lens))) } .mapply(list, x, NULL) } obj <- list( var1 = list(), var2 = c(1,2,3) ) transpose_orig(obj) #> list() transpose_new(obj) #> [[1]] #> [[1]]$var1 #> NULL #> #> [[1]]$var2 #> [1] 1 #> #> #> [[2]] #> [[2]]$var1 #> NULL #> #> [[2]]$var2 #> [1] 2 #> #> #> [[3]] #> [[3]]$var1 #> NULL #> #> [[3]]$var2 #> [1] 3 purrr::list_transpose(obj, simplify = F) #> list()
Created on 2024-07-02 with reprex v2.1.0
I like this idea: it's a simple way to generally improve the default performance of list_transpose().
list_transpose()
If someone tackles this for TDD, it'll need some documentation updates and a test.
I came across a bug in paws.common that does something similar to
list_transpose
. https://github.com/paws-r/paws/issues/791#issuecomment-2202681892.When transposing a list the first element is taken to create the template (if one isn't already provided) https://github.com/tidyverse/purrr/blob/870696c7d9f3208298ea84a36d813ffd28e59e49/R/list-transpose.R#L78 If the first element is empty then
list_transpose
will return an empty list. Would taking the maximum length be more appropriate to avoid this?Created on 2024-07-02 with reprex v2.1.0
Session info
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