modify_depth fails when higher levels have NULLs

[gregleleu]

Hi,
modify_depth fails when higher levels have a mix of NULLs and non-NULLs e.g.

> aa <- list(a = NULL, b = list(b1 = NULL, b2 = "hello"))
> aa
$a
NULL

$b
$b$b1
NULL

$b$b2
[1] "hello"


> modify_depth(aa, 
+              .depth = 2,
+              is.character,
+              .ragged = TRUE
+              )
Error in .x[[i]] : subscript out of bounds

I would expect

$a
NULL

$b
$b$b1
NULL

$b$b2
[1] "TRUE"

Works when the first level has no NULLs

> aa <- list(a = "hi", b = list(b1 = NULL, b2 = "hello"))
> aa
$a
[1] "hi"

$b
$b$b1
NULL

$b$b2
[1] "hello"


> modify_depth(aa, 
+              .depth = 2,
+              is.character,
+              .ragged = TRUE
+              )
$a
[1] "TRUE"

$b
$b$b1
[1] FALSE

$b$b2
[1] TRUE

And btw why is the upper level type-stable, and not the lower level ?

And why is it the same when .ragged = FALSE ?

> modify_depth(aa, 
+              .depth = 2,
+              is.character
+              )
$a
[1] "TRUE"

$b
$b$b1
[1] FALSE

$b$b2
[1] TRUE

Thanks!

[hadley]

Reperex:

library(purrr)
aa <- list(a = NULL, b = list(b1 = NULL, b2 = "hello"))
modify_depth(aa, .depth = 2, is.character, .ragged = TRUE)
#> Error in .x[[i]]: subscript out of bounds

^{Created on 2022-08-25 by the reprex package (v2.0.1)}