Partial fix for #330

[damonbayer]

Closes #330.

This is not yet complete, but I think it is a good start. The remaining issue is that extraneous NAs in the .value column.

library(tidybayes)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
library(tidyr)
library(waldo)

my_tidy_draws <- 
  expand_grid(.chain = 1:2, .iteration = 1:5) |> 
  mutate(.draw = tidybayes:::draw_from_chain_and_iteration_(.chain, .iteration)) |> 
  mutate(`aa[1]` = rnorm(n()), `aa[2]` = rnorm(n()), `ab[1]` = rnorm(n())) |> 
  tidy_draws()

gather_draws_explicit <- my_tidy_draws |> gather_draws(aa[i], ab[i])

gather_draws_regex <- my_tidy_draws |> gather_draws(`a.*`[i], regex = T)

compare(gather_draws_explicit, gather_draws_regex)
#> `attr(attr(old, 'groups'), 'row.names')`: 1 2 3  
#> `attr(attr(new, 'groups'), 'row.names')`: 1 2 3 4
#> 
#> `attr(old, 'groups')$i`: 1 1 2  
#> `attr(new, 'groups')$i`: 1 1 2 2
#> 
#> `attr(old, 'groups')$.variable`: "aa" "ab" "aa"     
#> `attr(new, 'groups')$.variable`: "aa" "ab" "aa" "ab"
#> 
#> `attr(old, 'groups')$.rows` is length 3
#> `attr(new, 'groups')$.rows` is length 4
#> 
#> `attr(old, 'groups')$.rows[[4]]` is absent
#> `attr(new, 'groups')$.rows[[4]]` is an integer vector (31, 32, 33, 34, 35, ...)
#> 
#> `attr(old, 'row.names')[28:30]`: 28 29 30                      and 3 more...
#> `attr(new, 'row.names')[28:40]`: 28 29 30 31 32 33 34 35 36 37           ...
#> 
#> old vs new
#>             i .chain .iteration .draw .variable        .value
#>   old[27, ] 1      2          2     7        ab  0.3754198033
#>   old[28, ] 1      2          3     8        ab  0.2663837133
#>   old[29, ] 1      2          4     9        ab  0.7981538291
#>   old[30, ] 1      2          5    10        ab  0.6497445085
#> + new[31, ] 2      1          1     1        ab            NA
#> + new[32, ] 2      1          2     2        ab            NA
#> + new[33, ] 2      1          3     3        ab            NA
#> + new[34, ] 2      1          4     4        ab            NA
#> + new[35, ] 2      1          5     5        ab            NA
#> + new[36, ] 2      2          1     6        ab            NA
#> + new[37, ] 2      2          2     7        ab            NA
#> and 3 more ...
#> 
#> `old$i[28:30]`: 1 1 1               and 3 more...
#> `new$i[28:40]`: 1 1 1 2 2 2 2 2 2 2           ...
#> 
#> `old$.chain[28:30]`: 2 2 2               and 3 more...
#> `new$.chain[28:40]`: 2 2 2 1 1 1 1 1 2 2           ...
#> 
#> `old$.iteration[28:30]`: 3 4 5               and 3 more...
#> `new$.iteration[28:40]`: 3 4 5 1 2 3 4 5 1 2           ...
#> 
#> And 3 more differences ...

^{Created on 2025-03-19 with reprex v2.1.1}