Actually while attempting this problem I came across a weird situation where baseR's if() else() is working as expected but neither of ifelse and if_else are working. Let me rephrase the actual problem here.
The values in a vector are to be accumulated over set operation union until unique count reaches >3 and in that case it resets. So for a df say y with a single column a, the expected outcome is-
y <- data.frame(a=c(1, 2, 2, 3, 3, 4, 3, 2, 2, 5, 6, 7, 9, 8))
y
a b
1 1 1
2 2 1, 2
3 2 1, 2
4 3 1, 2, 3
5 3 1, 2, 3
6 4 4
7 3 4, 3
8 2 4, 3, 2
9 2 4, 3, 2
10 5 5
11 6 5, 6
12 7 5, 6, 7
13 9 9
14 8 9, 8
Now the problem is, that base R 's if() else () is working inside purrr::accumulate whereas neither if_else nor ifelse is working! Can anyone elaborate the reasons?
y <- data.frame(a=c(1, 2, 2, 3, 3, 4, 3, 2, 2, 5, 6, 7, 9, 8))
y
#> a
#> 1 1
#> 2 2
#> 3 2
#> 4 3
#> 5 3
#> 6 4
#> 7 3
#> 8 2
#> 9 2
#> 10 5
#> 11 6
#> 12 7
#> 13 9
#> 14 8
library(tidyverse)
#this works
accumulate(y$a, ~if(length(union(.x, .y)) == 4) .y else union(.x, .y))
#> [[1]]
#> [1] 1
#>
#> [[2]]
#> [1] 1 2
#>
#> [[3]]
#> [1] 1 2
#>
#> [[4]]
#> [1] 1 2 3
#>
#> [[5]]
#> [1] 1 2 3
#>
#> [[6]]
#> [1] 4
#>
#> [[7]]
#> [1] 4 3
#>
#> [[8]]
#> [1] 4 3 2
#>
#> [[9]]
#> [1] 4 3 2
#>
#> [[10]]
#> [1] 5
#>
#> [[11]]
#> [1] 5 6
#>
#> [[12]]
#> [1] 5 6 7
#>
#> [[13]]
#> [1] 9
#>
#> [[14]]
#> [1] 9 8
# While these didn't
accumulate(y$a, ~ifelse(length(union(.x, .y)) == 4, .y, union(.x, .y)))
#> [1] 1 1 1 1 1 1 1 1 1 1 1 1 1 1
accumulate(y$a, ~if_else(length(union(.x, .y)) == 4, .y, union(.x, .y)))
#> Error: `false` must be length 1 (length of `condition`), not 2.
Created on 2021-05-14 by the reprex package (v2.0.0)
