Provide rbind() and cbind() methods

[krlmlr]

for R >= 4.0.0.

Closes #34.

[krlmlr]

After #890, do we still want to use vec_rbind() here? Should rbind() (and also dplyr::bind_rows() for that matter) call dplyr_row_slice() to support data frame classes with variable-length attributes?

[krlmlr]

Tried that, doesn't work: vec_rbind() does much more, e.g. adjustment of factor levels.

I still wonder what the desired semantics for dplyr_reconstruct() are if nrow(x) != nrow(to) .

[krlmlr]

Docs say "you need to carefully check and think about it", I guess we're fine here.

[hadley]

Just started the revdeps with

library(revdepcheck)

pkgs <- unique(c(cran_revdeps("tidyr"), cran_revdeps("tibble"), cran_revdeps("dplyr")))
cloud_check(revdep_packages = pkgs)

[krlmlr]

Thanks @hadley!

This shows that:

1. The following packages are using rbind() or cbind() in a way that is incompatible with vec_rbind() and vec_cbind(): - dat - designr - ExpertChoice - ggiraph - ggiraphExtra - groupr - heemod - neonstore - prettyglm - RKorAPClient - VarBundle - visR - vlda - wpa
2. All other failing packages might be incompatible with vec_rbind() and vec_cbind(), but they also have failing tests.
3. We don't know anything yet about the packages we failed to check.

Do we have an easy way to send a message to all affected maintainers?

[hadley]

Before we notify the maintainers, I think it would be worth digging into 2-5 of the failures in more detail to see if there's a common underlying cause.

[krlmlr]

We can find the underlying cause by replacing rbind() with vctrs::vec_rbind() one by one in the packages, same with cbind().

egor rbind() failure has the following underlying reason:

library(tibble)

rbind(tibble(.b = integer()), tibble(a = 1, .b = 2))
#> # A tibble: 1 × 2
#>       a    .b
#>   <dbl> <dbl>
#> 1     1     2
vctrs::vec_rbind(tibble(.b = integer()), tibble(a = 1, .b = 2))
#> # A tibble: 1 × 2
#>      .b     a
#>   <dbl> <dbl>
#> 1     2     1

^{Created on 2021-10-20 by the reprex package (v2.0.1)}

[krlmlr]

ypr checks for row names in its tests:

library(tibble)

row.names(rbind(tibble(a = 1), data.frame(a = c(x = 2))))
#> [1] "1" "x"
row.names(vctrs::vec_rbind(tibble(a = 1), data.frame(a = c(x = 2))))
#> [1] "...1" "x"

^{Created on 2021-10-20 by the reprex package (v2.0.1)}

[krlmlr]

twoxtwo binds a vector and a tibble:

library(tibble)

base::rbind.data.frame(c("a", "b"), tibble(a = 1, b = 2))
#> # A tibble: 2 × 2
#>   a     b    
#>   <chr> <chr>
#> 1 a     b    
#> 2 1     2
vctrs::vec_rbind(c("a", "b"), tibble(a = 1, b = 2))
#> New names:
#> * `` -> ...1
#> * `` -> ...2
#> # A tibble: 2 × 4
#>   ...1  ...2      a     b
#>   <chr> <chr> <dbl> <dbl>
#> 1 a     b        NA    NA
#> 2 <NA>  <NA>      1     2

^{Created on 2021-10-20 by the reprex package (v2.0.1)}

[krlmlr]

optimall calls cbind() with a vector and relies on auto-naming:

library(tibble)

x <- 2

base:::cbind.data.frame(tibble(a = 1), x)
#>   a x
#> 1 1 2
vctrs::vec_cbind(tibble(a = 1), x)
#> New names:
#> * `` -> ...2
#> # A tibble: 1 × 2
#>       a  ...2
#>   <dbl> <dbl>
#> 1     1     2

^{Created on 2021-10-20 by the reprex package (v2.0.1)}

[krlmlr]

Especially the last issue looks like a serious incompatibility:

library(tibble)

x <- 2

base:::cbind.data.frame(tibble(a = 1), x)
#>   a x
#> 1 1 2
vctrs::vec_cbind(tibble(a = 1), x)
#> New names:
#> * `` -> ...2
#> # A tibble: 1 × 2
#>       a  ...2
#>   <dbl> <dbl>
#> 1     1     2

^{Created on 2021-10-20 by the reprex package (v2.0.1)}

I suggest the following:

• separate the changes to rbind() from the changes to cbind()
• support fine-grained enabling and disabling of the new functionality
  • cbind() calls tbl_cbind() which is provided by us and exported, if and only if getOption("tibble.cbind_base") is unset or FALSE
  • otherwise cbind() forwards to NextMethod()
  • in tbl_cbind() we check another option, "tibble.cbind_trace", which prints diagnostics on the input and output of these methods
  • similarly for rbind()
• depending on the new revdepcheck results, we might need to take action and tweak tbl_rbind() and tbl_cbind()
• we schedule the change for tibble 4.0.0 and warn the maintainers well ahead of the release

This allows us and the maintainers to easier locate the source of a problem: we can gradually replace cbind() by tbl_cbind() and set option(tibble.cbind_base = TRUE), and/or set options(Tibble.cbind_trace = TRUE) to understand problems.

tbl_rbind(), tbl_cbind() and the options are implemented in this PR.

Do we still want to pursue this path?

[DavisVaughan]

The story with rbind() and cbind() is growing so complex, I'd almost prefer to just leave them as they are, and advise people to use vec_rbind() and vec_cbind() directly instead. Two reasons I feel this is reasonable:

• I imagine most data analysis focused users will already be using the tidyverse and bind_rows/cols() directly, so they wouldn't need this
• I imagine that package developers who might not want to depend on dplyr would be fine depending on vctrs, since tibble already Imports it.

I think the important point is the second one. We now at least have a good answer for people who want to be able to combine tibbles without relying on dplyr (i.e. use vctrs).

[DavisVaughan]

Seems like you could link to vec_rbind() in the tibble::add_row() documentation. i.e. "If you would like to row bind multiple data frames together, see..."

Similar for vec_cbind() and tibble::add_column().

[krlmlr]

Agreed, it's a lot of work for limited gain. Depends on how badly we want to support rbind() and cbind(), i.e. if we gain other advantages by overriding these methods for tibbles.