In R, Feather cannot read dataframe back if missing or having empty column header

[guojingyu]

In R, when calling read_feather function to load the cache, it could fail with error to ask to name columns, if the original dataframe is missing one, which is quite common for datasets (e.g. no index/rownames header).

The error seems to do with the tibble package in the implementation.

If the column name is required, write_feather should ask for it if missing in the first place; or the implementation should allow missing columns.

Code example to show the bug is as below:

> library(feather) 
> n = c(2, 3, 5) 
> s = c("aa", "bb", "cc") 
> b = c(TRUE, FALSE, TRUE) 
> df = data.frame(n, s, b)
> df
  n  s     b
1 2 aa  TRUE
2 3 bb FALSE
3 5 cc  TRUE
> colnames(df)[1] <- ""
> df
     s     b
1 2 aa  TRUE
2 3 bb FALSE
3 5 cc  TRUE
> write_feather(df, '~/cache/test.feather')
> df2 <- read_feather('~/cache/test.feather')
Error: Column 1 must be named.
Use .name_repair to specify repair.
Run `rlang::last_error()` to see where the error occurred.
>
> rlang::last_error()
<error/rlang_error>
Column 1 must be named.
Use .name_repair to specify repair.
Backtrace:
  1. feather::read_feather("~/cache/test.feather")
  3. tibble:::as_tibble.default(data)
  6. feather:::as.data.frame.feather(value, stringsAsFactors = FALSE)
  9. tibble:::as_tibble.data.frame(x[])
 10. tibble:::as_tibble.list(unclass(x), ..., .rows = .rows, .name_repair = .name_repair)
 11. tibble:::lst_to_tibble(x, .rows, .name_repair, col_lengths(x))
 12. tibble:::set_repaired_names(x, .name_repair)
 17. tibble:::repaired_names(names(x), .name_repair = .name_repair)
 18. tibble:::check_unique(new_name)
Run `rlang::last_trace()` to see the full context.

[wesm]

Is this issue present in the arrow::read_feather function? If so, could you open a JIRA issue?

[guojingyu]

@wesm Thanks for the tip. It works well with arrow::read_feather:

> library(arrow)
> n = c(2, 3, 5) 
> s = c("aa", "bb", "cc") 
> b = c(TRUE, FALSE, TRUE) 
> df = data.frame(n, s, b)
> df
  n  s     b
1 2 aa  TRUE
2 3 bb FALSE
3 5 cc  TRUE
> colnames(df)[1] <- ""
> write_feather(df, '~/cache/test.feather')
> df2 <- read_feather('~/cache/test.feather')
> df2
# A tibble: 3 x 3
     `` s     b    
  <dbl> <fct> <lgl>
1     2 aa    TRUE 
2     3 bb    FALSE
3     5 cc    TRUE 
> df2 <- as.data.frame(read_feather('~/cache/test.feather'))
> df2
     s     b
1 2 aa  TRUE
2 3 bb FALSE
3 5 cc  TRUE