[R] Read CSV from character vector

[asfimport]

readr::read_csv() lets you read in data from a character vector, useful for (e.g.) taking the results of a system call and reading it in as a data.frame.

> readr::read_csv(c("a,b", "1,2", "3,4"))
# A tibble: 2 x 2
      a     b
  <dbl> <dbl>
1     1     2
2     3     4

One solution would be similar to ARROW-9235, perhaps, treating it as a textConnection.

Another solution is to write to a tempfile.

Reporter: Neal Richardson / @nealrichardson

_{Note: This issue was originally created as ARROW-11441. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
cc @thisisnic

[asfimport]

Weston Pace / @westonpace:
If you can expose the character vector as an Arrow buffer and then wrap it with arrow::io::BufferReader you should be able to read it with the CSV reader.

[asfimport]

Neal Richardson / @nealrichardson:
Weston's suggestion works:

> x <- c("a,b", "1,2", "3,4")
> b <- buffer(charToRaw(paste(x, collapse = "\n")))
> read_csv_arrow(b)
  a b
1 1 2
2 3 4

read_csv_arrow already can read an arrow::Buffer, we just have to put the character vector into a Buffer. There's surely a more efficient way to do that, but this would work.

[asfimport]

Apache Arrow JIRA Bot:
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[eitsupi]

Note that this has not worked since readr 2.0.0.

readr::read_csv(c("a,b", "1,2", "3,4"))
#> Error: 'a,b' does not exist in current working directory ('/tmp/Rtmp5bv5aV/reprex-4864c762e4-bared-pika').

^{Created on 2023-01-19 with reprex v2.0.2}

AsIs I() must be used.

readr::read_csv(I(c("a,b", "1,2", "3,4")))
#> Rows: 2 Columns: 2
#> ── Column specification ────────────────────────────────────────────────────────
#> Delimiter: ","
#> dbl (2): a, b
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 2 × 2
#>       a     b
#>   <dbl> <dbl>
#> 1     1     2
#> 2     3     4

^{Created on 2023-01-19 with reprex v2.0.2}

Perhaps I() could be used here as well to make it do the same?