[jira] [Updated] (ARROW-18219) [R] read_csv_arrow fails when a string contains a backslash-escaped quote mark followed by a comma

["Nicola Crane (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-18219?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Nicola Crane updated ARROW-18219:
---------------------------------
    Priority: Critical  (was: Major)

> [R] read_csv_arrow fails when a string contains a backslash-escaped quote mark followed by a comma
> --------------------------------------------------------------------------------------------------
>
>                 Key: ARROW-18219
>                 URL: https://issues.apache.org/jira/browse/ARROW-18219
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: R
>    Affects Versions: 10.0.0
>            Reporter: Danielle Navarro
>            Priority: Critical
>
> `read_csv_arrow()` incorrectly parses CSV files when a string value contains a comma that appears after a backslash-escaped quote mark. Originally noted by Thomas Klebel [https://scicomm.xyz/@tklebel/109270436511066953]
> This is an example that throws the error:
> {code:r}
> x <- tempfile()
> readr::write_lines(
> '
> id,text
> 1,"some text on \\"BLAH
> " and X, and Y also"
> ', x)
> cat(system(paste('cat', x), intern = TRUE), sep = "\n")
> #> 
> #> id,text
> #> 1,"some text on \"BLAH\" and X, and Y also"
> arrow::read_csv_arrow(x, escape_backslash = TRUE)
> #> Error:
> #> ! Invalid: CSV parse error: Expected 2 columns, got 3: 1,"some text on \"BLAH\" and X, and Y also"
> #> Backtrace:
> #> ▆
> #> 1. └─arrow (local) `<fn>`(file = x, escape_backslash = TRUE, delim = ",")
> #> 2. └─base::tryCatch(...) at r/R/csv.R:217:2
> #> 3. └─base (local) tryCatchList(expr, classes, parentenv, handlers)
> #> 4. └─base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
> #> 5. └─value[[3L]](cond)
> #> 6. └─arrow:::augment_io_error_msg(e, call, schema = schema) at r/R/csv.R:222:6
> #> 7. └─rlang::abort(msg, call = call) at r/R/util.R:251:2
> {code}
> <sup>Created on 2022-11-02 with [reprex v2.0.2]([https://reprex.tidyverse.org|https://reprex.tidyverse.org/])</sup>
> This version includes four lines that might potentially error but do not:
> {code:r}
> x <- tempfile()
> readr::write_lines(
> '
> id,text
> 2,"some text on X and Y"
> 3,"some text on X, and Y"
> 4,"some text on \\"BLAH
> "
> 5,"some text on X and Y, and \\"BLAH
> " also"
> ', x)
> cat(system(paste('cat', x), intern = TRUE), sep = "\n")
> #> 
> #> id,text
> #> 2,"some text on X and Y"
> #> 3,"some text on X, and Y"
> #> 4,"some text on \"BLAH\"
> #> 5,"some text on X and Y, and \"BLAH\" also"
> arrow::read_csv_arrow(x, escape_backslash = TRUE)
> #> # A tibble: 4 × 2
> #> id text 
> #> <int> <chr> 
> #> 1 2 "some text on X and Y" 
> #> 2 3 "some text on X, and Y" 
> #> 3 4 "some text on \\BLAH\\\"" 
> #> 4 5 "some text on X and Y, and \\BLAH\\\" also\""
> {code}
> <sup>Created on 2022-11-02 with [reprex v2.0.2]([https://reprex.tidyverse.org|https://reprex.tidyverse.org/])</sup>
> I'm not sure if the problem is R specific. I've partially reproduced the error using reticulate and pyarrow as follows, but notice that this errors at a different point: the pyarrow version appears to fail with the comma preceding the backslash-escaped quote mark:
> {code:r}
> x <- tempfile()
> readr::write_lines(
> '
> id,text
> 1,"some text on X and Y"
> 2,"some text on X, and Y"
> 3,"some text on \\"BLAH
> "
> 4,"some text on X and Y, and \\"BLAH
> " also"
> 5,"some text on \\"BLAH
> " and X, and Y also"
> ', x)
> cat(system(paste('cat', x), intern = TRUE), sep = "\n")
> #> 
> #> id,text
> #> 1,"some text on X and Y"
> #> 2,"some text on X, and Y"
> #> 3,"some text on \"BLAH\"
> #> 4,"some text on X and Y, and \"BLAH\" also"
> #> 5,"some text on \"BLAH\" and X, and Y also"
> csv <- reticulate::import("pyarrow.csv")
> opt <- csv$ParseOptions(escape_char='
> ')
> csv$read_csv(x, parse_options = opt)
> #> Error in py_call_impl(callable, dots$args, dots$keywords): pyarrow.lib.ArrowInvalid: CSV parse error: Expected 2 columns, got 3: 3,"some text on \"BLAH\"
> #> 4,"some text on X and Y, and \"BLAH\" also"
> {code}
> <sup>Created on 2022-11-02 with [reprex v2.0.2]([https://reprex.tidyverse.org|https://reprex.tidyverse.org/])</sup>



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