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  1. Apache Arrow
  2. ARROW-15743

[R] `skip` not connected up to `skip_rows` on open_dataset despite error messages indicating otherwise

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Details

    • Bug
    • Status: Resolved
    • Major
    • Resolution: Fixed
    • None
    • 8.0.0
    • R

    Description

      If I open a dataset of CSVs with a schema, the error message tells me to supply `skip = 1` if my data contains a header row (to prevent it being read in as data), but only skip_rows = 1 actually works.

      
      library(arrow)
      library(dplyr)
      
      td <- tempfile()
      dir.create(td)
      write_dataset(mtcars, td, format = "csv")
      
      schema <- schema(mpg = float64(), cyl = float64(), disp = float64(), hp = float64(), 
          drat = float64(), wt = float64(), qsec = float64(), vs = float64(), 
          am = float64(), gear = float64(), carb = float64())
      
      
      open_dataset(td, format = "csv", schema = schema) %>%
        collect()
      #> Error in `handle_csv_read_error()`:
      #> ! Invalid: Could not open CSV input source '/tmp/RtmppZbpeF/file6cec135ed29c/part-0.csv': Invalid: In CSV column #0: Row #1: CSV conversion error to double: invalid value 'mpg'
      #> /home/nic2/arrow/cpp/src/arrow/csv/converter.cc:550  decoder_.Decode(data, size, quoted, &value)
      #> /home/nic2/arrow/cpp/src/arrow/csv/parser.h:123  status
      #> /home/nic2/arrow/cpp/src/arrow/csv/converter.cc:554  parser.VisitColumn(col_index, visit)
      #> /home/nic2/arrow/cpp/src/arrow/csv/reader.cc:463  arrow::internal::UnwrapOrRaise(maybe_decoded_arrays)
      #> /home/nic2/arrow/cpp/src/arrow/compute/exec/exec_plan.cc:445  iterator_.Next()
      #> /home/nic2/arrow/cpp/src/arrow/record_batch.cc:336  ReadNext(&batch)
      #> /home/nic2/arrow/cpp/src/arrow/record_batch.cc:347  ReadAll(&batches)
      #> ℹ If you have supplied a schema and your data contains a header row, you should supply the argument `skip = 1` to prevent the header being read in as data.
      
      open_dataset(td, format = "csv", schema = schema, skip = 1) %>%
        collect()
      #> Error: The following option is supported in "read_delim_arrow" functions but not yet supported here: "skip"
      
      open_dataset(td, format = "csv", schema = schema, skip_rows = 1) %>%
        collect()
      #> # A tibble: 32 × 11
      #>      mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb
      #>    <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
      #>  1  21       6  160    110  3.9   2.62  16.5     0     1     4     4
      #>  2  21       6  160    110  3.9   2.88  17.0     0     1     4     4
      #>  3  22.8     4  108     93  3.85  2.32  18.6     1     1     4     1
      #>  4  21.4     6  258    110  3.08  3.22  19.4     1     0     3     1
      #>  5  18.7     8  360    175  3.15  3.44  17.0     0     0     3     2
      #>  6  18.1     6  225    105  2.76  3.46  20.2     1     0     3     1
      #>  7  14.3     8  360    245  3.21  3.57  15.8     0     0     3     4
      #>  8  24.4     4  147.    62  3.69  3.19  20       1     0     4     2
      #>  9  22.8     4  141.    95  3.92  3.15  22.9     1     0     4     2
      #> 10  19.2     6  168.   123  3.92  3.44  18.3     1     0     4     4
      #> # … with 22 more rows
      
      

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              thisisnic Nicola Crane
              thisisnic Nicola Crane
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