eitsupi commented on issue #34589: URL: https://github.com/apache/arrow/issues/34589#issuecomment-1472233438
Is this perhaps related to the need to skip the header row when specifying schema in `read_csv_arrow`? https://arrow.apache.org/docs/r/reference/read_delim_arrow.html#ref-examples For CSV files, `col_types` should be used to change the type of a particular column. ``` r readr::readr_example("mtcars.csv") |> arrow::read_csv_arrow(schema = arrow::schema(cyl = arrow::utf8())) #> Error: #> ! Invalid: CSV parse error: Expected 1 columns, got 11: "mpg","cyl","disp","hp","drat","wt","qsec","vs","am","gear","carb" #> Backtrace: #> ▆ #> 1. └─arrow (local) `<fn>`(...) #> 2. └─base::tryCatch(...) #> 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) #> 7. └─rlang::abort(msg, call = call) readr::readr_example("mtcars.csv") |> arrow::open_dataset(schema = arrow::schema(cyl = arrow::utf8()), format = "csv") |> dplyr::collect() #> Error in `compute.Dataset()`: #> ! Invalid: Could not open CSV input source '/usr/local/lib/R/site-library/readr/extdata/mtcars.csv': Invalid: CSV parse error: Row #1: Expected 1 columns, got 11: "mpg","cyl","disp","hp","drat","wt","qsec","vs","am","gear","carb" #> Backtrace: #> ▆ #> 1. ├─dplyr::collect(...) #> 2. └─arrow:::collect.Dataset(...) #> 3. ├─arrow:::collect.ArrowTabular(compute.Dataset(x), as_data_frame) #> 4. │ └─base::as.data.frame(x, ...) #> 5. └─arrow:::compute.Dataset(x) #> 6. └─base::tryCatch(...) #> 7. └─base (local) tryCatchList(expr, classes, parentenv, handlers) #> 8. └─base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]]) #> 9. └─value[[3L]](cond) #> 10. └─arrow:::augment_io_error_msg(e, call, schema = schema()) #> 11. └─rlang::abort(msg, call = call) readr::readr_example("mtcars.csv") |> arrow::read_csv_arrow(col_types = arrow::schema(cyl = arrow::utf8())) #> # A tibble: 32 × 11 #> mpg cyl disp hp drat wt qsec vs am gear carb #> <dbl> <chr> <dbl> <int> <dbl> <dbl> <dbl> <int> <int> <int> <int> #> 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 readr::readr_example("mtcars.csv") |> arrow::open_dataset(col_types = arrow::schema(cyl = arrow::utf8()), format = "csv") |> dplyr::collect() #> # A tibble: 32 × 11 #> mpg cyl disp hp drat wt qsec vs am gear carb #> <dbl> <chr> <dbl> <int> <dbl> <dbl> <dbl> <int> <int> <int> <int> #> 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 ``` <sup>Created on 2023-03-16 with [reprex v2.0.2](https://reprex.tidyverse.org)</sup> If the schema option is used for Parquet files, only that columns will be read. ``` r readr::readr_example("mtcars.csv") |> readr::read_csv(show_col_types = FALSE) |> arrow::write_parquet("test.parquet") arrow::open_dataset("test.parquet", schema = arrow::schema(cyl = arrow::utf8())) |> dplyr::collect() #> # A tibble: 32 × 1 #> cyl #> <chr> #> 1 6 #> 2 6 #> 3 4 #> 4 6 #> 5 8 #> 6 6 #> 7 8 #> 8 4 #> 9 4 #> 10 6 #> # … with 22 more rows ``` <sup>Created on 2023-03-16 with [reprex v2.0.2](https://reprex.tidyverse.org)</sup> -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
