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Posted to jira@arrow.apache.org by "András Svraka (Jira)" <ji...@apache.org> on 2021/01/20 16:18:00 UTC
[jira] [Created] (ARROW-11328) Collecting zero columns from a
dataset returns entire dataset
András Svraka created ARROW-11328:
-------------------------------------
Summary: Collecting zero columns from a dataset returns entire dataset
Key: ARROW-11328
URL: https://issues.apache.org/jira/browse/ARROW-11328
Project: Apache Arrow
Issue Type: Bug
Components: R
Affects Versions: 2.0.0, 2.0.1
Reporter: András Svraka
Collecting a dataset with zero selected columns returns all columns of the dataset in a data frame without column names.
{code:r}
library(dplyr)
#>
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#>
#> filter, lag
#> The following objects are masked from 'package:base':
#>
#> intersect, setdiff, setequal, union
library(arrow)
#>
#> Attaching package: 'arrow'
#> The following object is masked from 'package:utils':
#>
#> timestamp
tmp <- tempfile()
write_dataset(mtcars, tmp, format = "parquet")
open_dataset(tmp) %>% select() %>% collect()
#>
#> 1 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4
#> 2 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4
#> 3 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1
#> 4 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1
#> 5 18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2
#> 6 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1
#> 7 14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4
#> 8 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2
#> 9 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2
#> 10 19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4
#> 11 17.8 6 167.6 123 3.92 3.440 18.90 1 0 4 4
#> 12 16.4 8 275.8 180 3.07 4.070 17.40 0 0 3 3
#> 13 17.3 8 275.8 180 3.07 3.730 17.60 0 0 3 3
#> 14 15.2 8 275.8 180 3.07 3.780 18.00 0 0 3 3
#> 15 10.4 8 472.0 205 2.93 5.250 17.98 0 0 3 4
#> 16 10.4 8 460.0 215 3.00 5.424 17.82 0 0 3 4
#> 17 14.7 8 440.0 230 3.23 5.345 17.42 0 0 3 4
#> 18 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1
#> 19 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2
#> 20 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1
#> 21 21.5 4 120.1 97 3.70 2.465 20.01 1 0 3 1
#> 22 15.5 8 318.0 150 2.76 3.520 16.87 0 0 3 2
#> 23 15.2 8 304.0 150 3.15 3.435 17.30 0 0 3 2
#> 24 13.3 8 350.0 245 3.73 3.840 15.41 0 0 3 4
#> 25 19.2 8 400.0 175 3.08 3.845 17.05 0 0 3 2
#> 26 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1
#> 27 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2
#> 28 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2
#> 29 15.8 8 351.0 264 4.22 3.170 14.50 0 1 5 4
#> 30 19.7 6 145.0 175 3.62 2.770 15.50 0 1 5 6
#> 31 15.0 8 301.0 335 3.54 3.570 14.60 0 1 5 8
#> 32 21.4 4 121.0 109 4.11 2.780 18.60 1 1 4 2
{code}
Empty selections in dplyr return data frames with zero columns and based on test cases covering [dplyr verbs|https://github.com/apache/arrow/blob/dfee3917dc011e184264187f505da1de3d1d6fbb/r/tests/testthat/test-dplyr.R#L413-L425] on RecordBatches already handle empty selections in the same way.
Created on 2021-01-20 by the [reprex package|https://reprex.tidyverse.org] \(v0.3.0)
Session info
{code:r}
devtools::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#> setting value
#> version R version 4.0.3 (2020-10-10)
#> os Ubuntu 20.04.1 LTS
#> system x86_64, linux-gnu
#> ui X11
#> language (EN)
#> collate en_US.UTF-8
#> ctype en_US.UTF-8
#> tz Etc/UTC
#> date 2021-01-20
#>
#> - Packages -------------------------------------------------------------------
#> package * version date lib source
#> arrow * 2.0.0.20210119 2021-01-20 [1] local
#> assertthat 0.2.1 2019-03-21 [1] RSPM (R 4.0.0)
#> bit 4.0.4 2020-08-04 [1] RSPM (R 4.0.2)
#> bit64 4.0.5 2020-08-30 [1] RSPM (R 4.0.2)
#> callr 3.5.1 2020-10-13 [1] RSPM (R 4.0.2)
#> cli 2.2.0 2020-11-20 [1] CRAN (R 4.0.3)
#> crayon 1.3.4 2017-09-16 [1] RSPM (R 4.0.0)
#> DBI 1.1.1 2021-01-15 [1] CRAN (R 4.0.3)
#> desc 1.2.0 2018-05-01 [1] RSPM (R 4.0.0)
#> devtools 2.3.2 2020-09-18 [1] RSPM (R 4.0.2)
#> digest 0.6.27 2020-10-24 [1] RSPM (R 4.0.3)
#> dplyr * 1.0.3 2021-01-15 [1] CRAN (R 4.0.3)
#> ellipsis 0.3.1 2020-05-15 [1] RSPM (R 4.0.0)
#> evaluate 0.14 2019-05-28 [1] RSPM (R 4.0.0)
#> fansi 0.4.2 2021-01-15 [1] CRAN (R 4.0.3)
#> fs 1.5.0 2020-07-31 [1] RSPM (R 4.0.2)
#> generics 0.1.0 2020-10-31 [1] CRAN (R 4.0.3)
#> glue 1.4.2 2020-08-27 [1] RSPM (R 4.0.2)
#> highr 0.8 2019-03-20 [1] RSPM (R 4.0.0)
#> htmltools 0.5.1 2021-01-12 [1] RSPM (R 4.0.3)
#> knitr 1.30 2020-09-22 [1] CRAN (R 4.0.2)
#> lifecycle 0.2.0 2020-03-06 [1] RSPM (R 4.0.0)
#> magrittr 2.0.1 2020-11-17 [1] RSPM (R 4.0.3)
#> memoise 1.1.0 2017-04-21 [1] RSPM (R 4.0.0)
#> pillar 1.4.7 2020-11-20 [1] CRAN (R 4.0.3)
#> pkgbuild 1.2.0 2020-12-15 [1] RSPM (R 4.0.3)
#> pkgconfig 2.0.3 2019-09-22 [1] RSPM (R 4.0.0)
#> pkgload 1.1.0 2020-05-29 [1] RSPM (R 4.0.0)
#> prettyunits 1.1.1 2020-01-24 [1] RSPM (R 4.0.0)
#> processx 3.4.5 2020-11-30 [1] RSPM (R 4.0.3)
#> ps 1.5.0 2020-12-05 [1] CRAN (R 4.0.3)
#> purrr 0.3.4 2020-04-17 [1] RSPM (R 4.0.0)
#> R6 2.5.0 2020-10-28 [1] RSPM (R 4.0.3)
#> remotes 2.2.0 2020-07-21 [1] RSPM (R 4.0.2)
#> rlang 0.4.10 2020-12-30 [1] CRAN (R 4.0.3)
#> rmarkdown 2.6 2020-12-14 [1] RSPM (R 4.0.3)
#> rprojroot 2.0.2 2020-11-15 [1] RSPM (R 4.0.3)
#> sessioninfo 1.1.1 2018-11-05 [1] RSPM (R 4.0.0)
#> stringi 1.5.3 2020-09-09 [1] RSPM (R 4.0.2)
#> stringr 1.4.0 2019-02-10 [1] RSPM (R 4.0.0)
#> testthat 3.0.1 2020-12-17 [1] RSPM (R 4.0.3)
#> tibble 3.0.5 2021-01-15 [1] CRAN (R 4.0.3)
#> tidyselect 1.1.0 2020-05-11 [1] RSPM (R 4.0.0)
#> usethis 2.0.0 2020-12-10 [1] RSPM (R 4.0.3)
#> vctrs 0.3.6 2020-12-17 [1] RSPM (R 4.0.3)
#> withr 2.4.0 2021-01-16 [1] CRAN (R 4.0.3)
#> xfun 0.20 2021-01-06 [1] RSPM (R 4.0.3)
#> yaml 2.2.1 2020-02-01 [1] RSPM (R 4.0.0)
#>
#> [1] /usr/local/lib/R/site-library
#> [2] /usr/lib/R/site-library
#> [3] /usr/lib/R/library
{code}
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