[ARROW-13434] [R] group_by() with an unnammed expression

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 6.0.0
• Component/s: R
• Labels: pull-request-available query-engine
• External issue URL: https://github.com/apache/arrow/issues/29101
• Assignee: Jonathan Keane
• Reporter: Jonathan Keane
• Created: 22/Jul/21 13:45
• Updated: 11/Jan/23 08:33
• Resolved: 24/Jul/21 14:17

Description

With dplyr, when we group_by with an unnamed expression, a column is added to the dataframe that has the result of the expression.

> example_data %>% 
+   group_by(int < 4) %>% collect()
# A tibble: 10 x 8
# Groups:   int < 4 [3]
     int   dbl  dbl2 lgl   false chr   fct   `int < 4`
   <int> <dbl> <dbl> <lgl> <lgl> <chr> <fct> <lgl>    
 1     1   1.1     5 TRUE  FALSE a     a     TRUE     
 2     2   2.1     5 NA    FALSE b     b     TRUE     
 3     3   3.1     5 TRUE  FALSE c     c     TRUE     
 4    NA   4.1     5 FALSE FALSE d     d     NA       
 5     5   5.1     5 TRUE  FALSE e     NA    FALSE    
 6     6   6.1     5 NA    FALSE NA    NA    FALSE    
 7     7   7.1     5 NA    FALSE g     g     FALSE    
 8     8   8.1     5 FALSE FALSE h     h     FALSE    
 9     9  NA       5 FALSE FALSE i     i     FALSE    
10    10  10.1     5 NA    FALSE j     j     FALSE    

Arrow doesn't do this, however because we (currently) only add columns when the expression is named.

> Table$create(example_data) %>% 
+   group_by(int < 4) %>% collect()
 Error: Invalid: No match for FieldRef.Name(int < 4) in int: int32
dbl: double
dbl2: double
lgl: bool
false: bool
chr: string
fct: dictionary<values=string, indices=int8, ordered=0> 

This isn't a big deal right now since grouped aggregations aren't (quite) here yet, but once we start having support for that, we will have people using examples like this.

Issue Links

• links to: GitHub Pull Request #10785