arrow

ARROW-14586  [R] summarise() with nested aggregate expressions has a confusing error

This PR:

- Improves error messages for aggregate expressions that are not supported
- Allows a scalar to be passed into an aggregate expression. This is related because it is valid in dplyr and currently gives very weird errors.

Reprex before this PR:

``` r
# remotes::install_github("apache/arrow/r@master")
library(arrow, warn.conflicts = FALSE)
library(dplyr, warn.conflicts = FALSE)

record_batch(x = 4) %>% summarise(y = mean(mean(x)))
#> Warning: Error in mean(..temp0) : object '..temp0' not found; pulling data into
#> R
#> # A tibble: 1 × 1
#>       y
#>   <dbl>
#> 1     4
record_batch(x = 4) %>% summarize(y = x + 1)
#> Warning: Error : Expression x + 1 not supported in Arrow; pulling data into R
#> # A tibble: 1 × 1
#>       y
#>   <dbl>
#> 1     5
record_batch(x = 4) %>% summarize(y = x)
#> Warning: Error in .f(.x[[i]], ...) : attempt to apply non-function; pulling data
#> into R
#> # A tibble: 1 × 1
#>       y
#>   <dbl>
#> 1     4

record_batch(x = 4) %>% summarise(y = 1)
#> Warning: Error in .$data : $ operator is invalid for atomic vectors; pulling
#> data into R
#> # A tibble: 1 × 1
#>       y
#>   <dbl>
#> 1     1
record_batch(x = 4) %>% summarise(y = Expression$scalar(1))
#> InMemoryDataset (query)
#> y: double (1)
#>
#> See $.data for the source Arrow object
record_batch(x = 4) %>% summarise(y = Scalar$create(1))
#> Error in if (nzchar(name)) {: argument is of length zero

some_scalar_value <- 3
record_batch(x = 4) %>% summarise(y = some_scalar_value)
#> Warning: Error in .$data : $ operator is invalid for atomic vectors; pulling
#> data into R
#> # A tibble: 1 × 1
#>       y
#>   <dbl>
#> 1     3
record_batch(x = 4) %>% summarise(y = !! some_scalar_value)
#> Warning: Error in .$data : $ operator is invalid for atomic vectors; pulling
#> data into R
#> # A tibble: 1 × 1
#>       y
#>   <dbl>
#> 1     3
```

Reprex after this PR:

``` r
# remotes::install_github("paleolimbot/arrow/r@r-summarise-eval")
library(arrow, warn.conflicts = FALSE)
library(dplyr, warn.conflicts = FALSE)

record_batch(x = 4) %>% summarise(y = mean(mean(x)))
#> Warning: Error : Aggregate within aggregate expression mean(mean(x)) not
#> supported in Arrow; pulling data into R
#> # A tibble: 1 × 1
#>       y
#>   <dbl>
#> 1     4
record_batch(x = 4) %>% summarize(y = x + 1)
#> Warning: Error : Expression x + 1 is not an aggregate expression or is not
#> supported in Arrow; pulling data into R
#> # A tibble: 1 × 1
#>       y
#>   <dbl>
#> 1     5
record_batch(x = 4) %>% summarize(y = x)
#> Warning: Error : Expression x is not an aggregate expression or is not supported
#> in Arrow; pulling data into R
#> # A tibble: 1 × 1
#>       y
#>   <dbl>
#> 1     4

record_batch(x = 4) %>% summarise(y = 1)
#> InMemoryDataset (query)
#> y: double (1)
#>
#> See $.data for the source Arrow object
record_batch(x = 4) %>% summarise(y = Expression$scalar(1))
#> InMemoryDataset (query)
#> y: double (1)
#>
#> See $.data for the source Arrow object
record_batch(x = 4) %>% summarise(y = Scalar$create(1))
#> InMemoryDataset (query)
#> y: double (1)
#>
#> See $.data for the source Arrow object

some_scalar_value <- 3
record_batch(x = 4) %>% summarise(y = some_scalar_value)
#> InMemoryDataset (query)
#> y: double (3)
#>
#> See $.data for the source Arrow object
record_batch(x = 4) %>% summarise(y = !! some_scalar_value)
#> InMemoryDataset (query)
#> y: double (3)
#>
#> See $.data for the source Arrow object
```

<sup>Created on 2021-11-25 by the [reprex package](https://reprex.tidyverse.org) (v2.0.1)</sup>

Closes #11777 from paleolimbot/r-summarise-eval

Authored-by: Dewey Dunnington <dewey@fishandwhistle.net>
Signed-off-by: Nic Crane <thisisnic@gmail.com>