eitsupi commented on code in PR #35702:
URL: https://github.com/apache/arrow/pull/35702#discussion_r1200622342
##########
r/vignettes/data_wrangling.Rmd:
##########
@@ -165,6 +165,34 @@ sw2 %>%
transmute(name, height, mass, res = residuals(lm(mass ~ height)))
```
+Because window functions are not supported, computing an aggregation like
`mean()` on a grouped table or within a rowwise opertation like `filter()` is
not supported:
+
+```{r}
+sw %>%
+ select(1:4) %>%
+ filter(!is.na(hair_color)) %>%
+ group_by(hair_color) %>%
+ filter(height < mean(height, na.rm = TRUE))
+```
+
+This operation can be accomplished in arrow by computing the aggregation
separately, for example within a join operation:
+
+```{r}
+
+sw %>%
+ select(1:4) %>%
+ filter(!is.na(hair_color)) %>%
+ left_join(sw %>%
+ group_by(hair_color) %>%
+ summarize(mean_height = mean(height, na.rm = TRUE))
+ ) %>%
+ filter(height < mean_height) %>%
+ select(-mean_height) %>%
+ collect()
+
Review Comment:
How about formatting it as follows?
```suggestion
sw %>%
select(1:4) %>%
filter(!is.na(hair_color)) %>%
left_join(
sw %>%
group_by(hair_color) %>%
summarize(mean_height = mean(height, na.rm = TRUE))
) %>%
filter(height < mean_height) %>%
select(!mean_height) %>%
collect()
```
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