how to use group_by%>%sum in lapply?

Question

I have this df as an example

df = data.frame(x = c(rep(1,5),rep(2,5)),
                y = 1:10,
                z = 11:20)

and I wish to use lapply with group_by%>%sum so I have the following output

  x  y  z
1 1 15 65
2 2 40 90

Look at [`across()`](https://dplyr.tidyverse.org/reference/across.html) — bretauv, Feb 23 '23 at 13:54
In this case you can do `df %>% group_by(x) %>% summarise_all(sum)` — Sotos, Feb 23 '23 at 13:55
Why `lapply()`? You could use `aggregate()`: `aggregate(df[c('y', 'z')], df['x'], sum)` — s_baldur, Feb 23 '23 at 14:00

Julien · Accepted Answer · 2023-02-23T15:14:10.177

3

Here are 3 ways of doing it

library(dplyr)
# 1
df %>% 
  group_by(x) %>% 
  summarise(across(everything(), \(x) sum(x, na.rm = T))

# 2 (requires the new version of dplyr)
df %>% 
  summarise(across(everything(), \(x) sum(x, na.rm = T)), .by = x)

# 3 (deprecated, use with old versions of dplyr)
df %>% 
  group_by(x) %>% 
  summarise_all(\(x) sum(x, na.rm = T))

# A tibble: 2 × 3
      x     y     z
  <dbl> <int> <int>
1     1    15    65
2     2    40    90

edited Feb 23 '23 at 15:14

answered Feb 23 '23 at 13:56

Julien

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and if I had missing values and I wish to include the argument na.rm in the function sum. How can I make that happen ? – Anas116 Feb 23 '23 at 14:59

how to use group_by%>%sum in lapply?

1 Answers1