how to sum the values in similar group in dataframe?

Question

alpha <- c(11,12,21,24,33,11,33)
group <- c("a", "b", "a", "c", "a", "c","d")

df <- data.frame(group,alpha)
df <- df[with(df, order(group)),]

I want to sum the values for each group and append the result in the dataframe but I'm not sure how to do it. The output will be something like the result below.

   group alpha sum
1     a    11  65
2     a    21  65
3     a    33  65
4     b    12  12
5     c    24  35
6     c    11  35
7     d    33  33

`df %>% group_by(group) %>% mutate(alpha = sum(alpha)) %>% arrange(group)` — Ronak Shah, Jun 13 '20 at 09:41

score 1 · Accepted Answer · answered Jun 13 '20 at 09:39

You can use dplyr with group_by to calculate the sum and then join to append your original data.frame:

alpha <- c(11,12,21,24,33,11,33)
group <- c("a", "b", "a", "c", "a", "c","d")

df <- data.frame(group,alpha)
df <- df[with(df, order(group)),]

library(dplyr)
df_stat <- df %>% 
  group_by(group) %>% 
  summarise(sum = sum(alpha))

df <- df %>% 
  left_join(df_stat)

df
  group alpha sum
1     a    11  65
2     a    21  65
3     a    33  65
4     b    12  12
5     c    24  35
6     c    11  35
7     d    33  33

how to sum the values in similar group in dataframe?

1 Answers1