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Add new column named max column in dataframe

So I have this example df

:

df <- dput(structure(list(arts = structure(c(1L, 1L, 3L, 4L), .Label = c("art1", "art2"), class = "character"), scr1 = c(52L, 58L, 40L, 62L), scr2 = c(25L, 23L, 55L, 26L), scr3 = c(36L, 60L, 19L, 22L)), .Names = c("art_id", "scr1", "scr2", "scr3"), row.names = c(NA, -4L), class = "data.frame"))

> df
  art_id scr1 scr2 scr3
1      1   52   25   36
2      1   58   23   60
3      3   40   55   19
4      4   62   26   22

What do I use dplyr

to summarize onart_id 

df %>% 
  group_by(art_id) %>% 
  summarise_each(funs(sum))

  art_id  scr1  scr2  scr3
   <int> <int> <int> <int>
1      1   110    48    96
2      3    40    55    19
3      4    62    26    22

My question is , how can I add another top_r

named column that contains the column name from the maximum among src1:src3

. The resulting df will look like this:

  art_id  scr1  scr2  scr3  top_r
   <int> <int> <int> <int>  <char>
1      1   110    48    96   scr1  
2      3    40    55    19   scr2  
3      4    62    26    22   scr1

I'm comfortable using it dplyr

so if there's an answer that uses this library that's great!

+4


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3 answers


This will work:



df %>%
  group_by(art_id) %>%
  summarise_each(funs(sum)) %>%
  mutate(top_r=apply(.[,2:4], 1, function(x) names(x)[which.max(x)]))

# A tibble: 3 × 5
  art_id  scr1  scr2  scr3 top_r
   <int> <int> <int> <int> <chr>
1      1   110    48    96  scr1
2      3    40    55    19  scr2
3      4    62    26    22  scr1
+2


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Its just that simple in R base with max.col

:



df$top_r <- names(df)[-1][max.col(df[-1])]
+3


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library(dplyr)
library(tidyr)

df2 <- df %>% 
  group_by(art_id) %>% 
  summarise_each(funs(sum))

df3 <- df2 %>%
  gather(top_r, Value, -art_id) %>%
  arrange(art_id, desc(Value)) %>%
  group_by(art_id) %>%
  slice(1) %>%
  select(-Value)

df_final <- df2 %>%
  left_join(df3, by = "art_id")

df_final
# A tibble: 3 × 5
  art_id  scr1  scr2  scr3 top_r
   <int> <int> <int> <int> <chr>
1      1   110    48    96  scr1
2      3    40    55    19  scr2
3      4    62    26    22  scr1
0


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