Combine, merge, coalesce rows by group and replace certain value by another value without pivoting-CodePudding

Is there a tidyverse way to combine rows of the same group replacing certain values:

I don't want a pivot solution!

This is my dataframe:

df <- structure(list(A = c(1L, 1L, 2L, 3L, 4L, 5L), B = c("a", "a", 
"b", "c", "d", "e"), C = c("u", "t", "t", "u", "t", "t"), D = c("t", 
"u", "u", "t", "u", "u"), E = c("t", "t", "u", "u", "u", "u")), 
class = "data.frame", row.names = c(NA, -6L))

  A B C D E
1 1 a u t t
2 1 a t u t
3 2 b t u u
4 3 c u t u
5 4 d t u u
6 5 e t u u

My desired output:

  A B C D E
1 1 a u u t
2 2 b t u u
3 3 c u t u
4 4 d t u u
5 5 e t u u

Row 1 and 2 have the same group 1 and a (Column A and B) ->

This group should be combined to one row 1 a replacing t by u in column C to E

Lessons studied:

combine rows in data frame containing NA to make complete row

Merging two rows with some having missing values in R

CodePudding user response：

We can group by 'A', 'B', summarise across the columns, order the values so that 'u' will return before other values and select the first element

library(dplyr)
df %>%
    group_by(A, B) %>% 
    summarise(across(everything(), 
       ~ first(.[order(. != 'u')])), .groups = 'drop')

-output

# A tibble: 5 x 5
      A B     C     D     E    
  <int> <chr> <chr> <chr> <chr>
1     1 a     u     u     t    
2     2 b     t     u     u    
3     3 c     u     t     u    
4     4 d     t     u     u    
5     5 e     t     u     u