R aggregate by large number of columns

Question

I have a data frame (df) that has about 40 columns, and I want to aggregate using a sum on 4 of the columns. Outside of the 4 I want to sum, each unique value in column 1 co

Answer 1

This would be the current answer with dplyr:

library('dplyr')
mytb<-read.table(text="
A B C D Sum
1 A B C D   1
2 A B C D   2
3 A B C D   3
4 E F 1 R   4
5 E F 1 R   5", header=T, stringsAsFactors=F)

mytb %>% 
  group_by_at(names(select(mytb, -"Sum") ) )  %>% 
  summarise_all(.funs=sum)