How to group all columns exculding a single column

Question

How to tell group_by to group all data by columns except one?

I tried using group_by(data,-x) but this groups by the negative of -x which means same grouping by x.

Answer 1

You can either use group_by or group_by_at

Using group_by

# Generate data
set.seed(492)
data = data.frame(value=rnorm(1000), z1=sample(LETTERS,1000,replace=TRUE),                 z2=sample(letters,1000,replace=TRUE), z3=sample(1:10, replace=TRUE),           colour=sample(c("red","green","black"),1000,replace=TRUE))

data %>% group_by_(.dots=names(data)[-grep("value", names(data))]) %>%
  summarise(mean_value=mean(value)

#Output

 z1     z2    z3  colour   mean_value
   <fctr> <fctr> <int> <fctr>       <dbl>
1       A      a     2  green  0.89281475
2       A      b     2    red -0.03558775
3       A      b     5  black -1.79184218
4       A      c    10  black  0.17518610
5       A      e     5  black  0.25830392
...

You can also use group_by_at in the following way:

data %>% 
  group_by_at(names(data)[-grep("value", names(data))]) %>%
  summarise(mean_value=mean(value))

# Groups:   z1, z2, z3 [?]
       z1     z2    z3  colour   mean_value
   <fctr> <fctr> <int> <fctr>       <dbl>
 1      A      a     2  green  0.89281475
 2      A      b     2    red -0.03558775
 3      A      b     5  black -1.79184218
 4      A      c    10  black  0.17518610
 5      A      e     5  black  0.25830392
 6      A      e     5    red -0.81879788
 7      A      e     7  green  0.30836054
 8      A      f     2  green  0.05537047
 9      A      g     1  black  1.00156405
10      A      g    10  black  1.26884303
# ... with 949 more rows