Weighted mean with summarise_at dplyr

Question

I strictly need to use the summarise_at to compute a weighted mean, with weights based on the values of another column

df %>% summarise_at(.vars = vars(FACTOR,tv:`smart tv/console`), 
                  .funs = weighted.mean, w=INVESTMENT, na.rm=TRUE)

It always shows the error: 'INVESTMENT' is not found.

I then tried with:

df %>%summarise_at(.vars = vars(FACTOR,tv:`smart tv/console`), 
               .funs = weighted.mean, w=vars(INVESTMENT), na.rm=TRUE)

But in this case :  Evaluation error: 'x' and 'w' must have the same length.

Why is this? Am I doing anything wrong? Do you have hints to solve this issue? Thanks

mmk · Answer

You can specify the weights directly within the weighted.mean() function, within the call to funs() like so:

data.frame(x=rnorm(100), y=rnorm(100), weight=runif(100)) %>%
      summarise_at(vars(x,y), funs(weighted.mean(., w=weight)))

One Answer