Mean by groups by multiple columns in r

Question

I have the next dataframe

obs1   obs2   obs3   zone
1       0      1     Rural
1       1      1     Rural
0       1      1     Urban
1       0      0     Urban
0       1      0     Rural

I am trying to get something like this

Mean Rural    0.6666
Mean Urban    0.5

Is that possible?

Answer 1

You can try:

aggregate(values ~ zone, cbind(stack(df[-4]), df[4]), mean)

   zone    values
1 Rural 0.6666667
2 Urban 0.5000000

Or (assuming no missing values):

tapply(rowMeans(df[-4]), df[4], mean)

    Rural     Urban 
0.6666667 0.5000000