Appending Frequency Tables - With Missing Values

Question

The goal is to produce a frequency table of all my selected variables (about reading habits for 4 Newspapers) which in essence have the same possible values:

1=         


        

Answer 1

This is similar to @Anandas solution (I will post it because was already in middle of writing)

df <- data.frame(a, b, d, e)
do.call(cbind, lapply(df, function(x) table(factor(x, levels = 0:4))))
#   a b d  e
# 0 0 2 5  0
# 1 2 1 0  0
# 2 2 2 2  0
# 3 4 3 2 10
# 4 2 2 1  0