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

I think you are looking for factor:

> L <- list(a, b, d, e)
> A <- sort(unique(unlist(L, use.names = FALSE)))
> sapply(L, function(x) table(factor(x, A)))
  [,1] [,2] [,3] [,4]
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

---

Update

Here's an approach in base R that might even be more direct:

> L <- mget(c("a", "b", "d", "e"))
> table(stack(L))
      ind
values  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

Answer 2

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

Answer 3

You could use mtabulate from qdapTools

library(qdapTools)
t(mtabulate(list(a,b,d,e)))
#  [,1] [,2] [,3] [,4]
#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

Or

t(mtabulate(data.frame(a,b,d,e)))
#  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