How to build a confusion matrix for a dataframe

Question

I have the following dataframe:

v1  v2  v3  v4  v5
0   t   1   12  N/A
1   t   0   34  N/A
2   t   1   45  N/A
5   f   0   76  N/A
12  f   0   98  N/A
45  t   1   45  M

I want to be able to construct the following confusion matrix on the two columns v2 and v3:

    t  |  f
 0  1     2
 1  3     0

What is the most elegant way to do this in R

Answer 1

This is easily done with table...

table(df$v3,df$v2)

    f t
  0 2 1
  1 0 3