I need to do this on very large datasets ( > a few million data points). So
seeking help in figuring out an implementation of the task.

Input 4 vectors which contain values as 0 or 1. (as integers, not boolean
bits)
vec_A = ( 0, 1, 0, 0, ...... 1, 0, 1, 0)   etc
vec_B = (0,0,1,1.....)
vec_C, vec_D  (similar to above)
All four vectors are same length.

I need to compute frequency count of the boolean literals for DCBA,
DCBA
0000
0001
0010
0011
..
..
1111

Questions:
a) Is there a mechanism for combining the 4 vectors (in integer formats)
into 4 bits of a new vector or some other
type? (or treat them as boolean values true/false instead of 0 or 1
integers).
b) what is the most efficient mechanism for obtaining the frequency count of
each of the sixteen Boolean
combinations?

I need to do this frequently on large datasets. So am trying to get an
efficient implementation (instead of
a quick and dirty scheme). Thank you very very much in advance.

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