Zip lists in Python

Question

I am trying to learn how to "zip" lists. To this end, I have a program, where at a particular point, I do the following:

x1, x2, x3 = stuff.calculations(withdataa)

This gives me three lists, x1, x2, and x3, each of, say, size 20.

Now, I do:

zipall = zip(x1, x2, x3)

However, when I do:

print "len of zipall %s" % len(zipall)

I get 20, which is not what I expected. I expected three. I think I am doing something fundamentally wrong.

Answer 1

zip takes a bunch of lists likes

a: a1 a2 a3 a4 a5 a6 a7...
b: b1 b2 b3 b4 b5 b6 b7...
c: c1 c2 c3 c4 c5 c6 c7...

and "zips" them into one list whose entries are 3-tuples (ai, bi, ci). Imagine drawing a zipper horizontally from left to right.