smartest way to join two lists into a formatted string

Question

Lets say I have two lists of same length:

a = [\'a1\', \'a2\', \'a3\']
b = [\'b1\', \'b2\', \'b3\']

and I want to produce the following str

Answer 1

This implementation is, on my system, faster than either of your two functions and still more compact.

c = ', '.join('%s=%s' % t for t in zip(a, b))

Thanks to @JBernardo for the suggested improvement.

In more recent syntax, str.format is more appropriate:

c = ', '.join('{}={}'.format(*t) for t in zip(a, b))

This produces the largely the same output, though it can accept any object with a __str__ method, so two lists of integers could still work here.