Python: merge nested lists

Question

beginner to python here.

I have 2 nested lists that I want to merge:

list1 = ['a',
         (b, c),
         (d, e),
         (f, g, h) ]

list2 = [(p,q),
         (r, s),
         (t),
         (u, v, w) ]

the output I am looking for is:

list3 = [(a, p, q),
         (b, c, r, s),
         (d, e, t),
         (f, g, h, u, v, w) ]

Can this be done without any external libraries? note: len(list1) = len(list2)

Answer 1

Use the power of the zip function and list comprehensions:

list1 = [('a', ),
        ('b', 'c'),
        ('d', 'e'),
        ('f', 'g', 'h') ]

list2 = [('p', 'q'),
        ('r', 's'),
        ('t', ),
        ('u', 'v', 'w') ]

print [a + b for a, b in zip(list1, list2)]

Answer 2

from operator import add
list3 = map(add, list1, list2)

Answer 3

If the order within an inner list/tuple is not important, you can use the mathematical set operations.

print [tuple(set(a)|set(b)) for a,b in zip(x,y)]

The set(a)|set(b) converts the iterables a and b to sets and takes the union of the two sets. They are then converted back to tuple as desired in the output format.

As you are a beginner to python, it is strongly recommended to master list comprehensions. It is way too powerful and concise. In addition to making your code more 'pythonic', list comprehensions can act as a friendlier replacement to 'map' and 'filter' functions.