Merge Two Nested Lists In Python

I have two lists: x = [['a', 1], ['b', 2], ['c', 3]] y = [['a', 4], ['c', 6]] I would like to keep only the common elements of the letters and combine the 2 lists into: [['a', 1,

Solution 1:

>>> x = [['a', 1], ['b', 2], ['c', 3]]
>>> y = [['a', 4], ['c', 6]]
>>> lazy = dict
>>> lazyx = lazy(x)
>>> lazyy = lazy(y)
>>> [[lazy, lazyx[lazy], lazyy[lazy]] for lazy in lazyx if lazy in lazyy]
[['a', 1, 4], ['c', 3, 6]]

Solution 2:

Something like this (untested):

Z=[]
for x1, x2 in x:
    for y1, y2 in y:
        if x1 == y1:
            z.append([x1, x2, y2])

Solution 3:

A dictionary is generally a lot better for these kinds of things.

z = {}
for key, val in x + y:
    z[key] = z.get(key, []) + [val]
print z #{'a': [1, 4], 'c': [3, 6], 'b': [2]}
print a["b"] #[2]
print a["c"] #[3, 6]