Variable scope within list comprehension

Question

I have a list of tuples which comprise of a string and another list;

[('string1', ['a1', 'b1']),
 ('string2', ['a2', 'b2']),
 ('string3', ['a3', 'b3'])]

I cannot figure out using list comprehension to arrive at something like;

[['string1a1', 'string1b1'],
 ['string2a2', 'string2b2'],
 ['string3a3', 'string3b3']]

I tried something like

results = [join(ministring, i) for i in (miniarray for (ministring, miniarray) in myarray)]

but i am confused at each variables scope within the expansion/expression(?).

Answer 1

As simple as that:

lst = [('string1', ['a1', 'b1']),
 ('string2', ['a2', 'b2']),
 ('string3', ['a3', 'b3'])]

res = [[master + tail for tail in sublist] for master, sublist in lst]

which returns:

[['string1a1', 'string1b1'], ['string2a2', 'string2b2'], ['string3a3', 'string3b3']]

---

Note that with this approach the length of the sublist inside the tuple is not fixed. It can be arbitrarily long.

Answer 2

You could do something like this:

data = [('string1', ['a1', 'b1']),
 ('string2', ['a2', 'b2']),
 ('string3', ['a3', 'b3'])]

result = [[s + e1, s + e2] for s, [e1, e2] in data]
print(result)

Output

[['string1a1', 'string1b1'], ['string2a2', 'string2b2'], ['string3a3', 'string3b3']]

Note that this assumes the inner list have only two elements.

Answer 3

尝试这个：

new_list = list(map(lambda x: [x[0]+x[1][0], x[0]+x[1][1]],data))