Converting 2D String array into 1D String array in Python

Question

I have a string array that looks like this:

string = [ [ "this is a sample",
             "this is another sample"],
           [ "The third sample",
             "the fourth one"] ]

But I want to convert it to:

string = [   "this is a sample",
             "this is another sample",
             "The third sample",
             "the fourth one"  ]

How can I do it? I know I can do it by pre-allocating a string and iterating. But is there a simpler method?

Google "Python flatten list of lists". Also refer: http://stackoverflow.com/questions/11264684/flatten-list-of-lists — sisanared, Oct 21 '16 at 04:44

score 1 · Accepted Answer · answered Oct 21 '16 at 04:46

1

You can try like this using list comprehension. Code:

string = [ [ "this is a sample",
         "this is another sample"],
       [ "The third sample",
         "the fourth one"] ]

print([_ for i in range(len(string)) for _ in string[i]])

answered Oct 21 '16 at 04:46

Md Mahfuzur Rahman

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I did not know two for loops like this could be written. Thanks a lot. :) – ponir Oct 21 '16 at 04:51
It's called nested for loop. http://blog.teamtreehouse.com/python-single-line-loops – Md Mahfuzur Rahman Oct 21 '16 at 04:56

score 1 · Answer 2 · answered Oct 21 '16 at 04:46

1

Maybe use list comprehension. Something like

string = [s for S in string for s in S]

answered Oct 21 '16 at 04:46

Tammo Heeren

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Converting 2D String array into 1D String array in Python

2 Answers2