in python how to repeat an item N time into a list?

Question

say, i have a string A='baby', want to repeat A 4 times to generate a list looks like this:

['baby', 'baby', 'baby', 'baby']

my current solution is :

((A+".")*4).split('.')[:-1]

however, this looks really awkward.

is there any more civilized solution?

thanks!

score 4 · Accepted Answer · edited May 23 '17 at 11:49

Update This answer is expanded with more examples on the canonical question: https://stackoverflow.com/a/24557558/541136

You can do it like this:

['baby'] * 4

Note that this is best only used with immutable items in the list, because they all point to the same place in memory. I use this frequently when I have to build a table with a schema of all strings.

schema = ['string'] * len(columns)

Beware doing this with mutable objects, when you change one of them, they all change because they're all the same object:

foo = [[]] *4
foo[0].append('x')

foo now returns:

[['x'], ['x'], ['x'], ['x']]

score 0 · Answer 2 · answered Jun 18 '14 at 11:38

0

By using list comprehension:

['baby' for x in range(4)]

answered Jun 18 '14 at 11:38

Reloader

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['baby' for _ in range(4)] – volcano Jun 18 '14 at 11:39
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list comprehensions aren't the answer for everything – Russia Must Remove Putin Jun 18 '14 at 11:39
No, they are not. But they are certainly better than OP's current solution. – Reloader Jun 18 '14 at 11:40
@AaronHall, especially since in this case it's take about 1.5 longer than list multiplication – volcano Jun 18 '14 at 11:40

score 0 · Answer 3 · answered Jun 18 '14 at 11:38

0

Build a list with single element and multiply the list

['baby']*4

answered Jun 18 '14 at 11:38

volcano

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in python how to repeat an item N time into a list?

3 Answers3