CODEWITHSUNDEEP
pythonlist-comprehension
systempuntoout
systempuntoout

Reputation: 74084

Prepend prefix to list elements with list comprehension

Having a list like this:

['foo','spam','bar']

is it possible, using list comprehension, to obtain this list as result?

['foo','ok.foo', 'spam', 'ok.spam', 'bar', 'ok.bar']

Upvotes: 17

Views: 13420

Answers (2)

Ivo van der Wijk
Ivo van der Wijk

Reputation: 16775

With list comprehensions, you're creating new lists, not appending elements to an existing list (which may be relevant on really large datasets)

Why does it have to be a list comprehension anyway? Just because python has them doesn't make it bad coding practice to use a for-loop.

Upvotes: 1

unutbu
unutbu

Reputation: 879391

In [67]: alist = ['foo','spam', 'bar']

In [70]: [prefix+elt for elt in alist for prefix in ('','ok.') ]
Out[70]: ['foo', 'ok.foo', 'spam', 'ok.spam', 'bar', 'ok.bar']

Upvotes: 33

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