Swap values in a tuple/list inside a list in python?

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You could use map:

map (lambda t: (t[1], t[0]), mylist)

Or list comprehension:

[(t[1], t[0]) for t in mylist]

List comprehensions are preferred and supposedly much faster than map when lambda is needed, however note that list comprehension has a strict evaluation, that is it will be evaluated as soon as it gets bound to variable, if you’re worried about memory consumption use a generator instead:

g = ((t[1], t[0]) for t in mylist)
#call when you need a value
g.next()

There are some more details here: Python List Comprehension Vs. Map

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