CODEWITHSUNDEEP
pythonlistparsingtuples
rob-gordon
rob-gordon

Reputation: 1488

Find the first tuple in anything that is or might contain a tuple?

In Python, what is a simple way to always return a tuple whether the variable in question holds a tuple or a list containing at least one tuple?

# (3, 5) would return (3, 5)
#
# [(3, 5), [200, 100, 100]] would return (3, 5)
#
# [[100, 100, 100], (3, 5)] would return (3, 5)
#
# [(3, 5), (4, 7)] would return (3, 5)

Upvotes: 0

Views: 55

Answers (1)

mgilson
mgilson

Reputation: 310059

If I actually needed something like this, I would do something like: 

def first_tuple(t):
    return t if isinstance(t,tuple) else next(x for x in t if isinstance(x,tuple))

demo:

>>> first_tuple((3,5))
(3, 5)
>>> first_tuple([(3, 5), [200, 100, 100]])
(3, 5)
>>> first_tuple([[100, 100, 100], (3, 5)])
(3, 5)
>>> first_tuple([(3, 5), (4, 7)])
(3, 5)
>>> first_tuple([[],[]])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in first_tuple
StopIteration

Generally speaking, you shouldn't need something like this. IMHO, this seems like it is probably a poor design and the data-structure here should be reconsidered.

Upvotes: 3

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