CODEWITHSUNDEEP
python
null
null

Reputation: 1443

Test if variable has type "list of tuples"

How can I check if a variable is a list of tuples?

isinstance only reveals if a variable is a list or a tuple, but I don't know how to check nested structures.

Upvotes: 3

Views: 3125

Answers (2)

dawg
dawg

Reputation: 104092

Use all

>>> lit=[(1,),(2,),(3,)]
>>> lin=[(1,),(2,),(3,),4]

>>> all(isinstance(e,tuple) for e in lit)  
True
>>> all(isinstance(e,tuple) for e in lin)  
False

You can also negate a lambda in filter both to test and to find the elements that are not tuples:

>>> filter(lambda e: not isinstance(e, tuple), lit)
[]
>>> filter(lambda e: not isinstance(e, tuple), lin)
[4]

Or use a list comprehension to find the index of the non tuple:

>>> [i for i, e in enumerate(lit) if not isinstance(e, tuple)]
[]
>>> [i for i, e in enumerate(lin) if not isinstance(e, tuple)]
[3]

If you use filter or a list comprehension, an empty list is also 'falsy' so that can both be a test and a result if you are looking for the actual elements that are not tuples.

Upvotes: 1

Ofiris
Ofiris

Reputation: 6151

You can use a combination of all and instanceof:

>>> a = [(1,2),(3,5)]
>>> all(isinstance(item, tuple) for item in a)
True
>>> b = [(1,2),(3,5), "string"]
>>> all(isinstance(item, tuple) for item in b)
False
>>>

Upvotes: 9

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