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Python Functional Python Functional Workhorses Chaining Functions

Posted by Mark Chesney
Mark Chesney
11,747 Points

warning: using any() and all() on dictionaries

I started writing out a question, then found the answer, so now I'm just typing an FYI:

any() and all() are great because they work on lists, sets and tuples, just as you'd expect them to. one warning about dictionaries is that they don't work as expected (or as I'd expected). Example:

dict1 = {'a': True, 'b': False}

# >>> any(dict1)
# True, expected

# >>> all(dict1)
# True, NOT as expected

1 Answer

Mark Chesney
Mark Chesney
11,747 Points

As it turns out, any() and all() evaluate truthiness based on whether the dictionary is empty or not:

dict2 = dict([])

# >>> any(dict2)
# False, consistent with observation above

# >>> all(dict2)
# True, NOT consistent

wondering would anyone explain the latter case? (does it matter much?)