How Do Python's `any` and `all` Functions Work in List Comprehension, and Why Might This Return `[False, False, False]`?

Understanding Python's any and all Functions

Python's any and all are built-in functions that evaluate iterables and return a boolean value based on the truthiness of their elements.

any

any returns True if at least one element in the iterable is True (or non-zero for numeric values). It evaluates the iterable until a True value is encountered or all elements have been exhausted.

all

all returns True only if all elements in the iterable are True. If the iterable is empty, all returns True. It continues evaluating the iterable until a False value is encountered or all elements have been examined.

truthiness

Understanding truthiness is crucial for comprehending how any and all work. In Python, values are considered True if they are not zero, empty strings, or None (Null). Falsey values include 0, empty containers, and False itself.

Your Code

In your code, you are using the list comprehension:

[any(x) and not all(x) for x in zip(*d['Drd2'])]

To understand this expression, let's break it down:

• zip(*d['Drd2']): creates a list of tuples by grouping corresponding elements from different lists in d['Drd2'].
• for x in zip(*d['Drd2']): iterates over tuples in the created list of tuples.
• any(x): evaluates if any element in a given tuple is True.
• not all(x): evaluates if not all elements in a given tuple are True.
• and: combines the results of the preceding expressions.

Why False is Returned

Your code returns [False, False, False] because it checks if at least one value is True and simultaneously not all values are True for each tuple in the list of tuples. Since the tuples in d['Drd2'] have identical elements, all(x) is True for every tuple, making not all(x) False. Consequently, the overall expression becomes any(x) and not all(x) evaluates to False for each tuple.

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