{AND, OR, NOT} How to Apply Logical Operators to All List Elements in Python?

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Problem: Given a list of Boolean elements. What’s the best way to join all elements using the logical “OR” and logical “AND” operations?

Example: Convert the list [True, True, False] using

  • The logical “AND” operation to True and True and False = False,
  • The logical “OR” operation to True or True or False = True, and
  • The logical “NOT” operation to [not True, not True, not False] = [False, False, True].

Solution:

  • To perform logical “AND”, use the built-in Python function all(),
  • To perform logical “OR”, use the built-in Python function any(), and
  • To perform logical “NOT”, use a list comprehension statement [not x for x in list].

Here’s the solution for our three examples:

lst = [True, True, False]

# Logical "AND"
print(all(lst))
# False

# Logical "OR"
print(any(lst))
# True

# Logical "NOT"
print([not x for x in lst])
# [False, False, True]

This way, you can combine an arbitrary iterable of Booleans into a single Boolean value.

Puzzle: Guess the output of this interactive code snippet—and run it to check if you were correct!

The challenge in the puzzle is to know that Python comes with implicit Boolean type conversion: every object has an associated Boolean value. Per convention, all objects are True except “empty” or “zero” objects such as [], '', 0, and 0.0. Thus, the result of the function call all([True, True, 0]) is False.

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