boolean-expression

Priority of the logical operators (order of operations) for NOT, AND, OR in Python

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It’s NOT, AND, OR, from highest to lowest according to the documentation on Operator precedence Here is the complete precedence table, lowest precedence to highest. A row has the same precedence and groups from left to right 0. := 1. lambda 2. if – else 3. or 4. and 5. not x 6. in, not … Read more

Convert truthy or falsy to an explicit boolean, i.e. to True or False

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Yes, you can always use this: var tata = Boolean(toto); And here are some tests: for (var value of [0, 1, -1, “0”, “1”, “cat”, true, false, undefined, null]) { console.log(`Boolean(${typeof value} ${value}) is ${Boolean(value)}`); } Results: Boolean(number 0) is false Boolean(number 1) is true Boolean(number -1) is true Boolean(string 0) is true Boolean(string 1) … Read more

Why does `if None.__eq__(“a”)` seem to evaluate to True (but not quite)?

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This is a great example of why the __dunder__ methods should not be used directly as they are quite often not appropriate replacements for their equivalent operators; you should use the == operator instead for equality comparisons, or in this special case, when checking for None, use is (skip to the bottom of the answer … Read more

Why does “a == x or y or z” always evaluate to True? How can I compare “a” to all of those?

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In many cases, Python looks and behaves like natural English, but this is one case where that abstraction fails. People can use context clues to determine that “Jon” and “Inbar” are objects joined to the verb “equals”, but the Python interpreter is more literal minded. if name == “Kevin” or “Jon” or “Inbar”: is logically … Read more

‘and’ (boolean) vs ‘&’ (bitwise) – Why difference in behavior with lists vs numpy arrays?

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and tests whether both expressions are logically True while & (when used with True/False values) tests if both are True. In Python, empty built-in objects are typically treated as logically False while non-empty built-ins are logically True. This facilitates the common use case where you want to do something if a list is empty and … Read more

What is Truthy and Falsy? How is it different from True and False?

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We use “truthy” and “falsy” to differentiate from the bool values True and False. A “truthy” value will satisfy the check performed by if or while statements. As explained in the documentation, all values are considered “truthy” except for the following, which are “falsy”: None False Numbers that are numerically equal to zero, including: 0 … Read more

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