Tip 14 Chain Comparison Operators

Pythonic Programming — by Dmitry Zinoviev (23 / 116)

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★2.7, 3.4+ Remember how you could write in an algebra class that x < y < z? In Python, you can chain comparison operators, too: x < y < z. You can even write x < y <= z != w, why not? An expression like this is evaluated first by evaluating each comparison operator separately and then taking the and of the results:

​ x < y ​and​ y <= z ​and​ z != w

You could even evaluate bizarre expressions like x < y > z (check if y is greater than both x and z) — but they are confusing and better avoided.

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