Comparisons and truthiness in Python

Chained comparisons, identity against equality, and what counts as false.

x = 7
print(0 < x < 10, x != 3 == 3)

a, b = [1, 2], [1, 2]
print(a == b, a is b, a is a)
print(None is None, 1 == 1.0, 1 is 1.0)

for value in (0, "", [], {}, None, 0.0, "0", [0]):
    print(repr(value), bool(value))

How it works

1. 0 < x < 10 evaluates x once and reads like maths.
2. is compares identity; use == for value.
3. Empty containers, zero and None are all falsy.

Keywords and builtins used here

• bool
• for
• print
• repr

The run, in numbers

Lines

9

Characters to type

213

Tokens

100

Three-star pace

100 tpm

At the three-star pace of 100 tokens a minute, this run takes about 60 seconds.

Type this snippet

Step 3 of 3 in Expressions, step 67 of 72 in Language basics.

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