all Python 3operatorfunction

operator.isub

in-place

In-place subtraction: a -= b; for sets, an in-place difference.

Syntax

operator.isub(a, b)

For numbers nothing changes in place — assign the result: x = isub(x, 1). For a set it mutates in place, removing the second argument's items: after isub(s, {1}) the 1 is gone from s, and every reference to that object sees it. Lists have no -= at all: isub([1, 2], [1]) raises TypeError.

Examples

import operator
print(operator.isub(5, 2))   # → 3
print(operator.isub(0.3, 0.1))   # → 0.19999999999999998
tags = {'a', 'b', 'c'}
print(operator.isub(tags, {'b'}) is tags)   # → True
print(sorted(tags))   # → ['a', 'c']
print(operator.isub([1, 2, 3], [2]))   # → TypeError

See also

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