all Python 3Sets (set)function

set.difference_update

set theory

Remove from the set the elements found in the others (in-place difference).

Syntax

s.difference_update(*others)

It mutates the set in place and returns None, so assigning the result back to your variable silently replaces the set with None. Elements that were not there in the first place are ignored — no KeyError, unlike remove().

Examples

s = {1, 2, 3, 4}
s.difference_update({2, 4})
print(sorted(s))   # → [1, 3]

See also

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