all Python 3Sets (set)function

set.remove

removal

Remove an element; raises KeyError if it is absent (unlike discard).

Syntax

s.remove(elem)

A KeyError here means the element was already gone, which is normally a bug in your logic rather than an everyday case — wrapping the call in try/except is a smell, and if absence is expected you want discard. A separate trap is removing items while iterating over the same set: the loop dies with a RuntimeError about the size changing, so iterate over a copy.

Examples

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

See also

Common errors

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