This is documentation for an old release of SciPy (version 0.8.). Read this page in the documentation of the latest stable release (version 1.15.1).
Slices off the passed proportion of items from BOTH ends of the passed array (i.e., with proportiontocut=0.1, slices ‘leftmost’ 10% AND ‘rightmost’ 10% of scores. You must pre-sort the array if you want “proper” trimming. Slices off LESS if proportion results in a non-integer slice index (i.e., conservatively slices off proportiontocut).
Returns: trimmed version of array a