numpy.select — NumPy v2.2 Manual (original) (raw)
numpy.select(condlist, choicelist, default=0)[source]#
Return an array drawn from elements in choicelist, depending on conditions.
Parameters:
condlistlist of bool ndarrays
The list of conditions which determine from which array in _choicelist_the output elements are taken. When multiple conditions are satisfied, the first one encountered in condlist is used.
choicelistlist of ndarrays
The list of arrays from which the output elements are taken. It has to be of the same length as condlist.
defaultscalar, optional
The element inserted in output when all conditions evaluate to False.
Returns:
outputndarray
The output at position m is the m-th element of the array in_choicelist_ where the m-th element of the corresponding array in_condlist_ is True.
Examples
Beginning with an array of integers from 0 to 5 (inclusive), elements less than 3
are negated, elements greater than 3
are squared, and elements not meeting either of these conditions (exactly 3
) are replaced with a default value of 42
.
x = np.arange(6) condlist = [x<3, x>3] choicelist = [x, x**2] np.select(condlist, choicelist, 42) array([ 0, 1, 2, 42, 16, 25])
When multiple conditions are satisfied, the first one encountered in_condlist_ is used.
condlist = [x<=4, x>3] choicelist = [x, x**2] np.select(condlist, choicelist, 55) array([ 0, 1, 2, 3, 4, 25])