numpy.ma.where — NumPy v1.11 Manual (original) (raw)
numpy.ma.where(condition, x=<class numpy._NoValue at 0x40a1fe3c>, y=<class numpy._NoValue at 0x40a1fe3c>)[source]¶
Return a masked array with elements from x or y, depending on condition.
Returns a masked array, shaped like condition, where the elements are from x when condition is True, and from y otherwise. If neither x nor y are given, the function returns a tuple of indices where condition is True (the result ofcondition.nonzero()).
| Parameters: | condition : array_like, bool The condition to meet. For each True element, yield the corresponding element from x, otherwise from y. x, y : array_like, optional Values from which to choose. x and y need to have the same shape as condition, or be broadcast-able to that shape. |
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| Returns: | out : MaskedArray or tuple of ndarrays The resulting masked array if x and y were given, otherwise the result of condition.nonzero(). |
See also
Equivalent function in the top-level NumPy module.
Examples
x = np.ma.array(np.arange(9.).reshape(3, 3), mask=[[0, 1, 0], ... [1, 0, 1], ... [0, 1, 0]]) print(x) [[0.0 -- 2.0] [-- 4.0 --] [6.0 -- 8.0]] np.ma.where(x > 5) # return the indices where x > 5 (array([2, 2]), array([0, 2]))
print(np.ma.where(x > 5, x, -3.1416)) [[-3.1416 -- -3.1416] [-- -3.1416 --] [6.0 -- 8.0]]