where(condition, [x, y], /)
Some inconsistencies with the Dask version may exist.
Return elements chosen from x or y depending on :None:None:`condition`.
When only :None:None:`condition` is provided, this function is a shorthand for np.asarray(condition).nonzero()
. Using :None:None:`nonzero` directly should be preferred, as it behaves correctly for subclasses. The rest of this documentation covers only the case where all three arguments are provided.
If all the arrays are 1-D, where
is equivalent to:
[xv if c else yv for c, xv, yv in zip(condition, x, y)]
Values from which to choose. x, y and :None:None:`condition` need to be broadcastable to some shape.
An array with elements from x where :None:None:`condition` is True, and elements from y elsewhere.
This docstring was copied from numpy.where.
nonzero
The function that is called when x and y are omitted
>>> a = np.arange(10) # doctest: +SKIPThis example is valid syntax, but we were not able to check execution
... a # doctest: +SKIP array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> np.where(a < 5, a, 10*a) # doctest: +SKIP array([ 0, 1, 2, 3, 4, 50, 60, 70, 80, 90])
This can be used on multidimensional arrays too:
This example is valid syntax, but we were not able to check execution>>> np.where([[True, False], [True, True]], # doctest: +SKIP
... [[1, 2], [3, 4]],
... [[9, 8], [7, 6]]) array([[1, 8], [3, 4]])
The shapes of x, y, and the condition are broadcast together:
This example is valid syntax, but we were not able to check execution>>> x, y = np.ogrid[:3, :4] # doctest: +SKIPThis example is valid syntax, but we were not able to check execution
... np.where(x < y, x, 10 + y) # both x and 10+y are broadcast # doctest: +SKIP array([[10, 0, 0, 0], [10, 11, 1, 1], [10, 11, 12, 2]])
>>> a = np.array([[0, 1, 2], # doctest: +SKIPSee :
... [0, 2, 4],
... [0, 3, 6]])
... np.where(a < 4, a, -1) # -1 is broadcast # doctest: +SKIP array([[ 0, 1, 2], [ 0, 2, -1], [ 0, 3, -1]])
The following pages refer to to this document either explicitly or contain code examples using this.
dask.array.routines.piecewise
dask.array.routines.where
dask.array.routines.select
dask.array.routines.argwhere
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