jax.numpy.where

jax.numpy.where(condition, x=None, y=None, *, size=None, fill_value=None)

Return elements chosen from x or y depending on condition.

LAX-backend implementation of where().

At present, JAX does not support JIT-compilation of the single-argument form of jax.numpy.where() because its output shape is data-dependent. The three-argument form does not have a data-dependent shape and can be JIT-compiled successfully. Alternatively, you can specify the optional size keyword: if specified, the first size True elements will be returned; if there are fewer True elements than size indicates, the index arrays will be padded with fill_value (default is 0.)

Original docstring below.

Note

When only condition is provided, this function is a shorthand for np.asarray(condition).nonzero(). Using 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.

Parameters

• condition (array_like, bool) – Where True, yield x, otherwise yield y.

• x (array_like) – Values from which to choose. x, y and condition need to be broadcastable to some shape.

• y (array_like) – Values from which to choose. x, y and condition need to be broadcastable to some shape.

Returns

out – An array with elements from x where condition is True, and elements from y elsewhere.

Return type

ndarray