def pick_vector(cond,
true_vector,
false_vector,
name="pick_vector"):
"""Picks possibly different length row `Tensor`s based on condition.
Value `Tensor`s should have exactly one dimension.
If `cond` is a python Boolean or `tf.constant` then either `true_vector` or
`false_vector` is immediately returned. I.e., no graph nodes are created and
no validation happens.
Args:
cond: `Tensor`. Must have `dtype=tf.bool` and be scalar.
true_vector: `Tensor` of one dimension. Returned when cond is `True`.
false_vector: `Tensor` of one dimension. Returned when cond is `False`.
name: `String`. The name to give this op.
Example:
```python
pick_vector(tf.less(0, 5), tf.range(10, 12), tf.range(15, 18))
# result is tensor: [10, 11].
pick_vector(tf.less(5, 0), tf.range(10, 12), tf.range(15, 18))
# result is tensor: [15, 16, 17].
Returns:
true_or_false_vector: Tensor.
Raises:
TypeError: if cond.dtype != tf.bool
TypeError: if cond is not a constant and
true_vector.dtype != false_vector.dtype
"""
with ops.op_scope((cond, true_vector, false_vector), name):
cond = ops.convert_to_tensor(cond, name="cond")
if cond.dtype != dtypes.bool:
raise TypeError("%s.dtype=%s which is not %s" %
(cond.name, cond.dtype, dtypes.bool))
cond_value_static = tensor_util.constant_value(cond)
if cond_value_static is not None:
return true_vector if cond_value_static else false_vector
true_vector = ops.convert_to_tensor(true_vector, name="true_vector")
false_vector = ops.convert_to_tensor(false_vector, name="false_vector")
if true_vector.dtype != false_vector.dtype:
raise TypeError(
"%s.dtype=%s does not match %s.dtype=%s"
% (true_vector.name, true_vector.dtype,
false_vector.name, false_vector.dtype))
n = array_ops.shape(true_vector)[0]
return array_ops.slice(array_ops.concat(0, (true_vector, false_vector)),
[math_ops.select(cond, 0, n)],
[math_ops.select(cond, n, -1)])
```
