stack adhering to Array API standard

[juliagsy]

No description provided.

[juliagsy]

Hello! I'm working on the stack function for manipulation functions and I'm good to go once the Tensorflow test has passed. However, I'm kinda stuck now so could someone help in giving it a look?

[juliagsy]

The errors are as follows:

__________________________________ test_stack __________________________________
[183](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:183)

[184](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:184)
    @given(
[185](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:185)
>       shape=shared_shapes(min_dims=1),
[186](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:186)
        dtypes=hh.mutually_promotable_dtypes(None),
[187](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:187)
        kw=hh.kwargs(
[188](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:188)
            axis=shared_shapes(min_dims=1).flatmap(
[189](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:189)
                lambda s: st.integers(-len(s), len(s) - 1)
[190](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:190)
            )
[191](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:191)
        ),
[192](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:192)
        data=st.data(),
[193](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:193)
    )
[194](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:194)

[195](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:195)
ivy/ivy_tests/test_array_api/array_api_tests/test_manipulation_functions.py:322: 
[196](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:196)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
[197](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:197)
ivy/ivy_tests/test_array_api/array_api_tests/test_manipulation_functions.py:337: in test_stack
[198](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:198)
    out = xp.stack(arrays, **kw)
[199](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:199)
ivy/ivy/func_wrapper.py:50: in _method_wrapped
[200](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:200)
    native_ret = fn(*native_args, **native_kwargs)
[201](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:201)
usr/local/lib/python3.8/dist-packages/tensorflow/python/util/traceback_utils.py:153: in error_handler
[202](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:202)
    raise e.with_traceback(filtered_tb) from None
[203](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:203)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
[204](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:204)

[205](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:205)
e = _NotOkStatusException(), name = 'stack'
[206](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:206)

[207](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:207)
    def raise_from_not_ok_status(e, name):
[208](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:208)
      e.message += (" name: " + name if name is not None else "")
[209](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:209)
>     raise core._status_to_exception(e) from None  # pylint: disable=protected-access
[210](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:210)
E     tensorflow.python.framework.errors_impl.InvalidArgumentError: cannot compute Pack as input #1(zero-based) was expected to be a uint8 tensor but is a uint16 tensor [Op:Pack] name: stack
[211](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:211)

[212](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:212)
usr/local/lib/python3.8/dist-packages/tensorflow/python/framework/ops.py:7186: InvalidArgumentError
[213](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:213)
----------------------------- Captured stdout call -----------------------------
[214](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:214)
f_idx=':'
[215](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:215)
f_idx=':'
[216](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:216)
f_idx=':'
[217](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:217)
f_idx=':'
[218](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:218)
f_idx=':'
[219](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:219)
f_idx=':'
[220](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:220)
f_idx=':'
[221](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:221)
f_idx=':'
[222](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:222)
f_idx=':'
[223](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:223)
f_idx=':'
[224](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:224)
---------------------------------- Hypothesis ----------------------------------
[225](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:225)
Falsifying example: test_stack(
[226](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:226)
    shape=(0,), dtypes=(tf.uint8, tf.uint16), kw={}, data=data(...),
[227](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:227)
)
[228](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:228)
Draw 1 (x1): ivy.array([], dtype=uint8)
[229](https://github.com/unifyai/ivy/runs/5548977686?check_suite_focus=true#step:3:229)
Draw 2 (x2): ivy.array([], dtype=uint16)

[juliagsy]

My function implementation for Tensorflow backend stack is:

def stack(x: Union[Tuple[Tensor], List[Tensor]],
          axis: Optional[int] = None)\
          -> Tensor:
    x = tf.cast(x, dtype=tf.uint8)
    if axis is None:
        new_axis = 0
    else:
        new_axis = axis
    return tf.stack(x, axis=new_axis)

[juliagsy]

I've added type casting as I thought the errors looked associated with type (uint8 and uint16) but the error did not actually go off. Thanks in advance!

[mattbarrett98]

Thanks for contributing!