.. _ch_all_any:

Truth Value Testing: ``all`` and ``any``
========================================


In Python, we can use ``all`` and ``any`` to get the boolean return of a
list of values. ``all`` returns the logical ``and`` result while ``any``
returns the logical ``or`` result.

.. code:: python

    import numpy as np
    import d2ltvm 
    import tvm
    from tvm import te
    
    any((0, 1, 2)), all((0, 1, 2))




.. parsed-literal::
    :class: output

    (True, False)



TVM provides similar ``te.all`` and ``te.any``, which are useful to
construct complex conditional expression for ``te.if_then_else``.

The example we will use is padding the matrix ``a`` with 0s.

.. code:: python

    a = np.ones((3, 4), dtype='float32')
    # applying a zero padding of size 1 to a
    b = np.zeros((5, 6), dtype='float32')
    b[1:-1,1:-1] = a
    print(b)


.. parsed-literal::
    :class: output

    [[0. 0. 0. 0. 0. 0.]
     [0. 1. 1. 1. 1. 0.]
     [0. 1. 1. 1. 1. 0.]
     [0. 1. 1. 1. 1. 0.]
     [0. 0. 0. 0. 0. 0.]]


Now let's implement it in TVM. Note that we pass the four condition
values into ``tvm.any``.

.. code:: python

    p = 1 # padding size
    n, m = te.var('n'), te.var('m')
    A = te.placeholder((n, m), name='a')
    B = te.compute((n+p*2, m+p*2),
                    lambda i, j: te.if_then_else(
                        te.any(i<p, i>=n+p, j<p, j>=m+p), 0, A[i-p, j-p]),
                    name='b')

Verify the results.

.. code:: python

    s = te.create_schedule(B.op)
    mod = tvm.build(s, [A, B])
    c = tvm.nd.array(np.empty_like(b))
    mod(tvm.nd.array(a), c)
    print(c)


.. parsed-literal::
    :class: output

    [[0. 0. 0. 0. 0. 0.]
     [0. 1. 1. 1. 1. 0.]
     [0. 1. 1. 1. 1. 0.]
     [0. 1. 1. 1. 1. 0.]
     [0. 0. 0. 0. 0. 0.]]


Summary
-------

-  We can use ``tvm.any`` and ``tvm.all`` to construct complex
   conditional expressions.