BUG: optimize: linprog failing TestLinprogSimplexBland::test_unbounded_below_no_presolve_corrected

[mdhaber]

Failure on Travis CI X.2. See #10238

______ TestLinprogSimplexBland.test_unbounded_below_no_presolve_corrected ______
[gw0] linux -- Python 3.7.1 /home/travis/virtualenv/python3.7.1/bin/python

self = <scipy.optimize.tests.test_linprog.TestLinprogSimplexBland object at 0x7ff9ae535e10>

    def test_unbounded_below_no_presolve_corrected(self):
        c = [1]
        bounds = [(None, 1)]
    
        o = {key: self.options[key] for key in self.options}
        o["presolve"] = False
    
        res = linprog(c=c, bounds=bounds,
                      method=self.method,
>                     options=o)

bounds     = [(None, 1)]
c          = [1]
o          = {'bland': True, 'presolve': False}
self       = <scipy.optimize.tests.test_linprog.TestLinprogSimplexBland object at 0x7ff9ae535e10>

/home/travis/virtualenv/python3.7.1/lib/python3.7/site-packages/scipy/optimize/tests/test_linprog.py:681: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/home/travis/virtualenv/python3.7.1/lib/python3.7/site-packages/scipy/optimize/_linprog.py:525: in linprog
    c, c0=c0, A=A, b=b, callback=callback, _T_o=T_o, **solver_options)
/home/travis/virtualenv/python3.7.1/lib/python3.7/site-packages/scipy/optimize/_linprog_simplex.py:638: in _linprog_simplex
    nit0=nit1, bland=bland, _T_o=_T_o)
/home/travis/virtualenv/python3.7.1/lib/python3.7/site-packages/scipy/optimize/_linprog_simplex.py:386: in _solve_simplex
    pivcol_found, pivcol = _pivot_col(T, tol, bland)
/home/travis/virtualenv/python3.7.1/lib/python3.7/site-packages/scipy/optimize/_linprog_simplex.py:93: in _pivot_col
    return True, np.nonzero(ma.mask == False)[0][0]
<__array_function__ internals>:6: in nonzero
    ???
/home/travis/virtualenv/python3.7.1/lib/python3.7/site-packages/numpy/core/fromnumeric.py:1849: in nonzero
    return _wrapfunc(a, 'nonzero')
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

obj = True, method = 'nonzero', args = (), kwds = {}
bound = <built-in method nonzero of numpy.bool_ object at 0x7ff9cc0a82b8>

    def _wrapfunc(obj, method, *args, **kwds):
        bound = getattr(obj, method, None)
        if bound is None:
            return _wrapit(obj, method, *args, **kwds)
    
        try:
>           return bound(*args, **kwds)
E           DeprecationWarning: Calling nonzero on 0d arrays is deprecated, as it behaves surprisingly. Use `atleast_1d(cond).nonzero()` if the old behavior was intended. If the context of this warning is of the form `arr[nonzero(cond)]`, just use `arr[cond]`.

args       = ()
bound      = <built-in method nonzero of numpy.bool_ object at 0x7ff9cc0a82b8>
kwds       = {}
method     = 'nonzero'
obj        = True

/home/travis/virtualenv/python3.7.1/lib/python3.7/site-packages/numpy/core/fromnumeric.py:61: DeprecationWarning

[peterbell10]

In answer to why it's happening now #10238 (comment). The build is with a dev version of NumPy numpy-1.17.0.dev0+a84476d, apparently this was only deprecated yesterday numpy/numpy#13708.

[mdhaber]

Thanks!

[jdriscoll7]

I went through and tried to fix all the deprecated nonzero() calls. Waiting to see if I pass Travis tests - the commits will be on #10298.

I'll let you know if my changes actually fix anything (or maybe they will break more).

[mdhaber]

@jwd0023 Oh, I was already doing this in #10306. Unless #10298 is ready to merge, probably better to keep it separate.

[jdriscoll7]

@mdhaber I botched mine - yours looks like it will work. Thanks!

[ev-br]

Fixed by #10306, closing.