Fixed Dimshuffle for scalar result cases

[kc611]

Fixes #621

A simple fix which returns a scalar array for the particular case of DimShuffle

import numpy as np
import aesara
from aesara.graph.optdb import OptimizationQuery
from aesara.compile.mode import Mode
from aesara.link.numba.linker import NumbaLinker
from aesara.tensor.elemwise import DimShuffle
from aesara.tensor.type import TensorType

opts = OptimizationQuery(include=[None], exclude=["cxx_only", "BlasOpt"])
numba_mode = Mode(NumbaLinker(), opts)
py_mode = Mode("py", opts)

orig_shape = (1, 1, 1)
dims = ()
out_shape = ()

broadcastables = [(entry == 1) for entry in orig_shape]
x = TensorType(aesara.config.floatX, broadcastables)("x")
out = DimShuffle(broadcastables, dims)(x)

py_res = aesara.function(inputs=[x], outputs=[out], mode=py_mode)(np.ones(orig_shape, dtype=aesara.config.floatX)) # returns array([1.])
numba_res = aesara.function(inputs=[x], outputs=[out], mode=numba_mode)(np.ones(orig_shape, dtype=aesara.config.floatX)) # returns array([1.])
pass

[codecov]

Codecov Report

Merging #625 (cda0357) into main (0f8c81c) will increase coverage by 0.00%.
The diff coverage is 86.66%.

@@           Coverage Diff           @@
##             main     #625   +/-   ##
=======================================
  Coverage   77.02%   77.02%           
=======================================
  Files         157      157           
  Lines       46915    46918    +3     
  Branches    10265    10266    +1     
=======================================
+ Hits        36136    36139    +3     
  Misses       8196     8196           
  Partials     2583     2583           

Impacted Files	Coverage Δ
aesara/link/numba/dispatch/elemwise.py	97.54% <86.66%> (+0.03%)	⬆️