Bug in K.equal operator

[roywei]

The current K.equal(x, y) operator can not handle the situation when x and y have different shape with MXNet backend.

Reproducible code:

import numpy as np
from keras import backend as K

x = K.variable(np.array([[1,2],[2,3]]))
y = K.variable(np.array([[1],[3]]))
print(K.eval(K.equal(x, y)))

with TensorFlow backend output is:

[[ True False]
 [False  True]]

with MXNet backend, error msg:

Using MXNet backend
/Users/lawei/anaconda3/lib/python3.6/site-packages/h5py/__init__.py:36: FutureWarning: Conversion of the second argument of issubdtype from `float` to `np.floating` is deprecated. In future, it will be treated as `np.float64 == np.dtype(float).type`.
  from ._conv import register_converters as _register_converters
Traceback (most recent call last):
  File "/Users/lawei/anaconda3/lib/python3.6/site-packages/mxnet/symbol/symbol.py", line 1522, in simple_bind
    ctypes.byref(exe_handle)))
  File "/Users/lawei/anaconda3/lib/python3.6/site-packages/mxnet/base.py", line 235, in check_call
    raise MXNetError(py_str(_LIB.MXGetLastError()))
mxnet.base.MXNetError: Error in operator _equal0: [21:31:53] src/operator/contrib/../tensor/../elemwise_op_common.h:133: Check failed: assign(&dattr, (*vec)[i]) Incompatible attr in node _equal0 at 1-th input: expected [2,2], got [2,1]

Stack trace returned 10 entries:
[bt] (0) 0   libmxnet.so                         0x000000010ed336b4 libmxnet.so + 18100
[bt] (1) 1   libmxnet.so                         0x000000010ed3346f libmxnet.so + 17519
[bt] (2) 2   libmxnet.so                         0x000000010ed330e9 libmxnet.so + 16617
[bt] (3) 3   libmxnet.so                         0x000000010ee37245 libmxnet.so + 1081925
[bt] (4) 4   libmxnet.so                         0x000000010ee36ee3 libmxnet.so + 1081059
[bt] (5) 5   libmxnet.so                         0x000000010ef93a5b libmxnet.so + 2509403
[bt] (6) 6   libmxnet.so                         0x000000010fe956da MXNDListFree + 326538
[bt] (7) 7   libmxnet.so                         0x000000010fe8ddec MXNDListFree + 295580
[bt] (8) 8   libmxnet.so                         0x000000010fe80836 MXNDListFree + 240870
[bt] (9) 9   libmxnet.so                         0x000000010fe863aa MXNDListFree + 264282



During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/lawei/Documents/Workspace/roywei/keras/examples/test.py", line 6, in <module>
    print(K.eval(K.equal(x, y)))
  File "/Users/lawei/Documents/Workspace/roywei/keras/keras/backend/mxnet_backend.py", line 554, in eval
    executor = x.symbol.simple_bind(mx.cpu(), grad_req='null')
  File "/Users/lawei/anaconda3/lib/python3.6/site-packages/mxnet/symbol/symbol.py", line 1528, in simple_bind
    raise RuntimeError(error_msg)
RuntimeError: simple_bind error. Arguments:
Error in operator _equal0: [21:31:53] src/operator/contrib/../tensor/../elemwise_op_common.h:133: Check failed: assign(&dattr, (*vec)[i]) Incompatible attr in node _equal0 at 1-th input: expected [2,2], got [2,1]

Stack trace returned 10 entries:
[bt] (0) 0   libmxnet.so                         0x000000010ed336b4 libmxnet.so + 18100
[bt] (1) 1   libmxnet.so                         0x000000010ed3346f libmxnet.so + 17519
[bt] (2) 2   libmxnet.so                         0x000000010ed330e9 libmxnet.so + 16617
[bt] (3) 3   libmxnet.so                         0x000000010ee37245 libmxnet.so + 1081925
[bt] (4) 4   libmxnet.so                         0x000000010ee36ee3 libmxnet.so + 1081059
[bt] (5) 5   libmxnet.so                         0x000000010ef93a5b libmxnet.so + 2509403
[bt] (6) 6   libmxnet.so                         0x000000010fe956da MXNDListFree + 326538
[bt] (7) 7   libmxnet.so                         0x000000010fe8ddec MXNDListFree + 295580
[bt] (8) 8   libmxnet.so                         0x000000010fe80836 MXNDListFree + 240870
[bt] (9) 9   libmxnet.so                         0x000000010fe863aa MXNDListFree + 264282

however, pure mxnet ndarray and symbol works fine:

x = mx.sym.Variable('x')
y = mx.sym.Variable('y')
result = mx.sym.broadcast_equal(x, y)
e = result.bind(mx.cpu(), {'x': mx.nd.array([[1,2],[2,3]]), 'y':mx.nd.array([[1],[3]])})
print(e.forward())

produce

[
[[1. 0.]
 [0. 1.]]
<NDArray 2x2 @cpu(0)>]

[roywei]

Root Cause: we should use mx.sym.broadcast_equal() when x and y have different shape.

Will fix together in pr #145

Reproducible code in mxnet:

import mxnet as mx
x = mx.sym.Variable('x')
y = mx.sym.Variable('y')
#result = mx.sym.broadcast_equal(x, y)
result = x==y
e = result.bind(mx.cpu(), {'x': mx.nd.array([[1,2],[2,3]]), 'y':mx.nd.array([[1],[2]])})
print(e.forward())

Error Msg:

Using MXNet backend
/Users/lawei/anaconda3/lib/python3.6/site-packages/h5py/__init__.py:36: FutureWarning: Conversion of the second argument of issubdtype from `float` to `np.floating` is deprecated. In future, it will be treated as `np.float64 == np.dtype(float).type`.
  from ._conv import register_converters as _register_converters
Traceback (most recent call last):
  File "/Users/lawei/Documents/Workspace/roywei/keras/examples/test.py", line 17, in <module>
    e = result.bind(mx.cpu(), {'x': mx.nd.array([[1,2],[2,3]]), 'y':mx.nd.array([[1],[2]])})
  File "/Users/lawei/anaconda3/lib/python3.6/site-packages/mxnet/symbol/symbol.py", line 1703, in bind
    ctypes.byref(handle)))
  File "/Users/lawei/anaconda3/lib/python3.6/site-packages/mxnet/base.py", line 235, in check_call
    raise MXNetError(py_str(_LIB.MXGetLastError()))
mxnet.base.MXNetError: Error in operator _equal0: [00:22:46] src/operator/contrib/../tensor/../elemwise_op_common.h:133: Check failed: assign(&dattr, (*vec)[i]) Incompatible attr in node _equal0 at 1-th input: expected [2,2], got [2,1]

Stack trace returned 10 entries:
[bt] (0) 0   libmxnet.so                         0x0000000105be56b4 libmxnet.so + 18100
[bt] (1) 1   libmxnet.so                         0x0000000105be546f libmxnet.so + 17519
[bt] (2) 2   libmxnet.so                         0x0000000105be50e9 libmxnet.so + 16617
[bt] (3) 3   libmxnet.so                         0x0000000105ce9245 libmxnet.so + 1081925
[bt] (4) 4   libmxnet.so                         0x0000000105ce8ee3 libmxnet.so + 1081059
[bt] (5) 5   libmxnet.so                         0x0000000105e45a5b libmxnet.so + 2509403
[bt] (6) 6   libmxnet.so                         0x0000000106d476da MXNDListFree + 326538
[bt] (7) 7   libmxnet.so                         0x0000000106d3fdec MXNDListFree + 295580
[bt] (8) 8   libmxnet.so                         0x0000000106d22d60 MXNDListFree + 176656
[bt] (9) 9   libmxnet.so                         0x0000000106d3858d MXNDListFree + 264765

[roywei]

same applies to other element wise operators

• not_equal
• greater
• greater_equal
• less
• less_equal

[roywei]

closing as fixed in #145