Numexpr doesn't recognize float type (sparse m

问题:

I would like to evaluate the performance of numexpr module in python (2.7). For that purpose, I created a random sparse matrix of size (10^5, 10^5). However, the script below throws an error at the expression evaluation step already, saying that it doesn't recognize the object type.

What am I doing wrong?

Code:

import timeit
import scipy.sparse as sps
import numpy as np
import numexpr as ne

test_matrix = sps.rand(1e4, 1e4, density=0.01, format='coo', dtype = np.float32)
ne.evaluate('sum(test_matrix, axis = 1)')

setup = 'import numexpr as ne; import numpy as np'
print min(timeit.Timer('ne.evaluate(sum(test_matrix, axis = 1))', setup=setup).repeat(7, 1000))

Error:

Traceback (most recent call last):

File "benchmark_expressmath.py", line 19, in <module>
ne.evaluate('sum(test_matrix, axis = 1)')
File "C:\Users\blahblah\AppData\Local\Continuum\Anaconda\lib\site-packages\numexpr\necompiler.py", line 756, in evaluate
signature = [(name, getType(arg)) for (name, arg) in zip(names, arguments)]
File "C:\Users\blahblah\AppData\Local\Continuum\Anaconda\lib\site-packages\numexpr\necompiler.py", line 654, in getType
raise ValueError("unknown type %s" % a.dtype.name)
ValueError: unknown type object

回答1:

numexpr expects the variables to be numpy arrays. It doesn't handle scipy's sparse matrices. (See, for example, this email thread: http://numpy-discussion.10968.n7.nabble.com/ANN-numexpr-2-3-final-released-td36154.html)