我正在学习使用Theano。我想通过计算每个元素的二进制TF-IDF来填充一个术语-文档矩阵(一个numpy稀疏矩阵):
import theano
import theano.tensor as T
import numpy as np
from time import perf_counter
def tfidf_gpu(appearance_in_documents,num_documents,document_words):
start = perf_counter()
APP = T.scalar('APP',dtype='int32')
N = T.scalar('N',dtype='int32')
SF = T.scalar('S',dtype='int32')
F = (T.log(N)-T.log(APP)) / SF
TFIDF = theano.function([N,APP,SF],F)
ret = TFIDF(num_documents,appearance_in_documents,document_words)
end = perf_counter()
print("\nTFIDF_GPU ",end-start," secs.")
return ret
def tfidf_cpu(appearance_in_documents,num_documents,document_words):
start = perf_counter()
tfidf = (np.log(num_documents)-np.log(appearance_in_documents))/document_words
end = perf_counter()
print("TFIDF_CPU ",end-start," secs.\n")
return tfidf
但是,numpy的版本比theano实现要快得多:
Progress 1/43
TFIDF_GPU 0.05702276699594222 secs.
TFIDF_CPU 1.454801531508565e-05 secs.
Progress 2/43
TFIDF_GPU 0.023830442980397493 secs.
TFIDF_CPU 1.1073017958551645e-05 secs.
Progress 3/43
TFIDF_GPU 0.021920352999586612 secs.
TFIDF_CPU 1.0738993296399713e-05 secs.
Progress 4/43
TFIDF_GPU 0.02303648801171221 secs.
TFIDF_CPU 1.1675001587718725e-05 secs.
Progress 5/43
TFIDF_GPU 0.02359767400776036 secs.
TFIDF_CPU 1.4385004760697484e-05 secs.
....
我读到过这可能是由于开销造成的,对于小操作可能会影响性能。
我的代码有问题吗,还是应该避免使用GPU因为开销问题?
T.scalar
)进行操作。除非处理相当大的数组并执行涉及多个数组元素的向量化操作,否则使用GPU是没有意义的。 - ali_m