您好我有一个（numpy）优化问题。
下面我写了一段代码，这对我的计算类型很常见。
总的来说，我认为应该缩短一些时间。
我认为问题是循环。我看过numpy的linalg部分，但我找不到解决办法。我也搜索了一种方法矢量化数据，但由于我没有太多经验...我找不到任何解决方案......
我希望有人可以帮助我...
import numpy as np
from scipy import signal
from scipy.fftpack import fft
fs = 44100 # frequency sample
T = 5 # time max
t = np.arange(0, T*fs)/fs # time array
x = np.sin(2 * np.pi * 100 * t) + 0.7 * np.sin(2 * np.pi * 880 * t) + 0.2 * np.sin(2 * np.pi * 2400 * t)
# Define Window length and window:
wl = 4 # window lenght
overlap = 0.5
W = signal.get_window('hanning', wl) # window
Wx = np.zeros(len(x))
ul = wl
# loop added for window
if (len(x) / wl) % wl == 0:
while ul <= len(Wx):
Wx[ul-wl:ul] += x[ul-wl:ul] * W
ul += wl * overlap
else:
dsample = (len(x)/wl) % wl # delta in samples between mod (x/windw length)
x = np.append(x, np.zeros(wl - dsample))
while ul <= len(Wx):
Wx[ul-wl:ul] += x[ul-wl:ul] * W
ul += wl * overlap
NFFT = np.int(2 ** np.ceil(np.log2(len(x))))
NFFW = np.int(2 ** np.ceil(np.log2(len(Wx))))
# Frequency spectrums
X = fft(x, NFFT)
WX = fft(Wx, NFFW)
探查：
%run -p example.py
110367 function calls (110366 primitive calls) in 19.998 seconds
Ordered by: internal time
ncalls tottime percall cumtime percall filename:lineno(function)
1 19.561 19.561 19.994 19.994 example.py:6(<module>)
110258 0.233 0.000 0.233 0.000 {built-in method len}
2 0.181 0.091 0.189 0.095 basic.py:169(fft)
2 0.008 0.004 0.008 0.004 basic.py:131(_fix_shape)
2 0.008 0.004 0.008 0.004 {built-in method concatenate}
1 0.003 0.003 0.003 0.003 {built-in method compile}
2 0.002 0.001 0.002 0.001 {built-in method arange}
2 0.001 0.000 0.001 0.000 {built-in method open}
4 0.000 0.000 0.000 0.000 {built-in method zeros}
1 0.000 0.000 19.998 19.998 interactiveshell.py:2496(safe_execfile)
2/1 0.000 0.000 19.998 19.998 {built-in method exec}
1 0.000 0.000 0.000 0.000 windows.py:615(hann)
1 0.000 0.000 19.997 19.997 py3compat.py:108(execfile)
1 0.000 0.000 0.000 0.000 {method 'read' of '_io.BufferedReader' objects}
2 0.000 0.000 0.008 0.004 function_base.py:3503(append)
1 0.000 0.000 0.000 0.000 posixpath.py:318(normpath)
1 0.000 0.000 0.000 0.000 windows.py:1380(get_window)
1 0.000 0.000 0.000 0.000 posixpath.py:145(dirname)
4 0.000 0.000 0.000 0.000 {built-in method array}
2 0.000 0.000 0.000 0.000 {built-in method round}
1 0.000 0.000 0.000 0.000 {built-in method getcwd}
2 0.000 0.000 0.000 0.000 <frozen importlib._bootstrap>:2264(_handle_fromlist)
2 0.000 0.000 0.000 0.000 basic.py:116(_asfarray)
4 0.000 0.000 0.000 0.000 basic.py:24(istype)
2 0.000 0.000 0.000 0.000 fromnumeric.py:1281(ravel)
8 0.000 0.000 0.000 0.000 {built-in method isinstance}
1 0.000 0.000 0.000 0.000 posixpath.py:70(join)
2 0.000 0.000 0.000 0.000 numeric.py:462(asanyarray)
1 0.000 0.000 0.000 0.000 posixpath.py:355(abspath)
8 0.000 0.000 0.000 0.000 {built-in method hasattr}
1 0.000 0.000 19.998 19.998 <string>:1(<module>)
1 0.000 0.000 0.000 0.000 syspathcontext.py:64(__exit__)
1 0.000 0.000 0.000 0.000 posixpath.py:221(expanduser)
1 0.000 0.000 0.000 0.000 _bootlocale.py:23(getpreferredencoding)
1 0.000 0.000 0.000 0.000 syspathcontext.py:57(__enter__)
1 0.000 0.000 0.000 0.000 syspathcontext.py:54(__init__)
4 0.000 0.000 0.000 0.000 {built-in method issubclass}
3 0.000 0.000 0.000 0.000 posixpath.py:38(_get_sep)
2 0.000 0.000 0.000 0.000 {method 'ravel' of 'numpy.ndarray' objects}
2 0.000 0.000 0.000 0.000 numeric.py:392(asarray)
7 0.000 0.000 0.000 0.000 {method 'append' of 'list' objects}
1 0.000 0.000 0.000 0.000 {built-in method nl_langinfo}
5 0.000 0.000 0.000 0.000 {method 'startswith' of 'str' objects}
1 0.000 0.000 0.000 0.000 codecs.py:306(__init__)
1 0.000 0.000 0.000 0.000 posixpath.py:60(isabs)
1 0.000 0.000 0.000 0.000 {method 'split' of 'str' objects}
1 0.000 0.000 0.000 0.000 codecs.py:257(__init__)
2 0.000 0.000 0.000 0.000 {method 'setdefault' of 'dict' objects}
1 0.000 0.000 0.000 0.000 {method 'rfind' of 'str' objects}
1 0.000 0.000 0.000 0.000 {method 'remove' of 'list' objects}
1 0.000 0.000 0.000 0.000 {method 'join' of 'str' objects}
1 0.000 0.000 0.000 0.000 {method 'rstrip' of 'str' objects}
1 0.000 0.000 0.000 0.000 {method 'endswith' of 'str' objects}
1 0.000 0.000 0.000 0.000 {method 'insert' of 'list' objects}
1 0.000 0.000 0.000 0.000 {built-in method getdefaultencoding}
1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler' objects}
1 0.000 0.000 0.000 0.000 py3compat.py:13(no_code)
答案 0 :(得分：0)
预计算静态值可将我的循环从~4s缩短到0.7s执行时间：
nEntries = len(Wx)
step = int(wl * overlap)
while ul <= nEntries:
Wx[ul-wl:ul] += x[ul-wl:ul] * W
ul += step