爲什麼這個循環慢慢地運行？

Question

流動的代碼是一個簡單的python循環。

def getBestWeightsByRandomGradientAscent(featureDatasList, classTypes, maxCycles=1): 
    """ 
    :param featureDatasList: 
    :param classTypes: 
    :param maxCycles: the loop time 
    :return: 
    """ 
    import random 

    featureDatas = np.array(featureDatasList) 
    m, n = np.shape(featureDatas) 
    weights = np.ones(n) 

    # the loop goes here... # 
    for j in range(maxCycles): 
     featureIndexs = range(m) 
     featureLen = len(featureIndexs) 
     for i in range(m): 
      delta = 4/(1.0 + i + j) + 0.01 
      randIndex = int(random.uniform(0, featureLen)) 
      sigmodInput = sum(featureDatas[randIndex] * weights) 
      estimateClass = calculateSigmodEstimateClassType(sigmodInput) 
      error = classTypes[randIndex] - estimateClass 
      weights += (error * delta) * featureDatas[randIndex] 
      del (featureIndexs[randIndex]) 

    return weights 

我發現，當我運行這個循環1000次以上，它在開始跑得快，但它運行，並最終保持低速它會越來越慢......好奇，我不爲什麼。這是由變量的範圍還是我的硬件問題造成的？我該如何解決這個問題？非常感謝！

Answer 1

考慮使用xrange而不是range。它可能是記憶或GC。你可以用類似於http://www.vrplumber.com/programming/runsnakerun/