Question

我无法弄清楚为什么在以下程序中使用while循环总是在1次迭代后停止。基本上，权重是如何变成的无论输入如何，均等于一次迭代后的权重。基本上我想要跟踪两个连续运行的权重列表以及它们是否相等我想退出如果我使用具有固定大量迭代的for循环，我明白了连续的权重列表在第一次迭代中不相等，而while循环总是如此退出一个。任何帮助将不胜感激。

import random

def test(inputs, targets):
    inputDim = len(inputs[0])
    outputDim = len(targets[0])
    if (len(inputs) == len(targets)):
        dataSize = len(inputs)
    else:
        return

    weights = [];

    for i in range(inputDim + 1):
        weights.append([]);
        for j in range(outputDim):
            weights[i].append(2*random.random() - 1);

    weightsPrevious = 0

    iterCount = 0
    while (weightsPrevious != weights):
        iterCount += 1
        print("iteration", iterCount)
        weightsPrevious = weights.copy()
        for k in range(dataSize):
            for j in range(outputDim):
                weights[0][j] += 0.25*(targets[k][j] - 1)*(-1)
                for i in range(inputDim):
                    weights[i + 1][j] += 0.25*(targets[k][j] - 1)*inputs[k][i]

        return weights

test([[0,0],[0,1],[1,0],[1,1]],[[0],[1],[1],[1]])

编辑：即使删除了最后一个返回语句

，我也得到了相同的结果

Answer 1

这种情况正在发生，因为你在while循环结束时有一个return。 return停止执行该函数并返回weights。

我认为你需要取消它：

while (weightsPrevious != weights):
    iterCount += 1
    print("iteration", iterCount)
    ...

return weights # now this is going to be executed when 
               # the while loop is finished.

Answer 2

while (weightsPrevious != weights):
    iterCount += 1
    print("iteration", iterCount)
    weightsPrevious = weights.copy()
    for k in range(dataSize):
        for j in range(outputDim):
            weights[0][j] += 0.25*(targets[k][j] - 1)*(-1)
            for i in range(inputDim):
                weights[i + 1][j] += 0.25*(targets[k][j] - 1)*inputs[k][i]

    return weights

应该是

while (weightsPrevious != weights):
    iterCount += 1
    print("iteration", iterCount)
    weightsPrevious = weights.copy()
    for k in range(dataSize):
        for j in range(outputDim):
            weights[0][j] += 0.25*(targets[k][j] - 1)*(-1)
            for i in range(inputDim):
                weights[i + 1][j] += 0.25*(targets[k][j] - 1)*inputs[k][i]

return weights

注意返回的缩进

在python中使用while循环的问题

2 个答案: