python - 用于替换字符串中字符的 Lambda 函数

Question

下面是替换字符的Python代码。有人可以解释一下 lambda 部分吗？最初，X 取“p”并检查它是 a1 还是 a2。交换发生在哪里？

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def replaceUsingMapAndLambda(sent, a1, a2):
    # We create a lambda that only works if we input a1 or a2 and swaps them.
    newSent = map(lambda x: x if(x != a1 and x != a2) else a1 if x == a2 else a2, sent)
    print(newSent)
    return ''.join(newSent)


print(replaceUsingMapAndLambda("puporials toinp", "p", "t"))

输出:

$python main.py
['t', 'u', 't', 'o', 'r', 'i', 'a', 'l', 's', ' ', 'p', 'o', 'i', 'n', 't']
tutorials point 

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谢谢，雷西卡

Answer 1

这等同于:

def replaceUsingMapAndLambda(sent, a1, a2):
    # We create a lambda that only works if we input a1 or a2 and swaps them.
    newSent = []
    for x in sent:
        if x != a1 and x != a2:
            newSent.append(x)
        elif x == a2:
            newSent.append(a1)
        else:
            newSent.append(a2) 

    print(newSent)
    return ''.join(newSent)

Lambda是创建匿名函数的关键字，map将此匿名函数应用于列表的每个元素并返回结果。