遍历嵌套列表并修改值

Question

我试着找这个问题的答案，但只能找到一些零散的信息，拼凑起来有点困难。

假设我有：

aList = [["星期一", "2.03", "4.03"], ["星期二", "4.03", "5.03"], ["星期三", "3.2", "4.3"]]

我想要遍历这个嵌套的列表，把里面的数字字符串转换成浮点数。

Answer 1

for item in aList:
    item[1] = float(item[1])
    item[2] = float(item[2])

当然可以！请把你想要翻译的内容发给我，我会帮你把它变得更简单易懂。

Answer 2

aList = [["Monday", "2.03","4.03"],
         ["Tuesday","4.03","5.03"],
         ["Wednesday","3.2","4.3"]]

def helper(s):
    try: return float(s)
    except ValueError: return s

aList[:] = [[helper(item) for item in subl] for subl in aList]
print aList

输出：

[['Monday', 2.03, 4.03], ['Tuesday', 4.03, 5.03], ['Wednesday', 3.2, 4.3]]