迭代嵌套列表并更改值

Question

我试着找到这个答案，但只能找到一些我难以拼凑的碎片。在

假设我有：

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

我希望遍历这个嵌套列表，并将编号的字符串值更改为floats。在

Answer 1

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

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：

^{pr2}$