迭代嵌套列表并更改值

Question

我试图找到这个答案，但只能找到它，因为我在拼凑时遇到了麻烦。

假设我有：

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

我想遍历这个嵌套列表和编号的字符串值改为浮动。

Answer 1

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 

出来：

好的....

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

Answer 2

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