python - 获取空白列表 - 不知道为什么？

Question

我使用这段代码:

from __future__ import division
from __future__ import print_function

in_file = open("s:/Personal Folders/Andy/Python Projects/People Cancelled/Analyze Authorize Truncated.csv")
text = in_file.readlines()
in_file.close()

header = text[0:1]
text = text[1:]

for index, line in enumerate(text):
    text[index] = line.split(",")

name = text
dates = text

for index, line in enumerate(name):
    name[index] = line[3:5]

for stuff, area in enumerate(dates):
     dates[stuff] = area[7:8]

print(name)
print(dates)

我得到了这个输出:

 [[], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], []]
 [[], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], []]

知道为什么吗？出于某种原因，两个 for 循环之间似乎存在某种干扰 - 如果我单独执行其中一个，我会得到我想要的结果。

谢谢!

Answer 1

看这两行:

name = text
date = text

这些行不复制要指向的名称和日期的文本；相反，他们将名称和日期设置为实质上文本的替代名称。因此，在第三个 for 循环之后(主体 name[index] = line[3:5]，text 中的每一行都是两个项目长(因为 text 和 name 是同一个列表。事实上，我什至不明白为什么要将 name 和 date 设置为相等最初为 text；通过使 name 和 date 等于新的空列表并根据文本。