Python分割函数。解包错误的值太多
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Python split function. Too many values to unpack error
提问by user3156971
I have a python function that must read data from file and split it into two key and value, and then store it in dictionary. Example: file:
我有一个 python 函数，它必须从文件中读取数据并将其拆分为两个键和值，然后将其存储在字典中。示例：文件：
http://google.com 2
http://python.org 3
# and so on a lot of data
I use the split function for it, but when there is really a lot of data it raises value error
我为它使用了 split 函数，但是当真的有很多数据时，它会引发值错误
ValueError: too many values to unpack
What can I do about this ?
我该怎么办？
This is the exact code that fails
这是失败的确切代码
with open(urls_file_path, "r") as f:
for line in f.readlines():
url, count = line.split()# fails here
url_dict[url] = int(count)
采纳答案by thefourtheye
You are trying to unwrap the split list in to these two variables.
您正在尝试将拆分列表解包到这两个变量中。
url, count = line.split()
What if there is no space or two or more spaces? Where will the rest of the words go?
如果没有空格或两个或更多空格怎么办？剩下的单词会去哪里？
data = "abcd"
print data.split() # ['abcd']
data = "ab cd"
print data.split() # ['ab', 'cd']
data = "a b c d"
print data.split() # ['a', 'b', 'c', 'd']
You can actually check the length before assigning
您实际上可以在分配之前检查长度
with open(urls_file_path, "r") as f:
for idx, line in enumerate(f, 1):
split_list = line.split()
if len(split_list) != 2:
raise ValueError("Line {}: '{}' has {} spaces, expected 1"
.format(idx, line.rstrip(), len(split_list) - 1))
else:
url, count = split_list
print url, count
With the input file,
使用输入文件，
http://google.com 2
http://python.org 3
http://python.org 4 Welcome
http://python.org 5
This program produces,
这个程序产生，
$ python Test.py
Read Data: http://google.com 2
Read Data: http://python.org 3
Traceback (most recent call last):
File "Test.py", line 6, in <module>
.format(idx, line.rstrip(), len(split_list) - 1))
ValueError: Line 3: 'http://python.org 4 Welcome' has 2 spaces, expected 1
Following @abarnert's comment, you can use partitionfunction like this
按照@abernert 的评论，您可以使用这样的partition功能
url, _, count = data.partition(" ")
If there are more than one spaces/no space, then countwill hold rest of the string or empty string, respectively.
如果有多个空格/没有空格，count则将分别保存字符串的其余部分或空字符串。
If you are using Python 3.x,you can do something like this
如果您使用的是 Python 3.x，则可以执行以下操作
first, second, *rest = data.split()
First two values will be assigned in firstand secondrespectively and the rest of the list will be assigned to rest, in Python 3.x
在 Python 3.x 中，前两个值将分别分配给first和second，列表的其余部分将分配给rest,
