将 CSV 转换为列表会在列表中生成列表

Question

我正在尝试将以下 Unicode 字符串转换为列表 [我在其中添加了两个空格以使其适合...]：

"58478000","","NEW","2016-12-28T14:34:18","C","","","N","N","ON","2017-03-15","2022-03-15","30/360","EUR","IR","","InterestRate:IRSwap:FixedFloat","Trade","EUR-EURIBOR-Reuters","FIXED","Percent","-0.003","","","EUR","EUR","25,000,000","25,000,000","3M","1Y","3M","","","","","","","","","","","","",""

我使用以下代码将上面的字符串 abc 转换为列表：

csv.reader(abc, delimiter=',')
details = list(csvreader)

这导致了这个结果，我似乎无法轻易放弃['','']...

[['58478000'], ['', ''], [''], ['', ''], ['NEW'], ['', ''],['2016-12-28T14:34:18'], ['', ''], ['C'], ['', ''], [''], ['', ''],[''], ['', ''], ['N'], ['', ''], ['N'], ['', ''], ['ON'], ['', ''],['2017-03-15'], ['', ''], ['2022-03-15'], ['', ''], [' 30/360'], ['',''], ['EUR'], ['', ''], ['IR'], ['', ''], [''], ['', ''],['InterestRate:IRSwap:FixedFloat'], ['', ''], ['Trade'], ['', ''],['EUR-EURIBOR-Reuters'], ['', ''], ['FIXED'], ['', ''], ['Percent'],['', ''], ['-0.003'], ['', ''], [''], ['', ''], [''], ['', ''],['EUR'], ['', ''], ['EUR'], ['', ''], ['25,000,000'], ['', ''],['25,000,000'], ['', ''], ['3M'], ['', ''], ['1Y'], ['', ''], ['3M'],['', ''], [''], ['', ''], [''], ['', ''], [''], ['', ''], [''], ['',''], [''], ['', ''], [''], ['', ''], [''], ['', ''], [''], ['', ''],[''], ['', ''], [''], ['', ''], [''], ['', ''], [''], ['', ''], ['']]

我的目标是将其放入某种列表或任何其他集合中，以便更轻松地从中提取信息...

Answer 1

你很亲密。 documentation 中有一些关于字符串支持的内容：

虽然该模块不直接支持解析字符串，但可以轻松完成：

import csv
for row in csv.reader(['one,two,three']):
    print(row)

注意字符串周围的[]。如果没有这些大括号，csv 模块似乎每个元素返回 1 行，但这似乎没有记录。

由于我一开始并不知道文档中的上述部分，所以我的第一个“实用”方法是使用列表理解来获取行内的元素：

import csv

abc = '"58478000","","NEW","2016-12-28T14:34:18","C","","","N","N","ON","2017-03-15","2022-03-15","30/360","EUR","IR","","InterestRate:IRSwap:FixedFloat","Trade","EUR-EURIBOR-Reuters","FIXED","Percent","-0.003","","","EUR","EUR","25,000,000","25,000,000","3M","1Y","3M","","","","","","","","","","","","",""'

csvreader=csv.reader(abc, delimiter=',')
details = [x[0] for x in csvreader]
print(details)

产量：

['58478000', '', '', '', 'NEW', '', '2016-12-28T14:34:18', '', 'C', '', '', '', '', '', 'N', '', 'N', '', 'ON', '', '2017-03-15', '', '2022-03-15', '', '30/360', '', 'EUR', '', 'IR', '', '', '', 'InterestRate:IRSwap:FixedFloat', '', 'Trade', '', 'EUR-EURIBOR-Reuters', '', 'FIXED', '', 'Percent', '', '-0.003', '', '', '', '', '', 'EUR', '', 'EUR', '', '25,000,000', '', '25,000,000', '', '3M', '', '1Y', '', '3M', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '']

通过这种方法，我们必须去除空字符串（这只是一种解决方法），如果我们需要它们完整无缺，顺便说一句，我们会被卡住：

details = [x[0] for x in csvreader if x[0]]

结果：

['58478000', 'NEW', '2016-12-28T14:34:18', 'C', 'N', 'N', 'ON', '2017-03-15', '2022-03-15', '30/360', 'EUR', 'IR', 'InterestRate:IRSwap:FixedFloat', 'Trade', 'EUR-EURIBOR-Reuters', 'FIXED', 'Percent', '-0.003', 'EUR', 'EUR', '25,000,000', '25,000,000', '3M', '1Y', '3M']

但是在阅读了文档之后，正确的做法是：

import csv

abc = '"58478000","","NEW","2016-12-28T14:34:18","C","","","N","N","ON","2017-03-15","2022-03-15","30/360","EUR","IR","","InterestRate:IRSwap:FixedFloat","Trade","EUR-EURIBOR-Reuters","FIXED","Percent","-0.003","","","EUR","EUR","25,000,000","25,000,000","3M","1Y","3M","","","","","","","","","","","","",""'

csvreader=csv.reader([abc], delimiter=',') # pass a list of 1 element
details = list(csvreader)[0]
print(details)

result（注意现在考虑空字符串的数量）：

['58478000', '', 'NEW', '2016-12-28T14:34:18', 'C', '', '', 'N', 'N', 'ON', '2017-03-15', '2022-03-15', '30/360', 'EUR', 'IR', '', 'InterestRate:IRSwap:FixedFloat', 'Trade', 'EUR-EURIBOR-Reuters', 'FIXED', 'Percent', '-0.003', '', '', 'EUR', 'EUR', '25,000,000', '25,000,000', '3M', '1Y', '3M', '', '', '', '', '', '', '', '', '', '', '', '', '']

如果我们想删除空字符串，让我们用一个列表推导来做，比另一个简单：

csvreader=csv.reader([abc], delimiter=',')
details = [x for x in list(csvreader)[0] if x]
print(details)

结果：

['58478000', 'NEW', '2016-12-28T14:34:18', 'C', 'N', 'N', 'ON', '2017-03-15', '2022-03-15', '30/360', 'EUR', 'IR', 'InterestRate:IRSwap:FixedFloat', 'Trade', 'EUR-EURIBOR-Reuters', 'FIXED', 'Percent', '-0.003', 'EUR', 'EUR', '25,000,000', '25,000,000', '3M', '1Y', '3M']

Answer 2

一旦你有了 CSV 行，你就可以简单地使用

result = abc.split(",") 

要使列表避免使用逗号作为元素（您的方法似乎是使用引号作为字符串分隔符。

另外，使用 csv 库本身，this question 会有所帮助。

>>> import csv

>>> with open(name, 'rb') as f:
...     for row in csv.reader(abc, delimiter=',', skipinitialspace=True):
...             result = row

那里的答案说应该自动处理引号，而this answer 说您将行作为列表！

Answer 3

因为你只有一个字符串，你需要把它放在一个可迭代对象中，比如list，这样csv.reader 才能正确读取它。

import csv

abc = (u'"58478000","","NEW","2016-12-28T14:34:18","C","","","N","N","ON",'
       u'"2017-03-15","2022-03-15","30/360","EUR","IR","",'
       u'"InterestRate:IRSwap:FixedFloat","Trade","EUR-EURIBOR-Reuters","FIXED",'
       u'"Percent","-0.003","","","EUR","EUR","25,000,000","25,000,000","3M",'
       u'"1Y","3M","","","","","","","","","","","","",""')

reader = csv.reader([abc], delimiter=',')
details = next(reader)  # read and process single line that is in list [abc]
print(details)

输出：

['58478000', '', 'NEW', '2016-12-28T14:34:18', 'C', '', '', 'N', 'N', 'ON', '2017-03-15', '2022-03-15', '30/360', 'EUR', 'IR', '', 'InterestRate:IRSwap:FixedFloat', 'Trade', 'EUR-EURIBOR-Reuters', 'FIXED', 'Percent', '-0.003', '', '', 'EUR', 'EUR', '25,000,000', '25,000,000', '3M', '1Y', '3M', '', '', '', '', '', '', '', '', '', '', '', '', '']

Answer 4

如果第一个输入是一个字符串，可以使用ast.literal_eval()：

>>> import ast
>>> 
>>> s = '"58478000","","NEW","2016-12-28T14:34:18","C","",""'
>>> list(ast.literal_eval(s))
['58478000', '', 'NEW', '2016-12-28T14:34:18', 'C', '', '']

如果你想扁平化你的结果，你可以使用：

>>> import itertools
>>> 
>>> my_list = [['58478000'], ['', ''], [''], ['', ''], ['NEW'], ['', ''], ['2016-12-28T14:34:18'], ['', ''], ['C'], ['', ''], ['']]
>>>
>>> list(itertools.chain.from_iterable(my_list))
['58478000', '', '', '', '', '', 'NEW', '', '', '2016-12-28T14:34:18', '', '', 'C', '', '', '']

Answer 5

你试过 string.split(',') 吗？