python pandas没有从csv文件中读取第一列

Question

我有一个名为st1.csv的简单2列csv文件:

GRID    St1  
1457    614  
1458    657  
1459    679  
1460    732  
1461    754  
1462    811  
1463    748  

但是,当我尝试读取csv文件时,未加载第一列:

a = pandas.DataFrame.from_csv('st1.csv')  
a.columns

输出:

 Index([u'ST1'], dtype=object)

为什么没有读取第一列？

Answer 1

根据您的数据判断,您使用的分隔符看起来像是.

请尝试以下方法:

a = pandas.DataFrame.from_csv('st1.csv', sep=' ')

另一个问题是它假设你的第一列是一个索引,我们也可以禁用它:

a = pandas.DataFrame.from_csv('st1.csv', index_col=None)

Answer 2

对于较新版本的熊猫，pd.DataFrame.from_csv不再存在，并且index_col=None不再使用pd.read_csv. 你会想用pd.read_csvwithindex_col=False代替：

pd.read_csv('st1.csv', index_col=False)

例子：

(so) URSA-MattM-MacBook:stackoverflow mmessersmith$ cat input.csv 
Date                        Employee        Operation        Order

2001-01-01 08:32:17         User1           Approved         #00045
2001-01-01 08:36:23         User1           Edited           #00045
2001-01-01 08:41:04         User1           Rejected         #00046
2001-01-01 08:42:56         User1           Deleted          #00046
2001-01-02 09:01:11         User1           Created          #00047
2019-10-03 17:23:45         User1           Approved         #72681

(so) URSA-MattM-MacBook:stackoverflow mmessersmith$ python
Python 3.7.4 (default, Aug 13 2019, 15:17:50) 
[Clang 4.0.1 (tags/RELEASE_401/final)] :: Anaconda, Inc. on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import pandas as pd
>>> pd.__version__
'0.25.1'              
>>> df_bad_index = pd.read_csv('input.csv', delim_whitespace=True)
>>> df_bad_index
                Date Employee Operation   Order
2001-01-01  08:32:17    User1  Approved  #00045
2001-01-01  08:36:23    User1    Edited  #00045
2001-01-01  08:41:04    User1  Rejected  #00046
2001-01-01  08:42:56    User1   Deleted  #00046
2001-01-02  09:01:11    User1   Created  #00047
2019-10-03  17:23:45    User1  Approved  #72681
>>> df_bad_index.index
Index(['2001-01-01', '2001-01-01', '2001-01-01', '2001-01-01', '2001-01-02',
       '2019-10-03'],
      dtype='object')
>>> df_still_bad_index = pd.read_csv('input.csv', delim_whitespace=True, index_col=None)
>>> df_still_bad_index
                Date Employee Operation   Order
2001-01-01  08:32:17    User1  Approved  #00045
2001-01-01  08:36:23    User1    Edited  #00045
2001-01-01  08:41:04    User1  Rejected  #00046
2001-01-01  08:42:56    User1   Deleted  #00046
2001-01-02  09:01:11    User1   Created  #00047
2019-10-03  17:23:45    User1  Approved  #72681
>>> df_still_bad_index.index
Index(['2001-01-01', '2001-01-01', '2001-01-01', '2001-01-01', '2001-01-02',
       '2019-10-03'],
      dtype='object')
>>> df_good_index = pd.read_csv('input.csv', delim_whitespace=True, index_col=False)
>>> df_good_index
         Date  Employee Operation     Order
0  2001-01-01  08:32:17     User1  Approved
1  2001-01-01  08:36:23     User1    Edited
2  2001-01-01  08:41:04     User1  Rejected
3  2001-01-01  08:42:56     User1   Deleted
4  2001-01-02  09:01:11     User1   Created
5  2019-10-03  17:23:45     User1  Approved
>>> df_good_index.index
RangeIndex(start=0, stop=6, step=1)

Answer 3

在此基础上进行比较的文档read_csv和from_csv,这表明,它有可能把index_col = None.我尝试了下面的工作:

DataFrame.from_csv('st1.csv', index_col=None);

这假定数据以逗号分隔.

请检查以下链接

http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.from_csv.html