大熊貓不能GROUPBY在CSV

每場我都大熊貓不能GROUPBY在CSV

Hour, L, Dr, Tag, Code, Vge 
0, L5, XI, PS, 4R,  15 
5, L5, XI, PS, 4R,  12 
2, L0, St, v2T, 4R,  11 
8, L2, TI, sst, 4R,  8 
12, L5, XI, PS, 4R,  18

我用下面的Python code.The想法是環繞大熊貓GROUPBY概念我的頭以下的CSV文件。

# !/usr/bin/env python3.4 
# -*- coding: utf-8 -*- 

import pandas as pd 
import pprint 

df = pd.read_csv('in.csv') 
gb = df.groupby('Hour') 
pprint.pprint(list(gb))

這是我得到的輸出。

[(0, 
     Hour  L Dr Tag Code Vge 
0  0  L5 XI PS 4R 15), 
(2, 
    Hour  L Dr Tag Code  Vge 
2  2   L0 St v2T 4R  11), 
(5, 
    Hour  L Dr Tag Code  Vge 
1  5   L5 XI PS 4R  12), 
(8, 
    Hour  L Dr Tag Code  Vge 
3  8   L2 TI sst 4R  8), 
(12, 
    Hour  L Dr Tag Code  Vge 
4 12   L5 XI PS 4R  18)]

上面的輸出是有意義的。但是，如果我這樣做，而不是gb = df.groupby('Vge')的gb = df.groupby('Hour')在上面的代碼中，我得到以下錯誤

Traceback (most recent call last): 
    File "C:/Test/python/concepts/pandas/test_pandas.py", line 12, in <module> 
    gb = df.groupby('Vge') 
    File "C:\Python34\lib\site-packages\pandas\core\generic.py", line 3324, in groupby 
    sort=sort, group_keys=group_keys, squeeze=squeeze) 
    File "C:\Python34\lib\site-packages\pandas\core\groupby.py", line 1252, in groupby 
    return klass(obj, by, **kwds) 
    File "C:\Python34\lib\site-packages\pandas\core\groupby.py", line 416, in __init__ 
    level=level, sort=sort) 
    File "C:\Python34\lib\site-packages\pandas\core\groupby.py", line 2166, in _get_grouper 
    in_axis, name, gpr = True, gpr, obj[gpr] 
    File "C:\Python34\lib\site-packages\pandas\core\frame.py", line 1914, in __getitem__ 
    return self._getitem_column(key) 
    File "C:\Python34\lib\site-packages\pandas\core\frame.py", line 1921, in _getitem_column 
    return self._get_item_cache(key) 
    File "C:\Python34\lib\site-packages\pandas\core\generic.py", line 1090, in _get_item_cache 
    values = self._data.get(item) 
    File "C:\Python34\lib\site-packages\pandas\core\internals.py", line 3102, in get 
    loc = self.items.get_loc(item) 
    File "C:\Python34\lib\site-packages\pandas\core\index.py", line 1692, in get_loc 
    return self._engine.get_loc(_values_from_object(key)) 
    File "pandas\index.pyx", line 137, in pandas.index.IndexEngine.get_loc (pandas\index.c:3979) 
    File "pandas\index.pyx", line 157, in pandas.index.IndexEngine.get_loc (pandas\index.c:3843) 
    File "pandas\hashtable.pyx", line 668, in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:12265) 
    File "pandas\hashtable.pyx", line 676, in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:12216) 
KeyError: 'Vge'

有人可以解釋爲什麼發生這種情況？

來源

2015-12-02 liv2hak

請輸入df.columns以查看您的列的名稱。我懷疑你的名爲'Vge'的列實際上並沒有命名爲'Vge'。

如果是這樣的：

df.columns = ['Hour', 'L', 'Dr', 'Tag', 'Code', 'Vge'] 
gb = df.groupby('Vge') 
print(gb)

來源

2015-12-02 22:45:22

大熊貓不能GROUPBY在CSV

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