简单数据帧读取\u csv,然后使用Count/KeyError分组

我只是想得到给定列中某个值的行数,例如:

'Occupation','data'
'Carpenter','data1'
'Carpenter','data2'
'Carpenter','data3'
'Painter','data1'
'Painter','data2'
'Programmer','data1'
'Programmer','data2'
'Programmer','data3'
'Programmer','data4'

filename = "./data/TestGroup.csv"

df = pd.read_csv(filename)
print(df.head())

print("Computing stats by HandRank... ")
df_stats = df[['data']].groupby(['Occupation']).agg(['count'])
# also tried:  df_stats = df[['Occupation']].groupby(['Occupation']).agg(['count'])
print(df_stats.head())

如何获得变量中的计数?.groupby和.agg是否返回另一个数据帧?

  'Occupation'   'data'
0  'Carpenter'  'data1'
1  'Carpenter'  'data2'
2  'Carpenter'  'data3'
3    'Painter'  'data1'
4    'Painter'  'data2'
    Computing stats by HandRank... 
    Traceback (most recent call last):
      File "C:\Apps\PokerHandGenerator_Copy_not_Source\Server\TestPandasGroupBy.py", line 17, in <module>
        df_stats = df.groupby(['Occupation']).agg(['count'])
      File "C:\Apps\ProcessData\venv\lib\site-packages\pandas\core\frame.py", line 6714, in groupby
        return DataFrameGroupBy(
      File "C:\Apps\ProcessData\venv\lib\site-packages\pandas\core\groupby\groupby.py", line 560, in __init__
        grouper, exclusions, obj = get_grouper(
      File "C:\Apps\ProcessData\venv\lib\site-packages\pandas\core\groupby\grouper.py", line 811, in get_grouper
        raise KeyError(gpr)
    KeyError: 'Occupation'

这个测向头()显示它正在使用“职业”作为我的列名。