groupby - TypeError 'DataFrame' object is not callable

Question

newbie here - my first foray seemed ok, but this is my 2nd use of pandas. In using Pandas 0.12.0 on windows 7, I read 2 dataframes from SQL One works with groupby as expected, so I'm sure my problem isn't syntax. But on the other, where type(reddf) return pandas.core.frame.DataFrame, when try reddf.groupby( 'any column') I get - last few lines -

    c:\python27\lib\site-packages\pandas\core\groupby.pyc in __init__(self, index, grouper,     name, level, sort)
   1197             # no level passed
   1198             if not isinstance(self.grouper, np.ndarray):
-> 1199                 self.grouper = self.index.map(self.grouper)
   1200                 if not (hasattr(self.grouper,"__len__") and \
   1201                    len(self.grouper) == len(self.index)):

c:\python27\lib\site-packages\pandas\algos.pyd in pandas.algos.arrmap_int64 (pandas\algos.c:62839)()

TypeError: 'DataFrame' object is not callable

I know groupby is OK, and the column exists, so there's some other constraint / condition on the dataframe that I'm just not aware of or blew past. So what could cause this error? And what should I do? What should I look for in the future?

info requested

print type(reddf.index)
<class 'pandas.core.index.Int64Index'>

print repr(reddf.index) 
Int64Index([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19], dtype=int64)

print type(reddf.index.map)
<type 'instancemethod'>

print repr(reddf.index.map)
<bound method Int64Index.map of Int64Index([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19], dtype=int64)>

Just in case
reddf gives
<class 'pandas.core.frame.DataFrame'>
Int64Index: 20 entries, 0 to 19
Data columns (total 24 columns):
AssetId                  20  non-null values
DateAdded                20  non-null values
ModelId                  20  non-null values
UsageTypeId              20  non-null values
DateAdded                20  non-null values
Name                     20  non-null values
NatureId                 20  non-null values
IsContainer              20  non-null values
SparePartNumber          8  non-null values
ProductNumber            19  non-null values
SupportCategoryOid       20  non-null values
SerialNumber             20  non-null values
IpAddress                20  non-null values
Description              20  non-null values
CustomsId                15  non-null values
AssetTag                 20  non-null values
ParentId                 5  non-null values
ManagementProcessorId    7  non-null values
OperatingSystem          20  non-null values
OsVersion                20  non-null values
SystemName               20  non-null values
LocationId               10  non-null values
RomVersion               20  non-null values
MacAddress               19  non-null values
dtypes: bool(1), datetime64[ns](2), float64(3), int64(5), object(13)

and I get the error doing a reddf.groupby('ModelId'), in particular. thanks

Thanks to everyone, The duplicate field name caused me the issue, I can't believe I did not notice before the last comment.

Now, I don't understand how the .index output eliminated other problems, could you elaborate? What if the index were missing, should not groupby have been able to function properly, why not? Just looking for a short explanation and if you point to code, that's fine. appreciate the help, guys.

Solution

is caused by the duplication of 'DateAdded' column. Rename it and you are good to go.