python dataframe sum function returning negative number

Question

I am working with a test dataset of the Lending Club loan data and am trying to create some analysis with the set.

After loading the csv into a dataframe, I am just trying to do a simple sum on the entire funded_amnt column. I keep receiving a negative amount for the sum even though there are no negative numbers in the entire set. How can this be?

In[ ]: loans_df['funded_amnt'].sum()

Out[ ]: -1925852142

In[ ]: len(loans_df[loans_df['funded_amnt']<0])

Out[ ]: 0

Answer 1

This could be an overflow problem. But it's hard to tell without a [mcve]...

Example:

pd.DataFrame([2**61]*2).sum()
Out[345]: 
0    4611686018427387904
dtype: int64

pd.DataFrame([2**61]*3).sum()
Out[346]: 
0    6917529027641081856
dtype: int64

pd.DataFrame([2**61]*4).sum()
Out[347]: 
0   -9223372036854775808
dtype: int64

pd.DataFrame([2**61]*5).sum()
Out[348]: 
0   -6917529027641081856
dtype: int64