Pandas: What does the compound method is useful for?

Pandas: What does the compound method is useful for?



I found pandas compound dataframe method documentation but it is really terse. I've tried to run it on a simple dataframe, but didn't understand its utility. Here is my example:


In [5]: df = pd.DataFrame(np.arange(6).reshape(3,2), columns=['a', 'b'])

In [6]: df
Out[6]:
a b
0 0 1
1 2 3
2 4 5

In [7]: df.compound()
Out[7]:
a 14
b 47
dtype: int32



What should I use this method for?






Column a means you earn 0% the first year, 200% the second year and 400% the third, for a total of 15x the original amount, or an increase of 1400%. Time units are made up.

– Mad Physicist
Sep 10 '18 at 4:02



a






Its the same as df.a.add(1).cumprod().sub(1) . You can see the compounding evolving, and .compound() yields just the last number

– RafaelC
Sep 10 '18 at 4:04


df.a.add(1).cumprod().sub(1)


.compound()




1 Answer
1



This is more like loan calculation -- compound interest



enter image description here


df.compound()
Out[143]:
a 14
b 47
dtype: int32



So for columns a


a



enter image description here






Ops, I could have just ctrl-click to see the source: (1 + self).prod(axis=axis, skipna=skipna, level=level) - 1

– neves
Sep 11 '18 at 13:39


(1 + self).prod(axis=axis, skipna=skipna, level=level) - 1



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