CODEWITHSUNDEEP
pythonpandasdataframe
Lisle
Lisle

Reputation: 1690

Calculating forward or backwards with pandas dataframes

I want to calculate % differences in a dataframe by week, and put those calculations in a new dataframe.

Start with df:

index       Date     Zone      Amount
  0     2011-01-08  YQHDK   1691938000.0
  1     2011-02-05  YQHDK   1760009000.0
  2     2011-03-05  YQHDK   1893000000.0

New dataframe newdf would look like:

index       Date     Zone   % diff
  0     2011-02-05  YQHDK    4.02
  1     2011-03-05  YQHDK    7.56

How can I achieve this without going through a loop?

Upvotes: 0

Views: 1598

Answers (1)

MaxU - stand with Ukraine
MaxU - stand with Ukraine

Reputation: 210922

you can do it this way:

In [15]: df.Amount.pct_change()*100
Out[15]:
0         NaN
1    4.023256
2    7.556268
Name: Amount, dtype: float64

or 

In [16]: df.Amount.pct_change().shift(-1)*100
Out[16]:
0    4.023256
1    7.556268
2         NaN
Name: Amount, dtype: float64

In [8]: df['pct_diff'] = df.Amount.pct_change()*100

In [9]: df
Out[9]:
   index        Date   Zone        Amount  pct_diff
0      0  2011-01-08  YQHDK  1.691938e+09       NaN
1      1  2011-02-05  YQHDK  1.760009e+09  4.023256
2      2  2011-03-05  YQHDK  1.893000e+09  7.556268

Upvotes: 3

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