CODEWITHSUNDEEP
pythonpython-3.xpandas
Zmann3000
Zmann3000

Reputation: 816

How to average a pandas data frame column before and after a given row based on some odd value n?

If I have a pandas data frame like this: 

      Col A
 0      2
 1      3
 2      5
 3      4
 4      6
 5      2
 6      3
 7      1
 8      1
 9      7

and some odd numerical value like this 

 n = 3

How do I average the value I'm replacing, the values before, and after based on half of my n. For n = 3 I would be averaging the value before and after. Such that I get a pandas dataframe like this: 

      Col A   Col B
 0      2     np.nan
 1      3      3.33
 2      5       4
 3      4       5
 4      6       4
 5      2      3.67
 6      3       2
 7      1      2.5
 8      1       3
 9      7     np.nan

The first and last values are np.nan because there is not a value before/after them.

Upvotes: 1

Views: 125

Answers (1)

Quang Hoang
Quang Hoang

Reputation: 150785

You can use rolling with center option:

n = 3
df['Col A'].rolling(n, center=True).mean()

Output:

0         NaN
1    3.333333
2    4.000000
3    5.000000
4    4.000000
5    3.666667
6    2.000000
7    1.666667
8    3.000000
9         NaN
Name: Col A, dtype: float64

Upvotes: 1

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