average distance for a column in pandas

Question

I have a data frame like this:

sample = pd.DataFrame({'a': [10, 16, 7, 2, 5]})

How can I find the average distance for the column 'a'? For example, the average distance between 10 and 16 = (10 + 6) / 2 = 8

Answer 1

The "average distance" of x and y is defined as (x + (y - x))/2.

That's just y/2. Drop the first row and divide the rest by 2: sample.a[1:]/2

Answer 2

After the math you described, it is equivalent to "next value divided by 2". So we get the next values by shifting the series and then / 2 to halve them:

# data itself
>>> sample

    a
0  10
1  16
2   7
3   2
4   5

# shift the values upwards by 1 unit so 2nd becomes 1st etc.
# and the last becomes NaN as there is nothing below it to replace
>>> sample.shift(-1)

      a
0  16.0
1   7.0
2   2.0
3   5.0
4   NaN

# per your formula
>>> sample.shift(-1) / 2

     a
0  8.0
1  3.5
2  1.0
3  2.5
4  NaN