how do you divide each value from a pandas series in sequence-CodePudding

Hi I was trying to figure out how to divide values from a DataFrame. But here I made an example for pandas series

a = pd.Series([1, 2, 16,64,128,360,720])
a
-----------------
0     1
1     2
2     16
3     64
4    128
5    360
6    720

So is there any way I could divide a number in a given row by the value from the previous row?

Furthermore, I also tried to get the output like "if the value is double, print the index".

Thank you for your help!

CodePudding user response：

Well I don't know what exactly you want to divide your pandas Series by, but you can do it like this :

# If you want to store a new result
b = a / value_to_divive_by
# or if you want to apply it directly to your serie
a /= value_to_divive_by

or using list comprehension

b = [int(nb / your_value_here) for nb in a]
# with a min value to do the divison
b = [int(nb / your_value_here) for nb in a if nb > min_value]

There is probably other ways to do what you want, but there is two easy solutions

CodePudding user response：

What it seems to me is that you are trying to divide a number in a given row by the one of the previous. This can be achieved using this code

import pandas as pd
import numpy as np
a = pd.Series([1, 2, 16,64,128,360,720])
division = pd.Series(np.divide(a.values[1:],a.values[:-1]))
index = pd.Series(np.multiply(division == 2, [i for i in range(len(a)-1)]))

Note: your question is very ill posed. You didn't specify what you wanted to achieve, I figured out by myself from the example. You also added a wrong snipped of code. Pay attention to make a nicer question next time