Create a column in pandas which increments by 1 for every 10 rows-CodePudding

import pandas as pd
import numpy as np

rng = np.random.default_rng()
df = pd.DataFrame(rng.integers(0, 100, size=(100, 4)), columns=list('ABCD'))

This is my dataframe. I want to create a new column which starts from 1 and increases by 1 for every 10 rows. So, the column will have a value of 1 for the first ten rows, two for rows 11-20, 3 for 21-30... and so on.

CodePudding user response：

You can use numpy's arange with floor division by your step and addition of the start:

start = 1
step = 10
df['new'] = np.arange(len(df))//step start

output:

     A   B   C   D  new
0    6  80  51  21    1
1   74  52  18  24    1
2   14  25  19  89    1
3   21  89   2  69    1
4   46  32  77  98    1
..  ..  ..  ..  ..  ...
95  62  87  89  65   10
96  88  70  44  68   10
97  71  14   2  10   10
98  45  62  89  65   10
99  62  40  45  93   10

[100 rows x 5 columns]

CodePudding user response：

You can use repeat:

d['new'] = np.repeat(np.arange(1, 11), 10)