How can i sort values based on a specific condition in python?

Question

I have a dataframe

import pandas as pd
import numpy as np

df = pd.DataFrame({'Date':['01-01-2020','01-01-2020','01-01-2020','01-01-2020','01-01-2020'],
                  'Shift':['A','A','A','A','A'],
                  'heat_number':['HA1','HA10','HA8','HA18A','HA5']})

Looking like this

    Date        Shift   heat_number
0   01-01-2020    A        HA1
1   01-01-2020    A        HA10
2   01-01-2020    A        HA8
3   01-01-2020    A        HA18A
4   01-01-2020    A        HA5
5   01-01-2020    A        HA18

if i do df.sort_values(['Date','Shift',heat_number]) I get the below output:

    Date         Shift  heat_number
0   01-01-2020    A        HA1
1   01-01-2020    A        HA10
5   01-01-2020    A        HA18
3   01-01-2020    A        HA18A
4   01-01-2020    A        HA5
2   01-01-2020    A        HA8

But my desired output is:

    Date         Shift  heat_number
0   01-01-2020    A        HA1
4   01-01-2020    A        HA5
2   01-01-2020    A        HA8
1   01-01-2020    A        HA10
5   01-01-2020    A        HA18
3   01-01-2020    A        HA18A

Filter in the heat number column is not as per expectation. How can i fix this?

There's a pull request [https://github.com/pandas-dev/pandas/issues/3942#issuecomment-508588258] regarding this issue. — Rm4n
– Rm4n, Commented Jul 17, 2020 at 16:06

sushanth · Accepted Answer · 2020-07-17 15:32:20Z

1

You can, Assign new psuedo columns to the dataFrame DataFrame.assign which is extract of heat_number, apply sort_values on the psuedo column. Finally drop psuedo columns

(
    df.assign(sort_by=df.heat_number.str.extract("(\d+)").astype(int))
        .sort_values(by="sort_by")
        .drop(columns="sort_by")
)

         Date Shift heat_number
0  01-01-2020     A         HA1
4  01-01-2020     A         HA5
2  01-01-2020     A         HA8
1  01-01-2020     A        HA10
3  01-01-2020     A       HA18A

edited Jul 17, 2020 at 15:32

answered Jul 17, 2020 at 15:26

sushanth

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Comments

quest · Accepted Answer · 2020-07-17 15:25:41Z

0

Here is how I will go about it:

df['len_heat']  = df.heat_number.str.len()

df = df.sort_values(['Date','Shift',"len_heat"])

del df['len_heat']

Basically, it adds a column which has the length of string, sorts and drops this column.

answered Jul 17, 2020 at 15:25

quest

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