padding zeros before and after the decimal point

I am using python 3.

I have a column of decimal numbers called “CIPCODE” in a dataframe called “data”. The integer part of this column ranges from 1 to 60.

I want to format it such that:

the first condition is: if the value of the integer part is between 1 and 9 (inclusive), then add a zero in front of the number, for example -

4.2021 becomes 04.2021

25.3434 remains 25.3434

so basically, we should always have 2 digits before the decimal.

the second condition is: that there should always be 4 digits after the decimal, for example -

51.201 becomes 51.2010

34.5555 remains 34.5555

I have tried the following:

data['CIPCODE'] = data['CIPCODE'].astype(str).str.zfill(7)

but this only pads zeros to the part before the decimal point.

You can directly use python formatting (07.4f, meaning 4 digits after the decimal and padded to 7 characters) :

df['formatted'] = df['CIPCODE'].apply(lambda x: f'{x:07.4f}')

Output:

   CIPCODE formatted
0   4.2021   04.2021
1  25.3434   25.3434
2  12.3000   12.3000

Use python formating for custom string:

data = pd.DataFrame({'CIPCODE':[4.2021,25.3434,51.201,34.5555]})

data['CIPCODE'] = data['CIPCODE'].apply('{:07.4f}'.format)

print (data)
   CIPCODE
0  04.2021
1  25.3434
2  51.2010
3  34.5555

              {:07.4f}
                ↑ ↑ 
                | |
# digits to pad | | # of decimal places to display

Might not be the fastest way, but you can do this by putting this logic into a function and applying it to the dataframe.

Example:

import pandas as pd
from collections import deque

df = pd.DataFrame({'CIPCODE': [4.2021, 25.3434, 51.201, 34.5555]}) 

def format_cipcode(code):
    d = deque(code)
    if d[1] == '.':
        d.appendleft('0')
    if d[-4] == '.':
        d.append('0')
    return ''.join(d)


df['CIPCODE'] = df['CIPCODE'].astype(str).apply(format_cipcode)

print(df['CIPCODE'])

Output:

Name: CIPCODE, dtype: object
0    04.2021
1    25.3434
2    51.2010
3    34.5555

In this case I used a deque, which is a sort of list that you can append to left and right. For the left side, check if the second character in the string is a . and append a 0 if it is. For the right side, check if the fourth character from the right is a . and if so, append a 0