How to insert a character every nth character in a pandas dataframe column

user_361480 0
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One column of my dataframe contains mac addresses without colons. I would like to add a colon to every mac address after every 2nd character.

I was looking for a split every nth character option of pd.Series.split.str() so that I could split the mac address in six and concat afterwards but according to the documentation splitting on number of characters is not available. There is the regex option, but regex is not a skill I have.

I assume there is an even easier solution than splitting and concatting but I have not come across that.

Help would be much appreciated, thank you.

      mac_address
0     0003E6A584C2
1     0003E6A584CC
2     0003E6A584DA
3     0003E6A584DC
4     0003E6A584E4
pandas dataframe python
4 Answers

Let us try findall with map (.. means N = 2)

df.mac_address.str.findall('..').map(':'.join)
Out[368]: 
0    00;03;E6;A5;84;C2
1    00;03;E6;A5;84;CC
2    00;03;E6;A5;84;DA
3    00;03;E6;A5;84;DC
4    00;03;E6;A5;84;E4
Name: mac_address, dtype: object
user_79645270

How about something like this?

N = 2
df['mac_address'] = df['mac_address'].str[:N] + ':' + df['mac_address'].str[N:]

Output:

>>> df
     mac_address
0  00:03E6A584C2
1  00:03E6A584CC
2  00:03E6A584DA
3  00:03E6A584DC
4  00:03E6A584E4
Admin1

You're correct that regex is your friend:

df['mac_address'].replace(r'(\w{2})',r'\1:',regex=True).str.strip(':')

Output:

0    00:03:E6:A5:84:C2
1    00:03:E6:A5:84:CC
2    00:03:E6:A5:84:DA
3    00:03:E6:A5:84:DC
4    00:03:E6:A5:84:E4
Name: mac_address, dtype: object

Note: r'(\w{2})' finds all groups of two characters, then r'\1:' replaces each of the previous group with itself (\1) and a :. Finally, we chain that with str.strip(':') to remove the potential trailing :.

user_42384080

Using str.format and a df apply function, not the nicest but it works!

df['mac_address'] = df['mac_address'].apply(lambda x: '{}:{}:{}:{}:{}:{}'.format(x[:2],x[2:4],x[4:6],x[6:8],x[8:10],x[10:]))

         mac_address
0  00:03:E6:A5:84:C2
1  00:03:E6:A5:84:C2
2  00:03:E6:A5:84:C2
3  00:03:E6:A5:84:C2
4  00:03:E6:A5:84:C2
5  00:03:E6:A5:84:C2
user_70087270
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