[FIXED] Drop Duplicate Substrings from String with NO Spaces

Issue

Given a Pandas DF column that looks like this:

...how can I turn it into this:

XOM
ZM
AAPL
SOFI
NKLA
TIGR

Although these strings appear to be 4 characters in length maximum, I can't rely on that, I want to be able to have a string like ABCDEFGHIJABCDEFGHIJ and still be able to turn it into ABCDEFGHIJ in one column calculation. Preferably WITHOUT for looping/iterating through the rows.

Solution

You can use regex pattern like r'\b(\w+)\1\b' with str.extract like below:

df = pd.DataFrame({'Symbol':['ZOMZOM', 'ZMZM', 'SOFISOFI', 
                             'ABCDEFGHIJABCDEFGHIJ', 'NOTDUPLICATED']})
print(df['Symbol'].str.extract(r'\b(\w+)\1\b'))

Output:

           0
0         ZOM
1          ZM
2        SOFI
3  ABCDEFGHIJ
4         NaN # <- from `NOTDUPLICATED`

Explanation:

1. \b is a word boundary
2. (w+) capture a word
3. \1 references to captured (w+) of the first group

Answered By - I'mahdi