I need to extract all matches from a string in a column and populate a second column. The matches will be delimited by a comma.
df2 = pd.DataFrame([[1000, 'Jerry', 'string of text BR1001_BR1003_BR9009 more string','BR1003',''],
[1001, '', 'BR1010_BR1011 random text', 'BR1010',''],
['', '', 'test to discardBR3009', 'BR2002',''],
[1003, 'Perry','BR4009 pure gibberish','BR1001',''],
[1004, 'Perry2','','BR1001','']],
columns=['ID', 'Name', 'REGEX string', 'Member of','Status'])
Pattern representing the codes to be extracted.
BR_pat = re.compile(r'(BR[0-9]{4})', re.IGNORECASE)
Hoped for output in column
BR1001, BR1003, BR9009
BR1010,BR1011
BR3009
BR4009
My attempt:
df2['REGEX string'].str.extractall(BR_pat).unstack().fillna('').apply(lambda x: ", ".join(x))
Output:
match
0 0 BR1001, BR1010, BR3009, BR4009
1 BR1003, BR1011, ,
2 BR9009, , ,
There are extra commas and rows missing. What did I do wrong?
CodePudding user response:
You need to use
>>> df2['REGEX string'].str.findall(r'BR\d{4}').str.join(", ")
0 BR1001, BR1003, BR9009
1 BR1010, BR1011
2 BR3009
3 BR4009
4
Name: REGEX string, dtype: object
With Series.str.findall
, you extract all occurrences of the pattern inside a string value, it returns a "Series/Index of lists of strings". To concatenate them into a single string, the Series.str.join()
is used.
CodePudding user response:
You can also
- add
axis=1
toapply
to use columns instead of rows. - add
filter(None,x)
to filter out empty strings.
The result is
df['REGEX string'].str.extractall(BR_pat).unstack().fillna('').apply(lambda x : ",".join(filter(None,x)), axis=1)