How to label multi-word entities?

Issue

I’m quite new to data analysis (and Python in general), and I’m currently a bit stuck in my project.

For my NLP-task I need to create training data, i.e. find specific entities in sentences and label them. I have multiple csv files containing the entities I am trying to find, many of them consisting of multiple words. I have tokenized and lemmatized the unlabeled sentences with spaCy and loaded them into a pandas.DataFrame.

My main problem is: how do I now compare the tokenized sentences with the entity-lists and label the (often multi-word) entities? Having around 0.5 GB of sentences, I don’t think it is feasible to just for-loop every sentence and then for-loop every entity in every class-list and do a simple substring-search. Is there any smart way to use pandas.Series or DataFrame to do this labeling?

As mentioned, I don’t really have any experience regarding pandas/numpy etc. and after a lot of web searching I still haven’t seemed to find the answer to my problem

Say that this is a sample of finance.csv, one of my entity lists:

"Frontwave Credit Union",
"St. Mary's Bank",
"Center for Financial Services Innovation",
...

And that this is a sample of sport.csv, another one of my entity lists:

"Christiano Ronaldo",
"Lewis Hamilton",
...

And an example (dumb) sentence:

"Dear members of Frontwave Credit Union, any credit demanded by Lewis Hamilton is invalid, said Ronaldo"

The result I’d like would be something like a table of tokens with the matching entity labels (with IOB labeling):

"Dear "- O
"members" - O
"of" - O
"Frontwave" - B-FINANCE
"Credit" - I-FINANCE
"Union" - I-FINANCE
"," - O
"any" - O
...
"Lewis" - B-SPORT
"Hamilton" - I-SPORT
...
"said" - O
"Ronaldo" - O

Solution

Use:

FINANCE = ["Frontwave Credit Union",
"St. Mary's Bank",
"Center for Financial Services Innovation"]

SPORT = [
    "Christiano Ronaldo",
    "Lewis Hamilton",
]

FINANCE = '|'.join(FINANCE)
sent = pd.DataFrame({'sent': ["Dear members of Frontwave Credit Union, any credit demanded by Lewis Hamilton is invalid, said Ronaldo"]})
home = sent['sent'].str.extractall(f'({FINANCE})')

def labeler(row, group):
    l = len(row.split())
    return [f'I-{group}' if i !=0 else f'B-{group}' for i in range(l)]

home[0].apply(labeler, group='FINANCE').explode()

enter image description here

Answered By – keramat

Answer Checked By – David Marino (AngularFixing Volunteer)

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