How to go through each row with pandas apply() and lambda to clean sentence tokens?

Question

My goal is to created a cleaned column of the tokenized sentence within the existing dataframe. The dataset is a pandas dataframe looking like this:

Index	Tokenized_sents
First	[Donald, Trump, just, couldn, t, wish, all, Am]
Second	[On, Friday, ,, it, was, revealed, that]

dataset['cleaned_sents'] = dataset.apply(lambda row: [w for w in row["tokenized_sents"] if len(w)>2 and w.lower() not in stop_words], axis = 1)

My current output is the dataframe without that extra column.

Current outout:

    tokenized_sents  \
0  [Donald, Trump, just, couldn, t, wish, all, Am...  

Wanted output:

  tokenized_sents  \
0  [Donald, Trump, just, couldn, wish, all...   

Basically removing all the stopwords & short words

Answer 1

Create a sentence index

dataset['gid'] = range(1, dataset.shape[0] + 1)

       tokenized_sents  gid
0  [This, is, a, test]    1
1    [and, this, too!]    2

Then explode the dataframe

clean_df = dataset.explode('tokenized_sents')

  tokenized_sents  gid
0            This    1
0              is    1
0               a    1
0            test    1
1             and    2
1            this    2
1            too!    2

Do all the cleaning on this dataframe and use gid column to group them back. It will be the fastest way to go about doing it.

clean_df = clean_df[clean_df.tokenized_sents.str.len() >= 2]
.
.
.

To get it back,

clean_dataset = clean_df.groupby('gid').agg(list)

Answer 2

Fix your code

dataset['new'] = dataset['tokenized_sents'].\
                   map(lambda x : [t for t in x if len(t)>2 and t not in stop] )