CODEWITHSUNDEEP
pythonpandas
connor449
connor449

Reputation: 1679

How to combine row with previous row based on condition in dataframe

I have a dataframe where every row is a word or punctuation. I want to iterate through the dataframe and whenever a row contains punctuation, I want to combine it with the previous row.

For example, I want to convert:

   word 
0  hello      
1  ,
2  how
3  are
4  you
5  ?

Into:

   word 
0  hello,      
2  how
3  are
4  you?

Thanks.

Upvotes: 4

Views: 901

Answers (3)

Adam.Er8
Adam.Er8

Reputation: 13413

yet another approach, concatenating to previous row using .shift(-1):

df.loc[df["word"].shift(-1).isin(list(punctuation)), "word"] = df["word"] + df["word"].shift(-1)
df = df[~df["word"].isin(list(punctuation))][["word"]]

df:

     word
0  hello,
2     how
3     are
4    you?

Upvotes: 0

Quang Hoang
Quang Hoang

Reputation: 150825

You can use isin and cumsum:

# list of puctuations
punctuations = set([',','?']) 

# blocks
blocks = ~df['word'].isin(punctuations)).cumsum()

# groupby
df['word'].groupby(blocks).sum()

Output:

word
1    hello,
2       how
3       are
4      you?
Name: word, dtype: object

Upvotes: 0

piRSquared
piRSquared

Reputation: 294586

match and cumsum

df.groupby((~df.word.str.match('\W')).cumsum(), as_index=False).sum()

     word
0  hello,
1     how
2     are
3    you?

isin

Also, without the as_index=True

from string import punctuation

df.groupby((~df.word.isin(list(punctuation))).cumsum()).sum()

        word
word        
1     hello,
2        how
3        are
4       you?

Upvotes: 5

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