Introducere în codificarea textului

Ingineria caracteristicilor pentru Machine Learning în Python

Robert O'Callaghan

Director of Data Science, Ordergroove

Standardizarea textului

Exemplu de text liber:

Fellow-Citizens of the Senate and of the House of Representatives: AMONG the vicissitudes incident to life no event could have filled me with greater anxieties than that of which the notification was transmitted by your order, and received on the th day of the present month.

Ingineria caracteristicilor pentru Machine Learning în Python

Setul de date

print(speech_df.head())

                  Name           Inaugural Address    \ 
0    George Washington     First Inaugural Address
1    George Washington    Second Inaugural Address
2    John Adams                  Inaugural Address    
3    Thomas Jefferson      First Inaugural Address    
4    Thomas Jefferson     Second Inaugural Address

                        Date                               text
0    Thursday, April 30, 1789    Fellow-Citizens of the Sena...
1       Monday, March 4, 1793    Fellow Citizens: I AM again...
2     Saturday, March 4, 1797    WHEN it was first perceived...
3    Wednesday, March 4, 1801    Friends and Fellow-Citizens...
4       Monday, March 4, 1805    PROCEEDING, fellow-citizens...
Ingineria caracteristicilor pentru Machine Learning în Python

Eliminarea caracterelor nedorite

  • [a-zA-Z]: Toate literele
  • [^a-zA-Z]: Toate caracterele care nu sunt litere
speech_df['text'] = speech_df['text']\
                   .str.replace('[^a-zA-Z]', ' ')
Ingineria caracteristicilor pentru Machine Learning în Python

Eliminarea caracterelor nedorite

Înainte: 

"Fellow-Citizens of the Senate and of the House of  
Representatives: AMONG the vicissitudes incident to   
life no event could have filled me with greater" ...

După: 

"Fellow Citizens of the Senate and of the House of  
Representatives AMONG the vicissitudes incident to   
life no event could have filled me with greater" ...
Ingineria caracteristicilor pentru Machine Learning în Python

Standardizarea majusculelor

speech_df['text'] = speech_df['text'].str.lower()
print(speech_df['text'][0])

"fellow citizens of the senate and of the house of  
representatives among the vicissitudes incident to   
life no event could have filled me with greater"...
Ingineria caracteristicilor pentru Machine Learning în Python

Lungimea textului

speech_df['char_cnt'] = speech_df['text'].str.len()
print(speech_df['char_cnt'].head())

0    1889  
1     806  
2    2408  
3    1495  
4    2465
Name: char_cnt, dtype: int64
Ingineria caracteristicilor pentru Machine Learning în Python

Numărul de cuvinte

speech_df['word_cnt'] = 
    speech_df['text'].str.split()
speech_df['word_cnt'].head(1)

['fellow', 'citizens', 'of', 'the', 'senate', 'and',...
Ingineria caracteristicilor pentru Machine Learning în Python

Numărul de cuvinte

speech_df['word_counts'] = 
    speech_df['text'].str.split().str.len()
print(speech_df['word_splits'].head())

0    1432
1     135
2    2323
3    1736
4    2169
Name: word_cnt, dtype: int64
Ingineria caracteristicilor pentru Machine Learning în Python

Lungimea medie a cuvântului

speech_df['avg_word_len'] = 
         speech_df['char_cnt'] / speech_df['word_cnt']
Ingineria caracteristicilor pentru Machine Learning în Python

Să exersăm!

Ingineria caracteristicilor pentru Machine Learning în Python

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