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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
 Predicting sentiment from product reviews
Fire up GraphLab Create
Step1:  Read some product review data
Loading reviews for a set of baby products.
Step2:  Let's explore this data together
Data includes the product name, the review text and the rating of the review.
Step3:  Build the word count vector for each review
Step4:  Examining the reviews for most-sold product
Step5:  Build a sentiment classifier
Step6:  Define what's a positive and a negative sentiment
We will ignore all reviews with rating = 3, since they tend to have a neutral sentiment.  Reviews with a rating of 4 or higher will be considered positive, while the ones with rating of 2 or lower will have a negative sentiment.
Step7:  Let's train the sentiment classifier
Step8:  Evaluate the sentiment model
Step9:  Applying the learned model to understand sentiment for Giraffe
Step10:  Sort the reviews based on the predicted sentiment and explore
Step11:  Most positive reviews for the giraffe
Step12:  Show most negative reviews for giraffe
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Python Code:
import graphlab
Explanation: Predicting sentiment from product reviews
Fire up GraphLab Create
End of explanation
products = graphlab.SFrame('amazon_baby.gl/')
Explanation: Read some product review data
Loading reviews for a set of baby products.
End of explanation
products.head()
Explanation: Let's explore this data together
Data includes the product name, the review text and the rating of the review.
End of explanation
products['word_count'] = graphlab.text_analytics.count_words(products['review'])
products.head()
graphlab.canvas.set_target('ipynb')
products['name'].show()
Explanation: Build the word count vector for each review
End of explanation
giraffe_reviews = products[products['name'] == 'Vulli Sophie the Giraffe Teether']
len(giraffe_reviews)
giraffe_reviews['rating'].show(view='Categorical')
Explanation: Examining the reviews for most-sold product:  'Vulli Sophie the Giraffe Teether'
End of explanation
products['rating'].show(view='Categorical')
Explanation: Build a sentiment classifier
End of explanation
#ignore all 3* reviews
products = products[products['rating'] != 3]
#positive sentiment = 4* or 5* reviews
products['sentiment'] = products['rating'] >=4
products.head()
Explanation: Define what's a positive and a negative sentiment
We will ignore all reviews with rating = 3, since they tend to have a neutral sentiment.  Reviews with a rating of 4 or higher will be considered positive, while the ones with rating of 2 or lower will have a negative sentiment.
End of explanation
train_data,test_data = products.random_split(.8, seed=0)
sentiment_model = graphlab.logistic_classifier.create(train_data,
                                                     target='sentiment',
                                                     features=['word_count'],
                                                     validation_set=test_data)
Explanation: Let's train the sentiment classifier
End of explanation
sentiment_model.evaluate(test_data, metric='roc_curve')
graphlab.canvas.set_target('browser')
sentiment_model.show(view='Evaluation')
Explanation: Evaluate the sentiment model
End of explanation
giraffe_reviews['predicted_sentiment'] = sentiment_model.predict(giraffe_reviews, output_type='probability')
giraffe_reviews.head()
Explanation: Applying the learned model to understand sentiment for Giraffe
End of explanation
giraffe_reviews = giraffe_reviews.sort('predicted_sentiment', ascending=False)
giraffe_reviews.head()
Explanation: Sort the reviews based on the predicted sentiment and explore
End of explanation
giraffe_reviews[0]['review']
giraffe_reviews[1]['review']
Explanation: Most positive reviews for the giraffe
End of explanation
giraffe_reviews[-1]['review']
giraffe_reviews[-2]['review']
selected_words = ['awesome', 'great', 'fantastic', 'amazing', 'love', 'horrible', 'bad', 'terrible', 'awful', 'wow', 'hate']
Explanation: Show most negative reviews for giraffe
End of explanation
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