[Python] Pandas Course on Kaggle - 4

This is the solution of pandas course (Grouping and Sorting) on Kaggle site.

1. Group by Column

reviews_written = reviews.groupby('taster_twitter_handle').size()
# or
reviews_written = reviews.groupby('taster_twitter_handle')
                         .taster_twitter_handle
                         .count()
# or
reviews_written = reviews.groupby("taster_twitter_handle")[
    "taster_twitter_handle"
].count()

2. Group by Column and Sort by Index

best_rating_per_price = reviews.groupby('price').points.max().sort_index()
# or
best_rating_per_price = reviews.groupby('price')['points'].max().sort_index()

3. Group by Min and Max

price_extremes = reviews.groupby('variety').price.agg([min, max])
# or
price_extremes = reviews.groupby('variety')["price"].agg([min, max])

4. Sort by Columns

sorted_varieties = price_extremes.sort_values(by=['min', 'max'], ascending=False)

5. Group by Column and Apply mean() Function

reviewer_mean_ratings = reviews.groupby('taster_name').points.mean()
# or
reviewer_mean_ratings = reviews.groupby('taster_name')["points"].mean()

6. Group by Columns and Sort by Value

country_variety_counts = reviews.groupby(['country', 'variety'])
                                .size()
                                .sort_values(ascending=False)