Evaluation methods

Base Method

@author: Quoc-Tuan Truong <tuantq.vnu@gmail.com>

class cornac.eval_methods.base_method.BaseMethod(data=None, fmt='UIR', rating_threshold=1.0, exclude_unknowns=False, verbose=False, **kwargs)

Base Evaluation Method

Parameters:

• data (array-like) – The original data.
• data_format (str, default: 'UIR') – The format of given data.
• total_users (int, optional, default: None) – Total number of unique users in the data including train, val, and test sets.
• total_users – Total number of unique items in the data including train, val, and test sets.
• rating_threshold (float, optional, default: 1.0) – The threshold to convert ratings into positive or negative feedback for ranking metrics.
• exclude_unknowns (bool, optional, default: False) – Ignore unknown users and items (cold-start) during evaluation.
• verbose (bool, optional, default: False) – Output running log

evaluate(model, metrics, user_based)

Evaluate given models according to given metrics

Parameters:

• model (cornac.models.Recommender) – Recommender model to be evaluated.
• metrics (iterable) – List of metrics.
• user_based (bool) – Evaluation mode. Whether results are averaging based on number of users or number of ratings.

classmethod from_splits(train_data, test_data, val_data=None, data_format='UIR', rating_threshold=1.0, exclude_unknowns=False, verbose=False)

Constructing evaluation method given data.

Parameters:

• train_data (array-like) – Training data
• test_data (array-like) – Test data
• val_data (array-like) – Validation data
• data_format (str, default: 'UIR') – The format of given data.
• rating_threshold (float, default: 1.0) – Threshold to decide positive or negative preferences.
• exclude_unknowns (bool, default: False) – Whether to exclude unknown users/items in evaluation.
• verbose (bool, default: False) – The verbosity flag.

Returns:

method – Evaluation method object.

Return type:

<cornac.eval_methods.BaseMethod>

Ratio Split

@author: Quoc-Tuan Truong <tuantq.vnu@gmail.com>

class cornac.eval_methods.ratio_split.RatioSplit(data, fmt='UIR', test_size=0.2, val_size=0.0, rating_threshold=1.0, shuffle=True, seed=None, exclude_unknowns=False, verbose=False, **kwargs)

Train-Test Split Evaluation Method.

Parameters:

• data (.., required) – The input data in the form of triplets (user, item, rating).
• fmt (str, optional, default: "UIR") – The format of input data: - UIR: (user, item, rating) triplet data - UIRT: (user, item , rating, timestamp) quadruplet data
• test_size (float, optional, default: 0.2) – The proportion of the test set, if > 1 then it is treated as the size of the test set.
• val_size (float, optional, default: 0.0) – The proportion of the validation set, if > 1 then it is treated as the size of the validation set.
• rating_threshold (float, optional, default: 1.) – The minimum value that is considered to be a good rating used for ranking, e.g, if the ratings are in {1, …, 5}, then rating_threshold = 4.
• shuffle (bool, optional, default: True) – Shuffle the data before splitting.
• seed (bool, optional, default: None) – Random seed.
• exclude_unknowns (bool, optional, default: False) – Ignore unknown users and items (cold-start) during evaluation and testing
• verbose (bool, optional, default: False) – Output running log

evaluate(model, metrics, user_based)

Evaluate given models according to given metrics

Parameters:

• model (cornac.models.Recommender) – Recommender model to be evaluated.
• metrics (iterable) – List of metrics.
• user_based (bool) – Evaluation mode. Whether results are averaging based on number of users or number of ratings.

Cross Validation

@author: Aghiles Salah

class cornac.eval_methods.cross_validation.CrossValidation(data, fmt='UIR', n_folds=5, rating_threshold=1.0, partition=None, exclude_unknowns=True, verbose=False, **kwargs)

Cross Validation Evaluation Method.

Parameters:

• data (.. , required) – Input data in the triplet format (user_id, item_id, rating_val).
• n_folds (int, optional, default: 5) – The number of folds for cross validation.
• rating_threshold (float, optional, default: 1.) – The minimum value that is considered to be a good rating, e.g, if the ratings are in {1, … ,5}, then rating_threshold = 4.
• partition (array-like, shape (n_observed_ratings,), optional, default: None) – The partition of ratings into n_folds (fold label of each rating) If None, random partitioning is performed to assign each rating into a fold.
• rating_threshold – The minimum value that is considered to be a good rating used for ranking, e.g, if the ratings are in {1, …, 5}, then rating_threshold = 4.
• exclude_unknowns (bool, optional, default: False) – Ignore unknown users and items (cold-start) during evaluation and testing
• verbose (bool, optional, default: False) – Output running log

evaluate(model, metrics, user_based)

Evaluate given models according to given metrics

Parameters:

• model (cornac.models.Recommender) – Recommender model to be evaluated.
• metrics (iterable) – List of metrics.
• user_based (bool) – Evaluation mode. Whether results are averaging based on number of users or number of ratings.