def set_preference(self, user_id, item_id, value):
'''
Returns
--------
self
Sets a particular preference (item plus rating) for a user.
'''
if user_id not in self.prefsForUsers:
raise UserNotFoundError('user_id not found')
if item_id not in self.prefsForItems:
raise ItemNotFoundError('item_id not found')
self.prefsForUsers[user_id][item_id] = value
def remove_preference(self, user_id, item_id):
'''
Returns
--------
self
Removes a particular preference for a user.
'''
if user_id not in self.prefsForUsers:
raise UserNotFoundError('user_id not found')
if item_id not in self.prefsForItems:
raise ItemNotFoundError('item_id not found')
userPrefs = self.prefsForUsers[user_id]
if item_id in userPrefs:
del userPrefs[item_id]
def preferences_for_item(self, item_id, order_by_id=True):
'''
Returns
-------
preferences: numpy array of shape [(item_id,preference)]
Return all existing Preferences expressed for that item,
'''
item_id_loc = np.where(self._item_ids == item_id)
if not item_id_loc[0].size:
#item_id not found
raise ItemNotFoundError('Item not found')
preferences = self.index[:, item_id_loc]
preferences = preferences.flatten()
return self._user_ids[preferences]
def preferences_for_item(self, item_id, order_by_id=True):
'''
Returns
-------
preferences: list of shape [(item_id,preference)]
Return all existing Preferences expressed for that item,
'''
if item_id not in self.prefsForItems:
raise ItemNotFoundError('item_id not found')
if order_by_id:
return sorted(self.prefsForItems[item_id]
) if item_id in self.prefsForItems else []
else:
return sorted(
self.prefsForItems[item_id], key=itemgetter(1),
reverse=True) if item_id in self.prefsForItems else []
def preference_value(self, user_id, item_id):
'''
Returns
-------
preference: float
Retrieves the preference value for a single user and item.
'''
item_id_loc = np.where(self._item_ids == item_id)
user_id_loc = np.where(self._user_ids == user_id)
if not user_id_loc[0].size:
raise UserNotFoundError('user_id in the model not found')
if not item_id_loc[0].size:
raise ItemNotFoundError('item_id in the model not found')
return self.index[user_id_loc, item_id_loc].flatten()[0]
def remove_preference(self, user_id, item_id):
'''
Returns
--------
self
Removes a particular preference for a user.
'''
user_id_loc = np.where(self._user_ids == user_id)
item_id_loc = np.where(self._item_ids == item_id)
if not user_id_loc[0].size:
raise UserNotFoundError('user_id in the model not found')
if not item_id_loc[0].size:
raise ItemNotFoundError('item_id in the model not found')
self.dataset[user_id].remove(item_id)
self.build_model()
def preference_value(self, user_id, item_id):
'''
Returns
-------
preference: float
Retrieves the preference value for a single user and item.
'''
if user_id not in self.prefsForUsers:
raise UserNotFoundError('user_id not found')
if item_id not in self.prefsForItems:
raise ItemNotFoundError('item_id not found')
userPrefs = self.prefsForUsers[user_id]
if item_id not in userPrefs:
return np.nan
return userPrefs[item_id]
def preferences_for_item(self, item_id, order_by_id=True):
'''
Returns
-------
preferences: numpy array of shape [(item_id,preference)]
Return all existing Preferences expressed for that item,
'''
item_id_loc = np.where(self._item_ids == item_id)
if not item_id_loc[0].size:
#item_id not found
raise ItemNotFoundError('Item not found')
preferences = self.index[:, item_id_loc]
#think in a way to return as numpy array and how to remove the nan values efficiently.
data = zip(self._user_ids, preferences.flatten())
if order_by_id:
return [(user_id, preference) for user_id, preference in data \
if not np.isnan(preference)]
else:
return sorted([(user_id, preference) for user_id, preference in data \
if not np.isnan(preference)], key=lambda user: - user[1])