accuracy module

The surprise.accuracy module provides tools for computing accuracy metrics on a set of predictions.

Available accuracy metrics:

rmse	Compute RMSE (Root Mean Squared Error).
mse	Compute MSE (Mean Squared Error).
mae	Compute MAE (Mean Absolute Error).
fcp	Compute FCP (Fraction of Concordant Pairs).

surprise.accuracy.fcp(predictions, verbose=True)

Compute FCP (Fraction of Concordant Pairs).

Computed as described in paper Collaborative Filtering on Ordinal User Feedback by Koren and Sill, section 5.2.

Parameters

• predictions (list of Prediction) – A list of predictions, as returned by the test() method.

• verbose – If True, will print computed value. Default is True.

Returns

The Fraction of Concordant Pairs.

Raises

ValueError – When predictions is empty.

surprise.accuracy.mae(predictions, verbose=True)

Compute MAE (Mean Absolute Error).

\[\text{MAE} = \frac{1}{|\hat{R}|} \sum_{\hat{r}_{ui} \in \hat{R}}|r_{ui} - \hat{r}_{ui}|\]

Parameters

• predictions (list of Prediction) – A list of predictions, as returned by the test() method.

• verbose – If True, will print computed value. Default is True.

Returns

The Mean Absolute Error of predictions.

Raises

ValueError – When predictions is empty.

surprise.accuracy.mse(predictions, verbose=True)

Compute MSE (Mean Squared Error).

\[\text{MSE} = \frac{1}{|\hat{R}|} \sum_{\hat{r}_{ui} \in \hat{R}}(r_{ui} - \hat{r}_{ui})^2.\]

Parameters

• predictions (list of Prediction) – A list of predictions, as returned by the test() method.

• verbose – If True, will print computed value. Default is True.

Returns

The Mean Squared Error of predictions.

Raises

ValueError – When predictions is empty.

surprise.accuracy.rmse(predictions, verbose=True)

Compute RMSE (Root Mean Squared Error).

\[\text{RMSE} = \sqrt{\frac{1}{|\hat{R}|} \sum_{\hat{r}_{ui} \in \hat{R}}(r_{ui} - \hat{r}_{ui})^2}.\]

Parameters

• predictions (list of Prediction) – A list of predictions, as returned by the test() method.

• verbose – If True, will print computed value. Default is True.

Returns

The Root Mean Squared Error of predictions.

Raises

ValueError – When predictions is empty.