def _check_model(model: Model, data: Table) -> bool:
# return whether data.X and model_domain_data.X differ
if data.domain.has_discrete_class and isinstance(model, RegModel):
raise ValueError(
f"{model} can not be used for data with discrete class."
)
elif data.domain.has_continuous_class and isinstance(model, ClsModel):
raise ValueError(
f"{model} can not be used for data with continuous class."
)
mod_data_X = model.data_to_model_domain(data).X
if data.X.shape != mod_data_X.shape:
return True
elif sp.issparse(data.X) and sp.issparse(mod_data_X):
return (data.X != mod_data_X).nnz != 0
else:
return (data.X != mod_data_X).any()
def compute_shap_values(
model: Model,
data: Table,
reference_data: Table,
progress_callback: Callable = None,
) -> Tuple[List[np.ndarray], Table, np.ndarray, np.ndarray]:
"""
Compute SHAP values - explanation for a model. And also give a transformed
data table.
Parameters
----------
model
Model which is explained.
data
Data to be explained
reference_data
Background data for perturbation purposes
progress_callback
The callback for reporting the progress.
Returns
-------
shap_values
Shapely values for each data item computed by the SHAP library. The
result is a list of SHAP values for each class - the class order is
taken from values in the class_var. Each array in the list has shape
(num cases x num attributes) - explanation for the contribution of each
attribute to the final prediction.
data_transformed
The table on which explanation was made: table preprocessed by models
preprocessors
sample_mask
SHAP values are computed just for a data sample. It is a boolean mask
that tells which rows in data_transformed are explained.
base_value
The base value (average prediction on dataset) for each class.
"""
# ensure that sampling and SHAP value calculation is same for same data
with temp_seed(0):
if progress_callback is None:
progress_callback = dummy_callback
progress_callback(0, "Computing explanation ...")
data_transformed = model.data_to_model_domain(data)
reference_data_transformed = model.data_to_model_domain(reference_data)
shap_values, sample_mask, base_value = _explain_trees(
model,
data_transformed,
reference_data_transformed,
progress_callback,
)
if shap_values is None:
shap_values, sample_mask, base_value = _explain_other_models(
model,
data_transformed,
reference_data_transformed,
progress_callback,
)
# for regression return array with one value
if not isinstance(base_value, np.ndarray):
base_value = np.array([base_value])
progress_callback(1)
return shap_values, data_transformed, sample_mask, base_value