def update_predict_fn(self, x):
if np.argmax(self.models.sklearn(x).shape) == 0:
self.explainer.predictor = self.models.sklearn
self.explainer.samplers[0].predictor = self.models.sklearn
else:
self.explainer.predictor = ArgmaxTransformer(self.models.sklearn)
self.explainer.samplers[0].predictor = ArgmaxTransformer(self.models.sklearn)
def __init__(self,
nlp: 'spacy.language.Language',
predictor: Callable,
seed: int = None) -> None:
"""
Initialize anchor text explainer.
Parameters
----------
nlp
spaCy object.
predictor
A callable that takes a tensor of N data points as inputs and returns N outputs.
seed
If set, ensures identical random streams.
"""
super().__init__(meta=copy.deepcopy(DEFAULT_META_ANCHOR))
np.random.seed(seed)
self.nlp = nlp
# check if predictor returns predicted class or prediction probabilities for each class
# if needed adjust predictor so it returns the predicted class
if np.argmax(predictor(['Hello world']).shape) == 0:
self.predictor = predictor
else:
self.predictor = ArgmaxTransformer(predictor)
self._synonyms_generator = Neighbors(self.nlp)
self.tokens, self.words, self.positions, self.punctuation = [], [], [], [
] # type: List, List, List, List
# dict containing an np.array of similar words with same part of speech and an np.array of similarities
self.synonyms = {} # type: Dict[str, Dict[str, np.ndarray]]
# the method used to generate samples
self.perturbation = None # type: Union[Callable, None]
def _transform_predictor(self, predictor: Callable) -> Callable:
# check if predictor returns predicted class or prediction probabilities for each class
# if needed adjust predictor so it returns the predicted class
if np.argmax(predictor(['Hello world']).shape) == 0:
return predictor
else:
transformer = ArgmaxTransformer(predictor)
return transformer
def explain(self, inputs: List) -> Explanation:
arr = np.array(inputs)
# set anchor_tabular predict function so it always returns predicted class
# See anchor_tabular.__init__
logging.info("Arr shape %s ", (arr.shape,))
# check if predictor returns predicted class or prediction probabilities for each class
# if needed adjust predictor so it returns the predicted class
if np.argmax(self.predict_fn(arr).shape) == 0:
self.anchors_tabular.predictor = self.predict_fn
self.anchors_tabular.samplers[0].predictor = self.predict_fn
else:
self.anchors_tabular.predictor = ArgmaxTransformer(self.predict_fn)
self.anchors_tabular.samplers[0].predictor = ArgmaxTransformer(
self.predict_fn
)
# We assume the input has batch dimension but Alibi explainers presently assume no batch
anchor_exp = self.anchors_tabular.explain(arr[0], **self.kwargs)
return anchor_exp
def patch_transformer(monkeypatch, request):
out_dim, out_type, sz = request.param
transformer = ArgmaxTransformer(None)
monkeypatch.setattr(
transformer, "predictor",
MockPredictor(out_dim,
out_type=out_type,
sz=sz,
key=(out_dim, out_type, sz)))
return transformer
def explain(self, inputs: List) -> Explanation:
arr = np.array(inputs)
# check if predictor returns predicted class or prediction probabilities for each class
# if needed adjust predictor so it returns the predicted class
if np.argmax(self.predict_fn(arr).shape) == 0:
self.anchors_image.predictor = self.predict_fn
else:
self.anchors_image.predictor = ArgmaxTransformer(self.predict_fn)
logging.info("Calling explain on image of shape %s", (arr.shape, ))
logging.info("anchor image call with %s", self.kwargs)
anchor_exp = self.anchors_image.explain(arr[0], **self.kwargs)
return anchor_exp
def __init__(self,
predictor: Callable,
feature_names: list,
categorical_names: dict = None,
seed: int = None) -> None:
"""
Parameters
----------
predictor
A callable that takes a tensor of N data points as inputs and returns N outputs.
feature_names
List with feature names.
categorical_names
Dictionary where keys are feature columns and values are the categories for the feature.
seed
Used to set the random number generator for repeatability purposes.
"""
super().__init__(meta=copy.deepcopy(DEFAULT_META_ANCHOR))
self.feature_names = feature_names
# check if predictor returns predicted class or prediction probabilities for each class
# if needed adjust predictor so it returns the predicted class
if np.argmax(predictor(np.zeros([1, len(feature_names)])).shape) == 0:
self.predictor = predictor
else:
transformer = ArgmaxTransformer(predictor)
self.predictor = transformer
# define column indices of categorical and numerical (aka continuous) features
if categorical_names:
self.categorical_features = sorted(categorical_names.keys())
self.feature_values = categorical_names.copy(
) # dict with {col: categorical feature values}
else:
self.categorical_features = []
self.feature_values = {}
self.numerical_features = [
x for x in range(len(feature_names))
if x not in self.categorical_features
]
self.samplers = [] # type: list
self.seed = seed
self.instance_label = None
# update metadata
self.meta['params'].update(seed=seed)
def explain(self, inputs: List) -> Explanation:
if self.anchors_text is None:
self.anchors_text = alibi.explainers.AnchorText(self.nlp, self.predict_fn)
# We assume the input has batch dimension but Alibi explainers presently assume no batch
input_words = inputs[0]
# check if predictor returns predicted class or prediction probabilities for each class
# if needed adjust predictor so it returns the predicted class
if np.argmax(self.predict_fn([input_words]).shape) == 0:
self.anchors_text.predictor = self.predict_fn
else:
self.anchors_text.predictor = ArgmaxTransformer(self.predict_fn)
anchor_exp = self.anchors_text.explain(input_words, **self.kwargs)
return anchor_exp
def test_argmax_transformer(monkeypatch, out_dim, out_type):
"""
Test that the conversion of output probabilities to class labels works
for a range of classifier output types.
"""
# setup a transformer with a mock predictor
transformer = ArgmaxTransformer(None)
monkeypatch.setattr(
transformer,
"predictor",
MockPredictor(
out_dim,
out_type=out_type,
)
)
# fake predictor input
X = np.random.random(size=(50, 14))
result = transformer(X)
# argmax transformer should do get rid of the feature dimension
assert len(result.shape) == len(X.shape) - 1
def __init__(self,
predictor: Callable,
image_shape: tuple,
segmentation_fn: Any = 'slic',
segmentation_kwargs: dict = None,
images_background: np.ndarray = None,
seed: int = None) -> None:
"""
Initialize anchor image explainer.
Parameters
----------
predictor
A callable that takes a tensor of N data points as inputs and returns N outputs.
image_shape
Shape of the image to be explained.
segmentation_fn
Any of the built in segmentation function strings: 'felzenszwalb', 'slic' or 'quickshift' or a custom
segmentation function (callable) which returns an image mask with labels for each superpixel.
See http://scikit-image.org/docs/dev/api/skimage.segmentation.html for more info.
segmentation_kwargs
Keyword arguments for the built in segmentation functions.
images_background
Images to overlay superpixels on.
seed
If set, ensures different runs with the same input will yield same explanation.
"""
super().__init__(meta=copy.deepcopy(DEFAULT_META_ANCHOR))
np.random.seed(seed)
if isinstance(segmentation_fn, str) and not segmentation_kwargs:
try:
segmentation_kwargs = DEFAULT_SEGMENTATION_KWARGS[
segmentation_fn] # type: ignore
except KeyError:
logger.warning(
'DEFAULT_SEGMENTATION_KWARGS did not contain any entry'
'for segmentation method {}. No kwargs will be passed to'
'the segmentation function!'.format(segmentation_fn))
segmentation_kwargs = {}
elif callable(segmentation_fn) and segmentation_kwargs:
logger.warning(
'Specified both a segmentation function to create superpixels and '
'keyword arguments for built segmentation functions. By default '
'the specified segmentation function will be used.')
# check if predictor returns predicted class or prediction probabilities for each class
# if needed adjust predictor so it returns the predicted class
if np.argmax(predictor(np.zeros((1, ) + image_shape)).shape) == 0:
self.predictor = predictor
else:
self.predictor = ArgmaxTransformer(predictor)
# segmentation function is either a user-defined function or one of the values in
fn_options = {
'felzenszwalb': felzenszwalb,
'slic': slic,
'quickshift': quickshift
}
if callable(segmentation_fn):
self.custom_segmentation = True
self.segmentation_fn = segmentation_fn
else:
self.custom_segmentation = False
self.segmentation_fn = partial(fn_options[segmentation_fn],
**segmentation_kwargs)
self.images_background = images_background
self.image_shape = image_shape
# [H, W] int array; each int is a superpixel labels
self.segments = None # type: np.ndarray
self.segment_labels = None # type: list
self.image = None # type: np.ndarray
# a superpixel is perturbed with prob 1 - p_sample
self.p_sample = 0.5 # type: float
# update metadata
self.meta['params'].update(
custom_segmentation=self.custom_segmentation,
segmentation_kwargs=segmentation_kwargs,
p_sample=self.p_sample,
seed=seed,
image_shape=image_shape)
if not self.custom_segmentation:
self.meta['params'].update(segmentation_fn=segmentation_fn)
else:
self.meta['params'].update(segmentation_fn='custom')