"""
Explanation class, with visualization functions.
"""
from io import open
import os
import os.path
import json
import string
import numpy as np
from .exceptions import LimeError
from sklearn.utils import check_random_state
def id_generator(size=15, random_state=None):
"""Helper function to generate random div ids. This is useful for embedding
HTML into ipython notebooks."""
chars = list(string.ascii_uppercase + string.digits)
return ''.join(random_state.choice(chars, size, replace=True))
class DomainMapper(object):
"""Class for mapping features to the specific domain.
The idea is that there would be a subclass for each domain (text, tables,
images, etc), so that we can have a general Explanation class, and separate
out the specifics of visualizing features in here.
"""
def __init__(self):
pass
def map_exp_ids(self, exp, **kwargs):
"""Maps the feature ids to concrete names.
Default behaviour is the identity function. Subclasses can implement
this as they see fit.
Args:
exp: list of tuples [(id, weight), (id,weight)]
kwargs: optional keyword arguments
Returns:
exp: list of tuples [(name, weight), (name, weight)...]
"""
return exp
def visualize_instance_html(self,
exp,
label,
div_name,
exp_object_name,
**kwargs):
"""Produces html for visualizing the instance.
Default behaviour does nothing. Subclasses can implement this as they
see fit.
Args:
exp: list of tuples [(id, weight), (id,weight)]
label: label id (integer)
div_name: name of div object to be used for rendering(in js)
exp_object_name: name of js explanation object
kwargs: optional keyword arguments
Returns:
js code for visualizing the instance
"""
return ''
class Explanation(object):
"""Object returned by explainers."""
def __init__(self,
domain_mapper,
mode='classification',
class_names=None,
random_state=None):
"""
Initializer.
Args:
domain_mapper: must inherit from DomainMapper class
type: "classification" or "regression"
class_names: list of class names (only used for classification)
random_state: an integer or numpy.RandomState that will be used to
generate random numbers. If None, the random state will be
initialized using the internal numpy seed.
"""
self.random_state = random_state
self.mode = mode
self.domain_mapper = domain_mapper
self.local_exp = {}
self.intercept = {}
self.score = None
self.local_pred = None
if mode == 'classification':
self.class_names = class_names
self.top_labels = None
self.predict_proba = None
elif mode == 'regression':
self.class_names = ['negative', 'positive']
self.predicted_value = None
self.min_value = 0.0
self.max_value = 1.0
self.dummy_label = 1
else:
raise LimeError('Invalid explanation mode "{}". '
'Should be either "classification" '
'or "regression".'.format(mode))
def available_labels(self):
"""
Returns the list of classification labels for which we have any explanations.
"""
try:
assert self.mode == "classification"
except AssertionError:
raise NotImplementedError('Not supported for regression explanations.')
else:
ans = self.top_labels if self.top_labels else self.local_exp.keys()
return list(ans)
def as_list(self, label=1, **kwargs):
"""Returns the explanation as a list.
Args:
label: desired label. If you ask for a label for which an
explanation wasn't computed, will throw an exception.
Will be ignored for regression explanations.
kwargs: keyword arguments, passed to domain_mapper
Returns:
list of tuples (representation, weight), where representation is
given by domain_mapper. Weight is a float.
"""
label_to_use = label if self.mode == "classification" else self.dummy_label
ans = self.domain_mapper.map_exp_ids(self.local_exp[label_to_use], **kwargs)
ans = [(x[0], float(x[1])) for x in ans]
return ans
def as_map(self):
"""Returns the map of explanations.
Returns:
Map from label to list of tuples (feature_id, weight).
"""
return self.local_exp
def as_pyplot_figure(self, label=1, **kwargs):
"""Returns the explanation as a pyplot figure.
Will throw an error if you don't have matplotlib installed
Args:
label: desired label. If you ask for a label for which an
explanation wasn't computed, will throw an exception.
Will be ignored for regression explanations.
kwargs: keyword arguments, passed to domain_mapper
Returns:
pyplot figure (barchart).
"""
import matplotlib.pyplot as plt
exp = self.as_list(label=label, **kwargs)
fig = plt.figure()
vals = [x[1] for x in exp]
names = [x[0] for x in exp]
vals.reverse()
names.reverse()
colors = ['green' if x > 0 else 'red' for x in vals]
pos = np.arange(len(exp)) + .5
plt.barh(pos, vals, align='center', color=colors)
plt.yticks(pos, names)
if self.mode == "classification":
title = 'Local explanation for class %s' % self.class_names[label]
else:
title = 'Local explanation'
plt.title(title)
return fig
def show_in_notebook(self,
labels=None,
predict_proba=True,
show_predicted_value=True,
**kwargs):
"""Shows html explanation in ipython notebook.
See as_html() for parameters.
This will throw an error if you don't have IPython installed"""
from IPython.core.display import display, HTML
display(HTML(self.as_html(labels=labels,
predict_proba=predict_proba,
show_predicted_value=show_predicted_value,
**kwargs)))
def save_to_file(self,
file_path,
labels=None,
predict_proba=True,
show_predicted_value=True,
**kwargs):
"""Saves html explanation to file. .
Params:
file_path: file to save explanations to
See as_html() for additional parameters.
"""
file_ = open(file_path, 'w', encoding='utf8')
file_.write(self.as_html(labels=labels,
predict_proba=predict_proba,
show_predicted_value=show_predicted_value,
**kwargs))
file_.close()
def as_html(self,
labels=None,
predict_proba=True,
show_predicted_value=True,
**kwargs):
"""Returns the explanation as an html page.
Args:
labels: desired labels to show explanations for (as barcharts).
If you ask for a label for which an explanation wasn't
computed, will throw an exception. If None, will show
explanations for all available labels. (only used for classification)
predict_proba: if true, add barchart with prediction probabilities
for the top classes. (only used for classification)
show_predicted_value: if true, add barchart with expected value
(only used for regression)
kwargs: keyword arguments, passed to domain_mapper
Returns:
code for an html page, including javascript includes.
"""
def jsonize(x):
return json.dumps(x, ensure_ascii=False)
if labels is None and self.mode == "classification":
labels = self.available_labels()
this_dir, _ = os.path.split(__file__)
bundle = open(os.path.join(this_dir, 'bundle.js'),
encoding="utf8").read()
out = u'''
''' % bundle
random_id = id_generator(size=15, random_state=check_random_state(self.random_state))
out += u'''
''' % random_id
predict_proba_js = ''
if self.mode == "classification" and predict_proba:
predict_proba_js = u'''
var pp_div = top_div.append('div')
.classed('lime predict_proba', true);
var pp_svg = pp_div.append('svg').style('width', '100%%');
var pp = new lime.PredictProba(pp_svg, %s, %s);
''' % (jsonize([str(x) for x in self.class_names]),
jsonize(list(self.predict_proba.astype(float))))
predict_value_js = ''
if self.mode == "regression" and show_predicted_value:
# reference self.predicted_value
# (svg, predicted_value, min_value, max_value)
predict_value_js = u'''
var pp_div = top_div.append('div')
.classed('lime predicted_value', true);
var pp_svg = pp_div.append('svg').style('width', '100%%');
var pp = new lime.PredictedValue(pp_svg, %s, %s, %s);
''' % (jsonize(float(self.predicted_value)),
jsonize(float(self.min_value)),
jsonize(float(self.max_value)))
exp_js = '''var exp_div;
var exp = new lime.Explanation(%s);
''' % (jsonize([str(x) for x in self.class_names]))
if self.mode == "classification":
for label in labels:
exp = jsonize(self.as_list(label))
exp_js += u'''
exp_div = top_div.append('div').classed('lime explanation', true);
exp.show(%s, %d, exp_div);
''' % (exp, label)
else:
exp = jsonize(self.as_list())
exp_js += u'''
exp_div = top_div.append('div').classed('lime explanation', true);
exp.show(%s, %s, exp_div);
''' % (exp, self.dummy_label)
raw_js = '''var raw_div = top_div.append('div');'''
if self.mode == "classification":
html_data = self.local_exp[labels[0]]
else:
html_data = self.local_exp[self.dummy_label]
raw_js += self.domain_mapper.visualize_instance_html(
html_data,
labels[0] if self.mode == "classification" else self.dummy_label,
'raw_div',
'exp',
**kwargs)
out += u'''
''' % (random_id, predict_proba_js, predict_value_js, exp_js, raw_js)
out += u''
return out