examples/anchor_tabular_iris.ipynb

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 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Anchor explanations on the Iris dataset"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import numpy as np\n",
    "from sklearn.datasets import load_iris\n",
    "from sklearn.ensemble import RandomForestClassifier\n",
    "from alibi.explainers import AnchorTabular"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Load iris dataset"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "dataset = load_iris()\n",
    "feature_names = dataset.feature_names\n",
    "class_names = list(dataset.target_names)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Define training and test set"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "idx = 145\n",
    "X_train,Y_train = dataset.data[:idx,:], dataset.target[:idx]\n",
    "X_test, Y_test = dataset.data[idx+1:,:], dataset.target[idx+1:]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Train Random Forest model"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "RandomForestClassifier(bootstrap=True, class_weight=None, criterion='gini',\n",
       "            max_depth=None, max_features='auto', max_leaf_nodes=None,\n",
       "            min_impurity_decrease=0.0, min_impurity_split=None,\n",
       "            min_samples_leaf=1, min_samples_split=2,\n",
       "            min_weight_fraction_leaf=0.0, n_estimators=50, n_jobs=None,\n",
       "            oob_score=False, random_state=None, verbose=0,\n",
       "            warm_start=False)"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.random.seed(0)\n",
    "clf = RandomForestClassifier(n_estimators=50)\n",
    "clf.fit(X_train, Y_train)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Define predict function"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "predict_fn = lambda x: clf.predict_proba(x)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Initialize and fit anchor explainer for tabular data"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [],
   "source": [
    "explainer = AnchorTabular(predict_fn, feature_names)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Discretize the ordinal features into quartiles"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "explainer.fit(X_train, disc_perc=[25, 50, 75])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Getting an anchor\n",
    "\n",
    "Below, we get an anchor for the prediction of the first observation in the test set. An anchor is a sufficient condition - that is, when the anchor holds, the prediction should be the same as the prediction for this instance."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Prediction:  virginica\n"
     ]
    }
   ],
   "source": [
    "idx = 0\n",
    "print('Prediction: ', class_names[explainer.predict_fn(X_test[idx].reshape(1, -1))[0]])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We set the precision threshold to 0.95. This means that predictions on observations where the anchor holds will be the same as the prediction on the explained instance at least 95% of the time."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Anchor: petal width (cm) > 1.80 AND sepal width (cm) <= 2.80\n",
      "Precision: 0.99\n",
      "Coverage: 0.07\n"
     ]
    }
   ],
   "source": [
    "explanation = explainer.explain(X_test[idx], threshold=0.95)\n",
    "print('Anchor: %s' % (' AND '.join(explanation['names'])))\n",
    "print('Precision: %.2f' % explanation['precision'])\n",
    "print('Coverage: %.2f' % explanation['coverage'])"
   ]
  }
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