@tensorflow/tfjs-core
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Hardware-accelerated JavaScript library for machine intelligence
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JavaScript
/**
* @license
* Copyright 2018 Google LLC. All Rights Reserved.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* =============================================================================
*/
import { convertToTensor } from '../tensor_util_env';
import * as util from '../util';
import { cast } from './cast';
import { matMul } from './mat_mul';
import { oneHot } from './one_hot';
import { op } from './operation';
import { transpose } from './transpose';
/**
* Computes the confusion matrix from true labels and predicted labels.
*
* ```js
* const labels = tf.tensor1d([0, 1, 2, 1, 0], 'int32');
* const predictions = tf.tensor1d([0, 2, 2, 1, 0], 'int32');
* const numClasses = 3;
* const out = tf.math.confusionMatrix(labels, predictions, numClasses);
* out.print();
* // Expected output matrix:
* // [[2, 0, 0],
* // [0, 1, 1],
* // [0, 0, 1]]
* ```
*
* @param labels The target labels, assumed to be 0-based integers
* for the classes. The shape is `[numExamples]`, where
* `numExamples` is the number of examples included.
* @param predictions The predicted classes, assumed to be
* 0-based integers for the classes. Must have the same shape as `labels`.
* @param numClasses Number of all classes, as an integer.
* Its value must be larger than the largest element in `labels` and
* `predictions`.
* @returns The confusion matrix as a int32-type 2D tensor. The value at
* row `r` and column `c` is the number of times examples of actual class
* `r` were predicted as class `c`.
*
* @doc {heading: 'Operations', subheading: 'Evaluation'}
*/
export function confusionMatrix_(labels, predictions, numClasses) {
const $labels = convertToTensor(labels, 'labels', 'confusionMatrix');
const $predictions = convertToTensor(predictions, 'predictions', 'confusionMatrix');
util.assert(numClasses == null || numClasses > 0 && Number.isInteger(numClasses), () => `If provided, numClasses must be a positive integer, ` +
`but got ${numClasses}`);
util.assert($labels.rank === 1, () => `Expected the rank of labels to be 1, but got ${$labels.rank}`);
util.assert($predictions.rank === 1, () => `Expected the rank of predictions to be 1, ` +
`but got ${$predictions.rank}`);
util.assert($labels.shape[0] === $predictions.shape[0], () => `Mismatch in the number of examples: ` +
`${$labels.shape[0]} vs. ${$predictions.shape[0]}. ` +
`Labels and predictions should have the same number of elements.`);
util.assert(numClasses > 0 && Number.isInteger(numClasses), () => `numClasses is required to be a positive integer, but got ` +
`${numClasses}`);
// TODO(cais): In the future, if oneHot supports tensors inputs for
// `numClasses`, `confusionMatrix` can make `numClasses` optional.
const oneHotLabels = oneHot(cast($labels, 'int32'), numClasses);
const oneHotPredictions = oneHot(cast($predictions, 'int32'), numClasses);
const oneHotLabelsT = transpose(oneHotLabels);
const product = matMul(oneHotLabelsT, oneHotPredictions);
return cast(product, 'int32');
}
export const confusionMatrix = op({ confusionMatrix_ });
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