@tensorflow/tfjs-core/dist/ops/where.js

/**
 * @license
 * Copyright 2020 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 { ENGINE } from '../engine';
import { Select } from '../kernel_names';
import { convertToTensor } from '../tensor_util_env';
import { broadcastTo } from './broadcast_to';
import { assertAndGetBroadcastShape } from './broadcast_util';
import { op } from './operation';
/**
 * Returns the elements, either `a` or `b` depending on the `condition`.
 *
 * If the condition is true, select from `a`, otherwise select from `b`.
 *
 * ```js
 * const cond = tf.tensor1d([false, false, true], 'bool');
 * const a = tf.tensor1d([1 , 2, 3]);
 * const b = tf.tensor1d([-1, -2, -3]);
 *
 * a.where(cond, b).print();
 * ```
 *
 * @param condition The input condition. Must be of dtype bool.
 * @param a If `condition` is rank 1, `a` may have a higher rank but
 *     its first dimension must match the size of `condition`.
 * @param b A tensor with the same dtype as `a` and with shape that is
 *     compatible with `a`.
 * @return A tensor with same dtype as `a` and `b`, and shape that is
 *     broadcastable from `a` and `b`.
 *
 * @doc {heading: 'Operations', subheading: 'Logical'}
 */
function where_(condition, a, b) {
    const $a = convertToTensor(a, 'a', 'where');
    const $b = convertToTensor(b, 'b', 'where');
    const $condition = convertToTensor(condition, 'condition', 'where', 'bool');
    // TODO: move this logic to forward function when the broadcastTo op is
    // implemented in WASM.
    // Find the broadcastable shape for $condition, $a, and $b.
    const broadcastShape = assertAndGetBroadcastShape(assertAndGetBroadcastShape($condition.shape, $a.shape), $b.shape);
    const $broadcastedCondition = broadcastTo($condition, broadcastShape);
    const $broadcastedA = broadcastTo($a, broadcastShape);
    const $broadcastedB = broadcastTo($b, broadcastShape);
    const inputs = {
        condition: $broadcastedCondition,
        t: $broadcastedA,
        e: $broadcastedB
    };
    return ENGINE.runKernel(Select, inputs);
}
export const where = op({ where_ });
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