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python - replacement of "tf.gather_nd"

问题描述

I am doing a project but their tensorflow version does not support tf.gather_nd. I am asking if possible that use tf.gather, tf.slice or tf.strided_slice to rewrite a function of tf.gather_nd?

tf.gather_nd is used to gather slices from a tensor into a Tensor with shape specified by indices. details can be found in https://www.tensorflow.org/api_docs/python/tf/gather_nd

Thanks,

标签： pythontensorflowdeep-learning

解决方案

这个函数应该做同样的工作：

import tensorflow as tf
import numpy as np

def my_gather_nd(params, indices):
    idx_shape = tf.shape(indices)
    params_shape = tf.shape(params)
    idx_dims = idx_shape[-1]
    gather_shape = params_shape[idx_dims:]
    params_flat = tf.reshape(params, tf.concat([[-1], gather_shape], axis=0))
    axis_step = tf.cumprod(params_shape[:idx_dims], exclusive=True, reverse=True)
    indices_flat = tf.reduce_sum(indices * axis_step, axis=-1)
    result_flat = tf.gather(params_flat, indices_flat)
    return tf.reshape(result_flat, tf.concat([idx_shape[:-1], gather_shape], axis=0))

# Test
np.random.seed(0)
with tf.Graph().as_default(), tf.Session() as sess:
    params = tf.constant(np.random.rand(10, 20, 30).astype(np.float32))
    indices = tf.constant(np.stack([np.random.randint(10, size=(5, 8)),
                                    np.random.randint(20, size=(5, 8))], axis=-1))
    result1, result2 = sess.run((tf.gather_nd(params, indices),
                                 my_gather_nd(params, indices)))
    print(np.allclose(result1, result2))
    # True

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