在tensorflow中使用`dataset.map()`访问张量numpy数组

Question

我试图从使用https://www.tensorflow.org/api_docs/python/tf/data/Dataset#map处理的张量对象中访问numpy数组。

我得到了错误: AttributeError：‘张量’对象没有属性'numpy‘

当我尝试访问张量时，如: np_array = tensor.numpy()

如果使用: dataset.take(n)，则可以访问numpy数组。

为了更清楚地了解我所面临的情况，下面是google中错误的一个可复制的简短示例：

https://colab.research.google.com/drive/13ectGEMDSygcyuW4ip9zrWaHO3pSxc3p?usp=sharing

Tensorflow版本: 2.4.1

更新：在上面的colab之外添加代码：

import os
import numpy as np
import tensorflow as tf

# This works
def get_spectrogram_and_label_id(file_path):
    spectrogram, label = get_spectrogram(audio) # not showing the function here since it is irrelevant
    return spectrogram, label

# This doesn't!
def get_spec_and_label_time(spectrogram, label):
    time_step_spectrogram = generate_time_step_samples(spectrogram)
    return time_step_spectrogram, label

# I want to manipulate the Tensor by extracting the numpy array as part of the map function
def generate_time_step_samples(tensor):
    np_array = tensor.numpy() # ERROR: AttributeError: 'Tensor' object has no attribute 'numpy'
    # Do something with the numpy array
    return np_array

filenames = ['file1.wav', 'file2.wav', ...]
files_ds = tf.data.Dataset.from_tensor_slices(filenames)
spectrogram_ds = files_ds.map(get_spectrogram_and_label_id) # this works
spectrogram_time_ds = spectrogram_ds.map(get_spec_and_label_time) # this doesn't

更多的细节在谷歌colab。

Answer 1

不能在.numpy()函数中访问.map()。

这不是一个bug，它是TensorFlow如何在幕后处理静态图形的。

在这里阅读我的答案，以获得更全面的解释。

AttributeError: 'Tensor' object has no attribute 'numpy' in Tensorflow 2.1