How to use a pre-trained keras model for inference in tf.data.Dataset.map?

问题

I have a pre-trained model, and I'm trying to build another model that takes as input the output of the previous model. I don't want to train the models end-to-end, and want to use the first model for inference only. The first model was trained using tf.data.Dataset pipeline, and my first inclination was to integrate the model as just another dataset.map() operation at the tail of the pipeline, but I'm having issues with that. I've encountered 20 different errors in the process, each unrelated to the prior one. The batch-normalization layer particularly seems to be a pain-point for this.

Below is a minimal starter example that illustrates the issue. It's written in R but answers in python are also welcome.

I'm using tensorflow-gpu version 1.13.1 and keras from tf.keras

library(reticulate)
library(tensorflow)
library(keras)
library(tfdatasets)
use_implementation("tensorflow")

model_weights_path <- 'model-weights.h5'

arr <- function(...) 
  np_array(array(seq_len(prod(unlist(c(...)))), unlist(c(...))), dtype = 'float32')

new_model <- function(load_weights = TRUE) {
  model <- keras_model_sequential() %>% 
    layer_conv_1d(5, 5, activation = 'relu', input_shape = shape(150, 10)) %>%
    layer_batch_normalization() %>%
    layer_flatten() %>%
    layer_dense(10, activation = 'softmax')
  if (load_weights)
    load_model_weights_hdf5(model, model_weights_path)
  freeze_weights(model)
  model
}

if(!file.exists(model_weights_path)) {
  model <- new_model(FALSE) 
  save_model_weights_hdf5(model, model_weights_path)
}

model <- new_model()

data <- arr(20, 150, 10)
ds <- tfdatasets::tensors_dataset(data) %>% 
  dataset_repeat()

ds2 <- ds %>% 
  dataset_map(function(x) {
    model(x)
  })

try(nb <- next_batch(ds2))

sess <- k_get_session()
it <- make_iterator_initializable(ds2)
sess$run(iterator_initializer(it))
nb <- it$get_next()

try(sess$run(nb))

sess$run(tf$initialize_all_variables())

try(sess$run(nb))

来源：https://stackoverflow.com/questions/55227732/how-to-use-a-pre-trained-keras-model-for-inference-in-tf-data-dataset-map

标签

python

tensorflow

keras

tensorflow-datasets