app.py

import json
import numpy as np
import tensorflow as tf
from tensorflow import keras

from huggingface_hub import from_pretrained_keras

import gradio as gr

latent_dim = 256
num_encoder_tokens = 71
max_encoder_seq_length = 15
num_decoder_tokens = 92
max_decoder_seq_length = 59

with open("input_vocab.json", "r", encoding="utf-8") as f:
    input_token_index = json.load(f)
with open("target_vocab.json", "r", encoding="utf-8") as f:
    target_token_index = json.load(f)

model = from_pretrained_keras("keras-io/char-lstm-seq2seq")

# Define sampling models
# Restore the model and construct the encoder and decoder.

encoder_inputs = model.input[0]  # input_1
encoder_outputs, state_h_enc, state_c_enc = model.layers[2].output  # lstm_1
encoder_states = [state_h_enc, state_c_enc]
encoder_model = keras.Model(encoder_inputs, encoder_states)

decoder_inputs = model.input[1]  # input_2
decoder_state_input_h = keras.Input(shape=(latent_dim,), name="input_3")
decoder_state_input_c = keras.Input(shape=(latent_dim,), name="input_4")
decoder_states_inputs = [decoder_state_input_h, decoder_state_input_c]
decoder_lstm = model.layers[3]
decoder_outputs, state_h_dec, state_c_dec = decoder_lstm(
    decoder_inputs, initial_state=decoder_states_inputs
)
decoder_states = [state_h_dec, state_c_dec]
decoder_dense = model.layers[4]
decoder_outputs = decoder_dense(decoder_outputs)

decoder_model = keras.Model(
    [decoder_inputs] + decoder_states_inputs, [decoder_outputs] + decoder_states
)

# Reverse-lookup token index to decode sequences back to
# something readable.
reverse_input_char_index = dict((i, char) for char, i in input_token_index.items())
reverse_target_char_index = dict((i, char) for char, i in target_token_index.items())


def decode_sequence(input_seq):
    # Encode the input as state vectors.
    states_value = encoder_model.predict(input_seq)

    # Generate empty target sequence of length 1.
    target_seq = np.zeros((1, 1, num_decoder_tokens))
    # Populate the first character of target sequence with the start character.
    target_seq[0, 0, target_token_index["\t"]] = 1.0

    # Sampling loop for a batch of sequences
    # (to simplify, here we assume a batch of size 1).
    stop_condition = False
    decoded_sentence = ""
    while not stop_condition:
        output_tokens, h, c = decoder_model.predict([target_seq] + states_value)

        # Sample a token
        sampled_token_index = np.argmax(output_tokens[0, -1, :])
        sampled_char = reverse_target_char_index[sampled_token_index]
        decoded_sentence += sampled_char

        # Exit condition: either hit max length
        # or find stop character.
        if sampled_char == "\n" or len(decoded_sentence) > max_decoder_seq_length:
            stop_condition = True

        # Update the target sequence (of length 1).
        target_seq = np.zeros((1, 1, num_decoder_tokens))
        target_seq[0, 0, sampled_token_index] = 1.0

        # Update states
        states_value = [h, c]
    return decoded_sentence


def translate(input_text):
    if len(input_text) > max_encoder_seq_length:
        input_text = input_text[:max_encoder_seq_length]
    encoder_input_data = np.zeros(
        (1, max_encoder_seq_length, num_encoder_tokens), dtype="float32"
    )
    for t, char in enumerate(input_text):
        encoder_input_data[0, t, input_token_index[char]] = 1.0
    encoder_input_data[0, t + 1 :, input_token_index[" "]] = 1.0
    target_text = decode_sequence(encoder_input_data)
    return target_text


input_box = gr.inputs.Textbox(type="str", label="Input Text")
target = gr.outputs.Textbox()

iface = gr.Interface(
    translate,
    input_box,
    target,
    title="Character-level recurrent sequence-to-sequence model",
    description="Model for Translating English to French using a Character-level recurrent sequence-to-sequence trained with small data.",
    article='Author: <a href="https://huggingface.co/anuragshas">Anurag Singh</a> . Based on the keras example from <a href="https://keras.io/examples/nlp/lstm_seq2seq//">fchollet</a>',
    examples=["Hi.", "Wait!", "Go on."],
)


iface.launch()