aitech-moj/cw/11_Model_rekurencyjny_z_atencją.ipynb

Modelowanie Języka

10. Model rekurencyjny z atencją [ćwiczenia]

Jakub Pokrywka (2022)

notebook na podstawie:

https://pytorch.org/tutorials/intermediate/seq2seq_translation_tutorial.html

from __future__ import unicode_literals, print_function, division
from io import open
import unicodedata
import string
import re
import random

import torch
import torch.nn as nn
from torch import optim
import torch.nn.functional as F

device = torch.device("cuda" if torch.cuda.is_available() else "cpu")

SOS_token = 0
EOS_token = 1

class Lang:
    def __init__(self):
        self.word2index = {}
        self.word2count = {}
        self.index2word = {0: "SOS", 1: "EOS"}
        self.n_words = 2  # Count SOS and EOS

    def addSentence(self, sentence):
        for word in sentence.split(' '):
            self.addWord(word)

    def addWord(self, word):
        if word not in self.word2index:
            self.word2index[word] = self.n_words
            self.word2count[word] = 1
            self.index2word[self.n_words] = word
            self.n_words += 1
        else:
            self.word2count[word] += 1

pairs = []
with open('data/eng-pol.txt') as f:
    for line in f:
        eng_line, pol_line = line.lower().rstrip().split('\t')

        eng_line = re.sub(r"([.!?])", r" \1", eng_line)
        eng_line = re.sub(r"[^a-zA-Z.!?]+", r" ", eng_line)

        pol_line = re.sub(r"([.!?])", r" \1", pol_line)
        pol_line = re.sub(r"[^a-zA-Z.!?ąćęłńóśźżĄĆĘŁŃÓŚŹŻ]+", r" ", pol_line)

        pairs.append([eng_line, pol_line])

pairs[1]

MAX_LENGTH = 10
eng_prefixes = (
    "i am ", "i m ",
    "he is", "he s ",
    "she is", "she s ",
    "you are", "you re ",
    "we are", "we re ",
    "they are", "they re "
)

pairs = [p for p in pairs if len(p[0].split(' ')) < MAX_LENGTH and len(p[1].split(' ')) < MAX_LENGTH]
pairs = [p for p in pairs if p[0].startswith(eng_prefixes)]

eng_lang = Lang()
pol_lang = Lang()

for pair in pairs:
    eng_lang.addSentence(pair[0])
    pol_lang.addSentence(pair[1])

pairs[0]

pairs[1]

pairs[2]

eng_lang.n_words

pol_lang.n_words

class EncoderRNN(nn.Module):
    def __init__(self, input_size, embedding_size, hidden_size):
        super(EncoderRNN, self).__init__()
        self.embedding_size = 200
        self.hidden_size = hidden_size

        self.embedding = nn.Embedding(input_size, self.embedding_size)
        self.gru = nn.GRU(self.embedding_size, hidden_size)

    def forward(self, input, hidden):
        embedded = self.embedding(input).view(1, 1, -1)
        output = embedded
        output, hidden = self.gru(output, hidden)
        return output, hidden

    def initHidden(self):
        return torch.zeros(1, 1, self.hidden_size, device=device)

class DecoderRNN(nn.Module):
    def __init__(self, embedding_size, hidden_size, output_size):
        super(DecoderRNN, self).__init__()
        self.embedding_size = embedding_size
        self.hidden_size = hidden_size

        self.embedding = nn.Embedding(output_size, self.embedding_size)
        self.gru = nn.GRU(self.embedding_size, hidden_size)
        self.out = nn.Linear(hidden_size, output_size)
        self.softmax = nn.LogSoftmax(dim=1)

    def forward(self, input, hidden):
        output = self.embedding(input).view(1, 1, -1)
        output = F.relu(output)
        output, hidden = self.gru(output, hidden)
        output = self.softmax(self.out(output[0]))
        return output, hidden

    def initHidden(self):
        return torch.zeros(1, 1, self.hidden_size, device=device)

class AttnDecoderRNN(nn.Module):
    def __init__(self, embedding_size, hidden_size, output_size, dropout_p=0.1, max_length=MAX_LENGTH):
        super(AttnDecoderRNN, self).__init__()
        self.embedding_size = embedding_size
        self.hidden_size = hidden_size
        self.output_size = output_size
        self.dropout_p = dropout_p
        self.max_length = max_length

        self.embedding = nn.Embedding(self.output_size, self.embedding_size)
        self.attn = nn.Linear(self.hidden_size + self.embedding_size, self.max_length)
        self.attn_combine = nn.Linear(self.hidden_size + self.embedding_size, self.embedding_size)
        self.dropout = nn.Dropout(self.dropout_p)
        self.gru = nn.GRU(self.embedding_size, self.hidden_size)
        self.out = nn.Linear(self.hidden_size, self.output_size)

    def forward(self, input, hidden, encoder_outputs):
        embedded = self.embedding(input).view(1, 1, -1)
        embedded = self.dropout(embedded)

        attn_weights = F.softmax(
            self.attn(torch.cat((embedded[0], hidden[0]), 1)), dim=1)
        attn_applied = torch.bmm(attn_weights.unsqueeze(0),
                                 encoder_outputs.unsqueeze(0))
        #import pdb; pdb.set_trace()

        output = torch.cat((embedded[0], attn_applied[0]), 1)
        output = self.attn_combine(output).unsqueeze(0)

        output = F.relu(output)
        output, hidden = self.gru(output, hidden)

        output = F.log_softmax(self.out(output[0]), dim=1)
        return output, hidden, attn_weights

    def initHidden(self):
        return torch.zeros(1, 1, self.hidden_size, device=device)

def tensorFromSentence(sentence, lang):
    indexes = [lang.word2index[word] for word in sentence.split(' ')]
    indexes.append(EOS_token)
    return torch.tensor(indexes, dtype=torch.long, device=device).view(-1, 1)

teacher_forcing_ratio = 0.5

def train_one_batch(input_tensor, target_tensor, encoder, decoder, optimizer, criterion, max_length=MAX_LENGTH):
    encoder_hidden = encoder.initHidden()


    optimizer.zero_grad()

    input_length = input_tensor.size(0)
    target_length = target_tensor.size(0)

    encoder_outputs = torch.zeros(max_length, encoder.hidden_size, device=device)

    loss = 0

    for ei in range(input_length):
        encoder_output, encoder_hidden = encoder(input_tensor[ei], encoder_hidden)
        encoder_outputs[ei] = encoder_output[0, 0]

    decoder_input = torch.tensor([[SOS_token]], device=device)

    decoder_hidden = encoder_hidden

    use_teacher_forcing = True if random.random() < teacher_forcing_ratio else False

    if use_teacher_forcing:
        for di in range(target_length):
            decoder_output, decoder_hidden, decoder_attention = decoder(decoder_input, decoder_hidden, encoder_outputs)
            loss += criterion(decoder_output, target_tensor[di])
            decoder_input = target_tensor[di]  # Teacher forcing

    else:
        for di in range(target_length):
            decoder_output, decoder_hidden, decoder_attention = decoder(decoder_input, decoder_hidden, encoder_outputs)
            topv, topi = decoder_output.topk(1)
            decoder_input = topi.squeeze().detach()  # detach from history as input

            loss += criterion(decoder_output, target_tensor[di])
            if decoder_input.item() == EOS_token:
                break

    loss.backward()

    optimizer.step()

    return loss.item() / target_length

def trainIters(encoder, decoder, n_iters, print_every=1000, learning_rate=0.01):
    print_loss_total = 0  # Reset every print_every
    encoder.train()
    decoder.train()

    optimizer = optim.SGD(list(encoder.parameters()) + list(decoder.parameters()), lr=learning_rate)
    
    training_pairs = [random.choice(pairs) for _ in range(n_iters)]
    training_pairs = [(tensorFromSentence(p[0], eng_lang), tensorFromSentence(p[1], pol_lang)) for p in training_pairs]
    
    criterion = nn.NLLLoss()

    for i in range(1, n_iters + 1):
        training_pair = training_pairs[i - 1]
        input_tensor = training_pair[0]
        target_tensor = training_pair[1]

        loss = train_one_batch(input_tensor,
                               target_tensor,
                               encoder,
                               decoder,
                               optimizer,

                               criterion)
        
        print_loss_total += loss

        if i % print_every == 0:
            print_loss_avg = print_loss_total / print_every
            print_loss_total = 0
            print(f'iter: {i}, loss: {print_loss_avg}')

def evaluate(encoder, decoder, sentence, max_length=MAX_LENGTH):
    encoder.eval()
    decoder.eval()
    with torch.no_grad():
        input_tensor = tensorFromSentence(sentence, eng_lang)
        input_length = input_tensor.size()[0]
        encoder_hidden = encoder.initHidden()

        encoder_outputs = torch.zeros(max_length, encoder.hidden_size, device=device)

        for ei in range(input_length):
            encoder_output, encoder_hidden = encoder(input_tensor[ei], encoder_hidden)
            encoder_outputs[ei] += encoder_output[0, 0]

        decoder_input = torch.tensor([[SOS_token]], device=device)

        decoder_hidden = encoder_hidden

        decoded_words = []
        decoder_attentions = torch.zeros(max_length, max_length)

        for di in range(max_length):
            decoder_output, decoder_hidden, decoder_attention = decoder(
                decoder_input, decoder_hidden, encoder_outputs)
            decoder_attentions[di] = decoder_attention.data
            topv, topi = decoder_output.data.topk(1)
            if topi.item() == EOS_token:
                decoded_words.append('<EOS>')
                break
            else:
                decoded_words.append(pol_lang.index2word[topi.item()])

            decoder_input = topi.squeeze().detach()

        return decoded_words, decoder_attentions[:di + 1]

def evaluateRandomly(encoder, decoder, n=10):
    for i in range(n):
        pair = random.choice(pairs)
        print('>', pair[0])
        print('=', pair[1])
        output_words, attentions = evaluate(encoder, decoder, pair[0])
        output_sentence = ' '.join(output_words)
        print('<', output_sentence)
        print('')

embedding_size = 200
hidden_size = 256
encoder1 = EncoderRNN(eng_lang.n_words, embedding_size, hidden_size).to(device)
attn_decoder1 = AttnDecoderRNN(embedding_size, hidden_size, pol_lang.n_words, dropout_p=0.1).to(device)

trainIters(encoder1, attn_decoder1, 10_000, print_every=50)

evaluateRandomly(encoder1, attn_decoder1)

## ZADANIE

Gonito "WMT2017 Czech-English machine translation challenge for news "

Proszę wytrenować najpierw model german -> english, a później dotrenować na czech-> english.
Można wziąć inicjalizować enkoder od nowa lub nie. Proszę w każdym razie użyć wytrenowanego dekodera.