model.py

# This is a modified version of the original file where we can use our own pretrained embeddings

import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.autograd import Variable


class CNN_Text(nn.Module):
    
    def __init__(self, args):
        super(CNN_Text, self).__init__()
        self.args = args
        
        V = args.embed_num
        D = args.embed_dim
        C = args.class_num
        Ci = 1
        Co = args.kernel_num
        Ks = args.kernel_sizes

        #### NEW ####
        # Load pretrained embeddings 
        # code from https://stackoverflow.com/questions/49710537/pytorch-gensim-how-to-load-pre-trained-word-embeddings/49802495
        if args.embeddings is None:
            self.embed = nn.Embedding(V, D)
        else:
            self.embed = nn.Embedding.from_pretrained(torch.FloatTensor(args.text_field.vocab.vectors))
        #### NEW ####
        
        self.convs = nn.ModuleList([nn.Conv2d(Ci, Co, (K, D)) for K in Ks])
        self.dropout = nn.Dropout(args.dropout)
        self.fc1 = nn.Linear(len(Ks) * Co, C)
        
        if self.args.static:
            self.embed.weight.requires_grad = False

    def forward(self, x):
        x = self.embed(x)  # (N, W, D)
    
        x = x.unsqueeze(1)  # (N, Ci, W, D)

        x = [F.relu(conv(x)).squeeze(3) for conv in self.convs]  # [(N, Co, W), ...]*len(Ks)

        x = [F.max_pool1d(i, i.size(2)).squeeze(2) for i in x]  # [(N, Co), ...]*len(Ks)

        x = torch.cat(x, 1)

        x = self.dropout(x)  # (N, len(Ks)*Co)
        
        logit = self.fc1(x)  # (N, C)
        return logit