from https://github.com/flairNLP/flair/blob/d66b016fa6d755f9016cab4efab5b7e75aaef721/flair/nn.py

word_dropout.py

import torch

class WordDropout(torch.nn.Module):
    """
    Implementation of word dropout. Randomly drops out entire words (or characters) in embedding space.
    """

    def __init__(self, dropout_rate=0.05, inplace=False):
        super(WordDropout, self).__init__()
        self.dropout_rate = dropout_rate
        self.inplace = inplace

    def forward(self, x):
        if not self.training or not self.dropout_rate:
            return x

        m = x.data.new(x.size(0), x.size(1), 1).bernoulli_(1 - self.dropout_rate)

        mask = torch.autograd.Variable(m, requires_grad=False)
        return mask * x

    def extra_repr(self):
        inplace_str = ", inplace" if self.inplace else ""
        return "p={}{}".format(self.dropout_rate, inplace_str)