functional.py

import torch
from torch.nn.parameter import Parameter
import torch.nn.functional as F
import math
import pdb
def log_sum_exp(x, axis = 1):
    m = torch.max(x, dim = 1)[0]
    return m + torch.log(torch.sum(torch.exp(x - m.unsqueeze(1)), dim = axis))
def reset_normal_param(L, stdv, weight_scale = 1.):
    assert type(L) == torch.nn.Linear
    torch.nn.init.normal(L.weight, std=weight_scale / math.sqrt(L.weight.size()[0]))
    
class LinearWeightNorm(torch.nn.Module):
    def __init__(self, in_features, out_features, bias=True, weight_scale=None, weight_init_stdv=0.1):
        super(LinearWeightNorm, self).__init__()
        self.in_features = in_features
        self.out_features = out_features
        self.weight = Parameter(torch.randn(out_features, in_features) * weight_init_stdv)
        if bias:
            self.bias = Parameter(torch.zeros(out_features))
        else:
            self.register_parameter('bias', None)
        if weight_scale is not None:
            assert type(weight_scale) == int
            self.weight_scale = Parameter(torch.ones(out_features, 1) * weight_scale)
        else:
            self.weight_scale = 1 
    def forward(self, x):
        W = self.weight * self.weight_scale / torch.sqrt(torch.sum(self.weight ** 2, dim = 1, keepdim = True))
        return F.linear(x, W, self.bias)
    def __repr__(self):
        return self.__class__.__name__ + '(' \
            + 'in_features=' + str(self.in_features) \
            + ', out_features=' + str(self.out_features) \
            + ', weight_scale=' + str(self.weight_scale) + ')'