IndexError: When performing advanced indexing the indexing objects must be LongTensors or convertible to LongTensors

import os
import argparse
import numpy as np
import torch
import torch.nn as nn
from torch.autograd import Variable
from torchvision import datasets, transforms
from models import *

# Prune settings
parser = argparse.ArgumentParser(description='PyTorch Slimming CIFAR prune')
parser.add_argument('--dataset', type=str, default='cifar100',
                    help='training dataset (default: cifar10)')
parser.add_argument('--test-batch-size', type=int, default=256, metavar='N',
                    help='input batch size for testing (default: 256)')
parser.add_argument('--no-cuda', action='store_true', default=False,
                    help='disables CUDA training')
parser.add_argument('--resume', default='', type=str, metavar='PATH',
                    help='path to latest checkpoint (default: none)')
parser.add_argument('--depth', type=int, default=19,
                    help='depth of the vgg')
parser.add_argument('--percent', type=float, default=0.5,
                    help='scale sparse rate (default: 0.5)')
parser.add_argument('--model', default='', type=str, metavar='PATH',
                    help='path to the model (default: none)')
parser.add_argument('--save', default='', type=str, metavar='PATH',
                    help='path to save pruned model (default: none)')
args = parser.parse_args()
args.cuda = not args.no_cuda and torch.cuda.is_available()

if not os.path.exists(

model = vgg(dataset=args.dataset, depth=args.depth)
if args.cuda:

if args.model:
    if os.path.isfile(args.model):
        print("=> loading checkpoint '{}'".format(args.model))
        checkpoint = torch.load(args.model)
        args.start_epoch = checkpoint['epoch']
        best_prec1 = checkpoint['best_prec1']
        print("=> loaded checkpoint '{}' (epoch {}) Prec1: {:f}"
              .format(args.model, checkpoint['epoch'], best_prec1))
        print("=> no checkpoint found at '{}'".format(args.resume))

total = 0
for m in model.modules():
    if isinstance(m, nn.BatchNorm2d):
        total +=[0]

bn = torch.zeros(total)
index = 0
for m in model.modules():
    if isinstance(m, nn.BatchNorm2d):
        size =[0]
        bn[index:(index+size)] =
        index += size

y, i = torch.sort(bn)
thre_index = int(total * args.percent)
thre = y[thre_index]
thre ="cuda:0")

pruned = 0
cfg = []
cfg_mask = []
for k, m in enumerate(model.modules()):
    if isinstance(m, nn.BatchNorm2d):
        weight_copy =
        mask = weight_copy.abs().gt(thre).float().cuda()
        pruned = pruned + mask.shape[0] - torch.sum(mask)
        print('layer index: {:d} \t total channel: {:d} \t remaining channel: {:d}'.
            format(k, mask.shape[0], int(torch.sum(mask))))
    elif isinstance(m, nn.MaxPool2d):

pruned_ratio = pruned/total

print('Pre-processing Successful!')

# simple test model after Pre-processing prune (simple set BN scales to zeros)
def test(model):
    kwargs = {'num_workers': 1, 'pin_memory': True} if args.cuda else {}
    if args.dataset == 'cifar10':
        test_loader =
            datasets.CIFAR10('./data.cifar10', train=False, transform=transforms.Compose([
                transforms.Normalize((0.4914, 0.4822, 0.4465), (0.2023, 0.1994, 0.2010))])),
            batch_size=args.test_batch_size, shuffle=True, **kwargs)
    elif args.dataset == 'cifar100':
        test_loader =
            datasets.CIFAR100('./data.cifar100', train=False, transform=transforms.Compose([
                transforms.Normalize((0.4914, 0.4822, 0.4465), (0.2023, 0.1994, 0.2010))])),
            batch_size=args.test_batch_size, shuffle=True, **kwargs)
        raise ValueError("No valid dataset is given.")
    correct = 0
    for data, target in test_loader:
        if args.cuda:
            data, target = data.cuda(), target.cuda()
        data, target = Variable(data, volatile=True), Variable(target)
        output = model(data)
        pred =, keepdim=True)[1] # get the index of the max log-probability
        correct += pred.eq(

    print('\nTest set: Accuracy: {}/{} ({:.1f}%)\n'.format(
        correct, len(test_loader.dataset), 100. * correct / len(test_loader.dataset)))
    return correct / float(len(test_loader.dataset))

acc = test(model)

# Make real prune
newmodel = vgg(dataset=args.dataset, cfg=cfg)
if args.cuda:

num_parameters = sum([param.nelement() for param in newmodel.parameters()])
savepath = os.path.join(, "prune.txt")
with open(savepath, "w") as fp:
    fp.write("Configuration: \n"+str(cfg)+"\n")
    fp.write("Number of parameters: \n"+str(num_parameters)+"\n")
    fp.write("Test accuracy: \n"+str(acc))

layer_id_in_cfg = 0
start_mask = torch.ones(3)
end_mask = cfg_mask[layer_id_in_cfg]
for [m0, m1] in zip(model.modules(), newmodel.modules()):
    if isinstance(m0, nn.BatchNorm2d):
        idx1 = np.squeeze(np.argwhere(np.asarray(end_mask.cpu().numpy())))
        if idx1.size == 1:
            idx1 = np.resize(idx1,(1,)) =[idx1.tolist()].clone() =[idx1.tolist()].clone()
        m1.running_mean = m0.running_mean[idx1.tolist()].clone()
        m1.running_var = m0.running_var[idx1.tolist()].clone()
        layer_id_in_cfg += 1
        start_mask = end_mask.clone()
        if layer_id_in_cfg < len(cfg_mask):  # do not change in Final FC
            end_mask = cfg_mask[layer_id_in_cfg]
    elif isinstance(m0, nn.Conv2d):
        idx0 = np.squeeze(np.argwhere(np.asarray(start_mask.cpu().numpy())))
        idx1 = np.squeeze(np.argwhere(np.asarray(end_mask.cpu().numpy())))
        print('In shape: {:d}, Out shape {:d}.'.format(idx0.size, idx1.size))
        if idx0.size == 1:
            idx0 = np.resize(idx0, (1,))
        if idx1.size == 1:
            idx1 = np.resize(idx1, (1,))
        w1 =[:, idx0.tolist(), :, :].clone()
        w1 = w1[idx1.tolist(), :, :, :].clone() = w1.clone()
    elif isinstance(m0, nn.Linear):
        idx0 = np.squeeze(np.argwhere(np.asarray(start_mask.cpu().numpy())))
        if idx0.size == 1:
            idx0 = np.resize(idx0, (1,)) =[:, idx0].clone() ={'cfg': cfg, 'state_dict': newmodel.state_dict()}, os.path.join(, 'pruned.pth.tar'))

model = newmodel
1 Like

Unfortunately, I cannot run the code as some modules are missing etc.

Which PyTorch version are you using?
I cannot find the stdv call in, which is apparently throwing the error.

My best bet is that you are somehow manipulating the parameters manually, so that probably some parameters are accidentally empty, which throws this error after initializing the model.

pytorch version 0.4.0
And i did not get about stdv call in do you mean normalizing the data? or give me some code snippet so i can check in my code. sorry i am very new in pytorch family.


Thanks for the information!
As you can see in these lines of code, reset_parameters tries to calculate the stddev using n, which is defined as the number of input channels and multiplied by the kernel size.
Since you get a division by zero error in this line, either the number of input channels or the kernel size is zero.
Could you check it in your code? I would recommend to add assert statements to your code and check for valid values.

hi @ptrblck sorry to disturb you again. so i updated my pytorch version to 1.0.1.post2, and python to 3.7. finally i might have managed to rid of previous error. Now i am getting this error. i know this error also comes from source code of pytorch. any thoughts on it. i would appreciate .

File “”, line 110, in
newmodel = vgg(cfg=cfg)
File “/home/akb/pytorch-slimming/”, line 13, in init
self.feature = self.make_layers(cfg, True)
File “/home/akb/pytorch-slimming/”, line 30, in make_layers
conv2d = nn.Conv2d(in_channels, v, kernel_size=3, padding=1, bias=False)
File “/home/akb/anaconda3/lib/python3.7/site-packages/torch/nn/modules/”, line 315, in init
False, pair(0), groups, bias)
File “/home/akb/anaconda3/lib/python3.7/site-packages/torch/nn/modules/”, line 43, in init
File “/home/akb/anaconda3/lib/python3.7/site-packages/torch/nn/modules/”, line 47, in reset_parameters
(self.weight, a=math.sqrt(5))
File “/home/akb/anaconda3/lib/python3.7/site-packages/torch/nn/”, line 288, in kaiming_uniform_
fan = _calculate_correct_fan(tensor, mode)
File “/home/akb/anaconda3/lib/python3.7/site-packages/torch/nn/”, line 257, in _calculate_correct_fan
fan_in, fan_out = _calculate_fan_in_and_fan_out(tensor)
File “/home/akb/anaconda3/lib/python3.7/site-packages/torch/nn/”, line 191, in _calculate_fan_in_and_fan_out
receptive_field_size = tensor[0][0].numel()
IndexError: index 0 is out of bounds for dimension 0 with size 0

It is most likely the same issue, but the error message changes since the init method has changed between the PyTorch versions.

It seems you are still passing a conv layer with 0 input channels:

nn.Conv2d(0, 1, 3, 1, 1)

This will yield the same error, so make sure your slicing is valid.