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ToolBox to make using Pytorch much easier.

Project description

Torch Toolbox

Stable Version: v0.1.5 (recommended)

Automatic upload to PyPI is finished.

This project aims to provide the most frequently used tools to help you write more concise and readable PyTorch code.

Pull requests and issues are highly encouraged. Please reach out!


An easy way to install Torch Toolbox is via pip:

pip install torchtoolbox

If you want to install the nightly version:

pip install -U git+


  • cv2 transforms.
  • Integrate with albumentations
  • Prepare tensorboard support with metric collection.


Toolbox have two main parts:

  1. Auxiliary tools to make using Pytorch easier.
  2. Some fashion work which don't exist in Pytorch core.

More examples could be found at ModelZoo.pytorch


0. Now CV2 transforms have been released.

Support as list:(need test)

__all__ = ["Compose", "ToTensor", "ToCVImage", "Normalize", "Resize", "Scale", "CenterCrop", "Pad",
           "Lambda", "RandomApply", "RandomChoice", "RandomOrder", "RandomCrop", "RandomHorizontalFlip",
           "RandomVerticalFlip", "RandomResizedCrop", "RandomSizedCrop", "FiveCrop", "TenCrop", "LinearTransformation",
           "ColorJitter", "RandomRotation", "RandomAffine", "Grayscale", "RandomGrayscale",
           "RandomPerspective", "RandomErasing", "RandomGaussianNoise", "RandomPoissonNoise", "RandomSPNoise",
           "RandomTransforms", "Cutout"]

Part of this code refers to opencv_transforms_torchvision

1. Show your model parameters and FLOPs.

import torch
from import summary
from torchvision.models.mobilenet import mobilenet_v2
model = mobilenet_v2()
summary(model, torch.rand((1, 3, 224, 224)))

Here are some short outputs.

        Layer (type)               Output Shape          Params    FLOPs(M+A) #
            Conv2d-1          [1, 64, 112, 112]            9408       235225088
       BatchNorm2d-2          [1, 64, 112, 112]             256         1605632
              ReLU-3          [1, 64, 112, 112]               0               0
         MaxPool2d-4            [1, 64, 56, 56]               0               0
          ...                      ...                      ...              ...
          Linear-158                  [1, 1000]         1281000         2560000
     MobileNetV2-159                  [1, 1000]               0               0
        Total parameters: 3,538,984  3.5M
    Trainable parameters: 3,504,872
Non-trainable parameters: 34,112
Total flops(M)  : 305,252,872  305.3M
Total flops(M+A): 610,505,744  610.5M
Parameters size (MB): 13.50

2. Metric collection

When we train a model we usually need to calculate some metrics like accuracy(top1-acc), loss etc. Now toolbox support the following:

  1. Accuracy: top-1 acc.
  2. TopKAccuracy: topK-acc.
  3. NumericalCost: This is a number metric collection which support mean, max, min calculate type.
  4. FeatureVerification.
    • This is widely used in margin based algorithm.
from torchtoolbox import metric

# define first
top1_acc = metric.Accuracy(name='Top1 Accuracy')
top5_acc = metric.TopKAccuracy(top=5, name='Top5 Accuracy')
loss_record = metric.NumericalCost(name='Loss')

# reset before using

for data, labels in val_data:
    data =, non_blocking=True)
    labels =, non_blocking=True)

    outputs = model(data)
    losses = Loss(outputs, labels)
    # update/record
    top1_acc.update(outputs, labels)
    top5_acc.update(outputs, labels)
    test_msg = 'Test Epoch {}: {}:{:.5}, {}:{:.5}, {}:{:.5}\n'.format(
    epoch,, top1_acc.get(),, top5_acc.get(),, loss_record.get())


Then you may get outputs like this

Test Epoch 101: Top1 Accuracy:0.7332, Top5 Accuracy:0.91514, Loss:1.0605

3. Model Initializer

Now ToolBox support XavierInitializer and KaimingInitializer.

from torchtoolbox.nn.init import KaimingInitializer

model = XXX
initializer = KaimingInitializer()

4. AdaptiveSequential

Make Pytorch nn.Sequential could handle multi input/output layer.

from torch import nn
from torchtoolbox.nn import AdaptiveSequential
import torch

class n_to_n(nn.Module):
    def __init__(self):
        self.conv1 = nn.Conv2d(3, 3, 1, 1, bias=False)
        self.conv2 = nn.Conv2d(3, 3, 1, 1, bias=False)

    def forward(self, x1, x2):
        y1 = self.conv1(x1)
        y2 = self.conv2(x2)
        return y1, y2

class n_to_one(nn.Module):
    def __init__(self):
        self.conv1 = nn.Conv2d(3, 3, 1, 1, bias=False)
        self.conv2 = nn.Conv2d(3, 3, 1, 1, bias=False)

    def forward(self, x1, x2):
        y1 = self.conv1(x1)
        y2 = self.conv2(x2)
        return y1 + y2

class one_to_n(nn.Module):
    def __init__(self):
        self.conv1 = nn.Conv2d(3, 3, 1, 1, bias=False)
        self.conv2 = nn.Conv2d(3, 3, 1, 1, bias=False)

    def forward(self, x):
        y1 = self.conv1(x)
        y2 = self.conv2(x)
        return y1, y2

seq = AdaptiveSequential(one_to_n(), n_to_n(), n_to_one()).cuda()
td = torch.rand(1, 3, 32, 32).cuda()

out = seq(td)

# output
# torch.Size([1, 3, 32, 32])

5. Make and Use LMDB dataset.

If you meet IO speed limit, you may think about LMDB format dataset. LMDB is a tiny database with some excellent properties.

Easy to generate a LMDB format dataset.

from import generate_lmdb_dataset, raw_reader
from torchvision.datasets import ImageFolder

dt = ImageFolder(..., loader=raw_reader)
save_dir = XXX 
dataset_name = YYY
generate_lmdb_dataset(dt, save_dir=save_dir, name=dataset_name)

Then if you use ImageFolder like dataset you can easily use ImageLMDB to load you dataset.

from import ImageLMDB

dt = ImageLMDB(db_path=save_dir, db_name=dataset_name, ...)

6. Non-Lable dataset

This dataset only return images.

More details please refers to codes

7. Activation Layer

A Activation Layer is provided to select a activation by string.

from torchtoolbox.nn import Activation

relu = Activation('relu', auto_optimize=True)

8. FeatureVerification Metric

A FeatureVerification Metric used to test feature based accuracy. More details refers to code.

Fashion work

1. LabelSmoothingLoss

from torchtoolbox.nn import LabelSmoothingLoss
# The num classes of your task should be defined.
classes = 10
# Loss
Loss = LabelSmoothingLoss(classes, smoothing=0.1)

for i, (data, labels) in enumerate(train_data):
    data =, non_blocking=True)
    labels =, non_blocking=True)

    outputs = model(data)
    # just use as usual.
    loss = Loss(outputs, labels)

2. CosineWarmupLr

Cosine lr scheduler with warm-up epochs.It's helpful to improve acc for classification models.

from torchtoolbox.optimizer import CosineWarmupLr

optimizer = optim.SGD(...)
# define scheduler
# `batches_pre_epoch` means how many batches(times update/step the model) within one epoch.
# `warmup_epochs` means increase lr how many epochs to `base_lr`.
# you can find more details in file.
lr_scheduler = CosineWarmupLr(optimizer, batches_pre_epoch, epochs,
                              base_lr=lr, warmup_epochs=warmup_epochs)
for i, (data, labels) in enumerate(train_data):
    # remember to step/update status here.

3. SwitchNorm2d/3d

from torchtoolbox.nn import SwitchNorm2d, SwitchNorm3d

Just use it like Batchnorm2d/3d. More details please refer to origin paper Differentiable Learning-to-Normalize via Switchable Normalization OpenSourse

4. Swish activation

from torchtoolbox.nn import Swish

Just use it like Relu. More details please refer to origin paper SEARCHING FOR ACTIVATION FUNCTIONS

5. Lookahead optimizer

A wrapper optimizer seems better than Adam. Lookahead Optimizer: k steps forward, 1 step back

from torchtoolbox.optimizer import Lookahead
from torch import optim

optimizer = optim.Adam(...)
optimizer = Lookahead(optimizer)

5. Mixup training

Mixup method to train a classification model. mixup: BEYOND EMPIRICAL RISK MINIMIZATION

from import mixup_data, mixup_criterion

# set beta distributed parm, 0.2 is recommend.
alpha = 0.2
for i, (data, labels) in enumerate(train_data):
    data =, non_blocking=True)
    labels =, non_blocking=True)

    data, labels_a, labels_b, lam = mixup_data(data, labels, alpha)
    outputs = model(data)
    loss = mixup_criterion(Loss, outputs, labels_a, labels_b, lam)


6. Cutout

A image transform method. Improved Regularization of Convolutional Neural Networks with Cutout

from torchvision import transforms
from torchtoolbox.transform import Cutout

_train_transform = transforms.Compose([
    transforms.ColorJitter(0.4, 0.4, 0.4),

7. No decay bias

If you train a model with big batch size, eg. 64k, you may need this, Highly Scalable Deep Learning Training System with Mixed-Precision: Training ImageNet in Four Minutes

from import no_decay_bias
from torch import optim

model = XXX
parameters = no_decay_bias(model)
optimizer = optim.SGD(parameters, ...)

8. Margin based classification loss

Now support:

  1. ArcLoss
  2. CosLoss
  3. L2Softmax
from torchtoolbox.nn.loss import ArcLoss, CosLoss, L2Softmax

You could use this like nn.CrossEntropyLoss

9. DCNv2

10. FocalLoss

11. SigmoidCrossEntropy

12. CircleLoss

13. EvoNrom

14. Activation Layer

  1. Swish
  2. HardSwish
  3. HardSigmoid Usage:
from torchtoolbox.nn import Swish, HardSwish, HardSigmoid

swish = Swish()
hswish = HardSwish()
hsigmoid = HardSigmoid()

15. Zero LastGamma Init

from torchtoolbox.nn.init import ZeroLastGamma

model == XXX
init = ZeroLastGamma(block_name='Bottleneck', bn_name='bn3')

16. SGC_GC

Gradient Centralization: A New Optimization Technique for Deep Neural Networks

from torchtoolbox.optimizer import SGD_GC

optimizer = SGD_GC(model.parameters())

17. Autoaugment

# for ImageNet
from torchtoolbox.transform import ImageNetPolicy, Compose, \
            RandomResizedCrop, RandomHorizontalFlip, ToTensor

transforms = Compose([RandomResizedCrop(224), 


Welcome pull requests and issues!!!

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