In [1]:

    

import torch 
import torchvision
import torch.nn as nn
import torch.utils.data as data
import numpy as np
import torchvision.transforms as transforms
import torchvision.datasets as dsets
from torch.autograd import Variable


    

In [2]:

    

# random normal
x = torch.randn(5, 3)
print (x)


    

    




 0.1125 -0.1725 -1.4885
-1.3278 -2.5332  0.3914
-0.1966 -1.2831 -0.5606
 0.3959  0.6616  1.6949
 1.3265 -0.0778  0.7417
[torch.FloatTensor of size 5x3]

In [3]:

    

# build a layer
linear = nn.Linear(3, 2)


    

In [5]:

    

# Sess weight and bias
print (linear.weight)
print (linear.bias)
print(linear)


    

    




Parameter containing:
 0.4115  0.2772  0.3197
-0.0429  0.4308  0.0986
[torch.FloatTensor of size 2x3]

Parameter containing:
-0.3531
 0.2728
[torch.FloatTensor of size 2]

Linear (3 -> 2)

In [6]:

    

# forward propagate
y = linear(Variable(x))
print (y)


    

    




Variable containing:
-0.8305  0.0469
-1.4765 -0.7231
-0.9689 -0.3269
 0.5350  0.7079
 0.4083  0.2554
[torch.FloatTensor of size 5x2]

In [7]:

    

# convert numpy array to tensor
a = np.array([[1,2], [3,4]])
b = torch.from_numpy(a)
print (b)


    

    




 1  2
 3  4
[torch.LongTensor of size 2x2]

In [18]:

    

# Image Preprocessing 
transform = transforms.Compose([
    transforms.Scale(40),
    transforms.RandomHorizontalFlip(),
    transforms.RandomCrop(32),
    transforms.ToTensor()])


    

In [14]:

    

# download and loading dataset f
train_dataset = dsets.CIFAR10(root='./data/',
                               train=True, 
                               transform=transform,
                               download=True)

image, label = train_dataset[0]
print (image.size())
print (label)


    

    




Files already downloaded and verified
torch.Size([3, 32, 32])
6

In [16]:

    

# data loader provides queue and thread in a very simple way
train_loader = data.DataLoader(dataset=train_dataset,
                               batch_size=100, 
                               shuffle=True,
                               num_workers=2)


    

In [ ]:

    

# iteration start then queue and thread start
data_iter = iter(train_loader)

# mini-batch images and labels
images, labels = data_iter.next()

for images, labels in train_loader:
    # your training code will be written here
    pass


    

In [25]:

    

class CustomDataset(data.Dataset):
    def __init__(self):
        pass
    def __getitem__(self, index):
        # You should build this function to return one data for given index
        pass
    def __len__(self):
        pass


    

In [26]:

    

custom_dataset = CustomDataset()
data.DataLoader(dataset=custom_dataset,
                batch_size=100, 
                shuffle=True,
                num_workers=2)


    

    




---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-26-a76c7b5c92c3> in <module>()
      3                 batch_size=100,
      4                 shuffle=True,
----> 5                 num_workers=2)

/home/yunjey/anaconda3/lib/python3.5/site-packages/torch/utils/data/dataloader.py in __init__(self, dataset, batch_size, shuffle, sampler, num_workers, collate_fn, pin_memory)
    250             self.sampler = sampler
    251         elif shuffle:
--> 252             self.sampler = RandomSampler(dataset)
    253         elif not shuffle:
    254             self.sampler = SequentialSampler(dataset)

/home/yunjey/anaconda3/lib/python3.5/site-packages/torch/utils/data/sampler.py in __init__(self, data_source)
     45 
     46     def __init__(self, data_source):
---> 47         self.num_samples = len(data_source)
     48 
     49     def __iter__(self):

TypeError: 'NoneType' object cannot be interpreted as an integer

In [17]:

    

# Download and load pretrained model
resnet = torchvision.models.resnet18(pretrained=True)


    

    




Downloading: "https://s3.amazonaws.com/pytorch/models/resnet18-5c106cde.pth" to /home/yunjey/.torch/models/resnet18-5c106cde.pth
100%|██████████| 46827520/46827520 [07:48<00:00, 99907.53it/s] 

In [ ]:

    

# delete top layer for finetuning
sub_model = nn.Sequentialtial(*list(resnet.children()[:-1]))

# for test
images = Variable(torch.randn(10, 3, 256, 256))
print (resnet(images).size())
print (sub_model(images).size())


    

In [ ]:

    

# Save and load the trained model
torch.save(sub_model, 'model.pkl')

model = torch.load('model.pkl')