The meaning of some python sentences

Just for the record, please skip it.

from future import

Introduce the features of the new version into the current version

Portal

.as_matrix()

Convert other forms to ndarray

assert

Used to set breakpoints:

Portal

isinstance

Used to determine the character type:

Portal

enumerate([scale, crop, composed]):

Select one by one from the array, and loop

(Select scale, crop, composed in turn)

.__ name __

Should be the name of the class

**in the transformed_sample**

It seems to be a dictionary type using transformed_sample

(Or change transformed_sample into a dictionary type-(1,2,3)→('a':1,'b':2,'c':3))

Portal

Portal

image[top: top + new_h,left: left + new_w]

即image(xstart + xend, ystart: yend)

Is a slice selection of the image

The difference between ndarrays and Tensors

Tensors are GPU read, ndarrays are memory read;
Tensors are immutable, ndarrays are variable

torch.utils.data.DataLoader

batch_size=4

Network training uses 4 sets of pictures-labels, parallel training

shuffle=True

Refers to the shuffle of each iteration

num_workers=4

Open 4 threads to import data

Portal-Brief Book

plt.ioff ()

Turn off the blocking mode of plt.show() (you must close the picture before you can continue to run the program)

Portal

Keep

imshow(out, title=[class_names[x] for x in classes])

The role of torchvision.utils.make_grid

The effect is将若干幅图像拼成一幅图像

# 获取一批训练数据
inputs, classes = next(iter(dataloaders['train']))

# 批量制作网格
out = torchvision.utils.make_grid(inputs)

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Portal

copy.deepcopy

copy.deepcopy is independent after copying. How the original data changes will not affect the copy copied to the clipboard-deep copy

Portal