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dataset.py
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dataset.py
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#!/usr/bin/python
# encoding: utf-8
import random
import torch
from torch.utils.data import Dataset
from torch.utils.data import sampler
import torchvision.transforms as transforms
import lmdb
import six
import sys
from PIL import Image
import numpy as np
class lmdbDataset(Dataset):
def __init__(self, root=None, transform=None, target_transform=None):
self.env = lmdb.open(
root,
max_readers=1,
readonly=True,
lock=False,
readahead=False,
meminit=False)
if not self.env:
print('cannot creat lmdb from %s' % (root))
sys.exit(0)
with self.env.begin(write=False) as txn:
nSamples = int(txn.get('num-samples'.encode('utf-8')))
self.nSamples = nSamples
self.transform = transform
self.target_transform = target_transform
def __len__(self):
return self.nSamples
def __getitem__(self, index):
assert index <= len(self), 'index range error'
index += 1
with self.env.begin(write=False) as txn:
img_key = 'image-%09d' % index
imgbuf = txn.get(img_key.encode('utf-8'))
buf = six.BytesIO()
buf.write(imgbuf)
buf.seek(0)
try:
img = Image.open(buf).convert('L')
except IOError:
print('Corrupted image for %d' % index)
return self[index + 1]
if self.transform is not None:
img = self.transform(img)
label_key = 'label-%09d' % index
label = txn.get(label_key.encode('utf-8'))
if self.target_transform is not None:
label = self.target_transform(label)
return (img, label)
class resizeNormalize(object):
def __init__(self, size, interpolation=Image.BILINEAR):
self.size = size
self.interpolation = interpolation
self.toTensor = transforms.ToTensor()
def __call__(self, img):
img = img.resize(self.size, self.interpolation)
img = self.toTensor(img)
img.sub_(0.5).div_(0.5)
return img
class randomSequentialSampler(sampler.Sampler):
def __init__(self, data_source, batch_size):
self.num_samples = len(data_source)
self.batch_size = batch_size
def __iter__(self):
n_batch = len(self) // self.batch_size
tail = len(self) % self.batch_size
index = torch.LongTensor(len(self)).fill_(0)
for i in range(n_batch):
random_start = random.randint(0, len(self) - self.batch_size)
batch_index = random_start + torch.range(0, self.batch_size - 1)
index[i * self.batch_size:(i + 1) * self.batch_size] = batch_index
# deal with tail
if tail:
random_start = random.randint(0, len(self) - self.batch_size)
tail_index = random_start + torch.range(0, tail - 1)
index[(i + 1) * self.batch_size:] = tail_index
return iter(index)
def __len__(self):
return self.num_samples
class alignCollate(object):
def __init__(self, imgH=32, imgW=100, keep_ratio=False, min_ratio=1):
self.imgH = imgH
self.imgW = imgW
self.keep_ratio = keep_ratio
self.min_ratio = min_ratio
def __call__(self, batch):
images, labels = zip(*batch)
imgH = self.imgH
imgW = self.imgW
if self.keep_ratio:
ratios = []
for image in images:
w, h = image.size
ratios.append(w / float(h))
ratios.sort()
max_ratio = ratios[-1]
imgW = int(np.floor(max_ratio * imgH))
imgW = max(imgH * self.min_ratio, imgW) # assure imgH >= imgW
transform = resizeNormalize((imgW, imgH))
images = [transform(image) for image in images]
images = torch.cat([t.unsqueeze(0) for t in images], 0)
return images, labels