本文实例讲述了pytorch制作自己的LMDB数据操作。分享给大家供大家参考，具体如下：

前言

记录下pytorch里如何使用lmdb的code，自用

制作部分的Code

code就是ASTER里数据制作部分的代码改了点，aster_train.txt里面就算图片的完整路径每行一个，图片同目录下有同名的txt，里面记着jpg的标签

import osimport lmdb # install lmdb by "pip install lmdb"import cv2import numpy as npfrom tqdm import tqdmimport sixfrom PIL import Imageimport scipy.io as siofrom tqdm import tqdmimport redef checkImageIsValid(imageBin): if imageBin is None: return False imageBuf = np.fromstring(imageBin, dtype=np.uint8) img = cv2.imdecode(imageBuf, cv2.IMREAD_GRAYSCALE) imgH, imgW = img.shape[0], img.shape[1] if imgH * imgW == 0: return False return Truedef writeCache(env, cache): with env.begin(write=True) as txn: for k, v in cache.items(): txn.put(k.encode(), v)def _is_difficult(word): assert isinstance(word, str) return not re.match('^[\w]+$', word)def createDataset(outputPath, imagePathList, labelList, lexiconList=None, checkValid=True): """ Create LMDB dataset for CRNN training. ARGS: outputPath : LMDB output path imagePathList : list of image path labelList : list of corresponding groundtruth texts lexiconList : (optional) list of lexicon lists checkValid : if true, check the validity of every image """ assert(len(imagePathList) == len(labelList)) nSamples = len(imagePathList) env = lmdb.open(outputPath, map_size=1099511627776)#最大空间1048576GB cache = {} cnt = 1 for i in range(nSamples): imagePath = imagePathList[i] label = labelList[i] if len(label) == 0: continue if not os.path.exists(imagePath): print('%s does not exist' % imagePath) continue with open(imagePath, 'rb') as f: imageBin = f.read() if checkValid: if not checkImageIsValid(imageBin): print('%s is not a valid image' % imagePath) continue #数据库中都是二进制数据 imageKey = 'image-%09d' % cnt#9位数不足填零 labelKey = 'label-%09d' % cnt cache[imageKey] = imageBin cache[labelKey] = label.encode() if lexiconList: lexiconKey = 'lexicon-%09d' % cnt cache[lexiconKey] = ' '.join(lexiconList[i]) if cnt % 1000 == 0: writeCache(env, cache) cache = {} print('Written %d / %d' % (cnt, nSamples)) cnt += 1 nSamples = cnt-1 cache['num-samples'] = str(nSamples).encode() writeCache(env, cache) print('Created dataset with %d samples' % nSamples)def get_sample_list(txt_path:str): with open(txt_path,'r') as fr: jpg_list=[x.strip() for x in fr.readlines() if os.path.exists(x.replace('.jpg','.txt').strip())] txt_content_list=[] for jpg in jpg_list: label_path=jpg.replace('.jpg','.txt') with open(label_path,'r') as fr: try: str_tmp=fr.readline() except UnicodeDecodeError as e: print(label_path) raise(e) txt_content_list.append(str_tmp.strip()) return jpg_list,txt_content_listif __name__ == "__main__": txt_path='/home/gpu-server/disk/disk1/NumberData/8NumberSample/aster_train.txt' lmdb_output_path = '/home/gpu-server/project/aster/dataset/train' imagePathList,labelList=get_sample_list(txt_path) createDataset(lmdb_output_path, imagePathList, labelList)

读取部分

这里用的pytorch的dataloader，简单记录一下,人比较懒，代码就直接抄过来，不整理拆分了，重点看__getitem__

from __future__ import absolute_import# import sys# sys.path.append('./')import os# import moxing as moximport picklefrom tqdm import tqdmfrom PIL import Image, ImageFileimport numpy as npimport randomimport cv2import lmdbimport sysimport siximport torchfrom torch.utils import datafrom torch.utils.data import samplerfrom torchvision import transformsfrom lib.utils.labelmaps import get_vocabulary, labels2strsfrom lib.utils import to_numpyImageFile.LOAD_TRUNCATED_IMAGES = Truefrom config import get_argsglobal_args = get_args(sys.argv[1:])if global_args.run_on_remote: import moxing as mox #moxing是一个分布式的框架 跳过class LmdbDataset(data.Dataset): def __init__(self, root, voc_type, max_len, num_samples, transform=None): super(LmdbDataset, self).__init__() if global_args.run_on_remote: dataset_name = os.path.basename(root) data_cache_url = "/cache/%s" % dataset_name if not os.path.exists(data_cache_url): os.makedirs(data_cache_url) if mox.file.exists(root): mox.file.copy_parallel(root, data_cache_url) else: raise ValueError("%s not exists!" % root) self.env = lmdb.open(data_cache_url, max_readers=32, readonly=True) else: self.env = lmdb.open(root, max_readers=32, readonly=True) assert self.env is not None, "cannot create lmdb from %s" % root self.txn = self.env.begin() self.voc_type = voc_type self.transform = transform self.max_len = max_len self.nSamples = int(self.txn.get(b"num-samples")) self.nSamples = min(self.nSamples, num_samples) assert voc_type in ['LOWERCASE', 'ALLCASES', 'ALLCASES_SYMBOLS','DIGITS'] self.EOS = 'EOS' self.PADDING = 'PADDING' self.UNKNOWN = 'UNKNOWN' self.voc = get_vocabulary(voc_type, EOS=self.EOS, PADDING=self.PADDING, UNKNOWN=self.UNKNOWN) self.char2id = dict(zip(self.voc, range(len(self.voc)))) self.id2char = dict(zip(range(len(self.voc)), self.voc)) self.rec_num_classes = len(self.voc) self.lowercase = (voc_type == 'LOWERCASE') def __len__(self): return self.nSamples def __getitem__(self, index): assert index <= len(self), 'index range error' index += 1 img_key = b'image-%09d' % index imgbuf = self.txn.get(img_key) #由于Image.open需要一个类文件对象 所以这里需要把二进制转为一个类文件对象 buf = six.BytesIO() buf.write(imgbuf) buf.seek(0) try: img = Image.open(buf).convert('RGB') # img = Image.open(buf).convert('L') # img = img.convert('RGB') except IOError: print('Corrupted image for %d' % index) return self[index + 1] # reconition labels label_key = b'label-%09d' % index word = self.txn.get(label_key).decode() if self.lowercase: word = word.lower() ## fill with the padding token label = np.full((self.max_len,), self.char2id[self.PADDING], dtype=np.int) label_list = [] for char in word: if char in self.char2id: label_list.append(self.char2id[char]) else: ## add the unknown token print('{0} is out of vocabulary.'.format(char)) label_list.append(self.char2id[self.UNKNOWN]) ## add a stop token label_list = label_list + [self.char2id[self.EOS]] assert len(label_list) <= self.max_len label[:len(label_list)] = np.array(label_list) if len(label) <= 0: return self[index + 1] # label length label_len = len(label_list) if self.transform is not None: img = self.transform(img) return img, label, label_len

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