Dataset自定义VOC2012数据集代码
from torch.utils.data import Dataset
import os
import torch
import json
from PIL import Image
from lxml import etree
class VOC2012DataSet(Dataset):
"""读取解析PASCAL VOC2012数据集"""
def __init__(self, voc_root, transforms, txt_name: str = "train.txt"):
self.root = os.path.join(voc_root, "VOCdevkit", "VOC2012")
self.img_root = os.path.join(self.root, "JPEGImages")
self.annotations_root = os.path.join(self.root, "Annotations")
# read train.txt or val.txt file
txt_path = os.path.join(self.root, "ImageSets", "Main", txt_name)
assert os.path.exists(txt_path), "not found {} file.".format(txt_name)
with open(txt_path) as read:
self.xml_list = [os.path.join(self.annotations_root, line.strip() + ".xml")
for line in read.readlines()]
# check file
assert len(self.xml_list) > 0, "in '{}' file does not find any information.".format(txt_path)
for xml_path in self.xml_list:
assert os.path.exists(xml_path), "not found '{}' file.".format(xml_path)
# read class_indict
json_file = './pascal_voc_classes.json'
assert os.path.exists(json_file), "{} file not exist.".format(json_file)
json_file = open(json_file, 'r')
self.class_dict = json.load(json_file)
self.transforms = transforms
def __len__(self):
return len(self.xml_list)
def __getitem__(self, idx):
# read xml
xml_path = self.xml_list[idx]
with open(xml_path) as fid:
xml_str = fid.read()
xml = etree.fromstring(xml_str.encode('utf-8'))
data = self.parse_xml_to_dict(xml)["annotation"]
img_path = os.path.join(self.img_root, data["filename"])
image = Image.open(img_path)
if image.format != "JPEG":
raise ValueError("Image '{}' format not JPEG".format(img_path))
boxes = []
labels = []
iscrowd = []
assert "object" in data, "{} lack of object information.".format(xml_path)
for obj in data["object"]:
xmin = float(obj["bndbox"]["xmin"])
xmax = float(obj["bndbox"]["xmax"])
ymin = float(obj["bndbox"]["ymin"])
ymax = float(obj["bndbox"]["ymax"])
# 进一步检查数据，有的标注信息中可能有w或h为0的情况，这样的数据会导致计算回归loss为nan
if xmax <= xmin or ymax <= ymin:
print("Warning: in '{}' xml, there are some bbox w/h <=0".format(xml_path))
continue
boxes.append([xmin, ymin, xmax, ymax])
labels.append(self.class_dict[obj["name"]])
if "difficult" in obj:
iscrowd.append(int(obj["difficult"]))
else:
iscrowd.append(0)
# convert everything into a torch.Tensor
boxes = torch.as_tensor(boxes, dtype=torch.float32)
labels = torch.as_tensor(labels, dtype=torch.int64)
iscrowd = torch.as_tensor(iscrowd, dtype=torch.int64)
image_id = torch.tensor([idx])
area = (boxes[:, 3] - boxes[:, 1]) * (boxes[:, 2] - boxes[:, 0])
target = {}
target["boxes"] = boxes
target["labels"] = labels
target["image_id"] = image_id
target["area"] = area
target["iscrowd"] = iscrowd
if self.transforms is not None:
image, target = self.transforms(image, target)
return image, target
def get_height_and_width(self, idx):
# read xml
xml_path = self.xml_list[idx]
with open(xml_path) as fid:
xml_str = fid.read()
xml = etree.fromstring(xml_str)
data = self.parse_xml_to_dict(xml)["annotation"]
data_height = int(data["size"]["height"])
data_width = int(data["size"]["width"])
return data_height, data_width
def parse_xml_to_dict(self, xml):
"""
将xml文件解析成字典形式，参考tensorflow的recursive_parse_xml_to_dict
Args:
xml: xml tree obtained by parsing XML file contents using lxml.etree
Returns:
Python dictionary holding XML contents.
"""
if len(xml) == 0: # 遍历到底层，直接返回tag对应的信息
return {xml.tag: xml.text}
result = {}
for child in xml:
child_result = self.parse_xml_to_dict(child) # 递归遍历标签信息
if child.tag != 'object':
result[child.tag] = child_result[child.tag]
else:
if child.tag not in result: # 因为object可能有多个，所以需要放入列表里
result[child.tag] = []
result[child.tag].append(child_result[child.tag])
return {xml.tag: result}
def coco_index(self, idx):
"""
该方法是专门为pycocotools统计标签信息准备，不对图像和标签作任何处理
由于不用去读取图片，可大幅缩减统计时间
Args:
idx: 输入需要获取图像的索引
"""
# read xml
xml_path = self.xml_list[idx]
with open(xml_path) as fid:
xml_str = fid.read()
xml = etree.fromstring(xml_str)
data = self.parse_xml_to_dict(xml)["annotation"]
data_height = int(data["size"]["height"])
data_width = int(data["size"]["width"])
# img_path = os.path.join(self.img_root, data["filename"])
# image = Image.open(img_path)
# if image.format != "JPEG":
# raise ValueError("Image format not JPEG")
boxes = []
labels = []
iscrowd = []
for obj in data["object"]:
xmin = float(obj["bndbox"]["xmin"])
xmax = float(obj["bndbox"]["xmax"])
ymin = float(obj["bndbox"]["ymin"])
ymax = float(obj["bndbox"]["ymax"])
boxes.append([xmin, ymin, xmax, ymax])
labels.append(self.class_dict[obj["name"]])
iscrowd.append(int(obj["difficult"]))
# convert everything into a torch.Tensor
boxes = torch.as_tensor(boxes, dtype=torch.float32)
labels = torch.as_tensor(labels, dtype=torch.int64)
iscrowd = torch.as_tensor(iscrowd, dtype=torch.int64)
image_id = torch.tensor([idx])
area = (boxes[:, 3] - boxes[:, 1]) * (boxes[:, 2] - boxes[:, 0])
target = {}
target["boxes"] = boxes
target["labels"] = labels
target["image_id"] = image_id
target["area"] = area
target["iscrowd"] = iscrowd
return (data_height, data_width), target
@staticmethod
def collate_fn(batch):
return tuple(zip(*batch))
import transforms
from draw_box_utils import draw_box
from PIL import Image
import json
import matplotlib.pyplot as plt
import torchvision.transforms as ts
import random
# read class_indict
category_index = {}
try:
json_file = open('pascal_voc_classes.json', 'r')
class_dict = json.load(json_file)
category_index = {v: k for k, v in class_dict.items()}
except Exception as e:
print(e)
exit(-1)
data_transform = {
"train": transforms.Compose([transforms.ToTensor(),
transforms.RandomHorizontalFlip(0.5)]),
"val": transforms.Compose([transforms.ToTensor()])
}
voc_path = 'D:\\Pytorch\\zsffuture-yolov5-master'
# load train data set
train_data_set = VOC2012DataSet(voc_path, data_transform["train"], "train.txt")
print(len(train_data_set))
for index in random.sample(range(0, len(train_data_set)), k=5):
img, target = train_data_set[index]
img = ts.ToPILImage()(img)
draw_box(img,
target["boxes"].numpy(),
target["labels"].numpy(),
[1 for i in range(len(target["labels"].numpy()))],
category_index,
thresh=0.5,
line_thickness=5)
plt.imshow(img)
plt.show()
