在深度学习中，第一步要做的往往就是处理数据集,尤其是学习百度飞桨PaddlePaddle的小伙伴，数据集经常要用Voc格式的，比如性能突出的ppyolo等模型。所以学会数据集转化的本领是十分必要的。这篇博客就带你一起进行Yolo与Voc格式的相互转化，附详细代码！

文章目录

• YOLO数据集介绍
• VOC数据集介绍
• Yolo转VOC
• VOC转Yolo
• from lxml import etree
• classes=["ball"]

YOLO数据集介绍

Yolo数据集主要是txt文件，一般包括train文件夹和val文件夹，每一个文件夹下有与图片同名的txt文件，基本结构如下：

|–image

• ||–train
• ||–val

|–label

• ||–train
• ||–val

txt的标签如下图所示：

第一列为目标类别，后面四个数字为方框左上角与右下角的坐标，可以看到都是小于1的数字，是因为对应的整张图片的比例，所以就算图像被拉伸放缩，这种txt格式的标签也可以找到相应的目标。

VOC数据集介绍

VOC格式数据集一般有着如下的目录结构：

VOC_ROOT     #根目录
    ├── JPEGImages         # 存放源图片
    │     ├── aaaa.jpg     
    │     ├── bbbb.jpg  
    │     └── cccc.jpg
    ├── Annotations        # 存放xml文件，与JPEGImages中的图片一一对应，解释图片的内容等等
    │     ├── aaaa.xml 
    │     ├── bbbb.xml 
    │     └── cccc.xml 
    └── ImageSets          
        └── Main
          ├── train.txt    # txt文件中每一行包含一个图片的名称
          └── val.txt
 

其中JPEGImages目录中存放的是源图片的数据，(当然图片并不一定要是.jpg格式的，只是规定文件夹名字叫JPEGImages)；Annotations目录中存放的是标注数据，VOC的标注是xml格式的，文件名与JPEGImages中的图片一一对应。
重点看下xml格式的标注格式：

<annotation>
    <folder>VOC_ROOT</folder>                           
    <filename>aaaa.jpg</filename>  # 文件名
    <size>                         # 图像尺寸（长宽以及通道数）                      
        <width>500</width>
        <height>332</height>
        <depth>3</depth>
    </size>
    <segmented>1</segmented>       # 是否用于分割（在图像物体识别中无所谓）
    <object>                       # 检测到的物体
        <name>horse</name>         # 物体类别
        <pose>Unspecified</pose>   # 拍摄角度，如果是自己的数据集就Unspecified
        <truncated>0</truncated>   # 是否被截断（0表示完整)
        <difficult>0</difficult>   # 目标是否难以识别（0表示容易识别）
        <bndbox>                   # bounding-box（包含左下角和右上角xy坐标）
            <xmin>100</xmin>
            <ymin>96</ymin>
            <xmax>355</xmax>
            <ymax>324</ymax>
        </bndbox>
    </object>
    <object>                       # 检测到多个物体
        <name>person</name>
        <pose>Unspecified</pose>
        <truncated>0</truncated>
        <difficult>0</difficult>
        <bndbox>
            <xmin>198</xmin>
            <ymin>58</ymin>
            <xmax>286</xmax>
            <ymax>197</ymax>
        </bndbox>
    </object>
</annotation>

Yolo转VOC

文件结构如下：

Yolo转VOC     #根目录
    ├── dataset         
    │     ├── Annotations     
    │     ├── image  
               └──image图像
    │     └── label
               └──txt文件
    ├── Yolo转VOC.py        # 代码文件

具体代码:

#!/usr/bin/env python
# -*- coding: UTF-8 -*-
"""
@Project ：Yolo与VOC转化 
@File    ：Yolo转Voc.py
@IDE     ：PyCharm 
@Author  ：咋
@Date    ：2023/3/6 16:45 
"""
from xml.dom.minidom import Document
import os
import cv2


# def makexml(txtPath, xmlPath, picPath):  # txt所在文件夹路径，xml文件保存路径，图片所在文件夹路径
def makexml(picPath, txtPath, xmlPath):  # txt所在文件夹路径，xml文件保存路径，图片所在文件夹路径
    """此函数用于将yolo格式txt标注文件转换为voc格式xml标注文件
    """
    dic = {'0': "blue",  # 创建字典用来对类型进行转换
           '1': "red",  # 此处的字典要与自己的classes.txt文件中的类对应，且顺序要一致
           }
    files = os.listdir(txtPath)
    for i, name in enumerate(files):
        xmlBuilder = Document()
        annotation = xmlBuilder.createElement("annotation")  # 创建annotation标签
        xmlBuilder.appendChild(annotation)
        txtFile = open(txtPath + name)
        txtList = txtFile.readlines()
        img = cv2.imread(picPath + name[0:-4] + ".jpg")
        Pheight, Pwidth, Pdepth = img.shape

        folder = xmlBuilder.createElement("folder")  # folder标签
        foldercontent = xmlBuilder.createTextNode("driving_annotation_dataset")
        folder.appendChild(foldercontent)
        annotation.appendChild(folder)  # folder标签结束

        filename = xmlBuilder.createElement("filename")  # filename标签
        filenamecontent = xmlBuilder.createTextNode(name[0:-4] + ".jpg")
        filename.appendChild(filenamecontent)
        annotation.appendChild(filename)  # filename标签结束

        size = xmlBuilder.createElement("size")  # size标签
        width = xmlBuilder.createElement("width")  # size子标签width
        widthcontent = xmlBuilder.createTextNode(str(Pwidth))
        width.appendChild(widthcontent)
        size.appendChild(width)  # size子标签width结束

        height = xmlBuilder.createElement("height")  # size子标签height
        heightcontent = xmlBuilder.createTextNode(str(Pheight))
        height.appendChild(heightcontent)
        size.appendChild(height)  # size子标签height结束

        depth = xmlBuilder.createElement("depth")  # size子标签depth
        depthcontent = xmlBuilder.createTextNode(str(Pdepth))
        depth.appendChild(depthcontent)
        size.appendChild(depth)  # size子标签depth结束

        annotation.appendChild(size)  # size标签结束

        for j in txtList:
            oneline = j.strip().split(" ")
            object = xmlBuilder.createElement("object")  # object 标签
            picname = xmlBuilder.createElement("name")  # name标签
            namecontent = xmlBuilder.createTextNode(dic[oneline[0]])
            picname.appendChild(namecontent)
            object.appendChild(picname)  # name标签结束

            pose = xmlBuilder.createElement("pose")  # pose标签
            posecontent = xmlBuilder.createTextNode("Unspecified")
            pose.appendChild(posecontent)
            object.appendChild(pose)  # pose标签结束

            truncated = xmlBuilder.createElement("truncated")  # truncated标签
            truncatedContent = xmlBuilder.createTextNode("0")
            truncated.appendChild(truncatedContent)
            object.appendChild(truncated)  # truncated标签结束

            difficult = xmlBuilder.createElement("difficult")  # difficult标签
            difficultcontent = xmlBuilder.createTextNode("0")
            difficult.appendChild(difficultcontent)
            object.appendChild(difficult)  # difficult标签结束

            bndbox = xmlBuilder.createElement("bndbox")  # bndbox标签
            xmin = xmlBuilder.createElement("xmin")  # xmin标签
            mathData = int(((float(oneline[1])) * Pwidth + 1) - (float(oneline[3])) * 0.5 * Pwidth)
            xminContent = xmlBuilder.createTextNode(str(mathData))
            xmin.appendChild(xminContent)
            bndbox.appendChild(xmin)  # xmin标签结束

            ymin = xmlBuilder.createElement("ymin")  # ymin标签
            mathData = int(((float(oneline[2])) * Pheight + 1) - (float(oneline[4])) * 0.5 * Pheight)
            yminContent = xmlBuilder.createTextNode(str(mathData))
            ymin.appendChild(yminContent)
            bndbox.appendChild(ymin)  # ymin标签结束

            xmax = xmlBuilder.createElement("xmax")  # xmax标签
            mathData = int(((float(oneline[1])) * Pwidth + 1) + (float(oneline[3])) * 0.5 * Pwidth)
            xmaxContent = xmlBuilder.createTextNode(str(mathData))
            xmax.appendChild(xmaxContent)
            bndbox.appendChild(xmax)  # xmax标签结束

            ymax = xmlBuilder.createElement("ymax")  # ymax标签
            mathData = int(((float(oneline[2])) * Pheight + 1) + (float(oneline[4])) * 0.5 * Pheight)
            ymaxContent = xmlBuilder.createTextNode(str(mathData))
            ymax.appendChild(ymaxContent)
            bndbox.appendChild(ymax)  # ymax标签结束

            object.appendChild(bndbox)  # bndbox标签结束

            annotation.appendChild(object)  # object标签结束

        f = open(xmlPath + name[0:-4] + ".xml", 'w')
        xmlBuilder.writexml(f, indent='\t', newl='\n', addindent='\t', encoding='utf-8')
        f.close()


if __name__ == "__main__":
    picPath = "dataset/JPEGImages/"  # 图片所在文件夹路径，后面的/一定要带上
    txtPath = "dataset/YOLOLables/"  # txt所在文件夹路径，后面的/一定要带上
    xmlPath = "dataset/annotations/"  # xml文件保存路径，后面的/一定要带上
    makexml(picPath, txtPath, xmlPath)

VOC转Yolo

相当于上述操作的逆运算，这里直接给出代码：
import xml.etree.ElementTree as ET
import pickle
import os
from os import listdir, getcwd
from os.path import join
import random
from shutil import copyfile

from lxml import etree

#自己的类别
classes = [“0”, “1”,‘2’,‘3’,‘person’]

classes=[“ball”]

TRAIN_RATIO = 80 #训练集比例

def clear_hidden_files(path):
dir_list = os.listdir(path)
for i in dir_list:
abspath = os.path.join(os.path.abspath(path), i)
if os.path.isfile(abspath):
if i.startswith(“._”):
os.remove(abspath)
else:
clear_hidden_files(abspath)

#数据转换
def convert(size, box):
dw = 1. / size[0]
dh = 1. / size[1]
x = (box[0] + box[1]) / 2.0
y = (box[2] + box[3]) / 2.0
w = box[1] - box[0]
h = box[3] - box[2]
x = x * dw
w = w * dw
y = y * dh
h = h * dh
return (x, y, w, h)

#编写格式
def convert_annotation(image_id):
in_file = open(‘./dataset/annotations/%s.xml’ % image_id)
out_file = open(‘./dataset/YOLOLabels/%s.txt’ % image_id, ‘w’)
tree = ET.parse(in_file)
root = tree.getroot()
size = root.find(‘size’)
w = int(size.find(‘width’).text)
h = int(size.find(‘height’).text)

for obj in root.iter('object'):
    difficult = obj.find('difficult').text
    cls = obj.find('name').text
    if cls not in classes or int(difficult) == 1:
        continue
    cls_id = classes.index(cls)
    xmlbox = obj.find('bndbox')
    b = (float(xmlbox.find('xmin').text), float(xmlbox.find('xmax').text), float(xmlbox.find('ymin').text),
         float(xmlbox.find('ymax').text))
    bb = convert((w, h), b)
    out_file.write(str(cls_id) + " " + " ".join([str(a) for a in bb]) + '\n')
in_file.close()
out_file.close()

#创建上述目录结构
wd = os.getcwd()

work_sapce_dir = os.path.join(wd, “dataset/”)
if not os.path.isdir(work_sapce_dir):
os.mkdir(work_sapce_dir)
annotation_dir = os.path.join(work_sapce_dir, “annotations/”)
if not os.path.isdir(annotation_dir):
os.mkdir(annotation_dir)
clear_hidden_files(annotation_dir)
image_dir = os.path.join(work_sapce_dir, “JPEGImages/”)
if not os.path.isdir(image_dir):
os.mkdir(image_dir)
clear_hidden_files(image_dir)
yolo_labels_dir = os.path.join(work_sapce_dir, “YOLOLabels/”)
if not os.path.isdir(yolo_labels_dir):
os.mkdir(yolo_labels_dir)
clear_hidden_files(yolo_labels_dir)
yolov5_images_dir = os.path.join(work_sapce_dir, “images/”)
if not os.path.isdir(yolov5_images_dir):
os.mkdir(yolov5_images_dir)
clear_hidden_files(yolov5_images_dir)
yolov5_labels_dir = os.path.join(work_sapce_dir, “labels/”)
if not os.path.isdir(yolov5_labels_dir):
os.mkdir(yolov5_labels_dir)
clear_hidden_files(yolov5_labels_dir)
yolov5_images_train_dir = os.path.join(yolov5_images_dir, “train/”)
if not os.path.isdir(yolov5_images_train_dir):
os.mkdir(yolov5_images_train_dir)
clear_hidden_files(yolov5_images_train_dir)
yolov5_images_test_dir = os.path.join(yolov5_images_dir, “val/”)
if not os.path.isdir(yolov5_images_test_dir):
os.mkdir(yolov5_images_test_dir)
clear_hidden_files(yolov5_images_test_dir)
yolov5_labels_train_dir = os.path.join(yolov5_labels_dir, “train/”)
if not os.path.isdir(yolov5_labels_train_dir):
os.mkdir(yolov5_labels_train_dir)
clear_hidden_files(yolov5_labels_train_dir)
yolov5_labels_test_dir = os.path.join(yolov5_labels_dir, “val/”)
if not os.path.isdir(yolov5_labels_test_dir):
os.mkdir(yolov5_labels_test_dir)
clear_hidden_files(yolov5_labels_test_dir)

#创建两个记录照片名字的文件
train_file = open(os.path.join(yolov5_images_dir, “yolov5_train.txt”), ‘w’)
test_file = open(os.path.join(yolov5_images_dir, “yolov5_val.txt”), ‘w’)
train_file.close()
test_file.close()
train_file = open(os.path.join(yolov5_images_dir, “yolov5_train.txt”), ‘a’)
test_file = open(os.path.join(yolov5_images_dir, “yolov5_val.txt”), ‘a’)

#随机划分
list_imgs = os.listdir(image_dir) # list image files
prob = random.randint(1, 100)
print(“Probability: %d” % prob)
for i in range(0, len(list_imgs)):
path = os.path.join(image_dir, list_imgs[i])
if os.path.isfile(path):
image_path = image_dir + list_imgs[i]
voc_path = list_imgs[i]
(nameWithoutExtention, extention) = os.path.splitext(os.path.basename(image_path))
(voc_nameWithoutExtention, voc_extention) = os.path.splitext(os.path.basename(voc_path))
annotation_name = nameWithoutExtention + ‘.xml’
annotation_path = os.path.join(annotation_dir, annotation_name)
label_name = nameWithoutExtention + ‘.txt’
label_path = os.path.join(yolo_labels_dir, label_name)
prob = random.randint(1, 100)
print(“Probability: %d” % prob)
if (prob < TRAIN_RATIO): # train dataset
if os.path.exists(annotation_path):
train_file.write(image_path + ‘\n’)
convert_annotation(nameWithoutExtention) # convert label
copyfile(image_path, yolov5_images_train_dir + voc_path)
copyfile(label_path, yolov5_labels_train_dir + label_name)
else: # test dataset
if os.path.exists(annotation_path):
test_file.write(image_path + ‘\n’)
convert_annotation(nameWithoutExtention) # convert label
copyfile(image_path, yolov5_images_test_dir + voc_path)
copyfile(label_path, yolov5_labels_test_dir + label_name)
train_file.close()
test_file.close()