目录

准备数据集 

python安装yolov8 

配置yaml 

从0开始训练

从预训练模型开始训练

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准备数据集 

首先得准备好数据集，你的数据集至少包含images和labels，严格来说你的images应该包含训练集train、验证集val和测试集test，不过为了简单说明使用步骤，其中test可以不要，val和train可以用同一个，因此我这里只用了一个images

其中images装的是图片数据，labels装的是与图片一一对应同名的yolo格式txt，即类别号，经过归一化的中心x和y坐标以及宽和高

python安装yolov8 

然后我们开始准备yolov8，使用python的API的话就比较简单，首先安装一下yolov8

用pip的话安装的话

pip install ultralytics

使用pycharm安装的话

配置yaml 

安装完了之后，差不多就可以开始了，我们首先看看官方给的代码

from ultralytics import YOLO# Load a model
model = YOLO("yolov8n.yaml")  # build a new model from scratch
model = YOLO("yolov8n.pt")  # load a pretrained model (recommended for training)# Use the model
model.train(data="coco128.yaml", epochs=3)  # train the model
metrics = model.val()  # evaluate model performance on the validation set
results = model("https://ultralytics.com/images/bus.jpg")  # predict on an image
path = model.export(format="onnx")  # export the model to ONNX format

其中迷惑的是yolov8n.yaml、yolov8n.pt和coco128.yaml这几个文件，yolov8n.yaml是yolov8的配置，yolov8n.pt是预训练的模型，coco128.yaml是coco数据集的配置参数

因此如果我们想要训练自己的模型的话，需要修改一下配置文件，首先到GitHub上下载yolov8n.yaml和coco128.yaml下来，这两个文件的位置有可能会变，所以最好在仓库上直接搜索

大概长这样，你也可以自己创建，然后把内容复制进去

yolov8n.yaml

# Ultralytics YOLO 🚀, AGPL-3.0 license
# YOLOv8 object detection model with P3-P5 outputs. For Usage examples see https://docs.ultralytics.com/tasks/detect# Parameters
nc: 80  # number of classes
scales: # model compound scaling constants, i.e. 'model=yolov8n.yaml' will call yolov8.yaml with scale 'n'# [depth, width, max_channels]n: [0.33, 0.25, 1024]  # YOLOv8n summary: 225 layers,  3157200 parameters,  3157184 gradients,   8.9 GFLOPss: [0.33, 0.50, 1024]  # YOLOv8s summary: 225 layers, 11166560 parameters, 11166544 gradients,  28.8 GFLOPsm: [0.67, 0.75, 768]   # YOLOv8m summary: 295 layers, 25902640 parameters, 25902624 gradients,  79.3 GFLOPsl: [1.00, 1.00, 512]   # YOLOv8l summary: 365 layers, 43691520 parameters, 43691504 gradients, 165.7 GFLOPsx: [1.00, 1.25, 512]   # YOLOv8x summary: 365 layers, 68229648 parameters, 68229632 gradients, 258.5 GFLOPs# YOLOv8.0n backbone
backbone:# [from, repeats, module, args]- [-1, 1, Conv, [64, 3, 2]]  # 0-P1/2- [-1, 1, Conv, [128, 3, 2]]  # 1-P2/4- [-1, 3, C2f, [128, True]]- [-1, 1, Conv, [256, 3, 2]]  # 3-P3/8- [-1, 6, C2f, [256, True]]- [-1, 1, Conv, [512, 3, 2]]  # 5-P4/16- [-1, 6, C2f, [512, True]]- [-1, 1, Conv, [1024, 3, 2]]  # 7-P5/32- [-1, 3, C2f, [1024, True]]- [-1, 1, SPPF, [1024, 5]]  # 9# YOLOv8.0n head
head:- [-1, 1, nn.Upsample, [None, 2, 'nearest']]- [[-1, 6], 1, Concat, [1]]  # cat backbone P4- [-1, 3, C2f, [512]]  # 12- [-1, 1, nn.Upsample, [None, 2, 'nearest']]- [[-1, 4], 1, Concat, [1]]  # cat backbone P3- [-1, 3, C2f, [256]]  # 15 (P3/8-small)- [-1, 1, Conv, [256, 3, 2]]- [[-1, 12], 1, Concat, [1]]  # cat head P4- [-1, 3, C2f, [512]]  # 18 (P4/16-medium)- [-1, 1, Conv, [512, 3, 2]]- [[-1, 9], 1, Concat, [1]]  # cat head P5- [-1, 3, C2f, [1024]]  # 21 (P5/32-large)- [[15, 18, 21], 1, Detect, [nc]]  # Detect(P3, P4, P5)

coco128.yaml

# Ultralytics YOLO 🚀, AGPL-3.0 license
# COCO128 dataset https://www.kaggle.com/ultralytics/coco128 (first 128 images from COCO train2017) by Ultralytics
# Example usage: yolo train data=coco128.yaml
# parent
# ├── ultralytics
# └── datasets
#     └── coco128  ← downloads here (7 MB)# Train/val/test sets as 1) dir: path/to/imgs, 2) file: path/to/imgs.txt, or 3) list: [path/to/imgs1, path/to/imgs2, ..]
path: ../datasets/coco128  # dataset root dir
train: images/train2017  # train images (relative to 'path') 128 images
val: images/train2017  # val images (relative to 'path') 128 images
test:  # test images (optional)# Classes
names:0: person1: bicycle2: car3: motorcycle4: airplane5: bus6: train7: truck8: boat9: traffic light10: fire hydrant11: stop sign12: parking meter13: bench14: bird15: cat16: dog17: horse18: sheep19: cow20: elephant21: bear22: zebra23: giraffe24: backpack25: umbrella26: handbag27: tie28: suitcase29: frisbee30: skis31: snowboard32: sports ball33: kite34: baseball bat35: baseball glove36: skateboard37: surfboard38: tennis racket39: bottle40: wine glass41: cup42: fork43: knife44: spoon45: bowl46: banana47: apple48: sandwich49: orange50: broccoli51: carrot52: hot dog53: pizza54: donut55: cake56: chair57: couch58: potted plant59: bed60: dining table61: toilet62: tv63: laptop64: mouse65: remote66: keyboard67: cell phone68: microwave69: oven70: toaster71: sink72: refrigerator73: book74: clock75: vase76: scissors77: teddy bear78: hair drier79: toothbrush# Download script/URL (optional)
download: https://ultralytics.com/assets/coco128.zip

然后修改yolov8n.yaml，把nc的数值改成你的数据集的类别数，我这里的数据集只有乌骨鸡和狮头鹅两个

# Ultralytics YOLO 🚀, AGPL-3.0 license
# YOLOv8 object detection model with P3-P5 outputs. For Usage examples see https://docs.ultralytics.com/tasks/detect# Parameters
nc: 2  # number of classes
scales: # model compound scaling constants, i.e. 'model=yolov8n.yaml' will call yolov8.yaml with scale 'n'# [depth, width, max_channels]n: [0.33, 0.25, 1024]  # YOLOv8n summary: 225 layers,  3157200 parameters,  3157184 gradients,   8.9 GFLOPss: [0.33, 0.50, 1024]  # YOLOv8s summary: 225 layers, 11166560 parameters, 11166544 gradients,  28.8 GFLOPsm: [0.67, 0.75, 768]   # YOLOv8m summary: 295 layers, 25902640 parameters, 25902624 gradients,  79.3 GFLOPsl: [1.00, 1.00, 512]   # YOLOv8l summary: 365 layers, 43691520 parameters, 43691504 gradients, 165.7 GFLOPsx: [1.00, 1.25, 512]   # YOLOv8x summary: 365 layers, 68229648 parameters, 68229632 gradients, 258.5 GFLOPs# YOLOv8.0n backbone
backbone:# [from, repeats, module, args]- [-1, 1, Conv, [64, 3, 2]]  # 0-P1/2- [-1, 1, Conv, [128, 3, 2]]  # 1-P2/4- [-1, 3, C2f, [128, True]]- [-1, 1, Conv, [256, 3, 2]]  # 3-P3/8- [-1, 6, C2f, [256, True]]- [-1, 1, Conv, [512, 3, 2]]  # 5-P4/16- [-1, 6, C2f, [512, True]]- [-1, 1, Conv, [1024, 3, 2]]  # 7-P5/32- [-1, 3, C2f, [1024, True]]- [-1, 1, SPPF, [1024, 5]]  # 9# YOLOv8.0n head
head:- [-1, 1, nn.Upsample, [None, 2, 'nearest']]- [[-1, 6], 1, Concat, [1]]  # cat backbone P4- [-1, 3, C2f, [512]]  # 12- [-1, 1, nn.Upsample, [None, 2, 'nearest']]- [[-1, 4], 1, Concat, [1]]  # cat backbone P3- [-1, 3, C2f, [256]]  # 15 (P3/8-small)- [-1, 1, Conv, [256, 3, 2]]- [[-1, 12], 1, Concat, [1]]  # cat head P4- [-1, 3, C2f, [512]]  # 18 (P4/16-medium)- [-1, 1, Conv, [512, 3, 2]]- [[-1, 9], 1, Concat, [1]]  # cat head P5- [-1, 3, C2f, [1024]]  # 21 (P5/32-large)- [[15, 18, 21], 1, Detect, [nc]]  # Detect(P3, P4, P5)

然后修改coco128.yaml，我把文件名也改成了data.yaml，path改成images和labels的上一级目录地址，train改成训练集相对于path的地址，val也是改成验证集的相对于path的地址，我这里训练集和验证集用的是同一个嘿嘿嘿，然后把test注释掉，因为我没用测试集，还有就是names那里改成你的训练集的类别名，并把多余的类别删掉

# Ultralytics YOLO 🚀, AGPL-3.0 license
# COCO128 dataset https://www.kaggle.com/ultralytics/coco128 (first 128 images from COCO train2017) by Ultralytics
# Example usage: yolo train data=coco128.yaml
# parent
# ├── ultralytics
# └── datasets
#     └── coco128  ← downloads here (7 MB)# Train/val/test sets as 1) dir: path/to/imgs, 2) file: path/to/imgs.txt, or 3) list: [path/to/imgs1, path/to/imgs2, ..]
path: C:/Users/Yezi/Desktop/人工智能实训/HW2/data # dataset root dir
train: images # train images (relative to 'path') 128 images
val: images # val images (relative to 'path') 128 images
#test:  # test images (optional)# Classes
names:0: goose1: chicken

这样子就配置好了

然后开始训练

从0开始训练

下面是从0开始训练的过程

其实训练的代码就两行

model = YOLO("yolov8n.yaml")  # build a new model from scratch
model.train(data="data.yaml", epochs=5)  # train the model

不过从0开始训练的效果并不好，下面是我自己的测试代码，由于我电脑比较烂，GPU摆不上用场，所以只能用cpu训练

from ultralytics import YOLO
import matplotlib.pyplot as pltmodel = YOLO("yolov8n.yaml")  # build a new model from scratch
model.train(data="data.yaml", epochs=30, device='cpu')  # train the model
model.val(data="data.yaml")
results = model(r"C:\Users\Yezi\Desktop\人工智能实训\HW2\data\images\00909.jpg")  # predict on an image
plt.imshow(results[0].plot())
plt.show()
results = model(r"C:\Users\Yezi\Desktop\人工智能实训\HW2\data\images\100318.jpg")  # predict on an image
plt.imshow(results[0].plot())
plt.show()

从预训练模型开始训练

官方推荐用预训练好的模型开始训练

首先下载一个官方预训练好的模型

我这里下载的是yolov8n

然后使用预训练模型训练我的数据集

from ultralytics import YOLO
import matplotlib.pyplot as pltmodel=YOLO("yolov8n.pt")
model.train(data="data.yaml", epochs=30, device='cpu')  # train the model
model.val(data="data.yaml")
results = model(r"C:\Users\Yezi\Desktop\人工智能实训\HW2\data\images\00909.jpg")  # predict on an image
plt.imshow(results[0].plot())
plt.show()
results = model(r"C:\Users\Yezi\Desktop\人工智能实训\HW2\data\images\100318.jpg")  # predict on an image
plt.imshow(results[0].plot())
plt.show()

 乌骨鸡的效果是这样的

狮头鹅的效果是这样的