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Python

The simplest way of simply using YOLOv8 directly in a Python environment.

Train

from ultralytics import YOLO

model = YOLO("yolov8n.pt") # pass any model type
model.train(epochs=5)

from ultralytics import YOLO

model = YOLO("yolov8n.yaml")
model.train(data="coco128.yaml", epochs=5)

# TODO: Resume feature is under development and should be released soon.
model = YOLO("last.pt")
model.train(resume=True)

Val

  from ultralytics import YOLO

  model = YOLO("yolov8n.yaml")
  model.train(data="coco128.yaml", epochs=5)
  model.val()  # It'll automatically evaluate the data you trained.

  from ultralytics import YOLO

  model = YOLO("model.pt")
  # It'll use the data yaml file in model.pt if you don't set data.
  model.val()
  # or you can set the data you want to val
  model.val(data="coco128.yaml")

Predict

from ultralytics import YOLO
from PIL import Image
import cv2

model = YOLO("model.pt")
# accepts all formats - image/dir/Path/URL/video/PIL/ndarray. 0 for webcam
results = model.predict(source="0")
results = model.predict(source="folder", show=True) # Display preds. Accepts all YOLO predict arguments

# from PIL
im1 = Image.open("bus.jpg")
results = model.predict(source=im1, save=True)  # save plotted images

# from ndarray
im2 = cv2.imread("bus.jpg")
results = model.predict(source=im2, save=True, save_txt=True)  # save predictions as labels

# from list of PIL/ndarray
results = model.predict(source=[im1, im2])

# results would be a list of Results object including all the predictions by default
# but be careful as it could occupy a lot memory when there're many images, 
# especially the task is segmentation.
# 1. return as a list
results = model.predict(source="folder")

# results would be a generator which is more friendly to memory by setting stream=True
# 2. return as a generator
results = model.predict(source=0, stream=True)

for result in results:
    # detection
    result.boxes.xyxy   # box with xyxy format, (N, 4)
    result.boxes.xywh   # box with xywh format, (N, 4)
    result.boxes.xyxyn  # box with xyxy format but normalized, (N, 4)
    result.boxes.xywhn  # box with xywh format but normalized, (N, 4)
    result.boxes.conf   # confidence score, (N, 1)
    result.boxes.cls    # cls, (N, 1)

    # segmentation
    result.masks.masks     # masks, (N, H, W)
    result.masks.segments  # bounding coordinates of masks, List[segment] * N

    # classification
    result.probs     # cls prob, (num_class, )

# Each result is composed of torch.Tensor by default, 
# in which you can easily use following functionality:
result = result.cuda()
result = result.cpu()
result = result.to("cpu")
result = result.numpy()

Export and Deployment

from ultralytics import YOLO

model = YOLO("model.pt")
model.fuse()  
model.info(verbose=True)  # Print model information
model.export(format=)  # TODO:

More functionality coming soon

To know more about using YOLO models, refer Model class Reference

Model reference

Using Trainers

YOLO model class is a high-level wrapper on the Trainer classes. Each YOLO task has its own trainer that inherits from BaseTrainer.

Detection Trainer Example

from ultralytics.yolo import v8 import DetectionTrainer, DetectionValidator, DetectionPredictor

# trainer
trainer = DetectionTrainer(overrides={})
trainer.train()
trained_model = trainer.best

# Validator
val = DetectionValidator(args=...)
val(model=trained_model)

# predictor
pred = DetectionPredictor(overrides={})
pred(source=SOURCE, model=trained_model)

# resume from last weight
overrides["resume"] = trainer.last
trainer = detect.DetectionTrainer(overrides=overrides)

You can easily customize Trainers to support custom tasks or explore R&D ideas. Learn more about Customizing Trainers, Validators and Predictors to suit your project needs in the Customization Section.

Customization tutorials