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# Ultralytics YOLO 🚀, GPL-3.0 license
import contextlib
from copy import deepcopy
from pathlib import Path
import thop
import torch
import torch.nn as nn
from ultralytics.nn.modules import * # noqa: F403
from ultralytics.yolo.utils import DEFAULT_CFG_DICT, DEFAULT_CFG_KEYS, LOGGER, RANK, colorstr, emojis, yaml_load
from ultralytics.yolo.utils.checks import check_requirements, check_yaml
from ultralytics.yolo.utils.torch_utils import (fuse_conv_and_bn, fuse_deconv_and_bn, initialize_weights,
intersect_dicts, make_divisible, model_info, scale_img, time_sync)
class BaseModel(nn.Module):
"""
The BaseModel class serves as a base class for all the models in the Ultralytics YOLO family.
"""
def forward(self, x, profile=False, visualize=False):
"""
Forward pass of the model on a single scale.
Wrapper for `_forward_once` method.
Args:
x (torch.Tensor): The input image tensor
profile (bool): Whether to profile the model, defaults to False
visualize (bool): Whether to return the intermediate feature maps, defaults to False
Returns:
(torch.Tensor): The output of the network.
"""
return self._forward_once(x, profile, visualize)
def _forward_once(self, x, profile=False, visualize=False):
"""
Perform a forward pass through the network.
Args:
x (torch.Tensor): The input tensor to the model
profile (bool): Print the computation time of each layer if True, defaults to False.
visualize (bool): Save the feature maps of the model if True, defaults to False
Returns:
(torch.Tensor): The last output of the model.
"""
y, dt = [], [] # outputs
for m in self.model:
if m.f != -1: # if not from previous layer
x = y[m.f] if isinstance(m.f, int) else [x if j == -1 else y[j] for j in m.f] # from earlier layers
if profile:
self._profile_one_layer(m, x, dt)
x = m(x) # run
y.append(x if m.i in self.save else None) # save output
if visualize:
LOGGER.info('visualize feature not yet supported')
# TODO: feature_visualization(x, m.type, m.i, save_dir=visualize)
return x
def _profile_one_layer(self, m, x, dt):
"""
Profile the computation time and FLOPs of a single layer of the model on a given input.
Appends the results to the provided list.
Args:
m (nn.Module): The layer to be profiled.
x (torch.Tensor): The input data to the layer.
dt (list): A list to store the computation time of the layer.
Returns:
None
"""
c = m == self.model[-1] # is final layer, copy input as inplace fix
o = thop.profile(m, inputs=[x.clone() if c else x], verbose=False)[0] / 1E9 * 2 if thop else 0 # FLOPs
t = time_sync()
for _ in range(10):
m(x.clone() if c else x)
dt.append((time_sync() - t) * 100)
if m == self.model[0]:
LOGGER.info(f"{'time (ms)':>10s} {'GFLOPs':>10s} {'params':>10s} module")
LOGGER.info(f'{dt[-1]:10.2f} {o:10.2f} {m.np:10.0f} {m.type}')
if c:
LOGGER.info(f"{sum(dt):10.2f} {'-':>10s} {'-':>10s} Total")
def fuse(self, verbose=True):
"""
Fuse the `Conv2d()` and `BatchNorm2d()` layers of the model into a single layer, in order to improve the
computation efficiency.
Returns:
(nn.Module): The fused model is returned.
"""
if not self.is_fused():
for m in self.model.modules():
if isinstance(m, (Conv, DWConv)) and hasattr(m, 'bn'):
m.conv = fuse_conv_and_bn(m.conv, m.bn) # update conv
delattr(m, 'bn') # remove batchnorm
m.forward = m.forward_fuse # update forward
if isinstance(m, ConvTranspose) and hasattr(m, 'bn'):
m.conv_transpose = fuse_deconv_and_bn(m.conv_transpose, m.bn)
delattr(m, 'bn') # remove batchnorm
m.forward = m.forward_fuse # update forward
self.info(verbose=verbose)
return self
def is_fused(self, thresh=10):
"""
Check if the model has less than a certain threshold of BatchNorm layers.
Args:
thresh (int, optional): The threshold number of BatchNorm layers. Default is 10.
Returns:
(bool): True if the number of BatchNorm layers in the model is less than the threshold, False otherwise.
"""
bn = tuple(v for k, v in nn.__dict__.items() if 'Norm' in k) # normalization layers, i.e. BatchNorm2d()
return sum(isinstance(v, bn) for v in self.modules()) < thresh # True if < 'thresh' BatchNorm layers in model
def info(self, verbose=False, imgsz=640):
"""
Prints model information
Args:
verbose (bool): if True, prints out the model information. Defaults to False
imgsz (int): the size of the image that the model will be trained on. Defaults to 640
"""
model_info(self, verbose=verbose, imgsz=imgsz)
def _apply(self, fn):
"""
`_apply()` is a function that applies a function to all the tensors in the model that are not
parameters or registered buffers
Args:
fn: the function to apply to the model
Returns:
A model that is a Detect() object.
"""
self = super()._apply(fn)
m = self.model[-1] # Detect()
if isinstance(m, (Detect, Segment)):
m.stride = fn(m.stride)
m.anchors = fn(m.anchors)
m.strides = fn(m.strides)
return self
def load(self, weights):
"""
This function loads the weights of the model from a file
Args:
weights (str): The weights to load into the model.
"""
# Force all tasks to implement this function
raise NotImplementedError('This function needs to be implemented by derived classes!')
class DetectionModel(BaseModel):
# YOLOv8 detection model
def __init__(self, cfg='yolov8n.yaml', ch=3, nc=None, verbose=True): # model, input channels, number of classes
super().__init__()
self.yaml = cfg if isinstance(cfg, dict) else yaml_load(check_yaml(cfg), append_filename=True) # cfg dict
# Define model
ch = self.yaml['ch'] = self.yaml.get('ch', ch) # input channels
if nc and nc != self.yaml['nc']:
LOGGER.info(f"Overriding model.yaml nc={self.yaml['nc']} with nc={nc}")
self.yaml['nc'] = nc # override yaml value
self.model, self.save = parse_model(deepcopy(self.yaml), ch=ch, verbose=verbose) # model, savelist
self.names = {i: f'{i}' for i in range(self.yaml['nc'])} # default names dict
self.inplace = self.yaml.get('inplace', True)
# Build strides
m = self.model[-1] # Detect()
if isinstance(m, (Detect, Segment)):
s = 256 # 2x min stride
m.inplace = self.inplace
forward = lambda x: self.forward(x)[0] if isinstance(m, Segment) else self.forward(x)
m.stride = torch.tensor([s / x.shape[-2] for x in forward(torch.zeros(1, ch, s, s))]) # forward
self.stride = m.stride
m.bias_init() # only run once
# Init weights, biases
initialize_weights(self)
if verbose:
self.info()
LOGGER.info('')
def forward(self, x, augment=False, profile=False, visualize=False):
if augment:
return self._forward_augment(x) # augmented inference, None
return self._forward_once(x, profile, visualize) # single-scale inference, train
def _forward_augment(self, x):
img_size = x.shape[-2:] # height, width
s = [1, 0.83, 0.67] # scales
f = [None, 3, None] # flips (2-ud, 3-lr)
y = [] # outputs
for si, fi in zip(s, f):
xi = scale_img(x.flip(fi) if fi else x, si, gs=int(self.stride.max()))
yi = self._forward_once(xi)[0] # forward
# cv2.imwrite(f'img_{si}.jpg', 255 * xi[0].cpu().numpy().transpose((1, 2, 0))[:, :, ::-1]) # save
yi = self._descale_pred(yi, fi, si, img_size)
y.append(yi)
y = self._clip_augmented(y) # clip augmented tails
return torch.cat(y, -1), None # augmented inference, train
@staticmethod
def _descale_pred(p, flips, scale, img_size, dim=1):
# de-scale predictions following augmented inference (inverse operation)
p[:, :4] /= scale # de-scale
x, y, wh, cls = p.split((1, 1, 2, p.shape[dim] - 4), dim)
if flips == 2:
y = img_size[0] - y # de-flip ud
elif flips == 3:
x = img_size[1] - x # de-flip lr
return torch.cat((x, y, wh, cls), dim)
def _clip_augmented(self, y):
# Clip YOLOv5 augmented inference tails
nl = self.model[-1].nl # number of detection layers (P3-P5)
g = sum(4 ** x for x in range(nl)) # grid points
e = 1 # exclude layer count
i = (y[0].shape[-1] // g) * sum(4 ** x for x in range(e)) # indices
y[0] = y[0][..., :-i] # large
i = (y[-1].shape[-1] // g) * sum(4 ** (nl - 1 - x) for x in range(e)) # indices
y[-1] = y[-1][..., i:] # small
return y
def load(self, weights, verbose=True):
csd = weights.float().state_dict() # checkpoint state_dict as FP32
csd = intersect_dicts(csd, self.state_dict()) # intersect
self.load_state_dict(csd, strict=False) # load
if verbose and RANK == -1:
LOGGER.info(f'Transferred {len(csd)}/{len(self.model.state_dict())} items from pretrained weights')
class SegmentationModel(DetectionModel):
# YOLOv8 segmentation model
def __init__(self, cfg='yolov8n-seg.yaml', ch=3, nc=None, verbose=True):
super().__init__(cfg, ch, nc, verbose)
def _forward_augment(self, x):
raise NotImplementedError('WARNING ⚠️ SegmentationModel has not supported augment inference yet!')
class ClassificationModel(BaseModel):
# YOLOv8 classification model
def __init__(self,
cfg=None,
model=None,
ch=3,
nc=None,
cutoff=10,
verbose=True): # yaml, model, channels, number of classes, cutoff index, verbose flag
super().__init__()
self._from_detection_model(model, nc, cutoff) if model is not None else self._from_yaml(cfg, ch, nc, verbose)
def _from_detection_model(self, model, nc=1000, cutoff=10):
# Create a YOLOv5 classification model from a YOLOv5 detection model
from ultralytics.nn.autobackend import AutoBackend
if isinstance(model, AutoBackend):
model = model.model # unwrap DetectMultiBackend
model.model = model.model[:cutoff] # backbone
m = model.model[-1] # last layer
ch = m.conv.in_channels if hasattr(m, 'conv') else m.cv1.conv.in_channels # ch into module
c = Classify(ch, nc) # Classify()
c.i, c.f, c.type = m.i, m.f, 'models.common.Classify' # index, from, type
model.model[-1] = c # replace
self.model = model.model
self.stride = model.stride
self.save = []
self.nc = nc
def _from_yaml(self, cfg, ch, nc, verbose):
self.yaml = cfg if isinstance(cfg, dict) else yaml_load(check_yaml(cfg), append_filename=True) # cfg dict
# Define model
ch = self.yaml['ch'] = self.yaml.get('ch', ch) # input channels
if nc and nc != self.yaml['nc']:
LOGGER.info(f"Overriding model.yaml nc={self.yaml['nc']} with nc={nc}")
self.yaml['nc'] = nc # override yaml value
elif not nc and not self.yaml.get('nc', None):
raise ValueError('nc not specified. Must specify nc in model.yaml or function arguments.')
self.model, self.save = parse_model(deepcopy(self.yaml), ch=ch, verbose=verbose) # model, savelist
self.stride = torch.Tensor([1]) # no stride constraints
self.names = {i: f'{i}' for i in range(self.yaml['nc'])} # default names dict
self.info()
def load(self, weights):
model = weights['model'] if isinstance(weights, dict) else weights # torchvision models are not dicts
csd = model.float().state_dict()
csd = intersect_dicts(csd, self.state_dict()) # intersect
self.load_state_dict(csd, strict=False) # load
@staticmethod
def reshape_outputs(model, nc):
# Update a TorchVision classification model to class count 'n' if required
name, m = list((model.model if hasattr(model, 'model') else model).named_children())[-1] # last module
if isinstance(m, Classify): # YOLO Classify() head
if m.linear.out_features != nc:
m.linear = nn.Linear(m.linear.in_features, nc)
elif isinstance(m, nn.Linear): # ResNet, EfficientNet
if m.out_features != nc:
setattr(model, name, nn.Linear(m.in_features, nc))
elif isinstance(m, nn.Sequential):
types = [type(x) for x in m]
if nn.Linear in types:
i = types.index(nn.Linear) # nn.Linear index
if m[i].out_features != nc:
m[i] = nn.Linear(m[i].in_features, nc)
elif nn.Conv2d in types:
i = types.index(nn.Conv2d) # nn.Conv2d index
if m[i].out_channels != nc:
m[i] = nn.Conv2d(m[i].in_channels, nc, m[i].kernel_size, m[i].stride, bias=m[i].bias is not None)
# Functions ------------------------------------------------------------------------------------------------------------
def torch_safe_load(weight):
"""
This function attempts to load a PyTorch model with the torch.load() function. If a ModuleNotFoundError is raised, it
catches the error, logs a warning message, and attempts to install the missing module via the check_requirements()
function. After installation, the function again attempts to load the model using torch.load().
Args:
weight (str): The file path of the PyTorch model.
Returns:
The loaded PyTorch model.
"""
from ultralytics.yolo.utils.downloads import attempt_download_asset
file = attempt_download_asset(weight) # search online if missing locally
try:
return torch.load(file, map_location='cpu'), file # load
except ModuleNotFoundError as e: # e.name is missing module name
if e.name == 'models':
raise TypeError(
emojis(f'ERROR ❌️ {weight} appears to be an Ultralytics YOLOv5 model originally trained '
f'with https://github.com/ultralytics/yolov5.\nThis model is NOT forwards compatible with '
f'YOLOv8 at https://github.com/ultralytics/ultralytics.'
f"\nRecommend fixes are to train a new model using the latest 'ultralytics' package or to "
f"run a command with an official YOLOv8 model, i.e. 'yolo predict model=yolov8n.pt'")) from e
LOGGER.warning(f"WARNING ⚠️ {weight} appears to require '{e.name}', which is not in ultralytics requirements."
f"\nAutoInstall will run now for '{e.name}' but this feature will be removed in the future."
f"\nRecommend fixes are to train a new model using the latest 'ultralytics' package or to "
f"run a command with an official YOLOv8 model, i.e. 'yolo predict model=yolov8n.pt'")
check_requirements(e.name) # install missing module
return torch.load(file, map_location='cpu'), file # load
def attempt_load_weights(weights, device=None, inplace=True, fuse=False):
# Loads an ensemble of models weights=[a,b,c] or a single model weights=[a] or weights=a
ensemble = Ensemble()
for w in weights if isinstance(weights, list) else [weights]:
ckpt, w = torch_safe_load(w) # load ckpt
args = {**DEFAULT_CFG_DICT, **ckpt['train_args']} # combine model and default args, preferring model args
model = (ckpt.get('ema') or ckpt['model']).to(device).float() # FP32 model
# Model compatibility updates
model.args = args # attach args to model
model.pt_path = w # attach *.pt file path to model
model.task = guess_model_task(model)
if not hasattr(model, 'stride'):
model.stride = torch.tensor([32.])
# Append
ensemble.append(model.fuse().eval() if fuse and hasattr(model, 'fuse') else model.eval()) # model in eval mode
# Module compatibility updates
for m in ensemble.modules():
t = type(m)
if t in (nn.Hardswish, nn.LeakyReLU, nn.ReLU, nn.ReLU6, nn.SiLU, Detect, Segment):
m.inplace = inplace # torch 1.7.0 compatibility
elif t is nn.Upsample and not hasattr(m, 'recompute_scale_factor'):
m.recompute_scale_factor = None # torch 1.11.0 compatibility
# Return model
if len(ensemble) == 1:
return ensemble[-1]
# Return ensemble
LOGGER.info(f'Ensemble created with {weights}\n')
for k in 'names', 'nc', 'yaml':
setattr(ensemble, k, getattr(ensemble[0], k))
ensemble.stride = ensemble[torch.argmax(torch.tensor([m.stride.max() for m in ensemble])).int()].stride
assert all(ensemble[0].nc == m.nc for m in ensemble), f'Models differ in class counts: {[m.nc for m in ensemble]}'
return ensemble
def attempt_load_one_weight(weight, device=None, inplace=True, fuse=False):
# Loads a single model weights
ckpt, weight = torch_safe_load(weight) # load ckpt
args = {**DEFAULT_CFG_DICT, **ckpt['train_args']} # combine model and default args, preferring model args
model = (ckpt.get('ema') or ckpt['model']).to(device).float() # FP32 model
# Model compatibility updates
model.args = {k: v for k, v in args.items() if k in DEFAULT_CFG_KEYS} # attach args to model
model.pt_path = weight # attach *.pt file path to model
model.task = guess_model_task(model)
if not hasattr(model, 'stride'):
model.stride = torch.tensor([32.])
model = model.fuse().eval() if fuse and hasattr(model, 'fuse') else model.eval() # model in eval mode
# Module compatibility updates
for m in model.modules():
t = type(m)
if t in (nn.Hardswish, nn.LeakyReLU, nn.ReLU, nn.ReLU6, nn.SiLU, Detect, Segment):
m.inplace = inplace # torch 1.7.0 compatibility
elif t is nn.Upsample and not hasattr(m, 'recompute_scale_factor'):
m.recompute_scale_factor = None # torch 1.11.0 compatibility
# Return model and ckpt
return model, ckpt
def parse_model(d, ch, verbose=True): # model_dict, input_channels(3)
# Parse a YOLO model.yaml dictionary
if verbose:
LOGGER.info(f"\n{'':>3}{'from':>20}{'n':>3}{'params':>10} {'module':<45}{'arguments':<30}")
nc, gd, gw, act = d['nc'], d['depth_multiple'], d['width_multiple'], d.get('activation')
if act:
Conv.default_act = eval(act) # redefine default activation, i.e. Conv.default_act = nn.SiLU()
if verbose:
LOGGER.info(f"{colorstr('activation:')} {act}") # print
ch = [ch]
layers, save, c2 = [], [], ch[-1] # layers, savelist, ch out
for i, (f, n, m, args) in enumerate(d['backbone'] + d['head']): # from, number, module, args
m = getattr(torch.nn, m[3:]) if 'nn.' in m else globals()[m] # get module
for j, a in enumerate(args):
# TODO: re-implement with eval() removal if possible
# args[j] = (locals()[a] if a in locals() else ast.literal_eval(a)) if isinstance(a, str) else a
with contextlib.suppress(NameError):
args[j] = eval(a) if isinstance(a, str) else a # eval strings
n = n_ = max(round(n * gd), 1) if n > 1 else n # depth gain
if m in (Classify, Conv, ConvTranspose, GhostConv, Bottleneck, GhostBottleneck, SPP, SPPF, DWConv, Focus,
BottleneckCSP, C1, C2, C2f, C3, C3TR, C3Ghost, nn.ConvTranspose2d, DWConvTranspose2d, C3x):
c1, c2 = ch[f], args[0]
if c2 != nc: # if c2 not equal to number of classes (i.e. for Classify() output)
c2 = make_divisible(c2 * gw, 8)
args = [c1, c2, *args[1:]]
if m in (BottleneckCSP, C1, C2, C2f, C3, C3TR, C3Ghost, C3x):
args.insert(2, n) # number of repeats
n = 1
elif m is nn.BatchNorm2d:
args = [ch[f]]
elif m is Concat:
c2 = sum(ch[x] for x in f)
elif m in (Detect, Segment):
args.append([ch[x] for x in f])
if m is Segment:
args[2] = make_divisible(args[2] * gw, 8)
else:
c2 = ch[f]
m_ = nn.Sequential(*(m(*args) for _ in range(n))) if n > 1 else m(*args) # module
t = str(m)[8:-2].replace('__main__.', '') # module type
m.np = sum(x.numel() for x in m_.parameters()) # number params
m_.i, m_.f, m_.type = i, f, t # attach index, 'from' index, type
if verbose:
LOGGER.info(f'{i:>3}{str(f):>20}{n_:>3}{m.np:10.0f} {t:<45}{str(args):<30}') # print
save.extend(x % i for x in ([f] if isinstance(f, int) else f) if x != -1) # append to savelist
layers.append(m_)
if i == 0:
ch = []
ch.append(c2)
return nn.Sequential(*layers), sorted(save)
def guess_model_task(model):
"""
Guess the task of a PyTorch model from its architecture or configuration.
Args:
model (nn.Module) or (dict): PyTorch model or model configuration in YAML format.
Returns:
str: Task of the model ('detect', 'segment', 'classify').
Raises:
SyntaxError: If the task of the model could not be determined.
"""
def cfg2task(cfg):
# Guess from YAML dictionary
m = cfg['head'][-1][-2].lower() # output module name
if m in ('classify', 'classifier', 'cls', 'fc'):
return 'classify'
if m == 'detect':
return 'detect'
if m == 'segment':
return 'segment'
# Guess from model cfg
if isinstance(model, dict):
with contextlib.suppress(Exception):
return cfg2task(model)
# Guess from PyTorch model
if isinstance(model, nn.Module): # PyTorch model
for x in 'model.args', 'model.model.args', 'model.model.model.args':
with contextlib.suppress(Exception):
return eval(x)['task']
for x in 'model.yaml', 'model.model.yaml', 'model.model.model.yaml':
with contextlib.suppress(Exception):
return cfg2task(eval(x))
for m in model.modules():
if isinstance(m, Detect):
return 'detect'
elif isinstance(m, Segment):
return 'segment'
elif isinstance(m, Classify):
return 'classify'
# Guess from model filename
if isinstance(model, (str, Path)):
model = Path(model)
if '-seg' in model.stem or 'segment' in model.parts:
return 'segment'
elif '-cls' in model.stem or 'classify' in model.parts:
return 'classify'
elif 'detect' in model.parts:
return 'detect'
# Unable to determine task from model
LOGGER.warning("WARNING ⚠️ Unable to automatically guess model task, assuming 'task=detect'. "
"Explicitly define task for your model, i.e. 'task=detect', 'task=segment' or 'task=classify'.")
return 'detect' # assume detect