ERA-SESSION13 / utils /utils.py
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import config
import matplotlib.pyplot as plt
import matplotlib.patches as patches
import numpy as np
import os
import random
import torch
from collections import Counter
from torch.utils.data import DataLoader
from tqdm import tqdm
def iou_width_height(boxes1, boxes2):
"""
Parameters:
boxes1 (tensor): width and height of the first bounding boxes
boxes2 (tensor): width and height of the second bounding boxes
Returns:
tensor: Intersection over union of the corresponding boxes
"""
intersection = torch.min(boxes1[..., 0], boxes2[..., 0]) * torch.min(
boxes1[..., 1], boxes2[..., 1]
)
union = (
boxes1[..., 0] * boxes1[..., 1] + boxes2[..., 0] * boxes2[..., 1] - intersection
)
return intersection / union
def intersection_over_union(boxes_preds, boxes_labels, box_format="midpoint"):
"""
Video explanation of this function:
https://youtu.be/XXYG5ZWtjj0
This function calculates intersection over union (iou) given pred boxes
and target boxes.
Parameters:
boxes_preds (tensor): Predictions of Bounding Boxes (BATCH_SIZE, 4)
boxes_labels (tensor): Correct labels of Bounding Boxes (BATCH_SIZE, 4)
box_format (str): midpoint/corners, if boxes (x,y,w,h) or (x1,y1,x2,y2)
Returns:
tensor: Intersection over union for all examples
"""
if box_format == "midpoint":
box1_x1 = boxes_preds[..., 0:1] - boxes_preds[..., 2:3] / 2
box1_y1 = boxes_preds[..., 1:2] - boxes_preds[..., 3:4] / 2
box1_x2 = boxes_preds[..., 0:1] + boxes_preds[..., 2:3] / 2
box1_y2 = boxes_preds[..., 1:2] + boxes_preds[..., 3:4] / 2
box2_x1 = boxes_labels[..., 0:1] - boxes_labels[..., 2:3] / 2
box2_y1 = boxes_labels[..., 1:2] - boxes_labels[..., 3:4] / 2
box2_x2 = boxes_labels[..., 0:1] + boxes_labels[..., 2:3] / 2
box2_y2 = boxes_labels[..., 1:2] + boxes_labels[..., 3:4] / 2
if box_format == "corners":
box1_x1 = boxes_preds[..., 0:1]
box1_y1 = boxes_preds[..., 1:2]
box1_x2 = boxes_preds[..., 2:3]
box1_y2 = boxes_preds[..., 3:4]
box2_x1 = boxes_labels[..., 0:1]
box2_y1 = boxes_labels[..., 1:2]
box2_x2 = boxes_labels[..., 2:3]
box2_y2 = boxes_labels[..., 3:4]
x1 = torch.max(box1_x1, box2_x1)
y1 = torch.max(box1_y1, box2_y1)
x2 = torch.min(box1_x2, box2_x2)
y2 = torch.min(box1_y2, box2_y2)
intersection = (x2 - x1).clamp(0) * (y2 - y1).clamp(0)
box1_area = abs((box1_x2 - box1_x1) * (box1_y2 - box1_y1))
box2_area = abs((box2_x2 - box2_x1) * (box2_y2 - box2_y1))
return intersection / (box1_area + box2_area - intersection + 1e-6)
def non_max_suppression(bboxes, iou_threshold, threshold, box_format="corners"):
"""
Video explanation of this function:
https://youtu.be/YDkjWEN8jNA
Does Non Max Suppression given bboxes
Parameters:
bboxes (list): list of lists containing all bboxes with each bboxes
specified as [class_pred, prob_score, x1, y1, x2, y2]
iou_threshold (float): threshold where predicted bboxes is correct
threshold (float): threshold to remove predicted bboxes (independent of IoU)
box_format (str): "midpoint" or "corners" used to specify bboxes
Returns:
list: bboxes after performing NMS given a specific IoU threshold
"""
assert type(bboxes) == list
bboxes = [box for box in bboxes if box[1] > threshold]
bboxes = sorted(bboxes, key=lambda x: x[1], reverse=True)
bboxes_after_nms = []
while bboxes:
chosen_box = bboxes.pop(0)
bboxes = [
box
for box in bboxes
if box[0] != chosen_box[0]
or intersection_over_union(
torch.tensor(chosen_box[2:]),
torch.tensor(box[2:]),
box_format=box_format,
)
< iou_threshold
]
bboxes_after_nms.append(chosen_box)
return bboxes_after_nms
def mean_average_precision(
pred_boxes, true_boxes, iou_threshold=0.5, box_format="midpoint", num_classes=20
):
"""
Video explanation of this function:
https://youtu.be/FppOzcDvaDI
This function calculates mean average precision (mAP)
Parameters:
pred_boxes (list): list of lists containing all bboxes with each bboxes
specified as [train_idx, class_prediction, prob_score, x1, y1, x2, y2]
true_boxes (list): Similar as pred_boxes except all the correct ones
iou_threshold (float): threshold where predicted bboxes is correct
box_format (str): "midpoint" or "corners" used to specify bboxes
num_classes (int): number of classes
Returns:
float: mAP value across all classes given a specific IoU threshold
"""
# list storing all AP for respective classes
average_precisions = []
# used for numerical stability later on
epsilon = 1e-6
for c in range(num_classes):
detections = []
ground_truths = []
# Go through all predictions and targets,
# and only add the ones that belong to the
# current class c
for detection in pred_boxes:
if detection[1] == c:
detections.append(detection)
for true_box in true_boxes:
if true_box[1] == c:
ground_truths.append(true_box)
# find the amount of bboxes for each training example
# Counter here finds how many ground truth bboxes we get
# for each training example, so let's say img 0 has 3,
# img 1 has 5 then we will obtain a dictionary with:
# amount_bboxes = {0:3, 1:5}
amount_bboxes = Counter([gt[0] for gt in ground_truths])
# We then go through each key, val in this dictionary
# and convert to the following (w.r.t same example):
# ammount_bboxes = {0:torch.tensor[0,0,0], 1:torch.tensor[0,0,0,0,0]}
for key, val in amount_bboxes.items():
amount_bboxes[key] = torch.zeros(val)
# sort by box probabilities which is index 2
detections.sort(key=lambda x: x[2], reverse=True)
TP = torch.zeros((len(detections)))
FP = torch.zeros((len(detections)))
total_true_bboxes = len(ground_truths)
# If none exists for this class then we can safely skip
if total_true_bboxes == 0:
continue
for detection_idx, detection in enumerate(detections):
# Only take out the ground_truths that have the same
# training idx as detection
ground_truth_img = [
bbox for bbox in ground_truths if bbox[0] == detection[0]
]
num_gts = len(ground_truth_img)
best_iou = 0
for idx, gt in enumerate(ground_truth_img):
iou = intersection_over_union(
torch.tensor(detection[3:]),
torch.tensor(gt[3:]),
box_format=box_format,
)
if iou > best_iou:
best_iou = iou
best_gt_idx = idx
if best_iou > iou_threshold:
# only detect ground truth detection once
if amount_bboxes[detection[0]][best_gt_idx] == 0:
# true positive and add this bounding box to seen
TP[detection_idx] = 1
amount_bboxes[detection[0]][best_gt_idx] = 1
else:
FP[detection_idx] = 1
# if IOU is lower then the detection is a false positive
else:
FP[detection_idx] = 1
TP_cumsum = torch.cumsum(TP, dim=0)
FP_cumsum = torch.cumsum(FP, dim=0)
recalls = TP_cumsum / (total_true_bboxes + epsilon)
precisions = TP_cumsum / (TP_cumsum + FP_cumsum + epsilon)
precisions = torch.cat((torch.tensor([1]), precisions))
recalls = torch.cat((torch.tensor([0]), recalls))
# torch.trapz for numerical integration
average_precisions.append(torch.trapz(precisions, recalls))
return sum(average_precisions) / len(average_precisions)
def plot_image(image, boxes):
"""Plots predicted bounding boxes on the image"""
cmap = plt.get_cmap("tab20b")
class_labels = (
config.COCO_LABELS if config.DATASET == "COCO" else config.PASCAL_CLASSES
)
colors = [cmap(i) for i in np.linspace(0, 1, len(class_labels))]
im = np.array(image)
height, width, _ = im.shape
# Create figure and axes
fig, ax = plt.subplots(1)
# Display the image
ax.imshow(im)
# box[0] is x midpoint, box[2] is width
# box[1] is y midpoint, box[3] is height
# Create a Rectangle patch
for box in boxes:
assert (
len(box) == 6
), "box should contain class pred, confidence, x, y, width, height"
class_pred = box[0]
box = box[2:]
upper_left_x = box[0] - box[2] / 2
upper_left_y = box[1] - box[3] / 2
rect = patches.Rectangle(
(upper_left_x * width, upper_left_y * height),
box[2] * width,
box[3] * height,
linewidth=2,
edgecolor=colors[int(class_pred)],
facecolor="none",
)
# Add the patch to the Axes
ax.add_patch(rect)
plt.text(
upper_left_x * width,
upper_left_y * height,
s=class_labels[int(class_pred)],
color="white",
verticalalignment="top",
bbox={"color": colors[int(class_pred)], "pad": 0},
)
plt.show()
def get_evaluation_bboxes(
loader,
model,
iou_threshold,
anchors,
threshold,
box_format="midpoint",
device="cuda",
):
# make sure model is in eval before get bboxes
model.eval()
train_idx = 0
all_pred_boxes = []
all_true_boxes = []
for batch_idx, (x, labels) in enumerate(tqdm(loader)):
x = x.to(device)
with torch.no_grad():
predictions = model(x)
batch_size = x.shape[0]
bboxes = [[] for _ in range(batch_size)]
for i in range(3):
S = predictions[i].shape[2]
anchor = torch.tensor([*anchors[i]]).to(device) * S
boxes_scale_i = cells_to_bboxes(predictions[i], anchor, S=S, is_preds=True)
for idx, (box) in enumerate(boxes_scale_i):
bboxes[idx] += box
# we just want one bbox for each label, not one for each scale
true_bboxes = cells_to_bboxes(labels[2], anchor, S=S, is_preds=False)
for idx in range(batch_size):
nms_boxes = non_max_suppression(
bboxes[idx],
iou_threshold=iou_threshold,
threshold=threshold,
box_format=box_format,
)
for nms_box in nms_boxes:
all_pred_boxes.append([train_idx] + nms_box)
for box in true_bboxes[idx]:
if box[1] > threshold:
all_true_boxes.append([train_idx] + box)
train_idx += 1
model.train()
return all_pred_boxes, all_true_boxes
def cells_to_bboxes(predictions, anchors, S, is_preds=True):
"""
Scales the predictions coming from the model to
be relative to the entire image such that they for example later
can be plotted or.
INPUT:
predictions: tensor of size (N, 3, S, S, num_classes+5)
anchors: the anchors used for the predictions
S: the number of cells the image is divided in on the width (and height)
is_preds: whether the input is predictions or the true bounding boxes
OUTPUT:
converted_bboxes: the converted boxes of sizes (N, num_anchors, S, S, 1+5) with class index,
object score, bounding box coordinates
"""
BATCH_SIZE = predictions.shape[0]
num_anchors = len(anchors)
box_predictions = predictions[..., 1:5]
if is_preds:
anchors = anchors.reshape(1, len(anchors), 1, 1, 2)
box_predictions[..., 0:2] = torch.sigmoid(box_predictions[..., 0:2])
box_predictions[..., 2:] = torch.exp(box_predictions[..., 2:]) * anchors
scores = torch.sigmoid(predictions[..., 0:1])
best_class = torch.argmax(predictions[..., 5:], dim=-1).unsqueeze(-1)
else:
scores = predictions[..., 0:1]
best_class = predictions[..., 5:6]
cell_indices = (
torch.arange(S)
.repeat(predictions.shape[0], 3, S, 1)
.unsqueeze(-1)
.to(predictions.device)
)
x = 1 / S * (box_predictions[..., 0:1] + cell_indices)
y = 1 / S * (box_predictions[..., 1:2] + cell_indices.permute(0, 1, 3, 2, 4))
w_h = 1 / S * box_predictions[..., 2:4]
converted_bboxes = torch.cat((best_class, scores, x, y, w_h), dim=-1).reshape(
BATCH_SIZE, num_anchors * S * S, 6
)
return converted_bboxes.tolist()
def check_class_accuracy(model, loader, threshold):
model.eval()
tot_class_preds, correct_class = 0, 0
tot_noobj, correct_noobj = 0, 0
tot_obj, correct_obj = 0, 0
for idx, (x, y) in enumerate(tqdm(loader)):
x = x.to(config.DEVICE)
with torch.no_grad():
out = model(x)
for i in range(3):
y[i] = y[i].to(config.DEVICE)
obj = y[i][..., 0] == 1 # in paper this is Iobj_i
noobj = y[i][..., 0] == 0 # in paper this is Iobj_i
correct_class += torch.sum(
torch.argmax(out[i][..., 5:][obj], dim=-1) == y[i][..., 5][obj]
)
tot_class_preds += torch.sum(obj)
obj_preds = torch.sigmoid(out[i][..., 0]) > threshold
correct_obj += torch.sum(obj_preds[obj] == y[i][..., 0][obj])
tot_obj += torch.sum(obj)
correct_noobj += torch.sum(obj_preds[noobj] == y[i][..., 0][noobj])
tot_noobj += torch.sum(noobj)
class_acc = (correct_class / (tot_class_preds + 1e-16)) * 100
noobj_acc = (correct_noobj / (tot_noobj + 1e-16)) * 100
obj_acc = (correct_obj / (tot_obj + 1e-16)) * 100
print(f"Class accuracy is: {class_acc:2f}%")
print(f"No obj accuracy is: {noobj_acc:2f}%")
print(f"Obj accuracy is: {obj_acc:2f}%")
model.train()
return class_acc, noobj_acc, obj_acc
def get_mean_std(loader):
# var[X] = E[X**2] - E[X]**2
channels_sum, channels_sqrd_sum, num_batches = 0, 0, 0
for data, _ in tqdm(loader):
channels_sum += torch.mean(data, dim=[0, 2, 3])
channels_sqrd_sum += torch.mean(data**2, dim=[0, 2, 3])
num_batches += 1
mean = channels_sum / num_batches
std = (channels_sqrd_sum / num_batches - mean**2) ** 0.5
return mean, std
def save_checkpoint(model, optimizer, filename="my_checkpoint.pth.tar"):
print("=> Saving checkpoint")
checkpoint = {
"state_dict": model.state_dict(),
"optimizer": optimizer.state_dict(),
}
torch.save(checkpoint, filename)
def load_checkpoint(checkpoint_file, model, optimizer, lr):
print("=> Loading checkpoint")
checkpoint = torch.load(checkpoint_file, map_location=config.DEVICE)
model.load_state_dict(checkpoint["state_dict"])
optimizer.load_state_dict(checkpoint["optimizer"])
# If we don't do this then it will just have learning rate of old checkpoint
# and it will lead to many hours of debugging \:
for param_group in optimizer.param_groups:
param_group["lr"] = lr
def get_loaders(train_csv_path, test_csv_path):
from dataset import YOLODataset
IMAGE_SIZE = config.IMAGE_SIZE
train_dataset = YOLODataset(
train_csv_path,
transform=config.train_transforms,
S=[IMAGE_SIZE // 32, IMAGE_SIZE // 16, IMAGE_SIZE // 8],
img_dir=config.IMG_DIR,
label_dir=config.LABEL_DIR,
anchors=config.ANCHORS,
)
test_dataset = YOLODataset(
test_csv_path,
transform=config.test_transforms,
S=[IMAGE_SIZE // 32, IMAGE_SIZE // 16, IMAGE_SIZE // 8],
img_dir=config.IMG_DIR,
label_dir=config.LABEL_DIR,
anchors=config.ANCHORS,
)
train_loader = DataLoader(
dataset=train_dataset,
batch_size=config.BATCH_SIZE,
num_workers=config.NUM_WORKERS,
pin_memory=config.PIN_MEMORY,
shuffle=True,
drop_last=False,
)
test_loader = DataLoader(
dataset=test_dataset,
batch_size=config.BATCH_SIZE,
num_workers=config.NUM_WORKERS,
pin_memory=config.PIN_MEMORY,
shuffle=False,
drop_last=False,
)
train_eval_dataset = YOLODataset(
train_csv_path,
transform=config.test_transforms,
S=[IMAGE_SIZE // 32, IMAGE_SIZE // 16, IMAGE_SIZE // 8],
img_dir=config.IMG_DIR,
label_dir=config.LABEL_DIR,
anchors=config.ANCHORS,
)
train_eval_loader = DataLoader(
dataset=train_eval_dataset,
batch_size=config.BATCH_SIZE,
num_workers=config.NUM_WORKERS,
pin_memory=config.PIN_MEMORY,
shuffle=False,
drop_last=False,
)
return train_loader, test_loader, train_eval_loader
def plot_couple_examples(model, loader, thresh, iou_thresh, anchors):
model.eval()
x, y = next(iter(loader))
x = x.to("cuda")
with torch.no_grad():
out = model(x)
bboxes = [[] for _ in range(x.shape[0])]
for i in range(3):
batch_size, A, S, _, _ = out[i].shape
anchor = anchors[i]
boxes_scale_i = cells_to_bboxes(out[i], anchor, S=S, is_preds=True)
for idx, (box) in enumerate(boxes_scale_i):
bboxes[idx] += box
model.train()
for i in range(batch_size // 4):
nms_boxes = non_max_suppression(
bboxes[i],
iou_threshold=iou_thresh,
threshold=thresh,
box_format="midpoint",
)
plot_image(x[i].permute(1, 2, 0).detach().cpu(), nms_boxes)
def seed_everything(seed=42):
os.environ["PYTHONHASHSEED"] = str(seed)
random.seed(seed)
np.random.seed(seed)
torch.manual_seed(seed)
torch.cuda.manual_seed(seed)
torch.cuda.manual_seed_all(seed)
torch.backends.cudnn.deterministic = True
torch.backends.cudnn.benchmark = False
def clip_coords(boxes, img_shape):
# Clip bounding xyxy bounding boxes to image shape (height, width)
boxes[:, 0].clamp_(0, img_shape[1]) # x1
boxes[:, 1].clamp_(0, img_shape[0]) # y1
boxes[:, 2].clamp_(0, img_shape[1]) # x2
boxes[:, 3].clamp_(0, img_shape[0]) # y2
def xywhn2xyxy(x, w=640, h=640, padw=0, padh=0):
# Convert nx4 boxes from [x, y, w, h] normalized to [x1, y1, x2, y2] where xy1=top-left, xy2=bottom-right
y = x.clone() if isinstance(x, torch.Tensor) else np.copy(x)
y[..., 0] = w * (x[..., 0] - x[..., 2] / 2) + padw # top left x
y[..., 1] = h * (x[..., 1] - x[..., 3] / 2) + padh # top left y
y[..., 2] = w * (x[..., 0] + x[..., 2] / 2) + padw # bottom right x
y[..., 3] = h * (x[..., 1] + x[..., 3] / 2) + padh # bottom right y
return y
def xyn2xy(x, w=640, h=640, padw=0, padh=0):
# Convert normalized segments into pixel segments, shape (n,2)
y = x.clone() if isinstance(x, torch.Tensor) else np.copy(x)
y[..., 0] = w * x[..., 0] + padw # top left x
y[..., 1] = h * x[..., 1] + padh # top left y
return y
def xyxy2xywhn(x, w=640, h=640, clip=False, eps=0.0):
# Convert nx4 boxes from [x1, y1, x2, y2] to [x, y, w, h] normalized where xy1=top-left, xy2=bottom-right
if clip:
clip_boxes(x, (h - eps, w - eps)) # warning: inplace clip
y = x.clone() if isinstance(x, torch.Tensor) else np.copy(x)
y[..., 0] = ((x[..., 0] + x[..., 2]) / 2) / w # x center
y[..., 1] = ((x[..., 1] + x[..., 3]) / 2) / h # y center
y[..., 2] = (x[..., 2] - x[..., 0]) / w # width
y[..., 3] = (x[..., 3] - x[..., 1]) / h # height
return y
def clip_boxes(boxes, shape):
# Clip boxes (xyxy) to image shape (height, width)
if isinstance(boxes, torch.Tensor): # faster individually
boxes[..., 0].clamp_(0, shape[1]) # x1
boxes[..., 1].clamp_(0, shape[0]) # y1
boxes[..., 2].clamp_(0, shape[1]) # x2
boxes[..., 3].clamp_(0, shape[0]) # y2
else: # np.array (faster grouped)
boxes[..., [0, 2]] = boxes[..., [0, 2]].clip(0, shape[1]) # x1, x2
boxes[..., [1, 3]] = boxes[..., [1, 3]].clip(0, shape[0]) # y1, y2
def save_result(image, boxes, index):
"""Plots predicted bounding boxes on the image"""
cmap = plt.get_cmap("tab20b")
class_labels = config.PASCAL_CLASSES
colors = [cmap(i) for i in np.linspace(0, 1, len(class_labels))]
im = np.array(image)
height, width, _ = im.shape
# Create figure and axes
fig, ax = plt.subplots(1)
# Display the image
ax.imshow(im)
# box[0] is x midpoint, box[2] is width
# box[1] is y midpoint, box[3] is height
# Create a Rectangle patch
for box in boxes:
assert (
len(box) == 6
), "box should contain class pred, confidence, x, y, width, height"
class_pred = box[0]
box = box[2:]
upper_left_x = box[0] - box[2] / 2
upper_left_y = box[1] - box[3] / 2
rect = patches.Rectangle(
(upper_left_x * width, upper_left_y * height),
box[2] * width,
box[3] * height,
linewidth=2,
edgecolor=colors[int(class_pred)],
facecolor="none",
)
# Add the patch to the Axes
ax.add_patch(rect)
plt.text(
upper_left_x * width,
upper_left_y * height,
s=class_labels[int(class_pred)],
color="white",
verticalalignment="top",
bbox={"color": colors[int(class_pred)], "pad": 0},
)
ax.grid(False)
ax.set_axis_off()
plt.savefig(f"output/img{index}.png")
def generate_result(model, data, thresh, iou_thresh, anchors):
model.eval()
x = data
# x = x.to("cuda")
with torch.no_grad():
out = model(x)
bboxes = [[] for _ in range(x.shape[0])]
for i in range(3):
batch_size, A, S, _, _ = out[i].shape
anchor = anchors[i]
boxes_scale_i = cells_to_bboxes(out[i], anchor, S=S, is_preds=True)
for idx, (box) in enumerate(boxes_scale_i):
bboxes[idx] += box
for i in range(batch_size):
nms_boxes = non_max_suppression(
bboxes[i],
iou_threshold=iou_thresh,
threshold=thresh,
box_format="midpoint",
)
save_result(x[i].permute(1, 2, 0).detach().cpu(), nms_boxes, i)