utils.py

import glob
import os
import random
from pathlib import Path

import cv2
import matplotlib
import matplotlib.pyplot as plt
import numpy as np
import torch
import torch.nn as nn
from PIL import Image
from tqdm import tqdm

from . import torch_utils  # , google_utils

matplotlib.rc('font', **{'size': 11})

# Set printoptions
torch.set_printoptions(linewidth=1320, precision=5, profile='long')
np.set_printoptions(linewidth=320, formatter={'float_kind': '{:11.5g}'.format})  # format short g, %precision=5

# Prevent OpenCV from multithreading (to use PyTorch DataLoader)
cv2.setNumThreads(0)


def floatn(x, n=3):  # format floats to n decimals
    return float(format(x, '.%gf' % n))


def init_seeds(seed=0):
    random.seed(seed)
    np.random.seed(seed)
    torch_utils.init_seeds(seed=seed)


def load_classes(path):
    # Loads *.names file at 'path'
    with open(path, 'r') as f:
        names = f.read().split('\n')
    return list(filter(None, names))  # filter removes empty strings (such as last line)


def model_info(model, report='summary'):
    # Plots a line-by-line description of a PyTorch model
    n_p = sum(x.numel() for x in model.parameters())  # number parameters
    n_g = sum(x.numel() for x in model.parameters() if x.requires_grad)  # number gradients
    if report is 'full':
        print('%5s %40s %9s %12s %20s %10s %10s' % ('layer', 'name', 'gradient', 'parameters', 'shape', 'mu', 'sigma'))
        for i, (name, p) in enumerate(model.named_parameters()):
            name = name.replace('module_list.', '')
            print('%5g %40s %9s %12g %20s %10.3g %10.3g' %
                  (i, name, p.requires_grad, p.numel(), list(p.shape), p.mean(), p.std()))
    print('Model Summary: %g layers, %g parameters, %g gradients' % (len(list(model.parameters())), n_p, n_g))


def labels_to_class_weights(labels, nc=80):
    # Get class weights (inverse frequency) from training labels
    labels = np.concatenate(labels, 0)  # labels.shape = (866643, 5) for COCO
    classes = labels[:, 0].astype(np.int)  # labels = [class xywh]
    weights = np.bincount(classes, minlength=nc)  # occurences per class
    weights[weights == 0] = 1  # replace empty bins with 1
    weights = 1 / weights  # number of targets per class
    weights /= weights.sum()  # normalize
    return torch.Tensor(weights)


def labels_to_image_weights(labels, nc=80, class_weights=np.ones(80)):
    # Produces image weights based on class mAPs
    n = len(labels)
    class_counts = np.array([np.bincount(labels[i][:, 0].astype(np.int), minlength=nc) for i in range(n)])
    image_weights = (class_weights.reshape(1, nc) * class_counts).sum(1)
    # index = random.choices(range(n), weights=image_weights, k=1)  # weight image sample
    return image_weights


def coco_class_weights():  # frequency of each class in coco train2014
    n = [187437, 4955, 30920, 6033, 3838, 4332, 3160, 7051, 7677, 9167, 1316, 1372, 833, 6757, 7355, 3302, 3776, 4671,
         6769, 5706, 3908, 903, 3686, 3596, 6200, 7920, 8779, 4505, 4272, 1862, 4698, 1962, 4403, 6659, 2402, 2689,
         4012, 4175, 3411, 17048, 5637, 14553, 3923, 5539, 4289, 10084, 7018, 4314, 3099, 4638, 4939, 5543, 2038, 4004,
         5053, 4578, 27292, 4113, 5931, 2905, 11174, 2873, 4036, 3415, 1517, 4122, 1980, 4464, 1190, 2302, 156, 3933,
         1877, 17630, 4337, 4624, 1075, 3468, 135, 1380]
    weights = 1 / torch.Tensor(n)
    weights /= weights.sum()
    return weights


def coco80_to_coco91_class():  # converts 80-index (val2014) to 91-index (paper)
    # https://tech.amikelive.com/node-718/what-object-categories-labels-are-in-coco-dataset/
    # a = np.loadtxt('data/coco.names', dtype='str', delimiter='\n')
    # b = np.loadtxt('data/coco_paper.names', dtype='str', delimiter='\n')
    # x = [list(a[i] == b).index(True) + 1 for i in range(80)]  # darknet to coco
    x = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 31, 32, 33, 34,
         35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
         64, 65, 67, 70, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 84, 85, 86, 87, 88, 89, 90]
    return x


def weights_init_normal(m):
    classname = m.__class__.__name__
    if classname.find('Conv') != -1:
        torch.nn.init.normal_(m.weight.data, 0.0, 0.03)
    elif classname.find('BatchNorm2d') != -1:
        torch.nn.init.normal_(m.weight.data, 1.0, 0.03)
        torch.nn.init.constant_(m.bias.data, 0.0)


def xyxy2xywh(x):
    # Convert bounding box format from [x1, y1, x2, y2] to [x, y, w, h]
    y = torch.zeros_like(x) if isinstance(x, torch.Tensor) else np.zeros_like(x)
    y[:, 0] = (x[:, 0] + x[:, 2]) / 2
    y[:, 1] = (x[:, 1] + x[:, 3]) / 2
    y[:, 2] = x[:, 2] - x[:, 0]
    y[:, 3] = x[:, 3] - x[:, 1]
    return y


def xywh2xyxy(x):
    # Convert bounding box format from [x, y, w, h] to [x1, y1, x2, y2]
    y = torch.zeros_like(x) if isinstance(x, torch.Tensor) else np.zeros_like(x)
    y[:, 0] = x[:, 0] - x[:, 2] / 2
    y[:, 1] = x[:, 1] - x[:, 3] / 2
    y[:, 2] = x[:, 0] + x[:, 2] / 2
    y[:, 3] = x[:, 1] + x[:, 3] / 2
    return y


def scale_coords(img1_shape, coords, img0_shape):
    # Rescale coords (xyxy) from img1_shape to img0_shape
    gain = max(img1_shape) / max(img0_shape)  # gain  = old / new
    coords[:, [0, 2]] -= (img1_shape[1] - img0_shape[1] * gain) / 2  # x padding
    coords[:, [1, 3]] -= (img1_shape[0] - img0_shape[0] * gain) / 2  # y padding
    coords[:, :4] /= gain
    clip_coords(coords, img0_shape)
    return coords


def clip_coords(boxes, img_shape):
    # Clip bounding xyxy bounding boxes to image shape (height, width)
    boxes[:, [0, 2]] = boxes[:, [0, 2]].clamp(min=0, max=img_shape[1])  # clip x
    boxes[:, [1, 3]] = boxes[:, [1, 3]].clamp(min=0, max=img_shape[0])  # clip y


def ap_per_class(tp, conf, pred_cls, target_cls):
    """ Compute the average precision, given the recall and precision curves.
    Source: https://github.com/rafaelpadilla/Object-Detection-Metrics.
    # Arguments
        tp:    True positives (list).
        conf:  Objectness value from 0-1 (list).
        pred_cls: Predicted object classes (list).
        target_cls: True object classes (list).
    # Returns
        The average precision as computed in py-faster-rcnn.
    """

    # Sort by objectness
    i = np.argsort(-conf)
    tp, conf, pred_cls = tp[i], conf[i], pred_cls[i]

    # Find unique classes
    unique_classes = np.unique(target_cls)

    # Create Precision-Recall curve and compute AP for each class
    ap, p, r = [], [], []
    for c in unique_classes:
        i = pred_cls == c
        n_gt = (target_cls == c).sum()  # Number of ground truth objects
        n_p = i.sum()  # Number of predicted objects

        if n_p == 0 and n_gt == 0:
            continue
        elif n_p == 0 or n_gt == 0:
            ap.append(0)
            r.append(0)
            p.append(0)
        else:
            # Accumulate FPs and TPs
            fpc = (1 - tp[i]).cumsum()
            tpc = (tp[i]).cumsum()

            # Recall
            recall_curve = tpc / (n_gt + 1e-16)
            r.append(recall_curve[-1])

            # Precision
            precision_curve = tpc / (tpc + fpc)
            p.append(precision_curve[-1])

            # AP from recall-precision curve
            ap.append(compute_ap(recall_curve, precision_curve))

            # Plot
            # plt.plot(recall_curve, precision_curve)

    # Compute F1 score (harmonic mean of precision and recall)
    p, r, ap = np.array(p), np.array(r), np.array(ap)
    f1 = 2 * p * r / (p + r + 1e-16)

    return p, r, ap, f1, unique_classes.astype('int32')


def compute_ap(recall, precision):
    """ Compute the average precision, given the recall and precision curves.
    Source: https://github.com/rbgirshick/py-faster-rcnn.
    # Arguments
        recall:    The recall curve (list).
        precision: The precision curve (list).
    # Returns
        The average precision as computed in py-faster-rcnn.
    """
    # correct AP calculation
    # first append sentinel values at the end

    mrec = np.concatenate(([0.], recall, [1.]))
    mpre = np.concatenate(([0.], precision, [0.]))

    # compute the precision envelope
    for i in range(mpre.size - 1, 0, -1):
        mpre[i - 1] = np.maximum(mpre[i - 1], mpre[i])

    # to calculate area under PR curve, look for points
    # where X axis (recall) changes value
    i = np.where(mrec[1:] != mrec[:-1])[0]

    # and sum (\Delta recall) * prec
    ap = np.sum((mrec[i + 1] - mrec[i]) * mpre[i + 1])
    return ap


def bbox_iou(box1, box2, x1y1x2y2=True, GIoU=False):
    # Returns the IoU of box1 to box2. box1 is 4, box2 is nx4
    box2 = box2.t()

    # Get the coordinates of bounding boxes
    if x1y1x2y2:
        # x1, y1, x2, y2 = box1
        b1_x1, b1_y1, b1_x2, b1_y2 = box1[0], box1[1], box1[2], box1[3]
        b2_x1, b2_y1, b2_x2, b2_y2 = box2[0], box2[1], box2[2], box2[3]
    else:
        # x, y, w, h = box1
        b1_x1, b1_x2 = box1[0] - box1[2] / 2, box1[0] + box1[2] / 2
        b1_y1, b1_y2 = box1[1] - box1[3] / 2, box1[1] + box1[3] / 2
        b2_x1, b2_x2 = box2[0] - box2[2] / 2, box2[0] + box2[2] / 2
        b2_y1, b2_y2 = box2[1] - box2[3] / 2, box2[1] + box2[3] / 2

    # Intersection area
    inter_area = (torch.min(b1_x2, b2_x2) - torch.max(b1_x1, b2_x1)).clamp(0) * \
                 (torch.min(b1_y2, b2_y2) - torch.max(b1_y1, b2_y1)).clamp(0)

    # Union Area
    union_area = ((b1_x2 - b1_x1) * (b1_y2 - b1_y1) + 1e-16) + \
                 (b2_x2 - b2_x1) * (b2_y2 - b2_y1) - inter_area

    iou = inter_area / union_area  # iou
    if GIoU:  # Generalized IoU https://arxiv.org/pdf/1902.09630.pdf
        c_x1, c_x2 = torch.min(b1_x1, b2_x1), torch.max(b1_x2, b2_x2)
        c_y1, c_y2 = torch.min(b1_y1, b2_y1), torch.max(b1_y2, b2_y2)
        c_area = (c_x2 - c_x1) * (c_y2 - c_y1)  # convex area
        return iou - (c_area - union_area) / c_area  # GIoU

    return iou


def wh_iou(box1, box2):
    # Returns the IoU of wh1 to wh2. wh1 is 2, wh2 is nx2
    box2 = box2.t()

    # w, h = box1
    w1, h1 = box1[0], box1[1]
    w2, h2 = box2[0], box2[1]

    # Intersection area
    inter_area = torch.min(w1, w2) * torch.min(h1, h2)

    # Union Area
    union_area = (w1 * h1 + 1e-16) + w2 * h2 - inter_area

    return inter_area / union_area  # iou


def compute_loss(p, targets, model, giou_loss=True):  # predictions, targets, model
    ft = torch.cuda.FloatTensor if p[0].is_cuda else torch.Tensor
    lxy, lwh, lcls, lobj = ft([0]), ft([0]), ft([0]), ft([0])
    txy, twh, tcls, tbox, indices, anchor_vec = build_targets(model, targets)
    h = model.hyp  # hyperparameters

    # Define criteria
    MSE = nn.MSELoss()
    BCEcls = nn.BCEWithLogitsLoss(pos_weight=ft([h['cls_pw']]))
    BCEobj = nn.BCEWithLogitsLoss(pos_weight=ft([h['obj_pw']]))
    # CE = nn.CrossEntropyLoss()  # (weight=model.class_weights)

    # Compute losses
    bs = p[0].shape[0]  # batch size
    k = bs / 64  # loss gain
    for i, pi0 in enumerate(p):  # layer i predictions, i
        b, a, gj, gi = indices[i]  # image, anchor, gridy, gridx
        tobj = torch.zeros_like(pi0[..., 0])  # target obj

        # Compute losses
        nb = len(b)
        if nb:  # number of targets
            pi = pi0[b, a, gj, gi]  # predictions closest to anchors
            tobj[b, a, gj, gi] = 1.0  # obj
            # pi[..., 2:4] = torch.sigmoid(pi[..., 2:4])  # wh power loss (uncomment)

            if giou_loss:
                pbox = torch.cat((torch.sigmoid(pi[..., 0:2]), torch.exp(pi[..., 2:4]) * anchor_vec[i]), 1)  # predicted
                giou = bbox_iou(pbox.t(), tbox[i], x1y1x2y2=False, GIoU=True)  # giou computation
                lxy += (k * h['giou']) * (1.0 - giou).mean()  # giou loss
            else:
                lxy += (k * h['xy']) * MSE(torch.sigmoid(pi[..., 0:2]), txy[i])  # xy loss
                lwh += (k * h['wh']) * MSE(pi[..., 2:4], twh[i])  # wh yolo loss

            tclsm = torch.zeros_like(pi[..., 5:])
            tclsm[range(nb), tcls[i]] = 1.0
            lcls += (k * h['cls']) * BCEcls(pi[..., 5:], tclsm)  # cls loss (BCE)
            # lcls += (k * h['cls']) * CE(pi[..., 5:], tcls[i])  # cls loss (CE)

            # Append targets to text file
            # with open('targets.txt', 'a') as file:
            #     [file.write('%11.5g ' * 4 % tuple(x) + '\n') for x in torch.cat((txy[i], twh[i]), 1)]

        lobj += (k * h['obj']) * BCEobj(pi0[..., 4], tobj)  # obj loss
    loss = lxy + lwh + lobj + lcls

    return loss, torch.cat((lxy, lwh, lobj, lcls, loss)).detach()


def build_targets(model, targets):
    # targets = [image, class, x, y, w, h]
    iou_thres = model.hyp['iou_t']  # hyperparameter
    if type(model) in (nn.parallel.DataParallel, nn.parallel.DistributedDataParallel):
        model = model.module

    nt = len(targets)
    txy, twh, tcls, tbox, indices, anchor_vec = [], [], [], [], [], []
    for i in model.yolo_layers:
        layer = model.module_list[i][0]

        # iou of targets-anchors
        t, a = targets, []
        gwh = t[:, 4:6] * layer.ng
        if nt:
            iou = torch.stack([wh_iou(x, gwh) for x in layer.anchor_vec], 0)

            use_best_anchor = False
            if use_best_anchor:
                iou, a = iou.max(0)  # best iou and anchor
            else:  # use all anchors
                na = len(layer.anchor_vec)  # number of anchors
                a = torch.arange(na).view((-1, 1)).repeat([1, nt]).view(-1)
                t = targets.repeat([na, 1])
                gwh = gwh.repeat([na, 1])
                iou = iou.view(-1)  # use all ious

            # reject anchors below iou_thres (OPTIONAL, increases P, lowers R)
            reject = True
            if reject:
                j = iou > iou_thres
                t, a, gwh = t[j], a[j], gwh[j]

        # Indices
        b, c = t[:, :2].long().t()  # target image, class
        gxy = t[:, 2:4] * layer.ng  # grid x, y
        gi, gj = gxy.long().t()  # grid x, y indices
        indices.append((b, a, gj, gi))

        # XY coordinates
        gxy -= gxy.floor()
        txy.append(gxy)

        # GIoU
        tbox.append(torch.cat((gxy, gwh), 1))  # xywh (grids)
        anchor_vec.append(layer.anchor_vec[a])

        # Width and height
        twh.append(torch.log(gwh / layer.anchor_vec[a]))  # wh yolo method
        # twh.append((gwh / layer.anchor_vec[a]) ** (1 / 3) / 2)  # wh power method

        # Class
        tcls.append(c)
        if c.shape[0]:
            assert c.max() <= layer.nc, 'Target classes exceed model classes'

    return txy, twh, tcls, tbox, indices, anchor_vec


def non_max_suppression(prediction, conf_thres=0.5, nms_thres=0.5):
    """
    Removes detections with lower object confidence score than 'conf_thres'
    Non-Maximum Suppression to further filter detections.
    Returns detections with shape:
        (x1, y1, x2, y2, object_conf, class_conf, class)
    """

    min_wh = 2  # (pixels) minimum box width and height

    output = [None] * len(prediction)
    for image_i, pred in enumerate(prediction):
        # Experiment: Prior class size rejection
        # x, y, w, h = pred[:, 0], pred[:, 1], pred[:, 2], pred[:, 3]
        # a = w * h  # area
        # ar = w / (h + 1e-16)  # aspect ratio
        # n = len(w)
        # log_w, log_h, log_a, log_ar = torch.log(w), torch.log(h), torch.log(a), torch.log(ar)
        # shape_likelihood = np.zeros((n, 60), dtype=np.float32)
        # x = np.concatenate((log_w.reshape(-1, 1), log_h.reshape(-1, 1)), 1)
        # from scipy.stats import multivariate_normal
        # for c in range(60):
        # shape_likelihood[:, c] =
        #   multivariate_normal.pdf(x, mean=mat['class_mu'][c, :2], cov=mat['class_cov'][c, :2, :2])

        # Multiply conf by class conf to get combined confidence
        class_conf, class_pred = pred[:, 5:].max(1)
        pred[:, 4] *= class_conf

        # Select only suitable predictions
        i = (pred[:, 4] > conf_thres) & (pred[:, 2:4] > min_wh).all(1) & torch.isfinite(pred).all(1)
        pred = pred[i]

        # If none are remaining => process next image
        if len(pred) == 0:
            continue

        # Select predicted classes
        class_conf = class_conf[i]
        class_pred = class_pred[i].unsqueeze(1).float()

        # Box (center x, center y, width, height) to (x1, y1, x2, y2)
        pred[:, :4] = xywh2xyxy(pred[:, :4])
        # pred[:, 4] *= class_conf  # improves mAP from 0.549 to 0.551

        # Detections ordered as (x1y1x2y2, obj_conf, class_conf, class_pred)
        pred = torch.cat((pred[:, :5], class_conf.unsqueeze(1), class_pred), 1)

        # Get detections sorted by decreasing confidence scores
        pred = pred[(-pred[:, 4]).argsort()]

        det_max = []
        nms_style = 'MERGE'  # 'OR' (default), 'AND', 'MERGE' (experimental)
        for c in pred[:, -1].unique():
            dc = pred[pred[:, -1] == c]  # select class c
            n = len(dc)
            if n == 1:
                det_max.append(dc)  # No NMS required if only 1 prediction
                continue
            elif n > 100:
                dc = dc[:100]  # limit to first 100 boxes: https://github.com/ultralytics/yolov3/issues/117

            # Non-maximum suppression
            if nms_style == 'OR':  # default
                # METHOD1
                # ind = list(range(len(dc)))
                # while len(ind):
                # j = ind[0]
                # det_max.append(dc[j:j + 1])  # save highest conf detection
                # reject = (bbox_iou(dc[j], dc[ind]) > nms_thres).nonzero()
                # [ind.pop(i) for i in reversed(reject)]

                # METHOD2
                while dc.shape[0]:
                    det_max.append(dc[:1])  # save highest conf detection
                    if len(dc) == 1:  # Stop if we're at the last detection
                        break
                    iou = bbox_iou(dc[0], dc[1:])  # iou with other boxes
                    dc = dc[1:][iou < nms_thres]  # remove ious > threshold

            elif nms_style == 'AND':  # requires overlap, single boxes erased
                while len(dc) > 1:
                    iou = bbox_iou(dc[0], dc[1:])  # iou with other boxes
                    if iou.max() > 0.5:
                        det_max.append(dc[:1])
                    dc = dc[1:][iou < nms_thres]  # remove ious > threshold

            elif nms_style == 'MERGE':  # weighted mixture box
                while len(dc):
                    if len(dc) == 1:
                        det_max.append(dc)
                        break
                    i = bbox_iou(dc[0], dc) > nms_thres  # iou with other boxes
                    weights = dc[i, 4:5]
                    dc[0, :4] = (weights * dc[i, :4]).sum(0) / weights.sum()
                    det_max.append(dc[:1])
                    dc = dc[i == 0]

            elif nms_style == 'SOFT':  # soft-NMS https://arxiv.org/abs/1704.04503
                sigma = 0.5  # soft-nms sigma parameter
                while len(dc):
                    if len(dc) == 1:
                        det_max.append(dc)
                        break
                    det_max.append(dc[:1])
                    iou = bbox_iou(dc[0], dc[1:])  # iou with other boxes
                    dc = dc[1:]
                    dc[:, 4] *= torch.exp(-iou ** 2 / sigma)  # decay confidences
                    # dc = dc[dc[:, 4] > nms_thres]  # new line per https://github.com/ultralytics/yolov3/issues/362

        if len(det_max):
            det_max = torch.cat(det_max)  # concatenate
            output[image_i] = det_max[(-det_max[:, 4]).argsort()]  # sort

    return output


def get_yolo_layers(model):
    bool_vec = [x['type'] == 'yolo' for x in model.module_defs]
    return [i for i, x in enumerate(bool_vec) if x]  # [82, 94, 106] for yolov3


def strip_optimizer_from_checkpoint(filename='weights/best.pt'):
    # Strip optimizer from *.pt files for lighter files (reduced by 2/3 size)
    a = torch.load(filename, map_location='cpu')
    a['optimizer'] = []
    torch.save(a, filename.replace('.pt', '_lite.pt'))


def coco_class_count(path='../coco/labels/train2014/'):
    # Histogram of occurrences per class
    nc = 80  # number classes
    x = np.zeros(nc, dtype='int32')
    files = sorted(glob.glob('%s/*.*' % path))
    for i, file in enumerate(files):
        labels = np.loadtxt(file, dtype=np.float32).reshape(-1, 5)
        x += np.bincount(labels[:, 0].astype('int32'), minlength=nc)
        print(i, len(files))


def coco_only_people(path='../coco/labels/val2014/'):
    # Find images with only people
    files = sorted(glob.glob('%s/*.*' % path))
    for i, file in enumerate(files):
        labels = np.loadtxt(file, dtype=np.float32).reshape(-1, 5)
        if all(labels[:, 0] == 0):
            print(labels.shape[0], file)


def select_best_evolve(path='evolve*.txt'):  # from utils.utils import *; select_best_evolve()
    # Find best evolved mutation
    for file in sorted(glob.glob(path)):
        x = np.loadtxt(file, dtype=np.float32)
        fitness = x[:, 2] * 0.5 + x[:, 3] * 0.5  # weighted mAP and F1 combination
        print(file, x[fitness.argmax()])


def kmeans_targets(path='./data/coco_64img.txt', n=9, img_size=320):  # from utils.utils import *; kmeans_targets()
    # Produces a list of target kmeans suitable for use in *.cfg files
    img_formats = ['.bmp', '.jpg', '.jpeg', '.png', '.tif']
    with open(path, 'r') as f:
        img_files = [x for x in f.read().splitlines() if os.path.splitext(x)[-1].lower() in img_formats]

    # Read shapes
    nf = len(img_files)
    assert nf > 0, 'No images found in %s' % path
    label_files = [x.replace('images', 'labels').replace(os.path.splitext(x)[-1], '.txt') for x in img_files]
    s = np.array([Image.open(f).size for f in tqdm(img_files, desc='Reading image shapes')])  # (width, height)

    # Read targets
    labels = [np.zeros((0, 5))] * nf
    iter = tqdm(label_files, desc='Reading labels')
    for i, file in enumerate(iter):
        try:
            with open(file, 'r') as f:
                l = np.array([x.split() for x in f.read().splitlines()], dtype=np.float32)
                if l.shape[0]:
                    assert l.shape[1] == 5, '> 5 label columns: %s' % file
                    assert (l >= 0).all(), 'negative labels: %s' % file
                    assert (l[:, 1:] <= 1).all(), 'non-normalized or out of bounds coordinate labels: %s' % file
                    l[:, [1, 3]] *= s[i][0]
                    l[:, [2, 4]] *= s[i][1]
                    l[:, 1:] *= img_size / max(s[i])  # nominal img_size for training here
                    labels[i] = l
        except:
            pass  # print('Warning: missing labels for %s' % self.img_files[i])  # missing label file
    assert len(np.concatenate(labels, 0)) > 0, 'No labels found. Incorrect label paths provided.'

    # kmeans calculation
    from scipy import cluster
    wh = np.concatenate(labels, 0)[:, 3:5]
    k = cluster.vq.kmeans(wh, n)[0]
    k = k[np.argsort(k.prod(1))]
    for x in k.ravel():
        print('%.1f, ' % x, end='')  # drop-in replacement for *.cfg anchors


def print_mutation(hyp, results, bucket=''):
    # Print mutation results to evolve.txt (for use with train.py --evolve)
    a = '%11s' * len(hyp) % tuple(hyp.keys())  # hyperparam keys
    b = '%11.3g' * len(hyp) % tuple(hyp.values())  # hyperparam values
    c = '%11.3g' * len(results) % results  # results (P, R, mAP, F1, test_loss)
    print('\n%s\n%s\nEvolved fitness: %s\n' % (a, b, c))

    if bucket:
        os.system('gsutil cp gs://%s/evolve.txt .' % bucket)  # download evolve.txt
        with open('evolve.txt', 'a') as f:  # append result
            f.write(c + b + '\n')
        x = np.unique(np.loadtxt('evolve.txt', ndmin=2), axis=0)  # load unique rows
        np.savetxt('evolve.txt', x[np.argsort(-fitness(x))], '%11.3g')  # save sort by fitness
        os.system('gsutil cp evolve.txt gs://%s' % bucket)  # upload evolve.txt
    else:
        with open('evolve.txt', 'a') as f:
            f.write(c + b + '\n')


def fitness(x):
    # Returns fitness (for use with results.txt or evolve.txt)
    return 0.5 * x[:, 2] + 0.5 * x[:, 3]  # fitness = 0.5 * mAP + 0.5 * F1


# Plotting functions ---------------------------------------------------------------------------------------------------
def plot_one_box(x, img, color=None, label=None, line_thickness=None):
    # Plots one bounding box on image img
    tl = line_thickness or round(0.002 * (img.shape[0] + img.shape[1]) / 2) + 1  # line thickness
    color = color or [random.randint(0, 255) for _ in range(3)]
    c1, c2 = (int(x[0]), int(x[1])), (int(x[2]), int(x[3]))
    cv2.rectangle(img, c1, c2, color, thickness=tl)
    if label:
        tf = max(tl - 1, 1)  # font thickness
        t_size = cv2.getTextSize(label, 0, fontScale=tl / 3, thickness=tf)[0]
        c2 = c1[0] + t_size[0], c1[1] - t_size[1] - 3
        cv2.rectangle(img, c1, c2, color, -1)  # filled
        cv2.putText(img, label, (c1[0], c1[1] - 2), 0, tl / 3, [225, 255, 255], thickness=tf, lineType=cv2.LINE_AA)


def plot_wh_methods():  # from utils.utils import *; plot_wh_methods()
    # Compares the two methods for width-height anchor multiplication
    # https://github.com/ultralytics/yolov3/issues/168
    x = np.arange(-4.0, 4.0, .1)
    ya = np.exp(x)
    yb = torch.sigmoid(torch.from_numpy(x)).numpy() * 2

    fig = plt.figure(figsize=(6, 3), dpi=150)
    plt.plot(x, ya, '.-', label='yolo method')
    plt.plot(x, yb ** 2, '.-', label='^2 power method')
    plt.plot(x, yb ** 2.5, '.-', label='^2.5 power method')
    plt.xlim(left=-4, right=4)
    plt.ylim(bottom=0, top=6)
    plt.xlabel('input')
    plt.ylabel('output')
    plt.legend()
    fig.tight_layout()
    fig.savefig('comparison.png', dpi=200)


def plot_images(imgs, targets, paths=None, fname='images.jpg'):
    # Plots training images overlaid with targets
    imgs = imgs.cpu().numpy()
    targets = targets.cpu().numpy()
    # targets = targets[targets[:, 1] == 21]  # plot only one class

    fig = plt.figure(figsize=(10, 10))
    bs, _, h, w = imgs.shape  # batch size, _, height, width
    bs = min(bs, 16)  # limit plot to 16 images
    ns = np.ceil(bs ** 0.5)  # number of subplots

    for i in range(bs):
        boxes = xywh2xyxy(targets[targets[:, 0] == i, 2:6]).T
        boxes[[0, 2]] *= w
        boxes[[1, 3]] *= h
        plt.subplot(ns, ns, i + 1).imshow(imgs[i].transpose(1, 2, 0))
        plt.plot(boxes[[0, 2, 2, 0, 0]], boxes[[1, 1, 3, 3, 1]], '.-')
        plt.axis('off')
        if paths is not None:
            s = Path(paths[i]).name
            plt.title(s[:min(len(s), 40)], fontdict={'size': 8})  # limit to 40 characters
    fig.tight_layout()
    fig.savefig(fname, dpi=200)
    plt.close()


def plot_test_txt():  # from utils.utils import *; plot_test()
    # Plot test.txt histograms
    x = np.loadtxt('test.txt', dtype=np.float32)
    box = xyxy2xywh(x[:, :4])
    cx, cy = box[:, 0], box[:, 1]

    fig, ax = plt.subplots(1, 1, figsize=(6, 6))
    ax.hist2d(cx, cy, bins=600, cmax=10, cmin=0)
    ax.set_aspect('equal')
    fig.tight_layout()
    plt.savefig('hist2d.jpg', dpi=300)

    fig, ax = plt.subplots(1, 2, figsize=(12, 6))
    ax[0].hist(cx, bins=600)
    ax[1].hist(cy, bins=600)
    fig.tight_layout()
    plt.savefig('hist1d.jpg', dpi=200)


def plot_targets_txt():  # from utils.utils import *; plot_targets_txt()
    # Plot test.txt histograms
    x = np.loadtxt('targets.txt', dtype=np.float32)
    x = x.T

    s = ['x targets', 'y targets', 'width targets', 'height targets']
    fig, ax = plt.subplots(2, 2, figsize=(8, 8))
    ax = ax.ravel()
    for i in range(4):
        ax[i].hist(x[i], bins=100, label='%.3g +/- %.3g' % (x[i].mean(), x[i].std()))
        ax[i].legend()
        ax[i].set_title(s[i])
    fig.tight_layout()
    plt.savefig('targets.jpg', dpi=200)


def plot_evolution_results(hyp):  # from utils.utils import *; plot_evolution_results()
    # Plot hyperparameter evolution results in evolve.txt
    x = np.loadtxt('evolve.txt')
    f = fitness(x)
    weights = (f - f.min()) ** 2  # for weighted results
    fig = plt.figure(figsize=(12, 10))
    matplotlib.rc('font', **{'size': 8})
    for i, (k, v) in enumerate(hyp.items()):
        y = x[:, i + 5]
        # mu = (y * weights).sum() / weights.sum()  # best weighted result
        mu = y[f.argmax()]  # best single result
        plt.subplot(4, 5, i + 1)
        plt.plot(mu, f.max(), 'o', markersize=10)
        plt.plot(y, f, '.')
        plt.title('%s = %g' % (k, v), fontdict={'size': 8})  # limit to 40 characters
        print(list(hyp.keys())[i], '%.4g' % mu)
    fig.tight_layout()
    plt.savefig('evolve.png', dpi=200)


def plot_results(start=0, stop=0):  # from utils.utils import *; plot_results()
    # Plot training results files 'results*.txt'
    # import os; os.system('wget https://storage.googleapis.com/ultralytics/yolov3/results_v3.txt')

    fig, ax = plt.subplots(2, 5, figsize=(14, 7))
    ax = ax.ravel()
    s = ['GIoU/XY', 'Width/Height', 'Confidence', 'Classification', 'Train Loss', 'Precision', 'Recall', 'mAP', 'F1',
         'Test Loss']
    for f in sorted(glob.glob('results*.txt') + glob.glob('../../Downloads/results*.txt')):
        results = np.loadtxt(f, usecols=[2, 3, 4, 5, 6, 9, 10, 11, 12, 13]).T
        n = results.shape[1]  # number of rows
        x = range(start, min(stop, n) if stop else n)
        for i in range(10):
            ax[i].plot(x, results[i, x], marker='.', label=f.replace('.txt', ''))
            ax[i].set_title(s[i])
    fig.tight_layout()
    ax[4].legend()
    fig.savefig('results.png', dpi=200)