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import numpy as np
import torch
from tqdm import tqdm
from scipy.cluster.vq import kmeans
from utils.datasets import LoadImagesAndLabels
# 类似遗传算法的方法，通过一代一代的筛选找到合适的Anchor
# 利用IOU值进行K-means聚类，遗传算法得出最佳的anchor
def wh_iou(wh1, wh2):
# Returns the nxm IoU matrix. wh1 is nx2, wh2 is mx2
wh1 = wh1[:, None] # [N,1,2]
wh2 = wh2[None] # [1,M,2]
inter = torch.min(wh1, wh2).prod(2) # [N,M]
return inter / (wh1.prod(2) + wh2.prod(2) - inter) # iou = inter / (area1 + area2 - inter)
def kmean_anchors(path='./data/coco64.txt', n=9, img_size=(608, 608), thr=0.20, gen=1000):
# Creates kmeans anchors for use in *.cfg files: from utils.utils import *; _ = kmean_anchors()
# n: number of anchors
# img_size: (min, max) image size used for multi-scale training (can be same values)
# thr: IoU threshold hyperparameter used for training (0.0 - 1.0)
# gen: generations to evolve anchors using genetic algorithm
# 遗传算法进化几代
def print_results(k):
k = k[np.argsort(k.prod(1))] # sort small to large
iou = wh_iou(wh, torch.Tensor(k))
max_iou = iou.max(1)[0]
bpr, aat = (max_iou > thr).float().mean(), (iou > thr).float().mean() * n # best possible recall, anch > thr
print('%.2f iou_thr: %.3f best possible recall, %.2f anchors > thr' % (thr, bpr, aat))
print('n=%g, img_size=%s, IoU_all=%.3f/%.3f-mean/best, IoU>thr=%.3f-mean: ' %
(n, img_size, iou.mean(), max_iou.mean(), iou[iou > thr].mean()), end='')
for i, x in enumerate(k):
print('%i,%i' % (round(x[0]), round(x[1])), end=', ' if i < len(k) - 1 else '\n') # use in *.cfg
return k
def fitness(k): # mutation fitness
iou = wh_iou(wh, torch.Tensor(k)) # iou
max_iou = iou.max(1)[0]
return (max_iou * (max_iou > thr).float()).mean() # product
# Get label wh
wh = []
dataset = LoadImagesAndLabels(path, augment=True, rect=True)
nr = 1 if img_size[0] == img_size[1] else 10 # number augmentation repetitions
for s, l in zip(dataset.shapes, dataset.labels):
wh.append(l[:, 3:5] * (s / s.max())) # image normalized to letterbox normalized wh
wh = np.concatenate(wh, 0).repeat(nr, axis=0) # augment 10x
wh *= np.random.uniform(img_size[0], img_size[1], size=(wh.shape[0], 1)) # normalized to pixels (multi-scale)
wh = wh[(wh > 2.0).all(1)] # remove below threshold boxes (< 2 pixels wh)
# Kmeans calculation
print('开始聚类Running kmeans for %g anchors on %g points...' % (n, len(wh)))
s = wh.std(0) # sigmas for whitening
k, dist = kmeans(wh / s, n, iter=30) # points, mean distance
k *= s
wh = torch.Tensor(wh)
k = print_results(k)
# # Plot
# k, d = [None] * 20, [None] * 20
# for i in tqdm(range(1, 21)):
# k[i-1], d[i-1] = kmeans(wh / s, i) # points, mean distance
# fig, ax = plt.subplots(1, 2, figsize=(14, 7))
# ax = ax.ravel()
# ax[0].plot(np.arange(1, 21), np.array(d) ** 2, marker='.')
# fig, ax = plt.subplots(1, 2, figsize=(14, 7)) # plot wh
# ax[0].hist(wh[wh[:, 0]<100, 0],400)
# ax[1].hist(wh[wh[:, 1]<100, 1],400)
# fig.tight_layout()
# fig.savefig('wh.png', dpi=200)
# Evolve
npr = np.random
f, sh, mp, s = fitness(k), k.shape, 0.9, 0.1 # fitness, generations, mutation prob, sigma
for _ in tqdm(range(gen), desc='Evolving anchors'):
v = np.ones(sh)
while (v == 1).all(): # mutate until a change occurs (prevent duplicates)
v = ((npr.random(sh) < mp) * npr.random() * npr.randn(*sh) * s + 1).clip(0.3, 3.0)
kg = (k.copy() * v).clip(min=2.0)
fg = fitness(kg)
if fg > f:
f, k = fg, kg.copy()
print_results(k)
k = print_results(k)
return k
result = kmean_anchors(path="/home/jiang/dfy_darknet_works/darknet-master/backup_person_vehicle/train_mini_balance.txt")
print("最终结果：", result)
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