Optimizing Partial AUROC Loss (pAUCLoss)

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Author: Zhuoning Yuan, Dixian Zhu, Gang Li, Tianbao Yang

Version: 1.4.0

Introduction

In this tutorial, you will learn how to quickly train a Resnet18 model by optimizing One way Partial AUC (OPAUC) with our novel pAUCLoss [ref] on a binary image classification task with the CIFAR-10 dataset. Please note that pAUCLoss is a wrapper function for different types of partial AUC losses. It currently supports two primary modes:

• pAUCLoss('1w'): This mode aims to optimize One-way Partial AUC using pAUC_DRO_Loss as the backend and utilizing the SOAPs optimizer for optimization.

• pAUCLoss('2w'): This mode aims to optimize Two-way Partial AUC using tpAUC_KL_Loss as the backend and utilizing the SOTAs optimizer for optimization.

This function allows for flexibility in handling varying partial AUC loss in different scenarios. For the original tutorials, please refer to SOPAs, SOPA, and SOTAs. After completing this tutorial, you should be able to use LibAUC to train your own models on your own datasets.

Reference:

If you find this tutorial helpful in your work, please cite our library paper and the following papers:

@inproceedings{zhu2022auc,
               title={When auc meets dro: Optimizing partial auc for deep learning with non-convex convergence guarantee},
               author={Zhu, Dixian and Li, Gang and Wang, Bokun and Wu, Xiaodong and Yang, Tianbao},
               booktitle={International Conference on Machine Learning},
               pages={27548--27573},
               year={2022},
               organization={PMLR}
            }

Install LibAUC

Let’s start with installing our library here. In this tutorial, we will use the lastest version for LibAUC by using pip install -U.

!pip install -U libauc

Importing LibAUC

Import required packages to use

from libauc.losses import pAUCLoss
from libauc.optimizers import SOPAs
from libauc.models import resnet18 as ResNet18
from libauc.datasets import CIFAR10
from libauc.utils import ImbalancedDataGenerator
from libauc.sampler import DualSampler
from libauc.metrics import auc_roc_score

import torchvision.transforms as transforms
from torch.utils.data import Dataset
import numpy as np
import torch
from PIL import Image

Reproducibility

The following function set_all_seeds limits the number of sources of randomness behaviors, such as model intialization, data shuffling, etcs. However, completely reproducible results are not guaranteed across PyTorch releases [Ref].

def set_all_seeds(SEED):
   # REPRODUCIBILITY
   np.random.seed(SEED)
   torch.manual_seed(SEED)
   torch.cuda.manual_seed(SEED)
   torch.backends.cudnn.deterministic = True
   torch.backends.cudnn.benchmark = False
set_all_seeds(2023)

Loading datasets

In this step, we will use the CIFAR10 as benchmark dataset. Before importing data to dataloader, we construct imbalanced version for CIFAR10 by ImbalanceDataGenerator. Specifically, it first randomly splits the training data by class ID (e.g., 10 classes) into two even portions as the positive and negative classes, and then it randomly removes some samples from the positive class to make it imbalanced. We refer imratio to the ratio of number of positive examples to number of all examples.

train_data, train_targets = CIFAR10(root='./data', train=True).as_array()
test_data, test_targets  = CIFAR10(root='./data', train=False).as_array()

imratio = 0.2
generator = ImbalancedDataGenerator(shuffle=True, verbose=True, random_seed=2023)
(train_images, train_labels) = generator.transform(train_data, train_targets, imratio=imratio)
(test_images, test_labels) = generator.transform(test_data, test_targets, imratio=imratio)

We define the data input pipeline such as data augmentations. In this tutorial, we use RandomCrop, RandomHorizontalFlip.

class ImageDataset(Dataset):
   def __init__(self, images, targets, image_size=32, crop_size=30, mode='train'):
      self.images = images.astype(np.uint8)
      self.targets = targets
      self.mode = mode
      self.transform_train = transforms.Compose([
                              transforms.ToTensor(),
                              transforms.RandomCrop((crop_size, crop_size), padding=None),
                              transforms.RandomHorizontalFlip(),
                              transforms.Resize((image_size, image_size), antialias=True),
                              ])
      self.transform_test = transforms.Compose([
                           transforms.ToTensor(),
                           transforms.Resize((image_size, image_size), antialias=True),
                              ])
   def __len__(self):
      return len(self.images)

   def __getitem__(self, idx):
      image = self.images[idx]
      target = self.targets[idx]
      image = Image.fromarray(image.astype('uint8'))
      if self.mode == 'train':
            image = self.transform_train(image)
      else:
            image = self.transform_test(image)
      return image, target, idx

Configuration

Hyper-Parameters

lr = 1e-3
margin = 0.6
gamma = 0.1
Lambda = 1.0
weight_decay = 2e-4
total_epoch = 60
decay_epoch = [30,45]
load_pretrain = False

Pretraining (Recommended)

Following the original paper, it’s recommended to start from a pretrained checkpoint with cross-entropy loss to significantly boost models’ performance. It includes a pre-training step with standard cross-entropy loss, and a Partial AUC maximization step that maximizes a Partial AUC surrogate loss of the pre-trained model.

from torch.optim import Adam
import warnings
warnings.filterwarnings('ignore')

load_pretrain = True
model = ResNet18(pretrained=False, last_activation=None, num_classes=1)
model = model.cuda()

loss_fn = torch.nn.BCELoss()
optimizer =Adam(model.parameters(), lr=lr, weight_decay=weight_decay)

trainloader = torch.utils.data.DataLoader(trainSet, batch_size=batch_size, shuffle=True, num_workers=2)
testloader = torch.utils.data.DataLoader(testSet, batch_size=batch_size, shuffle=False, num_workers=2)


best_test = 0
for epoch in range(total_epoch):
   if epoch in decay_epoch:
      for param_group in optimizer.param_groups:
            param_group['lr'] = 0.1 * param_group['lr']

   model.train()
   for idx, (data, targets, index) in enumerate(trainloader):
      data, targets, index  = data.cuda(), targets.cuda(), index.cuda()
      y_pred = model(data)
      y_prob = torch.sigmoid(y_pred)
      loss = loss_fn(y_prob, targets)
      optimizer.zero_grad()
      loss.backward()
      optimizer.step()

   ######***evaluation***####
   # evaluation on test sets
   model.eval()
   test_pred_list, test_true_list = [], []
   with torch.no_grad():
      for j, data in enumerate(testloader):
            test_data, test_targets, _ = data
            test_data = test_data.cuda()
            y_pred = model(test_data)
            y_prob = torch.sigmoid(y_pred)
            test_pred_list.append(y_prob.cpu().detach().numpy())
            test_true_list.append(test_targets.numpy())
   test_true = np.concatenate(test_true_list)
   test_pred = np.concatenate(test_pred_list)

   test_pauc =  auc_roc_score(test_true, test_pred,max_fpr=0.3)
   if best_test < test_pauc:
      best_test = test_pauc
      torch.save(model.state_dict(), 'ce_pretrained_model_wrapper.pth')

   model.train()
   print("epoch: %s, test_pauc: %.4f, best_test_pauc: %.4f, lr: %.4f"%(epoch, test_pauc, best_test, optimizer.param_groups[0]['lr'] ))

epoch: 0, test_pauc: 0.6030, best_test_pauc: 0.6030, lr: 0.0010
epoch: 1, test_pauc: 0.6749, best_test_pauc: 0.6749, lr: 0.0010
epoch: 2, test_pauc: 0.6666, best_test_pauc: 0.6749, lr: 0.0010
epoch: 3, test_pauc: 0.6917, best_test_pauc: 0.6917, lr: 0.0010
epoch: 4, test_pauc: 0.6525, best_test_pauc: 0.6917, lr: 0.0010
epoch: 5, test_pauc: 0.7070, best_test_pauc: 0.7070, lr: 0.0010
epoch: 6, test_pauc: 0.7555, best_test_pauc: 0.7555, lr: 0.0010
epoch: 7, test_pauc: 0.7448, best_test_pauc: 0.7555, lr: 0.0010
epoch: 8, test_pauc: 0.7583, best_test_pauc: 0.7583, lr: 0.0010
epoch: 9, test_pauc: 0.7545, best_test_pauc: 0.7583, lr: 0.0010
epoch: 10, test_pauc: 0.7258, best_test_pauc: 0.7583, lr: 0.0010
epoch: 11, test_pauc: 0.7956, best_test_pauc: 0.7956, lr: 0.0010
epoch: 12, test_pauc: 0.8150, best_test_pauc: 0.8150, lr: 0.0010
epoch: 13, test_pauc: 0.8036, best_test_pauc: 0.8150, lr: 0.0010
epoch: 14, test_pauc: 0.7952, best_test_pauc: 0.8150, lr: 0.0010
epoch: 15, test_pauc: 0.8003, best_test_pauc: 0.8150, lr: 0.0010
epoch: 16, test_pauc: 0.7778, best_test_pauc: 0.8150, lr: 0.0010
epoch: 17, test_pauc: 0.8249, best_test_pauc: 0.8249, lr: 0.0010
epoch: 18, test_pauc: 0.8038, best_test_pauc: 0.8249, lr: 0.0010
epoch: 19, test_pauc: 0.8295, best_test_pauc: 0.8295, lr: 0.0010
epoch: 20, test_pauc: 0.8236, best_test_pauc: 0.8295, lr: 0.0010
epoch: 21, test_pauc: 0.8370, best_test_pauc: 0.8370, lr: 0.0010
epoch: 22, test_pauc: 0.8464, best_test_pauc: 0.8464, lr: 0.0010
epoch: 23, test_pauc: 0.8088, best_test_pauc: 0.8464, lr: 0.0010
epoch: 24, test_pauc: 0.8337, best_test_pauc: 0.8464, lr: 0.0010
epoch: 25, test_pauc: 0.8365, best_test_pauc: 0.8464, lr: 0.0010
epoch: 26, test_pauc: 0.8448, best_test_pauc: 0.8464, lr: 0.0010
epoch: 27, test_pauc: 0.8076, best_test_pauc: 0.8464, lr: 0.0010
epoch: 28, test_pauc: 0.8388, best_test_pauc: 0.8464, lr: 0.0010
epoch: 29, test_pauc: 0.8477, best_test_pauc: 0.8477, lr: 0.0010
epoch: 30, test_pauc: 0.8617, best_test_pauc: 0.8617, lr: 0.0001
epoch: 31, test_pauc: 0.8637, best_test_pauc: 0.8637, lr: 0.0001
epoch: 32, test_pauc: 0.8625, best_test_pauc: 0.8637, lr: 0.0001
epoch: 33, test_pauc: 0.8640, best_test_pauc: 0.8640, lr: 0.0001
epoch: 34, test_pauc: 0.8611, best_test_pauc: 0.8640, lr: 0.0001
epoch: 35, test_pauc: 0.8651, best_test_pauc: 0.8651, lr: 0.0001
epoch: 36, test_pauc: 0.8583, best_test_pauc: 0.8651, lr: 0.0001
epoch: 37, test_pauc: 0.8665, best_test_pauc: 0.8665, lr: 0.0001
epoch: 38, test_pauc: 0.8643, best_test_pauc: 0.8665, lr: 0.0001
epoch: 39, test_pauc: 0.8634, best_test_pauc: 0.8665, lr: 0.0001
epoch: 40, test_pauc: 0.8619, best_test_pauc: 0.8665, lr: 0.0001
epoch: 41, test_pauc: 0.8612, best_test_pauc: 0.8665, lr: 0.0001
epoch: 42, test_pauc: 0.8610, best_test_pauc: 0.8665, lr: 0.0001
epoch: 43, test_pauc: 0.8600, best_test_pauc: 0.8665, lr: 0.0001
epoch: 44, test_pauc: 0.8612, best_test_pauc: 0.8665, lr: 0.0001
epoch: 45, test_pauc: 0.8629, best_test_pauc: 0.8665, lr: 0.0000
epoch: 46, test_pauc: 0.8630, best_test_pauc: 0.8665, lr: 0.0000
epoch: 47, test_pauc: 0.8625, best_test_pauc: 0.8665, lr: 0.0000
epoch: 48, test_pauc: 0.8627, best_test_pauc: 0.8665, lr: 0.0000
epoch: 49, test_pauc: 0.8642, best_test_pauc: 0.8665, lr: 0.0000
epoch: 50, test_pauc: 0.8619, best_test_pauc: 0.8665, lr: 0.0000
epoch: 51, test_pauc: 0.8629, best_test_pauc: 0.8665, lr: 0.0000
epoch: 52, test_pauc: 0.8627, best_test_pauc: 0.8665, lr: 0.0000
epoch: 53, test_pauc: 0.8637, best_test_pauc: 0.8665, lr: 0.0000
epoch: 54, test_pauc: 0.8598, best_test_pauc: 0.8665, lr: 0.0000
epoch: 55, test_pauc: 0.8605, best_test_pauc: 0.8665, lr: 0.0000
epoch: 56, test_pauc: 0.8606, best_test_pauc: 0.8665, lr: 0.0000
epoch: 57, test_pauc: 0.8622, best_test_pauc: 0.8665, lr: 0.0000
epoch: 58, test_pauc: 0.8618, best_test_pauc: 0.8665, lr: 0.0000
epoch: 59, test_pauc: 0.8610, best_test_pauc: 0.8665, lr: 0.0000

Optimizing pAUC Loss

We define dataset, DualSampler and dataloader here. By default, we use batch_size 64 and we oversample the minority class with pos:neg=1:1 by setting sampling_rate=0.5.

sampling_rate = 0.5

sampler = DualSampler(trainSet, batch_size, sampling_rate=sampling_rate)
trainloader = torch.utils.data.DataLoader(trainSet, batch_size=batch_size, sampler=sampler, num_workers=2)
trainloader_eval = torch.utils.data.DataLoader(trainSet_eval, batch_size=batch_size, shuffle=False, num_workers=2)
testloader = torch.utils.data.DataLoader(testSet, batch_size=batch_size, shuffle=False, num_workers=2)

Model, Loss and Optimizer

model = ResNet18(pretrained=False, last_activation=None, num_classes=1)
model = model.cuda()
# load pretrained model
if load_pretrain:
   PATH = 'ce_pretrained_model_wrapper.pth'
   state_dict = torch.load(PATH)
   filtered = {k:v for k,v in state_dict.items() if 'fc' not in k}
   msg = model.load_state_dict(filtered, False)
   print(msg)
   model.fc.reset_parameters()

loss_fn = pAUCLoss('1w', data_len=len(trainSet), margin=margin, gamma=gamma)
optimizer = SOPAs(model.parameters(), mode='adam', lr=lr, weight_decay=weight_decay)

Training

Now it’s time for training. And we evaluate partial AUC performance with False Positive Rate(FPR) less than or equal to 0.3, i.e., FPR ≤ 0.3.

print ('Start Training')
print ('-'*30)

train_log, test_log = [], []
best_test = 0
for epoch in range(total_epoch):
   if epoch in decay_epoch:
      optimizer.update_lr(decay_factor=10)

   train_loss = []
   model.train()
   for idx, (data, targets, index) in enumerate(trainloader):
      data, targets, index  = data.cuda(), targets.cuda(), index.cuda()
      y_pred = model(data)
      y_prob = torch.sigmoid(y_pred)
      loss = loss_fn(y_prob, targets, index)
      optimizer.zero_grad()
      loss.backward()
      optimizer.step()
      train_loss.append(loss.item())

   ######***evaluation***####
   # evaluation on training sets
   model.eval()
   train_pred_list, train_true_list = [], []
   with torch.no_grad():
      for i, data in enumerate(trainloader_eval):
            train_data, train_targets, _ = data
            train_data = train_data.cuda()
            y_pred = model(train_data)
            y_prob = torch.sigmoid(y_pred)
            train_pred_list.append(y_prob.cpu().detach().numpy())
            train_true_list.append(train_targets.cpu().detach().numpy())
   train_true = np.concatenate(train_true_list)
   train_pred = np.concatenate(train_pred_list)

   train_pauc = auc_roc_score(train_true, train_pred, max_fpr=0.3)
   train_loss = np.mean(train_loss)
   train_log.append(train_pauc)

   # evaluation on test sets
   model.eval()
   test_pred_list, test_true_list = [], []
   with torch.no_grad():
      for j, data in enumerate(testloader):
            test_data, test_targets, _ = data
            test_data = test_data.cuda()
            y_pred = model(test_data)
            y_prob = torch.sigmoid(y_pred)
            test_pred_list.append(y_prob.cpu().detach().numpy())
            test_true_list.append(test_targets.numpy())
   test_true = np.concatenate(test_true_list)
   test_pred = np.concatenate(test_pred_list)

   test_pauc =  auc_roc_score(test_true, test_pred,max_fpr=0.3)
   test_log.append(test_pauc)
   if best_test < test_pauc:
      best_test = test_pauc

   model.train()
   # print results
   print("epoch: %s, train_loss: %.4f, train_pauc: %.4f, test_pauc: %.4f, best_test_pauc: %.4f, lr: %.5f"%(epoch, train_loss, train_pauc, test_pauc, best_test, optimizer.lr ))

Start Training
------------------------------
epoch: 0, train_loss: 0.3522, train_pauc: 0.9630, test_pauc: 0.8541, best_test_pauc: 0.8541, lr: 0.00100
epoch: 1, train_loss: 0.0697, train_pauc: 0.9768, test_pauc: 0.8649, best_test_pauc: 0.8649, lr: 0.00100
epoch: 2, train_loss: 0.0506, train_pauc: 0.9738, test_pauc: 0.8564, best_test_pauc: 0.8649, lr: 0.00100
epoch: 3, train_loss: 0.0469, train_pauc: 0.9654, test_pauc: 0.8444, best_test_pauc: 0.8649, lr: 0.00100
epoch: 4, train_loss: 0.0520, train_pauc: 0.9526, test_pauc: 0.8472, best_test_pauc: 0.8649, lr: 0.00100
epoch: 5, train_loss: 0.0553, train_pauc: 0.9336, test_pauc: 0.8261, best_test_pauc: 0.8649, lr: 0.00100
epoch: 6, train_loss: 0.0549, train_pauc: 0.9498, test_pauc: 0.8424, best_test_pauc: 0.8649, lr: 0.00100
epoch: 7, train_loss: 0.0581, train_pauc: 0.9371, test_pauc: 0.8402, best_test_pauc: 0.8649, lr: 0.00100
epoch: 8, train_loss: 0.0574, train_pauc: 0.9286, test_pauc: 0.8284, best_test_pauc: 0.8649, lr: 0.00100
epoch: 9, train_loss: 0.0565, train_pauc: 0.9347, test_pauc: 0.8321, best_test_pauc: 0.8649, lr: 0.00100
epoch: 10, train_loss: 0.0549, train_pauc: 0.9601, test_pauc: 0.8605, best_test_pauc: 0.8649, lr: 0.00100
epoch: 11, train_loss: 0.0561, train_pauc: 0.9535, test_pauc: 0.8406, best_test_pauc: 0.8649, lr: 0.00100
epoch: 12, train_loss: 0.0580, train_pauc: 0.9267, test_pauc: 0.8260, best_test_pauc: 0.8649, lr: 0.00100
epoch: 13, train_loss: 0.0533, train_pauc: 0.9428, test_pauc: 0.8412, best_test_pauc: 0.8649, lr: 0.00100
epoch: 14, train_loss: 0.0559, train_pauc: 0.9352, test_pauc: 0.8281, best_test_pauc: 0.8649, lr: 0.00100
epoch: 15, train_loss: 0.0543, train_pauc: 0.9522, test_pauc: 0.8451, best_test_pauc: 0.8649, lr: 0.00100
epoch: 16, train_loss: 0.0540, train_pauc: 0.9401, test_pauc: 0.8430, best_test_pauc: 0.8649, lr: 0.00100
epoch: 17, train_loss: 0.0512, train_pauc: 0.9563, test_pauc: 0.8546, best_test_pauc: 0.8649, lr: 0.00100
epoch: 18, train_loss: 0.0546, train_pauc: 0.9514, test_pauc: 0.8495, best_test_pauc: 0.8649, lr: 0.00100
epoch: 19, train_loss: 0.0530, train_pauc: 0.9581, test_pauc: 0.8441, best_test_pauc: 0.8649, lr: 0.00100
epoch: 20, train_loss: 0.0512, train_pauc: 0.9253, test_pauc: 0.8182, best_test_pauc: 0.8649, lr: 0.00100
epoch: 21, train_loss: 0.0483, train_pauc: 0.9604, test_pauc: 0.8523, best_test_pauc: 0.8649, lr: 0.00100
epoch: 22, train_loss: 0.0519, train_pauc: 0.9605, test_pauc: 0.8637, best_test_pauc: 0.8649, lr: 0.00100
epoch: 23, train_loss: 0.0521, train_pauc: 0.9546, test_pauc: 0.8557, best_test_pauc: 0.8649, lr: 0.00100
epoch: 24, train_loss: 0.0522, train_pauc: 0.9569, test_pauc: 0.8489, best_test_pauc: 0.8649, lr: 0.00100
epoch: 25, train_loss: 0.0479, train_pauc: 0.9481, test_pauc: 0.8423, best_test_pauc: 0.8649, lr: 0.00100
epoch: 26, train_loss: 0.0504, train_pauc: 0.9369, test_pauc: 0.8345, best_test_pauc: 0.8649, lr: 0.00100
epoch: 27, train_loss: 0.0487, train_pauc: 0.9485, test_pauc: 0.8392, best_test_pauc: 0.8649, lr: 0.00100
epoch: 28, train_loss: 0.0509, train_pauc: 0.9250, test_pauc: 0.8219, best_test_pauc: 0.8649, lr: 0.00100
epoch: 29, train_loss: 0.0488, train_pauc: 0.9502, test_pauc: 0.8422, best_test_pauc: 0.8649, lr: 0.00100
Reducing learning rate to 0.00010 @ T=23430!
epoch: 30, train_loss: 0.0240, train_pauc: 0.9849, test_pauc: 0.8724, best_test_pauc: 0.8724, lr: 0.00010
epoch: 31, train_loss: 0.0153, train_pauc: 0.9880, test_pauc: 0.8733, best_test_pauc: 0.8733, lr: 0.00010
epoch: 32, train_loss: 0.0117, train_pauc: 0.9906, test_pauc: 0.8746, best_test_pauc: 0.8746, lr: 0.00010
epoch: 33, train_loss: 0.0100, train_pauc: 0.9914, test_pauc: 0.8739, best_test_pauc: 0.8746, lr: 0.00010
epoch: 34, train_loss: 0.0087, train_pauc: 0.9930, test_pauc: 0.8735, best_test_pauc: 0.8746, lr: 0.00010
epoch: 35, train_loss: 0.0082, train_pauc: 0.9927, test_pauc: 0.8746, best_test_pauc: 0.8746, lr: 0.00010
epoch: 36, train_loss: 0.0069, train_pauc: 0.9925, test_pauc: 0.8687, best_test_pauc: 0.8746, lr: 0.00010
epoch: 37, train_loss: 0.0059, train_pauc: 0.9939, test_pauc: 0.8746, best_test_pauc: 0.8746, lr: 0.00010
epoch: 38, train_loss: 0.0056, train_pauc: 0.9955, test_pauc: 0.8726, best_test_pauc: 0.8746, lr: 0.00010
epoch: 39, train_loss: 0.0051, train_pauc: 0.9939, test_pauc: 0.8707, best_test_pauc: 0.8746, lr: 0.00010
epoch: 40, train_loss: 0.0048, train_pauc: 0.9946, test_pauc: 0.8727, best_test_pauc: 0.8746, lr: 0.00010
epoch: 41, train_loss: 0.0048, train_pauc: 0.9954, test_pauc: 0.8733, best_test_pauc: 0.8746, lr: 0.00010
epoch: 42, train_loss: 0.0041, train_pauc: 0.9963, test_pauc: 0.8803, best_test_pauc: 0.8803, lr: 0.00010
epoch: 43, train_loss: 0.0041, train_pauc: 0.9952, test_pauc: 0.8714, best_test_pauc: 0.8803, lr: 0.00010
epoch: 44, train_loss: 0.0037, train_pauc: 0.9964, test_pauc: 0.8760, best_test_pauc: 0.8803, lr: 0.00010
Reducing learning rate to 0.00001 @ T=35145!
epoch: 45, train_loss: 0.0032, train_pauc: 0.9968, test_pauc: 0.8773, best_test_pauc: 0.8803, lr: 0.00001
epoch: 46, train_loss: 0.0027, train_pauc: 0.9970, test_pauc: 0.8776, best_test_pauc: 0.8803, lr: 0.00001
epoch: 47, train_loss: 0.0024, train_pauc: 0.9973, test_pauc: 0.8782, best_test_pauc: 0.8803, lr: 0.00001
epoch: 48, train_loss: 0.0022, train_pauc: 0.9966, test_pauc: 0.8763, best_test_pauc: 0.8803, lr: 0.00001
epoch: 49, train_loss: 0.0022, train_pauc: 0.9973, test_pauc: 0.8776, best_test_pauc: 0.8803, lr: 0.00001
epoch: 50, train_loss: 0.0019, train_pauc: 0.9970, test_pauc: 0.8769, best_test_pauc: 0.8803, lr: 0.00001
epoch: 51, train_loss: 0.0022, train_pauc: 0.9975, test_pauc: 0.8777, best_test_pauc: 0.8803, lr: 0.00001
epoch: 52, train_loss: 0.0018, train_pauc: 0.9970, test_pauc: 0.8773, best_test_pauc: 0.8803, lr: 0.00001
epoch: 53, train_loss: 0.0019, train_pauc: 0.9970, test_pauc: 0.8763, best_test_pauc: 0.8803, lr: 0.00001
epoch: 54, train_loss: 0.0019, train_pauc: 0.9975, test_pauc: 0.8776, best_test_pauc: 0.8803, lr: 0.00001
epoch: 55, train_loss: 0.0018, train_pauc: 0.9974, test_pauc: 0.8775, best_test_pauc: 0.8803, lr: 0.00001
epoch: 56, train_loss: 0.0019, train_pauc: 0.9973, test_pauc: 0.8778, best_test_pauc: 0.8803, lr: 0.00001
epoch: 57, train_loss: 0.0016, train_pauc: 0.9978, test_pauc: 0.8787, best_test_pauc: 0.8803, lr: 0.00001
epoch: 58, train_loss: 0.0018, train_pauc: 0.9974, test_pauc: 0.8767, best_test_pauc: 0.8803, lr: 0.00001
epoch: 59, train_loss: 0.0015, train_pauc: 0.9975, test_pauc: 0.8758, best_test_pauc: 0.8803, lr: 0.00001

Visualization

Now, let’s see the learning curves for optimizing pAUC from scratch and from a pretrained model with cross entropy loss.

import matplotlib.pyplot as plt
import numpy as np
train_log= [0.9629983121568626, 0.976789697254902, 0.9737728125490197, 0.9653674415686273, 0.9526080000000001, 0.9336441725490195, 0.9497985317647059, 0.9371098352941176, 0.9286405458823529, 0.9346945380392156, 0.9601394321568628, 0.953512702745098, 0.9266596831372549, 0.9428325396078432, 0.9351774494117648, 0.9522345788235294, 0.9401062211764706, 0.9563442384313725, 0.9514192501960784, 0.9580526368627451, 0.9253358619607843, 0.9603840376470587, 0.9605023058823529, 0.9546136219607844, 0.9568967592156863, 0.9480975999999999, 0.9369100862745098, 0.9484633725490195, 0.9249502117647059, 0.9502059231372548, 0.9849486870588235, 0.9879563984313726, 0.9905859952941177, 0.9913526462745099, 0.9930277772549019, 0.9927193474509803, 0.9925047341176472, 0.9938547639215686, 0.9954592501960785, 0.993869954509804, 0.9945825756862745, 0.995418591372549, 0.996329662745098, 0.9951745380392156, 0.9963752847058824, 0.9967506447058823, 0.9969702023529412, 0.9972820956862744, 0.9966350243137254, 0.9973091764705881, 0.9970341521568626, 0.9974569160784313, 0.9970073286274509, 0.997043074509804, 0.9975259356862745, 0.9974475294117646, 0.9973477584313726, 0.9977820172549019, 0.9974407278431374, 0.9975082290196078]
test_log = [0.8540740392156863, 0.8649267450980391, 0.8564147450980393, 0.8444150588235293, 0.8471686274509804, 0.826121725490196, 0.8424131764705882, 0.8401847843137256, 0.8284373333333332, 0.8320996078431373, 0.8604749803921569, 0.840553725490196, 0.8259722352941177, 0.8412304313725489, 0.8280956862745098, 0.8450829803921568, 0.843001725490196, 0.854564862745098, 0.8495196862745098, 0.8440784313725489, 0.8182186666666666, 0.8522569411764706, 0.8636740392156863, 0.8557358431372548, 0.8489019607843137, 0.8422538039215686, 0.8344840784313725, 0.8391745882352941, 0.8218570980392157, 0.8421825882352941, 0.8723526274509803, 0.8732980392156863, 0.8746343529411764, 0.8739411764705883, 0.8735287843137255, 0.8745794509803921, 0.8686682352941176, 0.8746359215686275, 0.8726382745098038, 0.8706779607843138, 0.8727118431372549, 0.8732894117647059, 0.880304156862745, 0.8714334117647058, 0.8760409411764706, 0.8772798431372548, 0.8776307450980392, 0.8781731764705882, 0.8763093333333334, 0.8776247843137255, 0.8768696470588234, 0.8777276862745098, 0.8773055686274509, 0.8763356862745098, 0.877628862745098, 0.8775463529411764, 0.8778290196078431, 0.8787496470588235, 0.876702431372549, 0.8758170980392157]
train_log_scratch = [0.6890966588235294, 0.7498066949019607, 0.77299424, 0.7538028737254903, 0.7556846180392157, 0.8407256533333333, 0.8185373364705881, 0.8357328627450981, 0.8290430870588235, 0.8706400188235295, 0.8983218823529411, 0.8901459952941176, 0.8762650792156863, 0.8643537192156863, 0.8762003952941176, 0.9327183498039215, 0.9058492549019608, 0.9225154133333333, 0.9391776564705883, 0.9153873443137255, 0.9427768156862745, 0.918611105882353, 0.9488297160784314, 0.9422692141176472, 0.9397862211764705, 0.9447884047058823, 0.9376482133333333, 0.9170201662745099, 0.9400590368627451, 0.9428715294117647, 0.9827926776470589, 0.9869608282352941, 0.9892946447058824, 0.9910100705882354, 0.9913128219607843, 0.993834779607843, 0.9938273317647058, 0.9955538698039215, 0.9949663435294117, 0.9957406619607845, 0.9957660737254902, 0.9957580674509803, 0.9957963294117649, 0.9963942901960784, 0.9965594917647058, 0.9969945600000001, 0.9972550839215686, 0.9974924862745098, 0.9969971074509804, 0.997616803137255, 0.9976887654901962, 0.9980113945098039, 0.9977375623529412, 0.9977079843137253, 0.9979535686274509, 0.998025951372549, 0.998142908235294, 0.9981611168627451, 0.9977764141176471, 0.9979765709803923]
test_log_scratch = [0.6823946666666666, 0.7297479215686274, 0.747155137254902, 0.7293926274509804, 0.7213540392156863, 0.7886792156862745, 0.7819234509803922, 0.7881909019607842, 0.7723794509803921, 0.7988341960784313, 0.8359945098039215, 0.8195965490196079, 0.8108655686274511, 0.7986409411764706, 0.7982105098039216, 0.852886274509804, 0.819928156862745, 0.8454426666666666, 0.8503579607843137, 0.8292087843137255, 0.8498487843137255, 0.8227733333333334, 0.8496687058823529, 0.8344301176470588, 0.84, 0.8395469803921568, 0.8437207843137255, 0.8221675294117646, 0.8352611764705882, 0.8306180392156863, 0.8663220392156863, 0.8681480784313725, 0.8710854901960785, 0.8700506666666667, 0.8700886274509803, 0.8714505098039216, 0.8706748235294117, 0.8733140392156862, 0.873332705882353, 0.874576, 0.8714436078431371, 0.8704718431372549, 0.8702296470588236, 0.8724760784313725, 0.8709339607843137, 0.8711752156862745, 0.8721429019607843, 0.8720614901960784, 0.869857725490196, 0.8717300392156864, 0.8717584313725489, 0.8734641568627451, 0.8732724705882353, 0.8717474509803922, 0.8723347450980391, 0.8721515294117648, 0.8720542745098039, 0.8722836078431372, 0.87048, 0.8709046274509804]


fig, (ax0, ax1) = plt.subplots(1, 2, figsize=(12,5))
plt.suptitle('CIFAR-10 (20% imbalanced)',fontsize=25)

x=np.arange(len(train_log))
ax0.plot(x, train_log_scratch,  label='From Scratch', linewidth=3)
ax0.plot(x, train_log,  label='From Pretraining', linewidth=3)
ax0.set_title('Training',fontsize=25)
ax1.plot(x, test_log_scratch, label='From Scratch', linewidth=3)
ax1.plot(x, test_log, label='From Pretraining', linewidth=3)
ax1.set_title('Testing',fontsize=25)

ax0.legend(fontsize=15)
ax1.legend(fontsize=15)
ax0.set_ylabel('pAUC(FPR≤0.3)', fontsize=20)
ax0.set_xlabel('Epoch', fontsize=20)
ax1.set_ylabel('pAUC(FPR≤0.3)', fontsize=20)
ax1.set_xlabel('Epoch', fontsize=20)

plt.tight_layout()