functorch/examples/maml_omniglot/maml-omniglot-higher.py - platform/external/pytorch - Git at Google

 #!/usr/bin/env python3
 #
 # Copyright (c) Facebook, Inc. and its affiliates.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.

 """
 This example shows how to use higher to do Model Agnostic Meta Learning (MAML)
 for few-shot Omniglot classification.
 For more details see the original MAML paper:
 https://arxiv.org/abs/1703.03400

 This code has been modified from Jackie Loong's PyTorch MAML implementation:
 https://github.com/dragen1860/MAML-Pytorch/blob/master/omniglot_train.py

 Our MAML++ fork and experiments are available at:
 https://github.com/bamos/HowToTrainYourMAMLPytorch
 """

 from support.omniglot_loaders import OmniglotNShot
 import higher
 import torch.optim as optim
 import torch.nn.functional as F
 from torch import nn
 import torch
 import matplotlib.pyplot as plt
 import argparse
 import time

 import pandas as pd
 import numpy as np
 import matplotlib as mpl
 mpl.use('Agg')
 plt.style.use('bmh')


 def main():
     argparser = argparse.ArgumentParser()
     argparser.add_argument('--n_way', type=int, help='n way', default=5)
     argparser.add_argument(
         '--k_spt', type=int, help='k shot for support set', default=5)
     argparser.add_argument(
         '--k_qry', type=int, help='k shot for query set', default=15)
     argparser.add_argument(
         '--device', type=str, help='device', default='cuda')
     argparser.add_argument(
         '--task_num',
         type=int,
         help='meta batch size, namely task num',
         default=32)
     argparser.add_argument('--seed', type=int, help='random seed', default=1)
     args = argparser.parse_args()

     torch.manual_seed(args.seed)
     if torch.cuda.is_available():
         torch.cuda.manual_seed_all(args.seed)
     np.random.seed(args.seed)

     # Set up the Omniglot loader.
     device = args.device
     db = OmniglotNShot(
         '/tmp/omniglot-data',
         batchsz=args.task_num,
         n_way=args.n_way,
         k_shot=args.k_spt,
         k_query=args.k_qry,
         imgsz=28,
         device=device,
     )

     # Create a vanilla PyTorch neural network that will be
     # automatically monkey-patched by higher later.
     # Before higher, models could *not* be created like this
     # and the parameters needed to be manually updated and copied
     # for the updates.
     net = nn.Sequential(
         nn.Conv2d(1, 64, 3),
         nn.BatchNorm2d(64, momentum=1, affine=True),
         nn.ReLU(inplace=True),
         nn.MaxPool2d(2, 2),
         nn.Conv2d(64, 64, 3),
         nn.BatchNorm2d(64, momentum=1, affine=True),
         nn.ReLU(inplace=True),
         nn.MaxPool2d(2, 2),
         nn.Conv2d(64, 64, 3),
         nn.BatchNorm2d(64, momentum=1, affine=True),
         nn.ReLU(inplace=True),
         nn.MaxPool2d(2, 2),
         Flatten(),
         nn.Linear(64, args.n_way)).to(device)

     # We will use Adam to (meta-)optimize the initial parameters
     # to be adapted.
     meta_opt = optim.Adam(net.parameters(), lr=1e-3)

     log = []
     for epoch in range(100):
         train(db, net, device, meta_opt, epoch, log)
         test(db, net, device, epoch, log)
         plot(log)


 def train(db, net, device, meta_opt, epoch, log):
     net.train()
     n_train_iter = db.x_train.shape[0] // db.batchsz

     for batch_idx in range(n_train_iter):
         start_time = time.time()
         # Sample a batch of support and query images and labels.
         x_spt, y_spt, x_qry, y_qry = db.next()

         task_num, setsz, c_, h, w = x_spt.size()
         querysz = x_qry.size(1)

         # TODO: Maybe pull this out into a separate module so it
         # doesn't have to be duplicated between `train` and `test`?

         # Initialize the inner optimizer to adapt the parameters to
         # the support set.
         n_inner_iter = 5
         inner_opt = torch.optim.SGD(net.parameters(), lr=1e-1)

         qry_losses = []
         qry_accs = []
         meta_opt.zero_grad()
         for i in range(task_num):
             with higher.innerloop_ctx(
                 net, inner_opt, copy_initial_weights=False
             ) as (fnet, diffopt):
                 # Optimize the likelihood of the support set by taking
                 # gradient steps w.r.t. the model's parameters.
                 # This adapts the model's meta-parameters to the task.
                 # higher is able to automatically keep copies of
                 # your network's parameters as they are being updated.
                 for _ in range(n_inner_iter):
                     spt_logits = fnet(x_spt[i])
                     spt_loss = F.cross_entropy(spt_logits, y_spt[i])
                     diffopt.step(spt_loss)

                 # The final set of adapted parameters will induce some
                 # final loss and accuracy on the query dataset.
                 # These will be used to update the model's meta-parameters.
                 qry_logits = fnet(x_qry[i])
                 qry_loss = F.cross_entropy(qry_logits, y_qry[i])
                 qry_losses.append(qry_loss.detach())
                 qry_acc = (qry_logits.argmax(
                     dim=1) == y_qry[i]).sum().item() / querysz
                 qry_accs.append(qry_acc)

                 # print([b.shape for b in fnet[1].buffers()])

                 # Update the model's meta-parameters to optimize the query
                 # losses across all of the tasks sampled in this batch.
                 # This unrolls through the gradient steps.
                 qry_loss.backward()

         meta_opt.step()
         qry_losses = sum(qry_losses) / task_num
         qry_accs = 100. * sum(qry_accs) / task_num
         i = epoch + float(batch_idx) / n_train_iter
         iter_time = time.time() - start_time
         if batch_idx % 4 == 0:
             print(
                 f'[Epoch {i:.2f}] Train Loss: {qry_losses:.2f} | Acc: {qry_accs:.2f} | Time: {iter_time:.2f}'
             )

         log.append({
             'epoch': i,
             'loss': qry_losses,
             'acc': qry_accs,
             'mode': 'train',
             'time': time.time(),
         })


 def test(db, net, device, epoch, log):
     # Crucially in our testing procedure here, we do *not* fine-tune
     # the model during testing for simplicity.
     # Most research papers using MAML for this task do an extra
     # stage of fine-tuning here that should be added if you are
     # adapting this code for research.
     net.train()
     n_test_iter = db.x_test.shape[0] // db.batchsz

     qry_losses = []
     qry_accs = []

     for _ in range(n_test_iter):
         x_spt, y_spt, x_qry, y_qry = db.next('test')

         task_num, setsz, c_, h, w = x_spt.size()

         # TODO: Maybe pull this out into a separate module so it
         # doesn't have to be duplicated between `train` and `test`?
         n_inner_iter = 5
         inner_opt = torch.optim.SGD(net.parameters(), lr=1e-1)

         for i in range(task_num):
             with higher.innerloop_ctx(net, inner_opt, track_higher_grads=False) as (fnet, diffopt):
                 # Optimize the likelihood of the support set by taking
                 # gradient steps w.r.t. the model's parameters.
                 # This adapts the model's meta-parameters to the task.
                 for _ in range(n_inner_iter):
                     spt_logits = fnet(x_spt[i])
                     spt_loss = F.cross_entropy(spt_logits, y_spt[i])
                     diffopt.step(spt_loss)

                 # The query loss and acc induced by these parameters.
                 qry_logits = fnet(x_qry[i]).detach()
                 qry_loss = F.cross_entropy(
                     qry_logits, y_qry[i], reduction='none')
                 qry_losses.append(qry_loss.detach())
                 qry_accs.append(
                     (qry_logits.argmax(dim=1) == y_qry[i]).detach())

     qry_losses = torch.cat(qry_losses).mean().item()
     qry_accs = 100. * torch.cat(qry_accs).float().mean().item()
     print(
         f'[Epoch {epoch+1:.2f}] Test Loss: {qry_losses:.2f} | Acc: {qry_accs:.2f}'
     )
     log.append({
         'epoch': epoch + 1,
         'loss': qry_losses,
         'acc': qry_accs,
         'mode': 'test',
         'time': time.time(),
     })


 def plot(log):
     # Generally you should pull your plotting code out of your training
     # script but we are doing it here for brevity.
     df = pd.DataFrame(log)

     fig, ax = plt.subplots(figsize=(6, 4))
     train_df = df[df['mode'] == 'train']
     test_df = df[df['mode'] == 'test']
     ax.plot(train_df['epoch'], train_df['acc'], label='Train')
     ax.plot(test_df['epoch'], test_df['acc'], label='Test')
     ax.set_xlabel('Epoch')
     ax.set_ylabel('Accuracy')
     ax.set_ylim(70, 100)
     fig.legend(ncol=2, loc='lower right')
     fig.tight_layout()
     fname = 'maml-accs.png'
     print(f'--- Plotting accuracy to {fname}')
     fig.savefig(fname)
     plt.close(fig)


 # Won't need this after this PR is merged in:
 # https://github.com/pytorch/pytorch/pull/22245
 class Flatten(nn.Module):
     def forward(self, input):
         return input.view(input.size(0), -1)


 if __name__ == '__main__':
     main()
	#!/usr/bin/env python3
	#
	# Copyright (c) Facebook, Inc. and its affiliates.
	#
	# Licensed under the Apache License, Version 2.0 (the "License");
	# you may not use this file except in compliance with the License.
	# You may obtain a copy of the License at
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS,
	# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	# See the License for the specific language governing permissions and
	# limitations under the License.

	"""
	This example shows how to use higher to do Model Agnostic Meta Learning (MAML)
	for few-shot Omniglot classification.
	For more details see the original MAML paper:
	https://arxiv.org/abs/1703.03400

	This code has been modified from Jackie Loong's PyTorch MAML implementation:
	https://github.com/dragen1860/MAML-Pytorch/blob/master/omniglot_train.py

	Our MAML++ fork and experiments are available at:
	https://github.com/bamos/HowToTrainYourMAMLPytorch
	"""

	from support.omniglot_loaders import OmniglotNShot
	import higher
	import torch.optim as optim
	import torch.nn.functional as F
	from torch import nn
	import torch
	import matplotlib.pyplot as plt
	import argparse
	import time

	import pandas as pd
	import numpy as np
	import matplotlib as mpl
	mpl.use('Agg')
	plt.style.use('bmh')


	def main():
	argparser = argparse.ArgumentParser()
	argparser.add_argument('--n_way', type=int, help='n way', default=5)
	argparser.add_argument(
	'--k_spt', type=int, help='k shot for support set', default=5)
	argparser.add_argument(
	'--k_qry', type=int, help='k shot for query set', default=15)
	argparser.add_argument(
	'--device', type=str, help='device', default='cuda')
	argparser.add_argument(
	'--task_num',
	type=int,
	help='meta batch size, namely task num',
	default=32)
	argparser.add_argument('--seed', type=int, help='random seed', default=1)
	args = argparser.parse_args()

	torch.manual_seed(args.seed)
	if torch.cuda.is_available():
	torch.cuda.manual_seed_all(args.seed)
	np.random.seed(args.seed)

	# Set up the Omniglot loader.
	device = args.device
	db = OmniglotNShot(
	'/tmp/omniglot-data',
	batchsz=args.task_num,
	n_way=args.n_way,
	k_shot=args.k_spt,
	k_query=args.k_qry,
	imgsz=28,
	device=device,
	)

	# Create a vanilla PyTorch neural network that will be
	# automatically monkey-patched by higher later.
	# Before higher, models could not be created like this
	# and the parameters needed to be manually updated and copied
	# for the updates.
	net = nn.Sequential(
	nn.Conv2d(1, 64, 3),
	nn.BatchNorm2d(64, momentum=1, affine=True),
	nn.ReLU(inplace=True),
	nn.MaxPool2d(2, 2),
	nn.Conv2d(64, 64, 3),
	nn.BatchNorm2d(64, momentum=1, affine=True),
	nn.ReLU(inplace=True),
	nn.MaxPool2d(2, 2),
	nn.Conv2d(64, 64, 3),
	nn.BatchNorm2d(64, momentum=1, affine=True),
	nn.ReLU(inplace=True),
	nn.MaxPool2d(2, 2),
	Flatten(),
	nn.Linear(64, args.n_way)).to(device)

	# We will use Adam to (meta-)optimize the initial parameters
	# to be adapted.
	meta_opt = optim.Adam(net.parameters(), lr=1e-3)

	log = []
	for epoch in range(100):
	train(db, net, device, meta_opt, epoch, log)
	test(db, net, device, epoch, log)
	plot(log)


	def train(db, net, device, meta_opt, epoch, log):
	net.train()
	n_train_iter = db.x_train.shape[0] // db.batchsz

	for batch_idx in range(n_train_iter):
	start_time = time.time()
	# Sample a batch of support and query images and labels.
	x_spt, y_spt, x_qry, y_qry = db.next()

	task_num, setsz, c_, h, w = x_spt.size()
	querysz = x_qry.size(1)

	# TODO: Maybe pull this out into a separate module so it
	# doesn't have to be duplicated between `train` and `test`?

	# Initialize the inner optimizer to adapt the parameters to
	# the support set.
	n_inner_iter = 5
	inner_opt = torch.optim.SGD(net.parameters(), lr=1e-1)

	qry_losses = []
	qry_accs = []
	meta_opt.zero_grad()
	for i in range(task_num):
	with higher.innerloop_ctx(
	net, inner_opt, copy_initial_weights=False
	) as (fnet, diffopt):
	# Optimize the likelihood of the support set by taking
	# gradient steps w.r.t. the model's parameters.
	# This adapts the model's meta-parameters to the task.
	# higher is able to automatically keep copies of
	# your network's parameters as they are being updated.
	for _ in range(n_inner_iter):
	spt_logits = fnet(x_spt[i])
	spt_loss = F.cross_entropy(spt_logits, y_spt[i])
	diffopt.step(spt_loss)

	# The final set of adapted parameters will induce some
	# final loss and accuracy on the query dataset.
	# These will be used to update the model's meta-parameters.
	qry_logits = fnet(x_qry[i])
	qry_loss = F.cross_entropy(qry_logits, y_qry[i])
	qry_losses.append(qry_loss.detach())
	qry_acc = (qry_logits.argmax(
	dim=1) == y_qry[i]).sum().item() / querysz
	qry_accs.append(qry_acc)

	# print([b.shape for b in fnet[1].buffers()])

	# Update the model's meta-parameters to optimize the query
	# losses across all of the tasks sampled in this batch.
	# This unrolls through the gradient steps.
	qry_loss.backward()

	meta_opt.step()
	qry_losses = sum(qry_losses) / task_num
	qry_accs = 100. * sum(qry_accs) / task_num
	i = epoch + float(batch_idx) / n_train_iter
	iter_time = time.time() - start_time
	if batch_idx % 4 == 0:
	print(
	f'[Epoch {i:.2f}] Train Loss: {qry_losses:.2f} \| Acc: {qry_accs:.2f} \| Time: {iter_time:.2f}'
	)

	log.append({
	'epoch': i,
	'loss': qry_losses,
	'acc': qry_accs,
	'mode': 'train',
	'time': time.time(),
	})


	def test(db, net, device, epoch, log):
	# Crucially in our testing procedure here, we do not fine-tune
	# the model during testing for simplicity.
	# Most research papers using MAML for this task do an extra
	# stage of fine-tuning here that should be added if you are
	# adapting this code for research.
	net.train()
	n_test_iter = db.x_test.shape[0] // db.batchsz

	qry_losses = []
	qry_accs = []

	for _ in range(n_test_iter):
	x_spt, y_spt, x_qry, y_qry = db.next('test')

	task_num, setsz, c_, h, w = x_spt.size()

	# TODO: Maybe pull this out into a separate module so it
	# doesn't have to be duplicated between `train` and `test`?
	n_inner_iter = 5
	inner_opt = torch.optim.SGD(net.parameters(), lr=1e-1)

	for i in range(task_num):
	with higher.innerloop_ctx(net, inner_opt, track_higher_grads=False) as (fnet, diffopt):
	# Optimize the likelihood of the support set by taking
	# gradient steps w.r.t. the model's parameters.
	# This adapts the model's meta-parameters to the task.
	for _ in range(n_inner_iter):
	spt_logits = fnet(x_spt[i])
	spt_loss = F.cross_entropy(spt_logits, y_spt[i])
	diffopt.step(spt_loss)

	# The query loss and acc induced by these parameters.
	qry_logits = fnet(x_qry[i]).detach()
	qry_loss = F.cross_entropy(
	qry_logits, y_qry[i], reduction='none')
	qry_losses.append(qry_loss.detach())
	qry_accs.append(
	(qry_logits.argmax(dim=1) == y_qry[i]).detach())

	qry_losses = torch.cat(qry_losses).mean().item()
	qry_accs = 100. * torch.cat(qry_accs).float().mean().item()
	print(
	f'[Epoch {epoch+1:.2f}] Test Loss: {qry_losses:.2f} \| Acc: {qry_accs:.2f}'
	)
	log.append({
	'epoch': epoch + 1,
	'loss': qry_losses,
	'acc': qry_accs,
	'mode': 'test',
	'time': time.time(),
	})


	def plot(log):
	# Generally you should pull your plotting code out of your training
	# script but we are doing it here for brevity.
	df = pd.DataFrame(log)

	fig, ax = plt.subplots(figsize=(6, 4))
	train_df = df[df['mode'] == 'train']
	test_df = df[df['mode'] == 'test']
	ax.plot(train_df['epoch'], train_df['acc'], label='Train')
	ax.plot(test_df['epoch'], test_df['acc'], label='Test')
	ax.set_xlabel('Epoch')
	ax.set_ylabel('Accuracy')
	ax.set_ylim(70, 100)
	fig.legend(ncol=2, loc='lower right')
	fig.tight_layout()
	fname = 'maml-accs.png'
	print(f'--- Plotting accuracy to {fname}')
	fig.savefig(fname)
	plt.close(fig)


	# Won't need this after this PR is merged in:
	# https://github.com/pytorch/pytorch/pull/22245
	class Flatten(nn.Module):
	def forward(self, input):
	return input.view(input.size(0), -1)


	if __name__ == '__main__':
	main()