# Licensed to the Apache Software Foundation (ASF) under one # or more contributor license agreements. See the NOTICE file # distributed with this work for additional information # regarding copyright ownership. The ASF licenses this file # to you 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. ''' Adapted from https://github.com/tornadomeet/ResNet/blob/master/symbol_resnet.py Original author Wei Wu Implemented the following paper: Kaiming He, Xiangyu Zhang, Shaoqing Ren, Jian Sun. "Identity Mappings in Deep Residual Networks" ''' import mxnet as mx import numpy as np def residual_unit(data, num_filter, stride, dim_match, name, bottle_neck=True, bn_mom=0.9, workspace=256, memonger=False): """Return ResNet Unit symbol for building ResNet Parameters ---------- data : str Input data num_filter : int Number of output channels bnf : int Bottle neck channels factor with regard to num_filter stride : tuple Stride used in convolution dim_match : Boolean True means channel number between input and output is the same, otherwise means differ name : str Base name of the operators workspace : int Workspace used in convolution operator """ if bottle_neck: # the same as https://github.com/facebook/fb.resnet.torch#notes, a bit difference with origin paper bn1 = mx.sym.BatchNorm(data=data, fix_gamma=False, eps=2e-5, momentum=bn_mom, name=name + '_bn1') act1 = mx.sym.Activation(data=bn1, act_type='relu', name=name + '_relu1') conv1 = mx.sym.Convolution(data=act1, num_filter=int(num_filter*0.25), kernel=(1,1), stride=(1,1), pad=(0,0), no_bias=True, workspace=workspace, name=name + '_conv1') bn2 = mx.sym.BatchNorm(data=conv1, fix_gamma=False, eps=2e-5, momentum=bn_mom, name=name + '_bn2') act2 = mx.sym.Activation(data=bn2, act_type='relu', name=name + '_relu2') conv2 = mx.sym.Convolution(data=act2, num_filter=int(num_filter*0.25), kernel=(3,3), stride=stride, pad=(1,1), no_bias=True, workspace=workspace, name=name + '_conv2') bn3 = mx.sym.BatchNorm(data=conv2, fix_gamma=False, eps=2e-5, momentum=bn_mom, name=name + '_bn3') act3 = mx.sym.Activation(data=bn3, act_type='relu', name=name + '_relu3') conv3 = mx.sym.Convolution(data=act3, num_filter=num_filter, kernel=(1,1), stride=(1,1), pad=(0,0), no_bias=True, workspace=workspace, name=name + '_conv3') if dim_match: shortcut = data else: shortcut = mx.sym.Convolution(data=act1, num_filter=num_filter, kernel=(1,1), stride=stride, no_bias=True, workspace=workspace, name=name+'_sc') if memonger: shortcut._set_attr(mirror_stage='True') return conv3 + shortcut else: bn1 = mx.sym.BatchNorm(data=data, fix_gamma=False, momentum=bn_mom, eps=2e-5, name=name + '_bn1') act1 = mx.sym.Activation(data=bn1, act_type='relu', name=name + '_relu1') conv1 = mx.sym.Convolution(data=act1, num_filter=num_filter, kernel=(3,3), stride=stride, pad=(1,1), no_bias=True, workspace=workspace, name=name + '_conv1') bn2 = mx.sym.BatchNorm(data=conv1, fix_gamma=False, momentum=bn_mom, eps=2e-5, name=name + '_bn2') act2 = mx.sym.Activation(data=bn2, act_type='relu', name=name + '_relu2') conv2 = mx.sym.Convolution(data=act2, num_filter=num_filter, kernel=(3,3), stride=(1,1), pad=(1,1), no_bias=True, workspace=workspace, name=name + '_conv2') if dim_match: shortcut = data else: shortcut = mx.sym.Convolution(data=act1, num_filter=num_filter, kernel=(1,1), stride=stride, no_bias=True, workspace=workspace, name=name+'_sc') if memonger: shortcut._set_attr(mirror_stage='True') return conv2 + shortcut def resnet(units, num_stages, filter_list, num_classes, image_shape, bottle_neck=True, bn_mom=0.9, workspace=256, dtype='float32', memonger=False): """Return ResNet symbol of Parameters ---------- units : list Number of units in each stage num_stages : int Number of stage filter_list : list Channel size of each stage num_classes : int Ouput size of symbol dataset : str Dataset type, only cifar10 and imagenet supports workspace : int Workspace used in convolution operator dtype : str Precision (float32 or float16) """ num_unit = len(units) assert(num_unit == num_stages) data = mx.sym.Variable(name='data') if dtype == 'float32': data = mx.sym.identity(data=data, name='id') else: if dtype == 'float16': data = mx.sym.Cast(data=data, dtype=np.float16) data = mx.sym.BatchNorm(data=data, fix_gamma=True, eps=2e-5, momentum=bn_mom, name='bn_data') (nchannel, height, width) = image_shape if height <= 32: # such as cifar10 body = mx.sym.Convolution(data=data, num_filter=filter_list[0], kernel=(3, 3), stride=(1,1), pad=(1, 1), no_bias=True, name="conv0", workspace=workspace) else: # often expected to be 224 such as imagenet body = mx.sym.Convolution(data=data, num_filter=filter_list[0], kernel=(7, 7), stride=(2,2), pad=(3, 3), no_bias=True, name="conv0", workspace=workspace) body = mx.sym.BatchNorm(data=body, fix_gamma=False, eps=2e-5, momentum=bn_mom, name='bn0') body = mx.sym.Activation(data=body, act_type='relu', name='relu0') body = mx.sym.Pooling(data=body, kernel=(3, 3), stride=(2,2), pad=(1,1), pool_type='max') for i in range(num_stages): body = residual_unit(body, filter_list[i+1], (1 if i==0 else 2, 1 if i==0 else 2), False, name='stage%d_unit%d' % (i + 1, 1), bottle_neck=bottle_neck, workspace=workspace, memonger=memonger) for j in range(units[i]-1): body = residual_unit(body, filter_list[i+1], (1,1), True, name='stage%d_unit%d' % (i + 1, j + 2), bottle_neck=bottle_neck, workspace=workspace, memonger=memonger) bn1 = mx.sym.BatchNorm(data=body, fix_gamma=False, eps=2e-5, momentum=bn_mom, name='bn1') relu1 = mx.sym.Activation(data=bn1, act_type='relu', name='relu1') # Although kernel is not used here when global_pool=True, we should put one pool1 = mx.sym.Pooling(data=relu1, global_pool=True, kernel=(7, 7), pool_type='avg', name='pool1') flat = mx.sym.Flatten(data=pool1) fc1 = mx.sym.FullyConnected(data=flat, num_hidden=num_classes, name='fc1') if dtype == 'float16': fc1 = mx.sym.Cast(data=fc1, dtype=np.float32) return mx.sym.SoftmaxOutput(data=fc1, name='softmax') def get_symbol(num_classes, num_layers, image_shape, conv_workspace=256, dtype='float32', **kwargs): """ Adapted from https://github.com/tornadomeet/ResNet/blob/master/train_resnet.py Original author Wei Wu """ image_shape = [int(l) for l in image_shape.split(',')] (nchannel, height, width) = image_shape if height <= 28: num_stages = 3 if (num_layers-2) % 9 == 0 and num_layers >= 164: per_unit = [(num_layers-2)//9] filter_list = [16, 64, 128, 256] bottle_neck = True elif (num_layers-2) % 6 == 0 and num_layers < 164: per_unit = [(num_layers-2)//6] filter_list = [16, 16, 32, 64] bottle_neck = False else: raise ValueError("no experiments done on num_layers {}, you can do it yourself".format(num_layers)) units = per_unit * num_stages else: if num_layers >= 50: filter_list = [64, 256, 512, 1024, 2048] bottle_neck = True else: filter_list = [64, 64, 128, 256, 512] bottle_neck = False num_stages = 4 if num_layers == 18: units = [2, 2, 2, 2] elif num_layers == 34: units = [3, 4, 6, 3] elif num_layers == 50: units = [3, 4, 6, 3] elif num_layers == 101: units = [3, 4, 23, 3] elif num_layers == 152: units = [3, 8, 36, 3] elif num_layers == 200: units = [3, 24, 36, 3] elif num_layers == 269: units = [3, 30, 48, 8] else: raise ValueError("no experiments done on num_layers {}, you can do it yourself".format(num_layers)) return resnet(units = units, num_stages = num_stages, filter_list = filter_list, num_classes = num_classes, image_shape = image_shape, bottle_neck = bottle_neck, workspace = conv_workspace, dtype = dtype)