[人工智能]深度学习框架拾遗：【Pytorch（三）】——Pytorch结构化数据建模流程

import os
import datetime
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import torch 
from torch import nn
from torch.utils.data import Dataset,DataLoader,TensorDataset

## 打印时间
def printbar():
    nowtime = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S')
    print("\n"+"========"*8+"%s"%nowtime)

Step 1.数据准备

从https://github.com/lyhue1991/eat_pytorch_in_20_days下载titanic数据集，titanic数据集的目标是根据乘客信息预测他们在Titanic号撞击冰山沉没后能否生存。结构化数据一般会使用Pandas中的DataFrame进行预处理。

dftrain_raw = pd.read_csv('../data/titanic/train.csv')
dftest_raw = pd.read_csv('../data/titanic/test.csv')
dftrain_raw.head(10)

字段说明：

• Survived:0代表死亡，1代表存活【y标签】
• Pclass:乘客所持票类，有三种值(1,2,3) 【转换成onehot编码】
• Name:乘客姓名 【舍去】
• Sex:乘客性别 【转换成bool特征】
• Age:乘客年龄(有缺失) 【数值特征，添加“年龄是否缺失”作为辅助特征】
• SibSp:乘客兄弟姐妹/配偶的个数(整数值) 【数值特征】
• Parch:乘客父母/孩子的个数(整数值)【数值特征】
• Ticket:票号(字符串)【舍去】
• Fare:乘客所持票的价格(浮点数，0-500不等) 【数值特征】
• Cabin:乘客所在船舱(有缺失) 【添加“所在船舱是否缺失”作为辅助特征】
• Embarked:乘客登船港口:S、C、Q(有缺失)【转换成onehot编码，四维度 S,C,Q,nan】

Step 2.数据分析

1）label分布情况

%matplotlib inline
%config InlineBackend.figure_format = 'png'

ax = dftrain_raw['Survived'].value_counts().plot(kind='bar',figsize=(12,8),fontsize=15,rot=0)
ax.set_ylabel('Counts',fontsize=15)
ax.set_xlabel('Survived',fontsize=15)
plt.show()

2）年龄分布情况

ax = dftrain_raw['Age'].plot(kind='hist',bins=20,color='purple',figsize=(12,8),fontsize=15)
ax.set_ylabel('Frequency',fontsize=15)
ax.set_xlabel('Age',fontsize=15)
plt.show()

3）年龄和label的相关性

ax = dftrain_raw.query("Survived==0")['Age'].plot(kind='density',figsize=(12,8),fontsize=15)
dftrain_raw.query("Survived==1")['Age'].plot(kind='density',figsize=(12,8),fontsize=15)
ax.legend(['Survived==0','Survived==1'],fontsize=12)
ax.set_ylabel('Density',fontsize=15)
ax.set_xlabel('Age',fontsize=15)
plt.show()

Step 3.数据预处理

def preprocessing(dfdata):

    dfresult= pd.DataFrame()

    #Pclass
    dfPclass = pd.get_dummies(dfdata['Pclass'])
    dfPclass.columns = ['Pclass_' +str(x) for x in dfPclass.columns ]
    dfresult = pd.concat([dfresult,dfPclass],axis = 1)

    #Sex
    dfSex = pd.get_dummies(dfdata['Sex'])
    dfresult = pd.concat([dfresult,dfSex],axis = 1)

    #Age
    dfresult['Age'] = dfdata['Age'].fillna(0)
    dfresult['Age_null'] = pd.isna(dfdata['Age']).astype('int32')

    #SibSp,Parch,Fare
    dfresult['SibSp'] = dfdata['SibSp']
    dfresult['Parch'] = dfdata['Parch']
    dfresult['Fare'] = dfdata['Fare']

    #Carbin
    dfresult['Cabin_null'] =  pd.isna(dfdata['Cabin']).astype('int32')

    #Embarked
    dfEmbarked = pd.get_dummies(dfdata['Embarked'],dummy_na=True)
    dfEmbarked.columns = ['Embarked_' + str(x) for x in dfEmbarked.columns]
    dfresult = pd.concat([dfresult,dfEmbarked],axis = 1)

    return(dfresult)


x_train = preprocessing(dftrain_raw).values
y_train = dftrain_raw[['Survived']].values

x_test=  preprocessing(dftest_raw).values
y_test = dftest_raw[['Survived']].values

print("x_train.shape",x_train.shape)
print("y_train.shape",y_train.shape)

print("x_test.shape",x_test.shape)
print("y_test.shape",y_test.shape)

进一步使用DataLoader和TensorDataset封装成可以迭代的数据管道

dl_train = DataLoader(TensorDataset(torch.tensor(x_train).float(),torch.tensor(y_train).float()),shuffle=True,batch_size=8)
dl_valid = DataLoader(TensorDataset(torch.tensor(x_test).float(),torch.tensor(y_test).float()),shuffle=False,batch_size=8)

# 测试数据管道
for features,labels in dl_train:
    print(features,labels)
    break

Step 4.定义模型

def creat_net():
    net = nn.Sequential()
    net.add_module("linear1",nn.Linear(15,20))
    net.add_module("relu1",nn.ReLU())
    net.add_module("linear2",nn.Linear(20,15))
    net.add_module("relu2",nn.ReLU())
    net.add_module("linear3",nn.Linear(15,1))
    net.add_module("sigmoid",nn.Sigmoid())
    return net

net = creat_net()
print(net)

模型结构打印

from torchkeras import summary
summary(net,input_shape=(15,))

Step 5.训练模型

1）定义相关函数

from sklearn.metrics import accuracy_score

loss_func = nn.BCELoss()
optimizer = torch.optim.Adam(params=net.parameters(),lr=0.01)
metric_func = lambda y_pred,y_true:accuracy_score(y_true.data.numpy(),y_pred.data.numpy()>0.5)
metric_name = "accuracy"

2)模型训练循环

epochs = 10
log_step_freq = 30

dfhistory = pd.DataFrame(columns=["epoch","loss",metric_name,"val_loss","val_"+metric_name])
print("Starting Training……")
nowtime = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S')
print("============"*8 + "%s"%nowtime)


for epoch in range(1,epochs+1):
    # 1,---------------训练循环----------------
    net.train()
    loss_sum = 0.0
    metric_sum = 0.0
    step = 1
    
    for step,(features,labels) in enumerate(dl_train,1):
        # 梯度清零
        optimizer.zero_grad()
        
        # 正向传播求损失
        predictions = net(features)
        loss = loss_func(predictions,labels)
        metric = metric_func(predictions,labels)
        
        # 反向传播求梯度
        loss.backward()
        optimizer.step()
        
        # 打印batch级别日志
        loss_sum += loss.item()
        metric_sum += metric.item()
        if step % log_step_freq == 0:
            print(f"step = {step}  loss:{(loss_sum/step):.3f}, {metric_name}:{(metric_sum/step):.3f}")
            
    
    # 2,---------------验证循环----------------
    net.eval()
    val_loss_sum = 0.0
    val_metric_sum = 0.0
    val_step = 1
    for val_step,(features,labels) in enumerate(dl_valid,1):
        # 关闭梯度计算
        with torch.no_grad():
            predictions = net(features)
            val_loss = loss_func(predictions,labels)
            val_metric = metric_func(predictions,labels)
            
        val_loss_sum += val_loss.item()
        val_metric_sum += val_metric.item()
        
    # 3,---------------记录日志----------------
    info = (epoch,loss_sum/step,metric_sum/step,val_loss_sum/val_step,val_metric_sum/val_step)
    dfhistory.loc[epoch-1] = info
    
    # 打印epoch级别日志
    print(("\nEPOCH = %d, loss = %.3f,"+ metric_name + \
          "  = %.3f, val_loss = %.3f, "+"val_"+ metric_name+" = %.3f") 
          %info)
    nowtime = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S')
    print("\n"+"============"*8+"%s"%nowtime)
    
print("Finished Training!")

Step 6.评估模型

dfhistory

def plot_metric(dfhistory, metric):
    train_metrics = dfhistory[metric]
    val_metrics = dfhistory['val_'+metric]
    epochs = range(1, len(train_metrics) + 1)
    plt.plot(epochs, train_metrics, 'bo--')
    plt.plot(epochs, val_metrics, 'ro-')
    plt.title('Training and validation '+ metric)
    plt.xlabel("Epochs")
    plt.ylabel(metric)
    plt.legend(["train_"+metric, 'val_'+metric])
    plt.show()

plot_metric(dfhistory,"loss")

plot_metric(dfhistory,"accuracy")

Step 7.保存模型

torch.save(net.state_dict(),"../data/net_parameter.pkl")

Step 8.加载模型

net_clone = creat_net()
net_clone.load_state_dict(torch.load("../data/net_parameter.pkl"))
net_clone.forward(torch.tensor(x_test[0:10]).float()).data