作者 | Lavanya Shukla

译者 | Monanfei

责编 | 夕颜

出品 | AI科技大本营（id：rgznai100）

导读：刚开始接触数据竞赛时，我们可能会被一些高大上的技术吓到。各界大佬云集，各种技术令人眼花缭乱，新手们就像蜉蝣一般渺小无助。今天本文就分享一下在 kaggle 的竞赛中，参赛者取得 top0.3% 的经验和技巧。让我们开始吧！

Top 0.3% 模型概览

赛题和目标

• 数据集中的每一行都描述了某一匹马的特征

• 在已知这些特征的条件下，预测每匹马的销售价格

• 预测价格对数和真实价格对数的RMSE（均方根误差）作为模型的评估指标。将RMSE转化为对数尺度，能够保证廉价马匹和高价马匹的预测误差，对模型分数的影响较为一致。

模型训练过程中的重要细节

• 交叉验证：使用12-折交叉验证

• 模型：在每次交叉验证中，同时训练七个模型（ridge, svr, gradient boosting, random forest, xgboost, lightgbm regressors）

• Stacking 方法：使用 xgboot 训练了元 StackingCVRegressor 学习器

• 模型融合：所有训练的模型都会在不同程度上过拟合，因此，为了做出最终的预测，将这些模型进行了融合，得到了鲁棒性更强的预测结果

模型性能

从下图可以看出，融合后的模型性能最好，RMSE 仅为 0.075，该融合模型用于最终预测。

 

In[1]：

from IPython.display import Image	Image("../input/kernel-files/model_training_advanced_regression.png")

 

Output[1]：

              

现在让我们正式开始吧！

 

In[2]：

# Essentials	import numpy as np	import pandas as pd	import datetime	import random

# Plots	import seaborn as sns	import matplotlib.pyplot as plt			# Models	from sklearn.ensemble import RandomForestRegressor, GradientBoostingRegressor, AdaBoostRegressor, BaggingRegressor	from sklearn.kernel_ridge import KernelRidge	from sklearn.linear_model import Ridge, RidgeCV	from sklearn.linear_model import ElasticNet, ElasticNetCV	from sklearn.svm import SVR	from mlxtend.regressor import StackingCVRegressor	import lightgbm as lgb	from lightgbm import LGBMRegressor	from xgboost import XGBRegressor			# Stats	from scipy.stats import skew, norm	from scipy.special import boxcox1p	from scipy.stats import boxcox_normmax			# Misc	from sklearn.model_selection import GridSearchCV	from sklearn.model_selection import KFold, cross_val_score	from sklearn.metrics import mean_squared_error	from sklearn.preprocessing import OneHotEncoder	from sklearn.preprocessing import LabelEncoder	from sklearn.pipeline import make_pipeline	from sklearn.preprocessing import scale	from sklearn.preprocessing import StandardScaler	from sklearn.preprocessing import RobustScaler	from sklearn.decomposition import PCA		pd.set_option('display.max_columns', None)		# Ignore useless warnings	import warnings	warnings.filterwarnings(action="ignore")	pd.options.display.max_seq_items = 8000	pd.options.display.max_rows = 8000		import os	print(os.listdir("../input/kernel-fi

 

Output[2]：

['model_training_advanced_regression.png']

In[3]：

# Read in the dataset as a dataframe	train = pd.read_csv('../input/house-prices-advanced-regression-techniques/train.csv')	test = pd.read_csv('../input/house-prices-advanced-regression-techniques/test.csv')	train.shape, test.shape

Output[3]：

((1460, 81), (1459, 80))

EDA

目标

• 数据集中的每一行都描述了某一匹马的特征

• 在已知这些特征的条件下，预测每匹马的销售价格

对原始数据进行可视化

In[4]：

# Preview the data we're working with	train.head()

Output[5]：

             

SalePrice：目标值的特性探究

In[5]：

sns.set_style("white")	sns.set_color_codes(palette='deep')	f, ax = plt.subplots(figsize=(8, 7))	#Check the new distribution	sns.distplot(train['SalePrice'], color="b");	ax.xaxis.grid(False)	ax.set(ylabel="Frequency")	ax.set(xlabel="SalePrice")	ax.set(title="SalePrice distribution")	sns.despine(trim=True, left=True)	plt.show()

      
     

In[6]：

# Skew and kurt	print("Skewness: %f" % train['SalePrice'].skew())	print("Kurtosis: %f" % train['SalePrice'].kurt())

Skewness: 1.882876

Kurtosis: 6.536282

可用的特征：深入探索

数据可视化

 

In[7]：

# Finding numeric features	numeric_dtypes = ['int16', 'int32', 'int64', 'float16', 'float32', 'float64']	numeric = []	for i in train.columns:	    if train[i].dtype in numeric_dtypes:	        if i in ['TotalSF', 'Total_Bathrooms','Total_porch_sf','haspool','hasgarage','hasbsmt','hasfireplace']:	            pass	        else:	            numeric.append(i)	# visualising some more outliers in the data values	fig, axs = plt.subplots(ncols=2, nrows=0, figsize=(12, 120))	plt.subplots_adjust(right=2)	plt.subplots_adjust(top=2)	sns.color_palette("husl", 8)	for i, feature in enumerate(list(train[numeric]), 1):	    if(feature=='MiscVal'):	        break	    plt.subplot(len(list(numeric)), 3, i)	    sns.scatterplot(x=feature, y='SalePrice', hue='SalePrice', palette='Blues', data=train)	        	    plt.xlabel('{}'.format(feature), size=15,labelpad=12.5)	    plt.ylabel('SalePrice', size=15, labelpad=12.5)	    	    for j in range(2):	        plt.tick_params(axis='x', labelsize=12)	        plt.tick_params(axis='y', labelsize=12)	    	    plt.legend(loc='best', prop={'size': 10})	        	plt.show()

   

      

 

探索这些特征以及 SalePrice 的相关性

 

In[8]：

corr = train.corr()	plt.subplots(figsize=(15,12))	sns.heatmap(corr, vmax=0.9, cmap="Blues", square=True)

Output[8]：

<matplotlib.axes._subplots.AxesSubplot at 0x7ff0e416e4e0>

 

选取部分特征，可视化它们和 SalePrice 的相关性

 

Input[9]：

data = pd.concat([train['SalePrice'], train['OverallQual']], axis=1)	f, ax = plt.subplots(figsize=(8, 6))	fig = sns.boxplot(x=train['OverallQual'], y="SalePrice", data=data)	fig.axis(ymin=0, ymax=800000);

             

Input[10]：

data = pd.concat([train['SalePrice'], train['YearBuilt']], axis=1)	f, ax = plt.subplots(figsize=(16, 8))	fig = sns.boxplot(x=train['YearBuilt'], y="SalePrice", data=data)	fig.axis(ymin=0, ymax=800000);	plt.xticks(rotation=45);

             

Input[11]：

data = pd.concat([train['SalePrice'], train['TotalBsmtSF']], axis=1)	data.plot.scatter(x='TotalBsmtSF', y='SalePrice', alpha=0

.3, ylim=(0,800000));

             

Input[12]：

data = pd.concat([train['SalePrice'], train['LotArea']], axis=1)	data.plot.scatter(x='LotArea', y='SalePrice', alpha=0.3, y

lim=(0,800000));

             

Input[13]：

data = pd.concat([train['SalePrice'], train['GrLivArea']], axis=1)	data.plot.scatter(x='GrLivArea', y='SalePrice', alpha=0.3,

ylim=(0,800000));

             

Input[14]：

# Remove the Ids from train and test, as they are unique for each row and hence not useful for the model	train_ID = train['Id']	test_ID = test['Id']	train.drop(['Id'], axis=1, inplace=True)	test.drop(['Id'], axis=1, inplace=True)	train.shape, test.shape

Output[14]：

((1460, 80), (1459, 79))

可视化 salePrice 的分布

Input[15]：

sns.set_style("white")	sns.set_color_codes(palette='deep')	f, ax = plt.subplots(figsize=(8, 7))	#Check the new distribution	sns.distplot(train['SalePrice'], color="b");	ax.xaxis.grid(False)	ax.set(ylabel="Frequency")	ax.set(xlabel="SalePrice")	ax.set(title="SalePrice distribution")	sns.despine(trim=True, left=True)	plt.show()

             

从上图中可以看出，SalePrice 有点向右边倾斜，由于大多数机器学习模型对非正态分布的数据的效果不佳，因此，我们对数据进行变换，修正这种倾斜：log(1+x) 

 

Input[16]：

# log(1+x) transform	train["SalePrice"] = np.log1p(train["SalePrice"])

对 SalePrice 重新进行可视化

 

Input[17]：

sns.set_style("white")	sns.set_color_codes(palette='deep')	f, ax = plt.subplots(figsize=(8, 7))	#Check the new distribution	sns.distplot(train['SalePrice'] , fit=norm, color="b");			# Get the fitted parameters used by the function	(mu, sigma) = norm.fit(train['SalePrice'])	print( '\n mu = {:.2f} and sigma = {:.2f}\n'.format(mu, sigma))			#Now plot the distribution	plt.legend(['Normal dist. ($\mu=$ {:.2f} and $\sigma=$ {:.2f} )'.format(mu, sigma)],	            loc='best')	ax.xaxis.grid(False)	ax.set(ylabel="Frequency")	ax.set(xlabel="SalePrice")	ax.set(title="SalePrice distribution")	sns.despine(trim=True, left=True)		plt.show

mu = 12.02 and sigma = 0.40

 

             

 

从图中可以看到，当前的 SalePrice 已经变成了正态分布

Input[18]：

# Remove outliers	train.drop(train[(train['OverallQual']<5) & (train['SalePrice']>200000)].index, inplace=True)	train.drop(train[(train['GrLivArea']>4500) & (train['SalePrice']<300000)].index, inplace=True)	train.reset_index(drop=True, inplace=True)

Input[19]：

# Split features and labels	train_labels = train['SalePrice'].reset_index(drop=True)	train_features = train.drop(['SalePrice'], axis=1)	test_features = test	# Combine train and test features in order to apply the feature transformation pipeline to the entire dataset	all_features = pd.concat([train_features, test_features]).reset_index(drop=True)	all_features.shape

 

Input[19]：

(2917, 79)

填充缺失值

Input[20]：

# determine the threshold for missing values	def percent_missing(df):	    data = pd.DataFrame(df)	    df_cols = list(pd.DataFrame(data))	    dict_x = {}	    for i in range(0, len(df_cols)):	        dict_x.update({df_cols[i]: round(data[df_cols[i]].isnull().mean()*100,2)})	    	    return dict_x		missing = percent_missing(all_features)	df_miss = sorted(missing.items(), key=lambda x: x[1], reverse=True)	print('Percent of missing data')	df_miss[0:10]

Percent of missing data

Output[20]：

[('PoolQC', 99.69),

('MiscFeature', 96.4),

('Alley', 93.21),

('Fence', 80.43),

('FireplaceQu', 48.68),

('LotFrontage', 16.66),

('GarageYrBlt', 5.45),

('GarageFinish', 5.45),

('GarageQual', 5.45),

('GarageCond', 5.45)]

 

Input[21]：

# Visualize missing values	sns.set_style("white")	f, ax = plt.subplots(figsize=(8, 7))	sns.set_color_codes(palette='deep')	missing = round(train.isnull().mean()*100,2)	missing = missing[missing > 0]	missing.sort_values(inplace=True)	missing.plot.bar(color="b")	# Tweak the visual presentation	ax.xaxis.grid(False)	ax.set(ylabel="Percent of missing values")	ax.set(xlabel="Features")	ax.set(title="Percent missing data by feature")	sns.despine(trim=True, left=True)

             

 

接下来，我们将分别对每一列填充缺失值

Input[22]：

# Some of the non-numeric predictors are stored as numbers; convert them into strings	all_features['MSSubClass'] = all_features['MSSubClass'].apply(str)	all_features['YrSold'] = all_features['YrSold'].astype(str)	all_features['MoSold'] = all_features['MoSold'].astype(str)

Input[23]：

def handle_missing(features):	    # the data description states that NA refers to typical ('Typ') values	    features['Functional'] = features['Functional'].fillna('Typ')	    # Replace the missing values in each of the columns below with their mode	    features['Electrical'] = features['Electrical'].fillna("SBrkr")	    features['KitchenQual'] = features['KitchenQual'].fillna("TA")	    features['Exterior1st'] = features['Exterior1st'].fillna(features['Exterior1st'].mode()[0])	    features['Exterior2nd'] = features['Exterior2nd'].fillna(features['Exterior2nd'].mode()[0])	    features['SaleType'] = features['SaleType'].fillna(features['SaleType'].mode()[0])	    features['MSZoning'] = features.groupby('MSSubClass')['MSZoning'].transform(lambda x: x.fillna(x.mode()[0]))	    	    # the data description stats that NA refers to "No Pool"	    features["PoolQC"] = features["PoolQC"].fillna("None")	    # Replacing the missing values with 0, since no garage = no cars in garage	    for col in ('GarageYrBlt', 'GarageArea', 'GarageCars'):	        features[col] = features[col].fillna(0)	    # Replacing the missing values with None	    for col in ['GarageType', 'GarageFinish', 'GarageQual', 'GarageCond']:	        features[col] = features[col].fillna('None')	    # NaN values for these categorical basement features, means there's no basement	    for col in ('BsmtQual', 'BsmtCond', 'BsmtExposure', 'BsmtFinType1', 'BsmtFinType2'):	        features[col] = features[col].fillna('None')	        	    # Group the by neighborhoods, and fill in missing value by the median LotFrontage of the neighborhood	    features['LotFrontage'] = features.groupby('Neighborhood')['LotFrontage'].transform(lambda x: x.fillna(x.median()))	    # We have no particular intuition around how to fill in the rest of the categorical features	    # So we replace their missing values with None	    objects = []	    for i in features.columns:	        if features[i].dtype == object:	            objects.append(i)	    features.update(features[objects].fillna('None'))	        	    # And we do the same thing for numerical features, but this time with 0s	    numeric_dtypes = ['int16', 'int32', 'int64', 'float16', 'float32', 'float64']	    numeric = []	    for i in features.columns:	        if features[i].dtype in numeric_dtypes:	            numeric.append(i)	    features.update(features[numeric].fillna(0))	    return features		all_features = handle_missing(all_features

Input[24]：

# Let's make sure we handled all the missing values	missing = percent_missing(all_features)	df_miss = sorted(missing.items(), key=lambda x: x[1], reverse=True)	print('Percent of missing data')	df_miss[0:10]

Output[14]：

Percent of missing data

 [('MSSubClass', 0.0),

('MSZoning', 0.0),

('LotFrontage', 0.0),

('LotArea', 0.0),

('Street', 0.0),

('Alley', 0.0),

('LotShape', 0.0),

('LandContour', 0.0),

('Utilities', 0.0),

('LotConfig', 0.0)]

从上面的结果可以看到，所有缺失值已经填充完毕

 

调整分布倾斜的特征

Input[25]：

# Fetch all numeric features	numeric_dtypes = ['int16', 'int32', 'int64', 'float16', 'float32', 'float64']	numeric = []	for i in all_features.columns:	    if all_features[i].dtype in numeric_dtypes:	        numeric.append(i)

Input[26]：

# Create box plots for all numeric features	sns.set_style("white")	f, ax = plt.subplots(figsize=(8, 7))	ax.set_xscale("log")	ax = sns.boxplot(data=all_features[numeric] , orient="h", palette="Set1")	ax.xaxis.grid(False)	ax.set(ylabel="Feature names")	ax.set(xlabel="Numeric values")	ax.set(title="Numeric Distribution of Features")	sns.despine(trim=True, left=True)

             

Input[27]：

# Find skewed numerical features	skew_features = all_features[numeric].apply(lambda x: skew(x)).sort_values(ascending=False)		high_skew = skew_features[skew_features > 0.5]	skew_index = high_skew.index		print("There are {} numerical features with Skew > 0.5 :".format(high_skew.shape[0]))	skewness = pd.DataFrame({'Skew' :high_skew})	skew_features.head(10

Output[27]：

There are 25 numerical features with Skew > 0.5 :

MiscVal          21.939672

PoolArea         17.688664

LotArea          13.109495

LowQualFinSF     12.084539

3SsnPorch        11.372080

KitchenAbvGr      4.300550

BsmtFinSF2        4.144503

EnclosedPorch     4.002344

ScreenPorch       3.945101

BsmtHalfBath      3.929996

dtype: float64

 

使用 scipy 的函数 boxcox1来进行 Box-Cox 转换，将数据正态化

Input[28]：	# Normalize skewed features	for i in skew_index:	    all_features[i] = boxcox1p(all_features[i], 	    boxcox_normmax(all_features[i] + 1))

Input[29]：

# Let's make sure we handled all the skewed values	sns.set_style("white")	f, ax = plt.subplots(figsize=(8, 7))	ax.set_xscale("log")	ax = sns.boxplot(data=all_features[skew_index] , orient="h", palette="Set1")	ax.xaxis.grid(False)	ax.set(ylabel="Feature names")	ax.set(xlabel="Numeric values")	ax.set(title="Numeric Distribution of Features")	sns.despine(trim=True, left=True)

              

从上图可以看到，所有特征都看上去呈正态分布了。

 

创建一些有用的特征

机器学习模型对复杂模型的认知较差，因此我们需要用我们的直觉来构建有效的特征，从而帮助模型更加有效的学习。

 

all_features['BsmtFinType1_Unf'] = 1*(all_features['BsmtFinType1'] == 'Unf')	all_features['HasWoodDeck'] = (all_features['WoodDeckSF'] == 0) * 1	all_features['HasOpenPorch'] = (all_features['OpenPorchSF'] == 0) * 1	all_features['HasEnclosedPorch'] = (all_features['EnclosedPorch'] == 0) * 1	all_features['Has3SsnPorch'] = (all_features['3SsnPorch'] == 0) * 1	all_features['HasScreenPorch'] = (all_features['ScreenPorch'] == 0) * 1	all_features['YearsSinceRemodel'] = all_features['YrSold'].astype(int) - all_features['YearRemodAdd'].astype(int)	all_features['Total_Home_Quality'] = all_features['OverallQual'] + all_features['OverallCond']	all_features = all_features.drop(['Utilities', 'Street', 'PoolQC',], axis=1)	all_features['TotalSF'] = all_features['TotalBsmtSF'] + all_features['1stFlrSF'] + all_features['2ndFlrSF']	all_features['YrBltAndRemod'] = all_features['YearBuilt'] + all_features['YearRemodAdd']		all_features['Total_sqr_footage'] = (all_features['BsmtFinSF1'] + all_features['BsmtFinSF2'] +	                                 all_features['1stFlrSF'] + all_features['2ndFlrSF'])	all_features['Total_Bathrooms'] = (all_features['FullBath'] + (0.5 * all_features['HalfBath']) +	                               all_features['BsmtFullBath'] + (0.5 * all_features['BsmtHalfBath']))	all_features['Total_porch_sf'] = (all_features['OpenPorchSF'] + all_features['3SsnPorch'] +	                              all_features['EnclosedPorch'] + all_features['ScreenPorch'] +	                              all_features['WoodDeckSF'])	all_features['TotalBsmtSF'] = all_features['TotalBsmtSF'].apply(lambda x: np.exp(6) if x <= 0.0 else x)	all_features['2ndFlrSF'] = all_features['2ndFlrSF'].apply(lambda x: np.exp(6.5) if x <= 0.0 else x)	all_features['GarageArea'] = all_features['GarageArea'].apply(lambda x: np.exp(6) if x <= 0.0 else x)	all_features['GarageCars'] = all_features['GarageCars'].apply(lambda x: 0 if x <= 0.0 else x)	all_features['LotFrontage'] = all_features['LotFrontage'].apply(lambda x: np.exp(4.2) if x <= 0.0 else x)	all_features['MasVnrArea'] = all_features['MasVnrArea'].apply(lambda x: np.exp(4) if x <= 0.0 else x)	all_features['BsmtFinSF1'] = all_features['BsmtFinSF1'].apply(lambda x: np.exp(6.5) if x <= 0.0 else x)			all_features['haspool'] = all_features['PoolArea'].apply(lambda x: 1 if x > 0 else 0)	all_features['has2ndfloor'] = all_features['2ndFlrSF'].apply(lambda x: 1 if x > 0 else 0)	all_features['hasgarage'] = all_features['GarageArea'].apply(lambda x: 1 if x > 0 else 0)	all_features['hasbsmt'] = all_features['TotalBsmtSF'].apply(lambda x: 1 if x > 0 else 0)	all_features['hasfireplace'] = all_features['Fireplaces'].apply(lambda x: 1 if x > 0 else 0

特征转换

通过对特征取对数或者平方，可以创造更多的特征，这些操作有利于发掘潜在的有用特征。

 

def logs(res, ls):	    m = res.shape[1]	    for l in ls:	        res = res.assign(newcol=pd.Series(np.log(1.01+res[l])).values)	        res.columns.values[m] = l + '_log'	        m += 1	    return res		log_features = ['LotFrontage','LotArea','MasVnrArea','BsmtFinSF1','BsmtFinSF2','BsmtUnfSF',	                 'TotalBsmtSF','1stFlrSF','2ndFlrSF','LowQualFinSF','GrLivArea',	                 'BsmtFullBath','BsmtHalfBath','FullBath','HalfBath','BedroomAbvGr','KitchenAbvGr',	                 'TotRmsAbvGrd','Fireplaces','GarageCars','GarageArea','WoodDeckSF','OpenPorchSF',	                 'EnclosedPorch','3SsnPorch','ScreenPorch','PoolArea','MiscVal','YearRemodAdd','TotalSF']		all_features = logs(all_features, log_features

def squares(res, ls):	    m = res.shape[1]	    for l in ls:	        res = res.assign(newcol=pd.Series(res[l]*res[l]).values)	        res.columns.values[m] = l + '_sq'	        m += 1	    return res		squared_features = ['YearRemodAdd', 'LotFrontage_log',	              'TotalBsmtSF_log', '1stFlrSF_log', '2ndFlrSF_log', 'GrLivArea_log',	              'GarageCars_log', 'GarageArea_log']	all_features = squares(all_features, squared_features)

对集合特征进行编码

对集合特征进行数值编码，使得机器学习模型能够处理这些特征。

 

all_features = pd.get_dummies(all_features).reset_index(drop=True)	all_features.shape

(2917, 379)

all_features.head()

         

all_features.shape

(2917, 379)

# Remove any duplicated column names	all_features = all_features.loc[:,~all_features.columns. duplicated()]

重新创建训练集和测试集

X = all_features.iloc[:len(train_labels), :]	X_test = all_features.iloc[len(train_labels):, :]	X.shape, train_labels.shape, X_test.shape

((1458, 378), (1458,), (1459, 378))

 

对训练集中的部分特征进行可视化

 

# Finding numeric features	numeric_dtypes = ['int16', 'int32', 'int64', 'float16', 'float32', 'float64']	numeric = []	for i in X.columns:	    if X[i].dtype in numeric_dtypes:	        if i in ['TotalSF', 'Total_Bathrooms','Total_porch_sf','haspool','hasgarage','hasbsmt','hasfireplace']:	            pass	        else:	            numeric.append(i)	# visualising some more outliers in the data values	fig, axs = plt.subplots(ncols=2, nrows=0, figsize=(12, 150))	plt.subplots_adjust(right=2)	plt.subplots_adjust(top=2)	sns.color_palette("husl", 8)	for i, feature in enumerate(list(X[numeric]), 1):	    if(feature=='MiscVal'):	        break	    plt.subplot(len(list(numeric)), 3, i)	    sns.scatterplot(x=feature, y='SalePrice', hue='SalePrice', palette='Blues', data=train)	        	    plt.xlabel('{}'.format(feature), size=15,labelpad=12.5)	    plt.ylabel('SalePrice', size=15, labelpad=12.5)	    	    for j in range(2):	        plt.tick_params(axis='x', labelsize=12)	        plt.tick_params(axis='y', labelsize=12)	    	    plt.legend(loc='best', prop={'size': 10})	        	plt.show()

            

模型训练

模型训练过程中的重要细节

• 交叉验证：使用12-折交叉验证

• 模型：在每次交叉验证中，同时训练七个模型（ridge, svr, gradient boosting, random forest, xgboost, lightgbm regressors）

• Stacking 方法：使用xgboot训练了元 StackingCVRegressor 学习器

• 模型融合：所有训练的模型都会在不同程度上过拟合，因此，为了做出最终的预测，将这些模型进行了融合，得到了鲁棒性更强的预测结果

初始化交叉验证，定义误差评估指标

# Setup cross validation folds	kf = KFold(n_splits=12, random_state=42, shuffle=True)

# Define error metrics	def rmsle(y, y_pred):	    return np.sqrt(mean_squared_error(y, y_pred))			def cv_rmse(model, X=X):	    rmse = np.sqrt(-cross_val_score(model, X, train_labels, scoring="neg_mean_squared_error", cv=kf))	    return (rmse)

建立模型

# Light Gradient Boosting Regressor	lightgbm = LGBMRegressor(objective='regression',	                       num_leaves=6,	                       learning_rate=0.01,	                       n_estimators=7000,	                       max_bin=200,	                       bagging_fraction=0.8,	                       bagging_freq=4,	                       bagging_seed=8,	                       feature_fraction=0.2,	                       feature_fraction_seed=8,	                       min_sum_hessian_in_leaf = 11,	                       verbose=-1,	                       random_state=42)		# XGBoost Regressor	xgboost = XGBRegressor(learning_rate=0.01,	                       n_estimators=6000,	                       max_depth=4,	                       min_child_weight=0,	                       gamma=0.6,	                       subsample=0.7,	                       colsample_bytree=0.7,	                       objective='reg:linear',	                       nthread=-1,	                       scale_pos_weight=1,	                       seed=27,	                       reg_alpha=0.00006,	                       random_state=42)			# Ridge Regressor	ridge_alphas = [1e-15, 1e-10, 1e-8, 9e-4, 7e-4, 5e-4, 3e-4, 1e-4, 1e-3, 5e-2, 1e-2, 0.1, 0.3, 1, 3, 5, 10, 15, 18, 20, 30, 50, 75, 100]	ridge = make_pipeline(RobustScaler(), RidgeCV(alphas=ridge_alphas, cv=kf))			# Support Vector Regressor	svr = make_pipeline(RobustScaler(), SVR(C= 20, epsilon= 0.008, gamma=0.0003))			# Gradient Boosting Regressor	gbr = GradientBoostingRegressor(n_estimators=6000,	                                learning_rate=0.01,	                                max_depth=4,	                                max_features='sqrt',	                                min_samples_leaf=15,	                                min_samples_split=10,	                                loss='huber',	                                random_state=42)			# Random Forest Regressor	rf = RandomForestRegressor(n_estimators=1200,	                          max_depth=15,	                          min_samples_split=5,	                          min_samples_leaf=5,	                          max_features=None,	                          oob_score=True,	                          random_state=42)			# Stack up all the models above, optimized using xgboost	stack_gen = StackingCVRegressor(regressors=(xgboost, lightgbm, svr, ridge, gbr, rf),	                                meta_regressor=xgboost,	                                use_features_in_secondary=True)

训练模型

计算每个模型的交叉验证的得分

 

scores = {}		score = cv_rmse(lightgbm)	print("lightgbm: {:.4f} ({:.4f})".format(score.mean(), score.std()))	scores['lgb'] = (score.mean(), score.std())

lightgbm: 0.1159 (0.0167)

score = cv_rmse(xgboost)	print("xgboost: {:.4f} ({:.4f})".format(score.mean(), score.std()))	scores['xgb'] = (score.mean(), score.std())

xgboost: 0.1364 (0.0175)

score = cv_rmse(svr)	print("SVR: {:.4f} ({:.4f})".format(score.mean(), score.std()))	scores['svr'] = (score.mean(), score.std())

SVR: 0.1094 (0.0200)

score = cv_rmse(ridge)	print("ridge: {:.4f} ({:.4f})".format(score.mean(), score.std()))	scores['ridge'] = (score.mean(), score.std())

ridge: 0.1101 (0.0161)

score = cv_rmse(rf)	print("rf: {:.4f} ({:.4f})".format(score.mean(), score.std()))	scores['rf'] = (score.mean(), score.std())

rf: 0.1366 (0.0188

score = cv_rmse(gbr)	print("gbr: {:.4f} ({:.4f})".format(score.mean(), score.std()))	scores['gbr'] = (score.mean(), score.std())

gbr: 0.1121 (0.0164)

 

拟合模型

print('stack_gen')	stack_gen_model = stack_gen.fit(np.array(X), np.array(train_labels))

stack_gen

print('lightgbm')	lgb_model_full_data = lightgbm.fit(X, train_labels)

lightgbm

print('xgboost')	xgb_model_full_data = xgboost.fit(X, train_labels)

xgboost

print('Svr')	svr_model_full_data = svr.fit(X, train_labels)

Svr

print('Ridge')	ridge_model_full_data = ridge.fit(X, train_labels)

Ridge

print('RandomForest')	rf_model_full_data = rf.fit(X, train_labels)

RandomForest

print('GradientBoosting')	gbr_model_full_data = gbr.fit(X, train_labels)

GradientBoosting

融合各个模型，并进行最终预测

# Blend models in order to make the final predictions more robust to overfitting	def blended_predictions(X):	    return ((0.1 * ridge_model_full_data.predict(X)) + \	            (0.2 * svr_model_full_data.predict(X)) + \	            (0.1 * gbr_model_full_data.predict(X)) + \	            (0.1 * xgb_model_full_data.predict(X)) + \	            (0.1 * lgb_model_full_data.predict(X)) + \	            (0.05 * rf_model_full_data.predict(X)) + \	            (0.35 * stack_gen_model.predict(np.array(X))))

 

# Get final precitions from the blended model	blended_score = rmsle(train_labels, blended_predictions(X))	scores['blended'] = (blended_score, 0)	print('RMSLE score on train data:')	print(blended_score)

RMSLE score on train data:

0.07537440195302639

各模型性能比较

# Plot the predictions for each model	sns.set_style("white")	fig = plt.figure(figsize=(24, 12))		ax = sns.pointplot(x=list(scores.keys()), y=[score for score, _ in scores.values()], markers=['o'], linestyles=['-'])	for i, score in enumerate(scores.values()):	    ax.text(i, score[0] + 0.002, '{:.6f}'.format(score[0]), horizontalalignment='left', size='large', color='black', weight='semibold')		plt.ylabel('Score (RMSE)', size=20, labelpad=12.5)	plt.xlabel('Model', size=20, labelpad=12.5)	plt.tick_params(axis='x', labelsize=13.5)	plt.tick_params(axis='y', labelsize=12.5)		plt.title('Scores of Models', size=20)		plt.sho

             

 

从上图可以看出，融合后的模型性能最好，RMSE 仅为 0.075，该融合模型用于最终预测。

提交预测结果

# Read in sample_submission dataframe	submission = pd.read_csv("../input/house-prices-advanced-regression-techniques/sample_submission.csv")	submission.shape

(1459, 2)

# Append predictions from blended models	submission.iloc[:,1] = np.floor(np.expm1(blended_predictions(X_test)))	 	# Fix outleir predictions	q1 = submission['SalePrice'].quantile(0.0045)	q2 = submission['SalePrice'].quantile(0.99)	submission['SalePrice'] = submission['SalePrice'].apply(lambda x: x if x > q1 else x*0.77)	submission['SalePrice'] = submission['SalePrice'].apply(lambda x: x if x < q2 else x*1.1)	submission.to_csv("submission_regression1.csv", index=False)

# Scale predictions	submission['SalePrice'] *= 1.001619	submission.to_csv("submission_regression2.csv", index=False)

原文链接：

https://www.kaggle.com/lavanyashukla01/how-i-made-top-0-3-on-a-kaggle-competition

（*本文为 AI科技大本营翻译文章，转载请联系 1092722531）

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