PyCaret是一个开源、低代码Python机器学习库，能够自动化机器学习工作流程。它是一个端到端的机器学习和模型管理工具，极大地加快了实验周期，提高了工作效率。PyCaret本质上是围绕几个机器学习库和框架（如scikit-learn、XGBoost、LightGBM、CatBoost、spaCy、Optuna、Hyperopt、Ray等）的Python包装器，与其他开源机器学习库相比，PyCaret可以用少量代码取代数百行代码。PyCaret开源仓库地址：pycaret，官方文档地址为：pycaret-docs。

PyCaret基础版安装命令如下：

pip install pycaret

完整版安装代码如下：

pip install pycaret[full]

此外以下模型可以调用GPU

• Extreme Gradient Boosting
• Catboost
• Light Gradient Boosting（需要安装lightgbm)
• Logistic Regression, Ridge Classifier, Random Forest, K Neighbors Classifier, K Neighbors Regressor, Support Vector Machine, Linear Regression, Ridge Regression, Lasso Regression（需要安装cuml0.15版本以上）

# 查看pycaret版本
import pycaret
pycaret.__version__

'3.3.2'

1 快速入门

PyCaret支持多种机器学习任务，包括分类、回归、聚类、异常检测和时序预测。本节主要介绍如何利用PyCaret构建相关任务模型的基础使用方法。关于更详细的PyCaret任务模型使用，请参考：

Topic	NotebookLink
二分类BinaryClassification	link
多分类MulticlassClassification	link
回归Regression	link
聚类Clustering	link
异常检测AnomalyDetection	link
时序预测TimeSeriesForecasting	link

1.1 分类

PyCaret的classification模块是一个可用于二分类或多分类的模块，用于将元素分类到不同的组中。一些常见的用例包括预测客户是否违约、预测客户是否流失、以及诊断疾病（阳性或阴性）。示例代码如下所示：

数据准备

加载糖尿病示例数据集：

from pycaret.datasets import get_data
# 从本地加载数据，注意dataset是数据的文件名
data = get_data(dataset='./datasets/diabetes', verbose=False)
# 从pycaret开源仓库下载公开数据
# data = get_data('diabetes', verbose=False)

# 查看数据类型和数据维度
type(data), data.shape

(pandas.core.frame.DataFrame, (768, 9))

# 最后一列表示是否为糖尿病患者，其他列为特征列
data.head()

	Number of times pregnant	Plasma glucose concentration a 2 hours in an oral glucose tolerance test	Diastolic blood pressure (mm Hg)	Triceps skin fold thickness (mm)	2-Hour serum insulin (mu U/ml)	Body mass index (weight in kg/(height in m)^2)	Diabetes pedigree function	Age (years)	Class variable
0	6	148	72	35	0	33.6	0.627	50	1
1	1	85	66	29	0	26.6	0.351	31	0
2	8	183	64	0	0	23.3	0.672	32	1
3	1	89	66	23	94	28.1	0.167	21	0
4	0	137	40	35	168	43.1	2.288	33	1

利用PyCaret核心函数setup，初始化建模环境并准备数据以供模型训练和评估使用：

from pycaret.classification import ClassificationExperiment
s = ClassificationExperiment()
# target目标列，session_id设置随机数种子, preprocesss是否清洗数据，train_size训练集比例, normalize是否归一化数据, normalize_method归一化方式
s.setup(data, target = 'Class variable', session_id = 0, verbose= False, train_size = 0.7, normalize = True, normalize_method = 'minmax')

<pycaret.classification.oop.ClassificationExperiment at 0x200b939df40>

查看基于setup函数创建的变量：

s.get_config()

{'USI','X','X_test','X_test_transformed','X_train','X_train_transformed','X_transformed','_available_plots','_ml_usecase','data','dataset','dataset_transformed','exp_id','exp_name_log','fix_imbalance','fold_generator','fold_groups_param','fold_shuffle_param','gpu_n_jobs_param','gpu_param','html_param','idx','is_multiclass','log_plots_param','logging_param','memory','n_jobs_param','pipeline','seed','target_param','test','test_transformed','train','train_transformed','variable_and_property_keys','variables','y','y_test','y_test_transformed','y_train','y_train_transformed','y_transformed'}

查看归一化的数据：

s.get_config('X_train_transformed')

	Number of times pregnant	Plasma glucose concentration a 2 hours in an oral glucose tolerance test	Diastolic blood pressure (mm Hg)	Triceps skin fold thickness (mm)	2-Hour serum insulin (mu U/ml)	Body mass index (weight in kg/(height in m)^2)	Diabetes pedigree function	Age (years)
34	0.588235	0.613065	0.639344	0.313131	0.000000	0.411326	0.185312	0.400000
221	0.117647	0.793970	0.737705	0.000000	0.000000	0.470939	0.310418	0.750000
531	0.000000	0.537688	0.622951	0.000000	0.000000	0.675112	0.259607	0.050000
518	0.764706	0.381910	0.491803	0.000000	0.000000	0.488823	0.043553	0.333333
650	0.058824	0.457286	0.442623	0.252525	0.118203	0.375559	0.066610	0.033333
...	...	...	...	...	...	...	...	...
628	0.294118	0.643216	0.655738	0.000000	0.000000	0.515648	0.028181	0.400000
456	0.058824	0.678392	0.442623	0.000000	0.000000	0.397914	0.260034	0.683333
398	0.176471	0.412060	0.573770	0.000000	0.000000	0.314456	0.132792	0.066667
6	0.176471	0.391960	0.409836	0.323232	0.104019	0.461997	0.072588	0.083333
294	0.000000	0.809045	0.409836	0.000000	0.000000	0.326379	0.075149	0.733333

537 rows × 8 columns

绘制某列数据的柱状图：

s.get_config('X_train_transformed')['Number of times pregnant'].hist()

<AxesSubplot:>

当然也可以利用如下代码创建任务示例来初始化环境：

from pycaret.classification import setup
# s = setup(data, target = 'Class variable', session_id = 0, preprocess = True, train_size = 0.7, verbose = False)

模型训练与评估

PyCaret提供了compare_models函数，通过使用默认的10折交叉验证来训练和评估模型库中所有可用估计器的性能：

best = s.compare_models()
# 选择某些模型进行比较
# best = s.compare_models(include = ['dt', 'rf', 'et', 'gbc', 'lightgbm'])
# 按照召回率返回n_select性能最佳的模型
# best_recall_models_top3 = s.compare_models(sort = 'Recall', n_select = 3)

	Model	Accuracy	AUC	Recall	Prec.	F1	Kappa	MCC	TT (Sec)
lr	Logistic Regression	0.7633	0.8132	0.4968	0.7436	0.5939	0.4358	0.4549	0.2720
ridge	Ridge Classifier	0.7633	0.8113	0.5178	0.7285	0.6017	0.4406	0.4560	0.0090
lda	Linear Discriminant Analysis	0.7633	0.8110	0.5497	0.7069	0.6154	0.4489	0.4583	0.0080
ada	Ada Boost Classifier	0.7465	0.7768	0.5655	0.6580	0.6051	0.4208	0.4255	0.0190
svm	SVM - Linear Kernel	0.7408	0.8087	0.5921	0.6980	0.6020	0.4196	0.4480	0.0080
nb	Naive Bayes	0.7391	0.7939	0.5442	0.6515	0.5857	0.3995	0.4081	0.0080
rf	Random Forest Classifier	0.7337	0.8033	0.5406	0.6331	0.5778	0.3883	0.3929	0.0350
et	Extra Trees Classifier	0.7298	0.7899	0.5181	0.6416	0.5677	0.3761	0.3840	0.0450
gbc	Gradient Boosting Classifier	0.7281	0.8007	0.5567	0.6267	0.5858	0.3857	0.3896	0.0260
lightgbm	Light Gradient Boosting Machine	0.7242	0.7811	0.5827	0.6096	0.5935	0.3859	0.3876	0.0860
qda	Quadratic Discriminant Analysis	0.7150	0.7875	0.4962	0.6225	0.5447	0.3428	0.3524	0.0080
knn	K Neighbors Classifier	0.7131	0.7425	0.5287	0.6005	0.5577	0.3480	0.3528	0.2200
dt	Decision Tree Classifier	0.6685	0.6461	0.5722	0.5266	0.5459	0.2868	0.2889	0.0100
dummy	Dummy Classifier	0.6518	0.5000	0.0000	0.0000	0.0000	0.0000	0.0000	0.0120

返回当前设置中所有经过训练的模型中的最佳模型:

best_ml = s.automl()
# best_ml

# 打印效果最佳的模型
print(best)

LogisticRegression(C=1.0, class_weight=None, dual=False, fit_intercept=True,intercept_scaling=1, l1_ratio=None, max_iter=1000,multi_class='auto', n_jobs=None, penalty='l2',random_state=0, solver='lbfgs', tol=0.0001, verbose=0,warm_start=False)

数据可视化

PyCaret也提供了plot_model函数可视化模型的评估指标，plot_model函数中的plot用于设置评估指标类型。plot可用参数如下（注意并不是所有的模型都支持以下评估指标）：

• pipeline: Schematic drawing of the preprocessing pipeline
• auc: Area Under the Curve
• threshold: Discrimination Threshold
• pr: Precision Recall Curve
• confusion_matrix: Confusion Matrix
• error: Class Prediction Error
• class_report: Classification Report
• boundary: Decision Boundary
• rfe: Recursive Feature Selection
• learning: Learning Curve
• manifold: Manifold Learning
• calibration: Calibration Curve
• vc: Validation Curve
• dimension: Dimension Learning
• feature: Feature Importance
• feature_all: Feature Importance (All)
• parameter: Model Hyperparameter
• lift: Lift Curve
• gain: Gain Chart
• tree: Decision Tree
• ks: KS Statistic Plot

# 提取所有模型预测结果
models_results = s.pull()
models_results

	Model	Accuracy	AUC	Recall	Prec.	F1	Kappa	MCC	TT (Sec)
lr	Logistic Regression	0.7633	0.8132	0.4968	0.7436	0.5939	0.4358	0.4549	0.272
ridge	Ridge Classifier	0.7633	0.8113	0.5178	0.7285	0.6017	0.4406	0.4560	0.009
lda	Linear Discriminant Analysis	0.7633	0.8110	0.5497	0.7069	0.6154	0.4489	0.4583	0.008
ada	Ada Boost Classifier	0.7465	0.7768	0.5655	0.6580	0.6051	0.4208	0.4255	0.019
svm	SVM - Linear Kernel	0.7408	0.8087	0.5921	0.6980	0.6020	0.4196	0.4480	0.008
nb	Naive Bayes	0.7391	0.7939	0.5442	0.6515	0.5857	0.3995	0.4081	0.008
rf	Random Forest Classifier	0.7337	0.8033	0.5406	0.6331	0.5778	0.3883	0.3929	0.035
et	Extra Trees Classifier	0.7298	0.7899	0.5181	0.6416	0.5677	0.3761	0.3840	0.045
gbc	Gradient Boosting Classifier	0.7281	0.8007	0.5567	0.6267	0.5858	0.3857	0.3896	0.026
lightgbm	Light Gradient Boosting Machine	0.7242	0.7811	0.5827	0.6096	0.5935	0.3859	0.3876	0.086
qda	Quadratic Discriminant Analysis	0.7150	0.7875	0.4962	0.6225	0.5447	0.3428	0.3524	0.008
knn	K Neighbors Classifier	0.7131	0.7425	0.5287	0.6005	0.5577	0.3480	0.3528	0.220
dt	Decision Tree Classifier	0.6685	0.6461	0.5722	0.5266	0.5459	0.2868	0.2889	0.010
dummy	Dummy Classifier	0.6518	0.5000	0.0000	0.0000	0.0000	0.0000	0.0000	0.012

s.plot_model(best, plot = 'confusion_matrix')

如果在jupyter环境，可以通过evaluate_model函数来交互式展示模型的性能：

# s.evaluate_model(best)

模型预测

predict_model函数实现对数据进行预测，并返回包含预测标签prediction_label和分数prediction_score的Pandas表格。当data为None时，它预测测试集（在设置功能期间创建）上的标签和分数。

# 预测整个数据集
res = s.predict_model(best, data=data)
# 查看各行预测结果
# res

	Model	Accuracy	AUC	Recall	Prec.	F1	Kappa	MCC
0	Logistic Regression	0.7708	0.8312	0.5149	0.7500	0.6106	0.4561	0.4723

# 预测用于数据训练的测试集
res = s.predict_model(best)

	Model	Accuracy	AUC	Recall	Prec.	F1	Kappa	MCC
0	Logistic Regression	0.7576	0.8553	0.5062	0.7193	0.5942	0.4287	0.4422

模型保存与导入

# 保存模型到本地
_ = s.save_model(best, 'best_model', verbose = False)

# 导入模型
model = s.load_model( 'best_model')
# 查看模型结构
# model

Transformation Pipeline and Model Successfully Loaded

# 预测整个数据集
res = s.predict_model(model, data=data)

	Model	Accuracy	AUC	Recall	Prec.	F1	Kappa	MCC
0	Logistic Regression	0.7708	0.8312	0.5149	0.7500	0.6106	0.4561	0.4723

1.2 回归

PyCaret提供了regression模型实现回归任务，regression模块与classification模块使用方法一致。

# 加载保险费用示例数据集
from pycaret.datasets import get_data
data = get_data(dataset='./datasets/insurance', verbose=False)
# 从网络下载
# data = get_data(dataset='insurance', verbose=False)

data.head()

	age	sex	bmi	children	smoker	region	charges
0	19	female	27.900	0	yes	southwest	16884.92400
1	18	male	33.770	1	no	southeast	1725.55230
2	28	male	33.000	3	no	southeast	4449.46200
3	33	male	22.705	0	no	northwest	21984.47061
4	32	male	28.880	0	no	northwest	3866.85520

# 创建数据管道
from pycaret.regression import RegressionExperiment
s = RegressionExperiment()
# 预测charges列
s.setup(data, target = 'charges', session_id = 0)
# 另一种数据管道创建方式
# from pycaret.regression import *
# s = setup(data, target = 'charges', session_id = 0)

	Description	Value
0	Session id	0
1	Target	charges
2	Target type	Regression
3	Original data shape	(1338, 7)
4	Transformed data shape	(1338, 10)
5	Transformed train set shape	(936, 10)
6	Transformed test set shape	(402, 10)
7	Numeric features	3
8	Categorical features	3
9	Preprocess	True
10	Imputation type	simple
11	Numeric imputation	mean
12	Categorical imputation	mode
13	Maximum one-hot encoding	25
14	Encoding method	None
15	Fold Generator	KFold
16	Fold Number	10
17	CPU Jobs	-1
18	Use GPU	False
19	Log Experiment	False
20	Experiment Name	reg-default-name
21	USI	eb9d

<pycaret.regression.oop.RegressionExperiment at 0x200dedc2d30>

# 评估各类模型
best = s.compare_models()

	Model	MAE	MSE	RMSE	R2	RMSLE	MAPE	TT (Sec)
gbr	Gradient Boosting Regressor	2723.2453	23787529.5872	4832.4785	0.8254	0.4427	0.3140	0.0550
lightgbm	Light Gradient Boosting Machine	2998.1311	25738691.2181	5012.2404	0.8106	0.5525	0.3709	0.1140
rf	Random Forest Regressor	2915.7018	26780127.0016	5109.5098	0.8031	0.4855	0.3520	0.0670
et	Extra Trees Regressor	2841.8257	28559316.9533	5243.5828	0.7931	0.4671	0.3218	0.0670
ada	AdaBoost Regressor	4180.2669	28289551.0048	5297.6817	0.7886	0.5935	0.6545	0.0210
ridge	Ridge Regression	4304.2640	38786967.4768	6188.6966	0.7152	0.5794	0.4283	0.0230
lar	Least Angle Regression	4293.9886	38781666.5991	6188.3301	0.7151	0.5893	0.4263	0.0210
llar	Lasso Least Angle Regression	4294.2135	38780221.0039	6188.1906	0.7151	0.5891	0.4264	0.0200
br	Bayesian Ridge	4299.8532	38785479.0984	6188.6026	0.7151	0.5784	0.4274	0.0200
lasso	Lasso Regression	4294.2186	38780210.5665	6188.1898	0.7151	0.5892	0.4264	0.0370
lr	Linear Regression	4293.9886	38781666.5991	6188.3301	0.7151	0.5893	0.4263	0.0350
dt	Decision Tree Regressor	3550.6534	51149204.9032	7095.9170	0.6127	0.5839	0.4537	0.0230
huber	Huber Regressor	3769.3076	53638697.2337	7254.7108	0.6095	0.4528	0.2187	0.0250
par	Passive Aggressive Regressor	4144.7180	62949698.1775	7862.7604	0.5433	0.4634	0.2465	0.0210
en	Elastic Net	7248.9376	89841235.9517	9405.5846	0.3534	0.7346	0.9238	0.0210
omp	Orthogonal Matching Pursuit	8916.1927	130904492.3067	11356.4120	0.0561	0.8781	1.1598	0.0180
knn	K Neighbors Regressor	8161.8875	137982796.8000	11676.3735	-0.0011	0.8744	0.9742	0.0250
dummy	Dummy Regressor	8892.4478	141597492.8000	11823.4271	-0.0221	0.9868	1.4909	0.0210

print(best)

GradientBoostingRegressor(alpha=0.9, ccp_alpha=0.0, criterion='friedman_mse',init=None, learning_rate=0.1, loss='squared_error',max_depth=3, max_features=None, max_leaf_nodes=None,min_impurity_decrease=0.0, min_samples_leaf=1,min_samples_split=2, min_weight_fraction_leaf=0.0,n_estimators=100, n_iter_no_change=None,random_state=0, subsample=1.0, tol=0.0001,validation_fraction=0.1, verbose=0, warm_start=False)

1.3 聚类

ParCaret提供了clustering模块实现无监督聚类。

数据准备

# 导入珠宝数据集
from pycaret.datasets import get_data
# 根据数据集特征进行聚类
data = get_data('./datasets/jewellery')
# data = get_data('jewellery')

	Age	Income	SpendingScore	Savings
0	58	77769	0.791329	6559.829923
1	59	81799	0.791082	5417.661426
2	62	74751	0.702657	9258.992965
3	59	74373	0.765680	7346.334504
4	87	17760	0.348778	16869.507130

# 创建数据管道
from pycaret.clustering import ClusteringExperiment
s = ClusteringExperiment()
# normalize归一化数据
s.setup(data, normalize = True, verbose = False)
# 另一种数据管道创建方式
# from pycaret.clustering import *
# s = setup(data, normalize = True)

<pycaret.clustering.oop.ClusteringExperiment at 0x200dec86340>

模型创建

PyCaret在聚类任务中提供create_model选择合适的方法来构建聚类模型，而不是全部比较。

kmeans = s.create_model('kmeans')

	Silhouette	Calinski-Harabasz	Davies-Bouldin	Homogeneity	Rand Index	Completeness
0	0.7581	1611.2647	0.3743	0	0	0

create_model函数支持的聚类方法如下：

s.models()

	Name	Reference
ID
kmeans	K-Means Clustering	sklearn.cluster._kmeans.KMeans
ap	Affinity Propagation	sklearn.cluster._affinity_propagation.Affinity...
meanshift	Mean Shift Clustering	sklearn.cluster._mean_shift.MeanShift
sc	Spectral Clustering	sklearn.cluster._spectral.SpectralClustering
hclust	Agglomerative Clustering	sklearn.cluster._agglomerative.AgglomerativeCl...
dbscan	Density-Based Spatial Clustering	sklearn.cluster._dbscan.DBSCAN
optics	OPTICS Clustering	sklearn.cluster._optics.OPTICS
birch	Birch Clustering	sklearn.cluster._birch.Birch

print(kmeans)
# 查看聚类数
print(kmeans.n_clusters)

KMeans(algorithm='lloyd', copy_x=True, init='k-means++', max_iter=300,n_clusters=4, n_init='auto', random_state=1459, tol=0.0001, verbose=0)
4

数据展示

# jupyter环境下交互可视化展示
# s.evaluate_model(kmeans)

# 结果可视化 
# 'cluster' - Cluster PCA Plot (2d)
# 'tsne' - Cluster t-SNE (3d)
# 'elbow' - Elbow Plot
# 'silhouette' - Silhouette Plot
# 'distance' - Distance Plot
# 'distribution' - Distribution Plot
s.plot_model(kmeans, plot = 'elbow')

标签分配与数据预测

为训练数据分配聚类标签：

result = s.assign_model(kmeans)
result.head()

	Age	Income	SpendingScore	Savings	Cluster
0	58	77769	0.791329	6559.830078	Cluster 2
1	59	81799	0.791082	5417.661621	Cluster 2
2	62	74751	0.702657	9258.993164	Cluster 2
3	59	74373	0.765680	7346.334473	Cluster 2
4	87	17760	0.348778	16869.507812	Cluster 1

为新的数据进行标签分配：

predictions = s.predict_model(kmeans, data = data)
predictions.head()

	Age	Income	SpendingScore	Savings	Cluster
0	-0.042287	0.062733	1.103593	-1.072467	Cluster 2
1	-0.000821	0.174811	1.102641	-1.303473	Cluster 2
2	0.123577	-0.021200	0.761727	-0.526556	Cluster 2
3	-0.000821	-0.031712	1.004705	-0.913395	Cluster 2
4	1.160228	-1.606165	-0.602619	1.012686	Cluster 1

1.4 异常检测

PyCaret的anomaly detection模块是一个无监督的机器学习模块，用于识别与大多数数据存在显著差异的罕见项目、事件或观测值。通常，这些异常项目会转化为某种问题，如银行欺诈、结构缺陷、医疗问题或错误。anomaly detection模块的使用类似于cluster模块。

数据准备

from pycaret.datasets import get_data
data = get_data('./datasets/anomaly')
# data = get_data('anomaly')

	Col1	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10
0	0.263995	0.764929	0.138424	0.935242	0.605867	0.518790	0.912225	0.608234	0.723782	0.733591
1	0.546092	0.653975	0.065575	0.227772	0.845269	0.837066	0.272379	0.331679	0.429297	0.367422
2	0.336714	0.538842	0.192801	0.553563	0.074515	0.332993	0.365792	0.861309	0.899017	0.088600
3	0.092108	0.995017	0.014465	0.176371	0.241530	0.514724	0.562208	0.158963	0.073715	0.208463
4	0.325261	0.805968	0.957033	0.331665	0.307923	0.355315	0.501899	0.558449	0.885169	0.182754

from pycaret.anomaly import AnomalyExperiment
s = AnomalyExperiment()
s.setup(data, session_id = 0)
# 另一种加载方式
# from pycaret.anomaly import *
# s = setup(data, session_id = 0)

	Description	Value
0	Session id	0
1	Original data shape	(1000, 10)
2	Transformed data shape	(1000, 10)
3	Numeric features	10
4	Preprocess	True
5	Imputation type	simple
6	Numeric imputation	mean
7	Categorical imputation	mode
8	CPU Jobs	-1
9	Use GPU	False
10	Log Experiment	False
11	Experiment Name	anomaly-default-name
12	USI	54db

<pycaret.anomaly.oop.AnomalyExperiment at 0x200e14f5250>

模型创建

iforest = s.create_model('iforest')
print(iforest)

IForest(behaviour='new', bootstrap=False, contamination=0.05,max_features=1.0, max_samples='auto', n_estimators=100, n_jobs=-1,random_state=0, verbose=0)

anomaly detection模块所支持的模型列表如下：

s.models()

	Name	Reference
ID
abod	Angle-base Outlier Detection	pyod.models.abod.ABOD
cluster	Clustering-Based Local Outlier	pycaret.internal.patches.pyod.CBLOFForceToDouble
cof	Connectivity-Based Local Outlier	pyod.models.cof.COF
iforest	Isolation Forest	pyod.models.iforest.IForest
histogram	Histogram-based Outlier Detection	pyod.models.hbos.HBOS
knn	K-Nearest Neighbors Detector	pyod.models.knn.KNN
lof	Local Outlier Factor	pyod.models.lof.LOF
svm	One-class SVM detector	pyod.models.ocsvm.OCSVM
pca	Principal Component Analysis	pyod.models.pca.PCA
mcd	Minimum Covariance Determinant	pyod.models.mcd.MCD
sod	Subspace Outlier Detection	pyod.models.sod.SOD
sos	Stochastic Outlier Selection	pyod.models.sos.SOS

标签分配与数据预测

为训练数据分配聚类标签：

result = s.assign_model(iforest)
result.head()

	Col1	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10	Anomaly	Anomaly_Score
0	0.263995	0.764929	0.138424	0.935242	0.605867	0.518790	0.912225	0.608234	0.723782	0.733591	0	-0.016205
1	0.546092	0.653975	0.065575	0.227772	0.845269	0.837066	0.272379	0.331679	0.429297	0.367422	0	-0.068052
2	0.336714	0.538842	0.192801	0.553563	0.074515	0.332993	0.365792	0.861309	0.899017	0.088600	1	0.009221
3	0.092108	0.995017	0.014465	0.176371	0.241530	0.514724	0.562208	0.158963	0.073715	0.208463	1	0.056690
4	0.325261	0.805968	0.957033	0.331665	0.307923	0.355315	0.501899	0.558449	0.885169	0.182754	0	-0.012945

为新的数据进行标签分配：

predictions = s.predict_model(iforest, data = data)
predictions.head()

	Col1	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10	Anomaly	Anomaly_Score
0	0.263995	0.764929	0.138424	0.935242	0.605867	0.518790	0.912225	0.608234	0.723782	0.733591	0	-0.016205
1	0.546092	0.653975	0.065575	0.227772	0.845269	0.837066	0.272379	0.331679	0.429297	0.367422	0	-0.068052
2	0.336714	0.538842	0.192801	0.553563	0.074515	0.332993	0.365792	0.861309	0.899017	0.088600	1	0.009221
3	0.092108	0.995017	0.014465	0.176371	0.241530	0.514724	0.562208	0.158963	0.073715	0.208463	1	0.056690
4	0.325261	0.805968	0.957033	0.331665	0.307923	0.355315	0.501899	0.558449	0.885169	0.182754	0	-0.012945

1.5 时序预测

PyCaret时间序列预测Time Series模块支持多种预测方法，如ARIMA、Prophet和LSTM。它还提供了各种功能来处理缺失值、时间序列分解和数据可视化。

数据准备

# 乘客时序数据
from pycaret.datasets import get_data
# 下载路径：https://raw.githubusercontent.com/sktime/sktime/main/sktime/datasets/data/Airline/Airline.csv
data = get_data('./datasets/airline')
# data = get_data('airline')

	Date	Passengers
0	1949-01	112
1	1949-02	118
2	1949-03	132
3	1949-04	129
4	1949-05	121

import pandas as pd
data['Date'] = pd.to_datetime(data['Date'])
# 并将Date设置为列号
data.set_index('Date', inplace=True)

from pycaret.time_series import TSForecastingExperiment
s = TSForecastingExperiment()
# fh: 用于预测的预测范围。默认值设置为1，即预测前方一点。,fold: 交叉验证中折数
s.setup(data, fh = 3, fold = 5, session_id = 0, verbose = False)
# from pycaret.time_series import *
# s = setup(data, fh = 3, fold = 5, session_id = 0)

<pycaret.time_series.forecasting.oop.TSForecastingExperiment at 0x200dee26910>

模型训练与评估

best = s.compare_models()

	Model	MASE	RMSSE	MAE	RMSE	MAPE	SMAPE	R2	TT (Sec)
stlf	STLF	0.4240	0.4429	12.8002	15.1933	0.0266	0.0268	0.4296	0.0300
exp_smooth	Exponential Smoothing	0.5063	0.5378	15.2900	18.4455	0.0334	0.0335	-0.0521	0.0500
ets	ETS	0.5520	0.5801	16.6164	19.8391	0.0354	0.0357	-0.0740	0.0680
arima	ARIMA	0.6480	0.6501	19.5728	22.3027	0.0412	0.0420	-0.0796	0.0420
auto_arima	Auto ARIMA	0.6526	0.6300	19.7405	21.6202	0.0414	0.0421	-0.0560	10.5220
theta	Theta Forecaster	0.8458	0.8223	25.7024	28.3332	0.0524	0.0541	-0.7710	0.0220
huber_cds_dt	Huber w/ Cond. Deseasonalize & Detrending	0.9002	0.8900	27.2568	30.5782	0.0550	0.0572	-0.0309	0.0680
knn_cds_dt	K Neighbors w/ Cond. Deseasonalize & Detrending	0.9381	0.8830	28.5678	30.5007	0.0555	0.0575	0.0908	0.0920
lr_cds_dt	Linear w/ Cond. Deseasonalize & Detrending	0.9469	0.9297	28.6337	31.9163	0.0581	0.0605	-0.1620	0.0820
ridge_cds_dt	Ridge w/ Cond. Deseasonalize & Detrending	0.9469	0.9297	28.6340	31.9164	0.0581	0.0605	-0.1620	0.0680
en_cds_dt	Elastic Net w/ Cond. Deseasonalize & Detrending	0.9499	0.9320	28.7271	31.9952	0.0582	0.0606	-0.1579	0.0700
llar_cds_dt	Lasso Least Angular Regressor w/ Cond. Deseasonalize & Detrending	0.9520	0.9336	28.7917	32.0528	0.0583	0.0607	-0.1559	0.0560
lasso_cds_dt	Lasso w/ Cond. Deseasonalize & Detrending	0.9521	0.9337	28.7941	32.0557	0.0583	0.0607	-0.1560	0.0720
br_cds_dt	Bayesian Ridge w/ Cond. Deseasonalize & Detrending	0.9551	0.9347	28.9018	32.1013	0.0582	0.0606	-0.1377	0.0580
et_cds_dt	Extra Trees w/ Cond. Deseasonalize & Detrending	1.0322	0.9942	31.4048	34.3054	0.0607	0.0633	-0.1660	0.1280
rf_cds_dt	Random Forest w/ Cond. Deseasonalize & Detrending	1.0851	1.0286	32.9791	35.4666	0.0641	0.0670	-0.3545	0.1400
lightgbm_cds_dt	Light Gradient Boosting w/ Cond. Deseasonalize & Detrending	1.1409	1.1040	34.5999	37.9918	0.0670	0.0701	-0.3994	0.0900
ada_cds_dt	AdaBoost w/ Cond. Deseasonalize & Detrending	1.1441	1.0843	34.7451	37.3681	0.0664	0.0697	-0.3004	0.0920
gbr_cds_dt	Gradient Boosting w/ Cond. Deseasonalize & Detrending	1.1697	1.1094	35.4408	38.1373	0.0697	0.0729	-0.4163	0.0900
omp_cds_dt	Orthogonal Matching Pursuit w/ Cond. Deseasonalize & Detrending	1.1793	1.1250	35.7348	38.6755	0.0706	0.0732	-0.5095	0.0620
dt_cds_dt	Decision Tree w/ Cond. Deseasonalize & Detrending	1.2704	1.2371	38.4976	42.4846	0.0773	0.0814	-1.0382	0.0860
snaive	Seasonal Naive Forecaster	1.7700	1.5999	53.5333	54.9143	0.1136	0.1211	-4.1630	0.1580
naive	Naive Forecaster	1.8145	1.7444	54.8667	59.8160	0.1135	0.1151	-3.7710	0.1460
polytrend	Polynomial Trend Forecaster	2.3154	2.2507	70.1138	77.3400	0.1363	0.1468	-4.6202	0.1080
croston	Croston	2.6211	2.4985	79.3645	85.8439	0.1515	0.1684	-5.2294	0.0140
grand_means	Grand Means Forecaster	7.1261	6.3506	216.0214	218.4259	0.4377	0.5682	-59.2684	0.1400

数据展示

# jupyter环境下交互可视化展示
# plot参数支持：
# - 'ts' - Time Series Plot
# - 'train_test_split' - Train Test Split
# - 'cv' - Cross Validation
# - 'acf' - Auto Correlation (ACF)
# - 'pacf' - Partial Auto Correlation (PACF)
# - 'decomp' - Classical Decomposition
# - 'decomp_stl' - STL Decomposition
# - 'diagnostics' - Diagnostics Plot
# - 'diff' - Difference Plot
# - 'periodogram' - Frequency Components (Periodogram)
# - 'fft' - Frequency Components (FFT)
# - 'ccf' - Cross Correlation (CCF)
# - 'forecast' - "Out-of-Sample" Forecast Plot
# - 'insample' - "In-Sample" Forecast Plot
# - 'residuals' - Residuals Plot
# s.plot_model(best, plot = 'forecast', data_kwargs = {'fh' : 24})

数据预测

# 使模型拟合包括测试样本在内的完整数据集
final_best = s.finalize_model(best)
s.predict_model(best, fh = 24)
s.save_model(final_best, 'final_best_model')

Transformation Pipeline and Model Successfully Saved(ForecastingPipeline(steps=[('forecaster',TransformedTargetForecaster(steps=[('model',ForecastingPipeline(steps=[('forecaster',TransformedTargetForecaster(steps=[('model',STLForecaster(sp=12))]))]))]))]),'final_best_model.pkl')

2 数据处理与清洗

2.1 缺失值处理

各种数据集可能由于多种原因存在缺失值或空记录。移除具有缺失值的样本是一种常见策略，但这会导致丢失可能有价值的数据。一种可替代的策略是对缺失值进行插值填充。在setup函数中可以指定如下参数，实现缺失值处理：

• imputation_type：取值可以是 ‘simple’ 或 'iterative’或 None。当imputation_type设置为 ‘simple’ 时，PyCaret 将使用简单的方式（numeric_imputation和categorical_imputation）对缺失值进行填充。而当设置为 ‘iterative’ 时，则会使用模型估计的方式（numeric_iterative_imputer，categorical_iterative_imputer）进行填充处理。如果设置为 None，则不会执行任何缺失值填充操作
• numeric_imputation: 设置数值类型的缺失值，方式如下：
  • mean: 用列的平均值填充，默认
  • drop: 删除包含缺失值的行
  • median: 用列的中值填充
  • mode: 用列最常见值填充
  • knn: 使用K-最近邻方法拟合
  • int or float: 用指定值替代
• categorical_imputation:
  • mode: 用列最常见值填充，默认
  • drop: 删除包含缺失值的行
  • str: 用指定字符替代
• numeric_iterative_imputer: 使用估计模型拟合值，可输入str或sklearn模型, 默认使用lightgbm
• categorical_iterative_imputer: 使用估计模型差值，可输入str或sklearn模型, 默认使用lightgbm

加载数据

# load dataset
from pycaret.datasets import get_data
# 从本地加载数据，注意dataset是数据的文件名
data = get_data(dataset='./datasets/hepatitis', verbose=False)
# data = get_data('hepatitis',verbose=False)
# 可以看到第三行STEROID列出现NaN值
data.head()

	Class	AGE	SEX	STEROID	ANTIVIRALS	FATIGUE	MALAISE	ANOREXIA	LIVER BIG	LIVER FIRM	SPLEEN PALPABLE	SPIDERS	ASCITES	VARICES	BILIRUBIN	ALK PHOSPHATE	SGOT	ALBUMIN	PROTIME	HISTOLOGY
0	0	30	2	1.0	2	2	2	2	1.0	2.0	2.0	2.0	2.0	2.0	1.0	85.0	18.0	4.0	NaN	1
1	0	50	1	1.0	2	1	2	2	1.0	2.0	2.0	2.0	2.0	2.0	0.9	135.0	42.0	3.5	NaN	1
2	0	78	1	2.0	2	1	2	2	2.0	2.0	2.0	2.0	2.0	2.0	0.7	96.0	32.0	4.0	NaN	1
3	0	31	1	NaN	1	2	2	2	2.0	2.0	2.0	2.0	2.0	2.0	0.7	46.0	52.0	4.0	80.0	1
4	0	34	1	2.0	2	2	2	2	2.0	2.0	2.0	2.0	2.0	2.0	1.0	NaN	200.0	4.0	NaN	1

# 使用均值填充数据
from pycaret.classification import ClassificationExperiment
s = ClassificationExperiment()
# 均值
# s.data['STEROID'].mean()
s.setup(data = data, session_id=0, target = 'Class',verbose=False, # 设置data_split_shuffle和data_split_stratify为False不打乱数据data_split_shuffle = False, data_split_stratify = False,imputation_type='simple', numeric_iterative_imputer='drop')
# 查看转换后的数据
s.get_config('dataset_transformed').head()

	AGE	SEX	STEROID	ANTIVIRALS	FATIGUE	MALAISE	ANOREXIA	LIVER BIG	LIVER FIRM	SPLEEN PALPABLE	SPIDERS	ASCITES	VARICES	BILIRUBIN	ALK PHOSPHATE	SGOT	ALBUMIN	PROTIME	HISTOLOGY	Class
0	30.0	2.0	1.000000	2.0	2.0	2.0	2.0	1.0	2.0	2.0	2.0	2.0	2.0	1.0	85.000000	18.0	4.0	66.53968	1.0	0
1	50.0	1.0	1.000000	2.0	1.0	2.0	2.0	1.0	2.0	2.0	2.0	2.0	2.0	0.9	135.000000	42.0	3.5	66.53968	1.0	0
2	78.0	1.0	2.000000	2.0	1.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	0.7	96.000000	32.0	4.0	66.53968	1.0	0
3	31.0	1.0	1.509434	1.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	0.7	46.000000	52.0	4.0	80.00000	1.0	0
4	34.0	1.0	2.000000	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	1.0	99.659088	200.0	4.0	66.53968	1.0	0

# 使用knn拟合数据
from pycaret.classification import ClassificationExperiment
s = ClassificationExperiment()
s.setup(data = data, session_id=0, target = 'Class',verbose=False, # 设置data_split_shuffle和data_split_stratify为False不打乱数据data_split_shuffle = False, data_split_stratify = False,imputation_type='simple', numeric_imputation = 'knn')
# 查看转换后的数据
s.get_config('dataset_transformed').head()

	AGE	SEX	STEROID	ANTIVIRALS	FATIGUE	MALAISE	ANOREXIA	LIVER BIG	LIVER FIRM	SPLEEN PALPABLE	SPIDERS	ASCITES	VARICES	BILIRUBIN	ALK PHOSPHATE	SGOT	ALBUMIN	PROTIME	HISTOLOGY	Class
0	30.0	2.0	1.0	2.0	2.0	2.0	2.0	1.0	2.0	2.0	2.0	2.0	2.0	1.0	85.000000	18.0	4.0	91.800003	1.0	0
1	50.0	1.0	1.0	2.0	1.0	2.0	2.0	1.0	2.0	2.0	2.0	2.0	2.0	0.9	135.000000	42.0	3.5	61.599998	1.0	0
2	78.0	1.0	2.0	2.0	1.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	0.7	96.000000	32.0	4.0	75.800003	1.0	0
3	31.0	1.0	1.8	1.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	0.7	46.000000	52.0	4.0	80.000000	1.0	0
4	34.0	1.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	1.0	108.400002	200.0	4.0	62.799999	1.0	0

# 使用lightgbmn拟合数据
# from pycaret.classification import ClassificationExperiment
# s = ClassificationExperiment()
# s.setup(data = data, session_id=0, target = 'Class',verbose=False, 
#         # 设置data_split_shuffle和data_split_stratify为False不打乱数据
#         data_split_shuffle = False, data_split_stratify = False,
#         imputation_type='iterative', numeric_iterative_imputer = 'lightgbm')
# 查看转换后的数据
# s.get_config('dataset_transformed').head()

2.2 类型转换

虽然 PyCaret具有自动识别特征类型的功能，但PyCaret提供了数据类型自定义参数，用户可以对数据集进行更精细的控制和指导，以确保模型训练和特征工程的效果更加符合用户的预期和需求。这些自定义参数如下：

• numeric_features：用于指定数据集中的数值特征列的参数。这些特征将被视为连续型变量进行处理
• categorical_features：用于指定数据集中的分类特征列的参数。这些特征将被视为离散型变量进行处理
• date_features：用于指定数据集中的日期特征列的参数。这些特征将被视为日期型变量进行处理
• create_date_columns：用于指定是否从日期特征中创建新的日期相关列的参数
• text_features：用于指定数据集中的文本特征列的参数。这些特征将被视为文本型变量进行处理
• text_features_method：用于指定对文本特征进行处理的方法的参数
• ignore_features：用于指定在建模过程中需要忽略的特征列的参数
• keep_features：用于指定在建模过程中需要保留的特征列的参数

# 转换变量类型
from pycaret.datasets import get_data
data = get_data(dataset='./datasets/hepatitis', verbose=False)from pycaret.classification import *
s = setup(data = data, target = 'Class', ignore_features  = ['SEX','AGE'], categorical_features=['STEROID'],verbose = False,data_split_shuffle = False, data_split_stratify = False)

# 查看转换后的数据，前两列消失，STEROID变为分类变量
s.get_config('dataset_transformed').head()

	STEROID	ANTIVIRALS	FATIGUE	MALAISE	ANOREXIA	LIVER BIG	LIVER FIRM	SPLEEN PALPABLE	SPIDERS	ASCITES	VARICES	BILIRUBIN	ALK PHOSPHATE	SGOT	ALBUMIN	PROTIME	HISTOLOGY	Class
0	0.0	2.0	2.0	2.0	2.0	1.0	2.0	2.0	2.0	2.0	2.0	1.0	85.000000	18.0	4.0	66.53968	1.0	0
1	0.0	2.0	1.0	2.0	2.0	1.0	2.0	2.0	2.0	2.0	2.0	0.9	135.000000	42.0	3.5	66.53968	1.0	0
2	1.0	2.0	1.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	0.7	96.000000	32.0	4.0	66.53968	1.0	0
3	1.0	1.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	0.7	46.000000	52.0	4.0	80.00000	1.0	0
4	1.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	1.0	99.659088	200.0	4.0	66.53968	1.0	0

2.3 独热编码

当数据集中包含分类变量时，这些变量通常需要转换为模型可以理解的数值形式。独热编码是一种常用的方法，它将每个分类变量转换为一组二进制变量，其中每个变量对应一个可能的分类值，并且只有一个变量在任何给定时间点上取值为 1，其余变量均为 0。可以通过传递参数categorical_features来指定要进行独热编码的列。例如：

# load dataset
from pycaret.datasets import get_data
data = get_data(dataset='./datasets/pokemon', verbose=False)
# data = get_data('pokemon')
data.head()

	#	Name	Type 1	Type 2	Total	HP	Attack	Defense	Sp. Atk	Sp. Def	Speed	Generation	Legendary
0	1	Bulbasaur	Grass	Poison	318	45	49	49	65	65	45	1	False
1	2	Ivysaur	Grass	Poison	405	60	62	63	80	80	60	1	False
2	3	Venusaur	Grass	Poison	525	80	82	83	100	100	80	1	False
3	3	VenusaurMega Venusaur	Grass	Poison	625	80	100	123	122	120	80	1	False
4	4	Charmander	Fire	NaN	309	39	52	43	60	50	65	1	False

# 对Type 1实现独热编码
len(set(data['Type 1']))

18

from pycaret.classification import *
s = setup(data = data, categorical_features =["Type 1"],target = 'Legendary', verbose=False)
# 查看转换后的数据Type 1变为独热编码
s.get_config('dataset_transformed').head()

	#	Name	Type 1_Grass	Type 1_Ghost	Type 1_Water	Type 1_Steel	Type 1_Psychic	Type 1_Fire	Type 1_Poison	Type 1_Fairy	...	Type 2	Total	HP	Attack	Defense	Sp. Atk	Sp. Def	Speed	Generation	Legendary
202	187.0	Hoppip	1.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	...	Flying	250.0	35.0	35.0	40.0	35.0	55.0	50.0	2.0	False
477	429.0	Mismagius	0.0	1.0	0.0	0.0	0.0	0.0	0.0	0.0	...	NaN	495.0	60.0	60.0	60.0	105.0	105.0	105.0	4.0	False
349	319.0	SharpedoMega Sharpedo	0.0	0.0	1.0	0.0	0.0	0.0	0.0	0.0	...	Dark	560.0	70.0	140.0	70.0	110.0	65.0	105.0	3.0	False
777	707.0	Klefki	0.0	0.0	0.0	1.0	0.0	0.0	0.0	0.0	...	Fairy	470.0	57.0	80.0	91.0	80.0	87.0	75.0	6.0	False
50	45.0	Vileplume	1.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	...	Poison	490.0	75.0	80.0	85.0	110.0	90.0	50.0	1.0	False

5 rows × 30 columns

2.4 数据平衡

在 PyCaret 中，fix_imbalance 和 fix_imbalance_method 是用于处理不平衡数据集的两个参数。这些参数通常用于在训练模型之前对数据集进行预处理，以解决类别不平衡问题。

• fix_imbalance 参数：这是一个布尔值参数，用于指示是否对不平衡数据集进行处理。当设置为 True 时，PyCaret 将自动检测数据集中的类别不平衡问题，并尝试通过采样方法来解决。当设置为 False 时，PyCaret 将使用原始的不平衡数据集进行模型训练
• fix_imbalance_method 参数：这是一个字符串参数，用于指定处理不平衡数据集的方法。可选的值包括：
  • 使用 SMOTE（Synthetic Minority Over-sampling Technique）来生成人工合成样本，从而平衡类别（默认参数smote）
  • 使用imbalanced-learn提供的估算模型

# 加载数据
from pycaret.datasets import get_data
data = get_data(dataset='./datasets/credit', verbose=False)
# data = get_data('credit')
data.head()

	LIMIT_BAL	SEX	EDUCATION	MARRIAGE	AGE	PAY_1	PAY_2	PAY_3	PAY_4	PAY_5	...	BILL_AMT4	BILL_AMT5	BILL_AMT6	PAY_AMT1	PAY_AMT2	PAY_AMT3	PAY_AMT4	PAY_AMT5	PAY_AMT6	default
0	20000	2	2	1	24	2	2	-1	-1	-2	...	0.0	0.0	0.0	0.0	689.0	0.0	0.0	0.0	0.0	1
1	90000	2	2	2	34	0	0	0	0	0	...	14331.0	14948.0	15549.0	1518.0	1500.0	1000.0	1000.0	1000.0	5000.0	0
2	50000	2	2	1	37	0	0	0	0	0	...	28314.0	28959.0	29547.0	2000.0	2019.0	1200.0	1100.0	1069.0	1000.0	0
3	50000	1	2	1	57	-1	0	-1	0	0	...	20940.0	19146.0	19131.0	2000.0	36681.0	10000.0	9000.0	689.0	679.0	0
4	50000	1	1	2	37	0	0	0	0	0	...	19394.0	19619.0	20024.0	2500.0	1815.0	657.0	1000.0	1000.0	800.0	0

5 rows × 24 columns

# 查看数据各类别数
category_counts = data['default'].value_counts()
category_counts

default
0    18694
1     5306
Name: count, dtype: int64

from pycaret.classification import *
s = setup(data = data, target = 'default', fix_imbalance = True, verbose = False)

# 可以看到类1数据量变多了
s.get_config('dataset_transformed')['default'].value_counts()

default
0    18694
1    14678
Name: count, dtype: int64

2.5 异常值处理

PyCaret的remove_outliers函数可以在训练模型之前识别和删除数据集中的异常值。它使用奇异值分解技术进行PCA线性降维来识别异常值，并可以通过setup中的outliers_threshold参数控制异常值的比例（默认0.05）。

from pycaret.datasets import get_datadata = get_data(dataset='./datasets/insurance', verbose=False)
# insurance = get_data('insurance')
# 数据维度
data.shape

(1338, 7)

from pycaret.regression import *
s = setup(data = data, target = 'charges', remove_outliers = True ,verbose = False, outliers_threshold = 0.02)
# 移除异常数据后，数据量变少
s.get_config('dataset_transformed').shape

(1319, 10)

2.6 特征重要性

特征重要性是一种用于选择数据集中对预测目标变量最有贡献的特征的过程。与使用所有特征相比，仅使用选定的特征可以减少过拟合的风险，提高准确性，并缩短训练时间。在PyCaret中，可以通过使用feature_selection参数来实现这一目的。对于PyCaret中几个与特征选择相关参数的解释如下：

• feature_selection：用于指定是否在模型训练过程中进行特征选择。可以设置为 True 或 False。
• feature_selection_method：特征选择方法：
  • ‘univariate’: 使用sklearn的SelectKBest，基于统计测试来选择与目标变量最相关的特征。
  • ‘classic（默认）’: 使用sklearn的SelectFromModel，利用监督学习模型的特征重要性或系数来选择最重要的特征。
  • ‘sequential’: 使用sklearn的SequentialFeatureSelector，该类根据指定的算法（如前向选择、后向选择等）以及性能指标（如交叉验证得分）逐步选择特征。
• n_features_to_select：特征选择的最大特征数量或比例。如果<1，则为起始特征的比例。默认为0.2。该参数在计数时不考虑 ignore_features 和 keep_features 中的特征。

from pycaret.datasets import get_data
data = get_data('./datasets/diabetes')

	Number of times pregnant	Plasma glucose concentration a 2 hours in an oral glucose tolerance test	Diastolic blood pressure (mm Hg)	Triceps skin fold thickness (mm)	2-Hour serum insulin (mu U/ml)	Body mass index (weight in kg/(height in m)^2)	Diabetes pedigree function	Age (years)	Class variable
0	6	148	72	35	0	33.6	0.627	50	1
1	1	85	66	29	0	26.6	0.351	31	0
2	8	183	64	0	0	23.3	0.672	32	1
3	1	89	66	23	94	28.1	0.167	21	0
4	0	137	40	35	168	43.1	2.288	33	1

from pycaret.regression import *
# feature_selection选择特征, n_features_to_select选择特征比例
s = setup(data = data, target = 'Class variable', feature_selection = True, feature_selection_method = 'univariate',n_features_to_select = 0.3, verbose = False)

# 查看哪些特征保留下来
s.get_config('X_transformed').columns
s.get_config('X_transformed').head()

	Plasma glucose concentration a 2 hours in an oral glucose tolerance test	Body mass index (weight in kg/(height in m)^2)
56	187.0	37.700001
541	128.0	32.400002
269	146.0	27.500000
304	150.0	21.000000
32	88.0	24.799999

2.7 归一化

数据归一化

在 PyCaret 中，normalize 和 normalize_method 参数用于数据预处理中的特征缩放操作。特征缩放是指将数据的特征值按比例缩放，使之落入一个小的特定范围，这样可以消除特征之间的量纲影响，使模型训练更加稳定和准确。下面是关于这两个参数的说明：

• normalize: 这是一个布尔值参数，用于指定是否对特征进行缩放。默认情况下，它的取值为 False，表示不进行特征缩放。如果将其设置为 True，则会启用特征缩放功能。
• normalize_method: 这是一个字符串参数，用于指定特征缩放的方法。可选的值有：
  • zscore（默认）: 使用 Z 分数标准化方法，也称为标准化或 Z 标准化。该方法将特征的值转换为其 Z 分数，即将特征值减去其均值，然后除以其标准差，从而使得特征的均值为 0，标准差为 1。
  • minmax: 使用 Min-Max 标准化方法，也称为归一化。该方法将特征的值线性转换到指定的最小值和最大值之间，默认情况下是 [0, 1] 范围。
  • maxabs: 使用 MaxAbs 标准化方法。该方法将特征的值除以特征的最大绝对值，将特征的值缩放到 [-1, 1] 范围内。
  • robust: 使用 RobustScaler 标准化方法。该方法对数据的每个特征进行中心化和缩放，使用特征的中位数和四分位数范围来缩放特征。

from pycaret.datasets import get_data
data = get_data('./datasets/pokemon')
data.head()

	#	Name	Type 1	Type 2	Total	HP	Attack	Defense	Sp. Atk	Sp. Def	Speed	Generation	Legendary
0	1	Bulbasaur	Grass	Poison	318	45	49	49	65	65	45	1	False
1	2	Ivysaur	Grass	Poison	405	60	62	63	80	80	60	1	False
2	3	Venusaur	Grass	Poison	525	80	82	83	100	100	80	1	False
3	3	VenusaurMega Venusaur	Grass	Poison	625	80	100	123	122	120	80	1	False
4	4	Charmander	Fire	NaN	309	39	52	43	60	50	65	1	False

	#	Name	Type 1	Type 2	Total	HP	Attack	Defense	Sp. Atk	Sp. Def	Speed	Generation	Legendary
0	1	Bulbasaur	Grass	Poison	318	45	49	49	65	65	45	1	False
1	2	Ivysaur	Grass	Poison	405	60	62	63	80	80	60	1	False
2	3	Venusaur	Grass	Poison	525	80	82	83	100	100	80	1	False
3	3	VenusaurMega Venusaur	Grass	Poison	625	80	100	123	122	120	80	1	False
4	4	Charmander	Fire	NaN	309	39	52	43	60	50	65	1	False

# 归一化
from pycaret.classification import *
s = setup(data, target='Legendary', normalize=True, normalize_method='robust', verbose=False)

数据归一化结果：

s.get_config('X_transformed').head()

	#	Name	Type 1_Water	Type 1_Normal	Type 1_Ice	Type 1_Psychic	Type 1_Fire	Type 1_Rock	Type 1_Fighting	Type 1_Grass	...	Type 2_Electric	Type 2_Normal	Total	HP	Attack	Defense	Sp. Atk	Sp. Def	Speed	Generation
403	-0.021629	0.0	1.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	...	0.0	0.0	0.195387	-0.333333	0.200000	0.875	1.088889	0.125	-0.288889	0.000000
471	0.139870	0.0	0.0	1.0	0.0	0.0	0.0	0.0	0.0	0.0	...	0.0	0.0	0.179104	0.333333	0.555556	-0.100	-0.111111	-0.100	1.111111	0.333333
238	-0.448450	0.0	0.0	0.0	1.0	0.0	0.0	0.0	0.0	0.0	...	0.0	0.0	-1.080054	-0.500000	-0.555556	-0.750	-0.777778	-1.000	-0.333333	-0.333333
646	0.604182	0.0	0.0	1.0	0.0	0.0	0.0	0.0	0.0	0.0	...	0.0	0.0	-0.618725	-0.166667	-0.333333	-0.500	-0.555556	-0.500	0.222222	0.666667
69	-0.898342	0.0	0.0	0.0	0.0	1.0	0.0	0.0	0.0	0.0	...	0.0	0.0	-0.265943	-0.833333	-0.888889	-1.000	1.222222	0.000	0.888889	-0.666667

5 rows × 46 columns

特征变换

归一化会重新调整数据，使其在新的范围内，以减少方差中幅度的影响。特征变换是一种更彻底的技术。通过转换改变数据的分布形状，使得转换后的数据可以被表示为正态分布或近似正态分布。PyCaret中通过transformation参数开启特征转换，transformation_method设置转换方法：yeo-johnson（默认）和分位数。此外除了特征变换，还有目标变换。目标变换它将改变目标变量而不是特征的分布形状。此功能仅在pycarte.regression模块中可用。使用transform_target开启目标变换，transformation_method设置转换方法。

from pycaret.classification import *
s = setup(data = data, target = 'Legendary', transformation = True, verbose = False)
# 特征变换结果
s.get_config('X_transformed').head()

	#	Name	Type 1_Psychic	Type 1_Water	Type 1_Rock	Type 1_Grass	Type 1_Dragon	Type 1_Ghost	Type 1_Bug	Type 1_Fairy	...	Type 2_Electric	Type 2_Bug	Total	HP	Attack	Defense	Sp. Atk	Sp. Def	Speed	Generation
165	52.899003	0.009216	0.043322	-0.000000	-0.000000	-0.000000	-0.000000	-0.0	-0.0	-0.0	...	-0.0	-0.0	93.118403	12.336844	23.649090	13.573010	10.692443	8.081703	26.134255	0.900773
625	140.730289	0.009216	-0.000000	0.095739	-0.000000	-0.000000	-0.000000	-0.0	-0.0	-0.0	...	-0.0	-0.0	66.091344	9.286671	20.259153	13.764668	8.160482	6.056644	9.552506	3.679456
628	141.283084	0.009216	-0.000000	-0.000000	0.043322	-0.000000	-0.000000	-0.0	-0.0	-0.0	...	-0.0	-0.0	89.747939	10.823299	29.105379	11.029571	11.203335	6.942091	27.793080	3.679456
606	137.396878	0.009216	-0.000000	-0.000000	-0.000000	0.061897	-0.000000	-0.0	-0.0	-0.0	...	-0.0	-0.0	56.560577	8.043018	10.276208	10.604937	6.949265	6.302465	19.943809	3.679456
672	149.303914	0.009216	-0.000000	-0.000000	-0.000000	-0.000000	0.029706	-0.0	-0.0	-0.0	...	-0.0	-0.0	72.626190	10.202245	26.061259	11.435493	7.199607	6.302465	20.141156	3.679456

5 rows × 46 columns

3 参考

• pycaret
• pycaret-docs
• pycaret-datasets
• lightgbm
• cuml
• imbalanced-learn