The sklearn preprocessing

Recently， I was writing module of feature engineering, i found two excellently packages -- tsfresh and sklearn.

tsfresh has been specialized for data of time series, tsfresh mainly include two modules, feature extract, and feature select:

 from tsfresh import feature_selection, feature_extraction

To limit the number of irrelevant features tsfresh deploys the fresh algorithms. The whole process consists of three steps.

Firstly. the algorithm characterizes time series with comprehensive and well-established feature mappings. the feature calculators used to derive the features are contained in tsfresh.feature_extraction.feature_calculators.

In a second step, each extracted feature vector is individually and evaluated with respect to its significance for predicting the target under investigation, those tests are contained in submodule tsfresh.feature_selection.significance_tests. the result of a significance test is a vector of p-value, quantifying the significance of each feature for predicting the target.

Finally, the vector of p-value is evaluated base on basis of the Benjamini-Yekutieli procedure in order to decide which feature could keep.

In summary, the tsfresh is a scalable and efficiency tool of feature engineering.

although the function of tsfresh was powerful, i choose sklearn.

I download data which is the heart disease data set. the data set target is binary and has a 13 dimension feature, I was just used MinMaxScaler to transform age,trestbps,chol three columns, the model had a choiced ensemble of AutoSklearnClassifer and ensemble of RandomForest. but bad performance for two models.

from sklearn.preprocessing import MinMaxScaler,StandardScaler

from sklearn.ensemble import RandomForestClassifier

from sklearn.model_selection import train_test_split

from numpy import set_printoptions, inf

set_printoptions(threshold=inf)

import pandas as pd

data = pd.read_csv("../data_set/heart.csv")

X = data[data.columns[:data.shape[1] - 1]].values

y = data[data.columns[-1]].values

data = MinMaxScaler().fit_transform(X[:, [0, 3, 4, 7]])

X[:, [0, 3, 4, 7]] = data

x_train, x_test, y_train, y_test = train_test_split(X, y, test_size=0.3, random_state=0)

from autosklearn.classification import AutoSklearnClassifier

model_auto = AutoSklearnClassifier(time_left_for_this_task=120, n_jobs=3, include_preprocessors=["no_preprocessing"], seed=3)

model_auto.fit(x_train, y_train)

from sklearn.metrics import accuracy_score

y_pred = model_auto.predict(x_test)

accuracy_score(y_test, y_pred)   >>> 0.8021978021978022

from sklearn.ensemble import RandomForestClassifier

model = RandomForestClassifier(n_estimators=500)

y_pred_rf = model.predict(x_test)

accuracy_score(y_test, y_pred_rf) >>> 0.8051648351648352

My personal web site which provides automl service, I upload this data set to my service, it gets a better score than my code: http://simple-code.cn/

巴特西

The sklearn preprocessing

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