book machine learning python

#数据预处理方法, mainly dealing with the dimension of data and the problem of the same trend.Import NumPy as NPFrom Sklearn Import preprocessing#零均值规范Data=np.random.rand (3,4) #随机生成3行4列的数据Data_standardized=preprocessing.scale (data) #对数据进行归一化处理, that is, each value minus the mean divided by the variance is primarily used for SVM#线性数据变换最大最小化处理Data_scaler=preprocessing. Minmaxscaler (feature_range= (0,1)) #选定区间 (0,1), raw Data-min/(max-min)Data_scaled=data_scaler.fit (data)#数据标准化处理normalizeddata_normaliz

as the similarity of two vectors.The commonly used kernel functions are: Polynomial cores: , which is the threshold value, is the index set by the user. Hyperbolic tangent (sigmoid) Cores: Radial basis function core (Gaussian core): Now summarize the steps of the nuclear PCA, taking the RBF nucleus as an example:1 compute the kernel (similarity) matrix K, which is the calculation of any two training samples:Get K:For example, if the training set has 10

This article describes the python Machine Learning Decision tree in detail (demo-trees, DTs) is an unsupervised learning method for classification and regression. Advantages: low computing complexity, easy to understand output results, insensitive to missing median values, and the ability to process irrelevant feature

See Original book section 1.5General process for building predictive modelsThe problem of the daily language expression--the problem of the mathematical language restatementRestatement of problems, extraction features, training algorithms, evaluation algorithmsFamiliar with the input data structure of the different algorithms:1. Features required to extract or combine predictions2. Set the training target3. Training model4. Evaluate the performance of

can be obtained through the best_score_ attribute, and the specific parameter information can be obtained through the Best_params_ attribute.Selecting algorithms by nested cross-validationCombined with the grid search for K-fold cross-validation, it is an effective way to improve the performance of machine learning model by optimizing the machine

): # Extend the Input feature vector as a feature matrix linenum = featurematrix.shape[0] featurematrixin = Np.tile ( Featurevectorin, (linenum,1)) # Calculate the Euclidean distance between the matrix Diffmatrix = featurematrixin -Featurematrix Sqdiffmatrix = Diffmatrix * * 2 Distancevaluearray = Sqdiffmatrix.sum (Axis=1) Distancevaluearray = Distancevaluearray * * 0.5 return DistancevaluearrayUsed in the numpy of the more distinctive things. The practice is to first

This section learns to use Sklearn for voting classification, see a specific example, the dataset uses the Iris DataSet, using only the sepal width and petal length two dimension features, Category we also only use two categories: Iris-versicolor and Iris-virginica, the standard uses ROC AUC.Python Machine learning Chinese catalog (http://www.aibbt.com/a/20787.html)Reprint please specify the source,

Recently learned about Python implementation of common machine learning algorithms on GitHubDirectory First, linear regression 1. Cost function2. Gradient Descent algorithm3. Normalization of the mean value4. Final running result5, using the linear model in the Scikit-learn library to implement Second, logistic regression 1. Cost funct

Full Stack Engineer Development Manual (author: Shangpeng) Python Tutorial Full solution installation Pip Install LIGHTGBM Gitup Web site: Https://github.com/Microsoft/LightGBM Chinese Course http://lightgbm.apachecn.org/cn/latest/index.html LIGHTGBM Introduction The emergence of xgboost, let data migrant workers farewell to the traditional machine learning algo

2.7.x,python 3.3.X and Python 3.4.X four series packages, which is a legacy of other distributions. Therefore, in various operating systems, whether it is Linux, or Windows, MAC, it is recommended anaconda!Since Anacoda is a collection of Python science and technology packages, different packages follow the same protocol, and you can see http://docs.continuum.io

~1000Importtimeitnormal_py_sec= Timeit.timeit ('sum (x*x for x in Xrange ())', number= 1000) Naive_np_sec= Timeit.timeit ('sum (na*na)', Setup="Import NumPy as Np;na=np.arange (+)", number= 1000) Good_np_sec= Timeit.timeit ('Na.dot (NA)', Setup="import NumPy as NP; Na=np.arange (+)", number= 1000)Print("Normal Python:%f sec"%normal_py_sec)Print("Naive Python:%f sec"%naive_np_sec)Print("Good NumPy:%f sec"%go

in the first section, the meta-algorithm briefly describesIn the case of rare cases, the hospital organizes a group of experts to conduct clinical consultations to analyze the case to determine the outcome. As with the panel's clinical consultations, it is often better to summarize a large number of individual opinions than a person's decision. Machine learning also absorbed the ' Three Stooges top Zhuge Li

from:http://blog.csdn.net/lsldd/article/details/41551797In this series of articles, it is mentioned that the use of Python to start machine learning (3: Data fitting and generalized linear regression) refers to the regression algorithm for numerical prediction. The logistic regression algorithm is essentially regression, but it introduces logic functions to help

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Rate the Fl-score the Support the 98 Logistic regression accuracy rate: 0.9707602339181286 About Other indicators of logistic regression: - Precision recall F1-score support101 102 benign 0.96 0.99 0.98103 Malignant 0.99 0.94 0.96104 the avg/total 0.97 0.97 0.97 171106 107 estimation accuracy of stochastic parameters: 0.9649122807017544108 Other indicators of stochastic parameter estimation:109 Precision recall F1-score support the 111 benign 0.97 0.97 0.97 the malignant 0.96 0.96 0.96113 th

matrix matrices, and the column represents the feature, where the percentage represents the variance ratio of the number of features required before taking the default to 0.9" "defPCA (datamat,percentage=0.9): #averaging for each column, because the mean value is subtracted from the calculation of the covarianceMeanvals=mean (datamat,axis=0) meanremoved=datamat-meanvals#CoV () Calculating varianceCovmat=cov (meanremoved,rowvar=0)#using the Eig () method in the module linalg for finding eigen

criteria for the end of recursion are:1: All class tags are exactly the same, return the class label (this is not nonsense, all the same, the class of the hair)2: Using all the groupings or not dividing the dataset into groups that contain only unique categories, since we cannot return a unique one, then we are represented by a wave. Is our majority voting mechanism above, returning the category with the most occurrences. This is not the NPC,.The code is as follows:People can not understand the

Naive Bayesian algorithm is simple and efficient, and it is one of the first ways to deal with classification problems. With this tutorial, you'll learn the fundamentals of naive Bayesian algorithms and the step-by-step implementation of the Python version. Update: View subsequent articles on naive Bayesian use tips "Better Naive bayes:12 tips to get the Most from the Naive Bayes algorithm"Naive Bayes classifier, Matt Buck retains part of the copyri

bestfeatue in creating is:0the bestfeatue in creating are : 0{' no surfacing ': {0: ' No ', 1: {' flippers ': {0: ' No ', 1: ' Yes '}}}It is best to increase the classification function using the decision treeAlso because building a decision tree is time-consuming, because it is best to serialize the constructed tree through Python's pickle and save the object inOn the disk, and then read it when neededdef classify (Inputtree,featlabels,testvec): firststr = Inputtree.keys () [0] seconddic

), + Ss_y.inverse_transform (dis_knr_y_predict))) the Print("the average absolute error of the distance weighted K-nearest neighbor regression is:", Mean_absolute_error (Ss_y.inverse_transform (y_test), - Ss_y.inverse_transform (dis_knr_y_predict))) $ the " " the the default evaluation value for the average K-nearest neighbor regression is: 0.6903454564606561 the the r_squared value of the average K-nearest neighbor regression is: 0.6903454564606561 the Mean square error of average K nearest ne