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Public Course address:Https://class.coursera.org/ml-003/class/index
INSTRUCTOR:Andrew Ng 1. deciding what to try next (
Determine what to do next
)
I have already introduced some machine learning methods. It is obviously not enough to know the specific process of these methods. The key is to learn how to use them. The so-called best way to master knowledge is to put it into practice. Consider the ear
design a system that allows it to learn in a certain way based on the training data provided; With the increase of training times, the system can continuously learn and improve the performance, through the learning model of parameter optimization, it can be used to predict the output of related problems.
4. Machine Learning Algorithm Classification:
(1) Supervi
Machine Learning Quick Start (2)
Machine Learning Quick Start (2)-Classification
Abstract: This article briefly describes how to use a classification algorithm to evaluate the bank's loan issuance model.
Statement: (the content of this article is not original, but it has been translated and summarized by myself. Plea
descent, batch gradient processing uses all M example for parameter updating, and the random gradient descent only uses 1 example to update the parameters, while the mini gradient descent uses B (1Repeat {For i = 1, 11, 21, ..., 991 {$\theta_j=\theta_j-\alpha\frac{1}{10}\sum\limits_{k=i}^{i+9} (H_\theta (x^{(k)})-y^{(k)}) x_j^{(k)}$}}Convergence of algorithmsBatch gradient processing can ensure that the algorithm converges to the minimum (if the selected le
Reprint Please specify source: http://www.cnblogs.com/ymingjingr/p/4271742.htmlDirectory machine Learning Cornerstone Note When you can use machine learning (1) Machine learning Cornerstone Note 2--When you can use
Scikit-learn.
Deep learning
Although deep learning is a sub-section of machine learning, the reason we have created a separate section here is that it has attracted a lot of attention from Google and Facebook talent recruitment departments.Theano
Theano is the most mature deep lea
1000, then each model will run 1000 times with 999 samples, so the usability is not high in the actual application, and the stability is not good, because it Causes the curve of the 15-6 curve to fluctuate too much and is very unstable. In practical applications, it is seldom to use a cross-validation method.In order to solve the two problems of the cross-validation, a cross-validation method is proposed,
sample is greater than that of the negative sample. The score is divided by m x n. Note that when scores are equal, you must assign the same rank value. The specific operation is to take the rank of all the samples with the same score to the average.
Note: The lift, F_1, and ROC curves can be obtained through the R language environment machine learning package.
listed in this article with a graphical user interface (graphical user Interface,gui). It is quite comprehensive and has some cross-validation methods for classification, aggregation, and feature selection methods. In some ways it is better than Scikit-learn (classification method, some preprocessing ability), but compared with other scientific computing systems (Numpy, Scipy, Matplotlib, Pandas) is less suitable than scikit-learn.
However, the inclusion of a GUI is an important advantage. You
. It is better than scikit-learn in some aspects (classification methods, some preprocessing capabilities) as well, but it D OES not fit well with the rest of the scientific computing Ecosystem (Numpy, Scipy, Matplotlib, Pandas) as nicely as Sciki T-learn.Have a GUI is an important advantage over other libraries however. Could visualize cross-validation results, models and feature selection methods (you need to install Graphviz for some of the capabilities separately). Orange has it own data str
have some cross-val Idation methods. It is better than scikit-learn in some aspects (classification methods, some preprocessing capabilities) as well, but it D OES not fit well with the rest of the scientific computing Ecosystem (Numpy, Scipy, Matplotlib, Pandas) as nicely as Sciki T-learn. Have a GUI is an important advantage over other libraries however. Could visualize cross-validation results, models and feature selection methods (you need to install Graphviz for some of the capabilities s
The process of building a machine learning algorithm:
Quickly build a simple algorithm and test the performance of the algorithm with a cross-validation set.
Draw the learning curve, check whether the algorithm has high variance or high deviation problem, so as to choose corresponding coping methods.
E
time, in order to avoid overfitting as much as possible, the regularization method is usually added to the model.3. Model evaluation: After the model is solved, a certain criterion is needed to measure the quality of the model, and the commonly used evaluation indexes include: accuracy rate, recall rate, TP, FN, FP, TN, Roc Curve and area, cross-validation, etc., the regression problem will also be measure
, the accuracy overall decreased, at the recall rate of 1 o'clock, the accuracy of the insts model was more than the INSTS2 model, which fully illustrates that we only use a point of accuracy and recall results are not fully measurable model performance, only through the overall performance of the p-r curve, To make a more comprehensive assessment of the model.(Pictures from Fawcett, Tom.) "An introduction-ROC
Nonlinear Transformation (nonlinear conversion)
ReviewIn the 11th lecture, we introduce how to deal with two classification problems through logistic regression, and how to solve multiple classification problems by Ova/ovo decomposition.
Quadratic hypothesesThe two-time hypothetical space linear hypothetical space is extremely flawed:
So far, the machine learning model we have introduced is linear model,
(Linear Discriminantanalysis/fisher Linear discriminant linear discriminant Analysis/fisher linear discriminant), EL (Ensemble Learning integrated Learning boosting,bagging, Stacking), AdaBoost (adaptiveboosting Adaptive Enhancement), MEM (Maximum Entropy model maximum entropy) Classification Effectivenessevaluation (Classification effect evaluation):Confusionmatrix (confusion matrix), Precision (accuracy)
the iterative speed of this method can be imagined. Advantages: Global optimal solution, easy to parallel implementation; disadvantage: When the number of samples is very large, the training process will be very slow. The number of BGD iterations is relatively small in terms of the number of iterations. The schematic diagram of its iterative convergence curve can be expressed as follows: 2, small batch gradient descent method Mbg
similar to LWLR, the formula is described in "machine learning combat". The formula adds a coefficient that we set ourselves, and we take 30 different values to see the change of W.STEP5:Ridge return:#岭回归def ridgeregression (data, L): Xmat = Mat (data) Ymat = Mat (l). T Ymean = mean (Ymat, 0) Ymat = Ymat-ymean Xmean = mean (Xmat, 0) v = var (xmat) Xmat = (Xmat-xmean) /V #取30次不同lam岭回
binary classification, we usually choose to evaluate the area below the receiver (receiver) of the running feature curve (ROC AUC or simple AUC).In multi-label and multi-type classification challenges, we typically choose to classify the interaction entropy, or multiple types of log loss, and reduce the squared error in regression problems.Data baseWatch and perform data processing: PandasVarious
)--composed of M weak classifiers. When classifying, the new data point x is entered, if the YM (X) is less than 0 assigns the category of x to-1, if the YM (X) is greater than 0 assigns the category of X to 1. The threshold value of uniform distribution is 0, and the unbalanced distribution is based on the ROC curve and other methods to determine the optimal threshold of a classification.Basic process: tra
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