This paper mainly introduces the related problems of logistic regression and the detailed realization method.1. What is logistic regressionLogistic regression is one of linear regression, so what is regression and what is linear r
Classification:
Binary classification:
Multi-Category classification: (as multiple two-yuan classification)
Logistic regression model:
Cost function:
Parameter--Gradient descent algorithm
The updates in logistic regression are in the same form as linear regression
estimated:One-element linear regression analysisMultivariate linear regression modelThe core problem of multivariate linear regression: Which variables should be selected?An atypical example (Shiry book p325)RSS (residuals squared sum) and R2 (correlation coefficient squared) selection method: traverse all possible combinations to select the model that minimizes
This article describes how to implement logistic regression in python. this is an experiment of the machine learning course. you can share the experiment with us. This article describes how to implement logistic regression in python. this is an experiment of the machine learning course. you can share the experiment wit
PS: This blog content based on Tang Yudi's machine learning Classic algorithm Learning video replication summary and Http://www.abcplus.com.cn/course/83/tasks
Logistic regressionProblem Description: We will establish a logistic regression model to predict whether a student is enrolled in a university. If you are an administrator of a university department, yo
built the word frequency vectors, you can use IDF to calculate the inverse document frequency and then multiply them by the word frequency to calculate the TF-IDF instance: Import Org.apache. Spark. Ml.feature. {HASHINGTF, IDF, Tokenizer} val sentencedata = Spark.createdataframe (Seq ( (0, "Hi I heard about Spark"), (0, "I wish ; java could use case classes "), (1," Logistic regression models is nea
Case 1: Predicting the customer's credit rating using a logistic regression modelThe data set takes defect as the dependent variable and the remaining variable as the argument1. Loading packages and datasetsLibrary (PROC) library (DMWR)MODEL.DF 2. View the data set,Dim (model.df) Head (MODEL.DF) str (MODEL.DF) Summary (MODEL.DF)Conclusion: There are 10000 rows of data, 56 variables, there is no null value i
coefficients can reach the stable value through a large number of iterations, and there is still a local fluctuation phenomenon.For the problems in the stochastic gradient algorithm, the improved stochastic gradient ascending algorithm can be used to solve the problem.def stocGradAscent1 (Datamatrix, Classlabels, numiter=150): m,n = shape (datamatrix) weights = Ones (n) # Initialize to all ones for J in Range (Numiter): dataindex = Range (m) for I in range (m):
) hθ (x) >0.5 indicates that the current data belongs to Class B
7. How to use generalized linear regression model
Considering the vector x= (x1,x2,x3,..., xn) with n independent variables, the conditional rate P (y=1| X) = P is the probability of the occurrence of an event relative to the observed amount. Then the logistic regression model can be expressed as
S
First the PO on the main Python code (2.7), this code can be found on the deep learning. 1 # Allocate symbolic variables for the data 2 index = T.lscalar () # Index to a [mini]batch 3 x = T.matrix (' x ') # The data is presented as rasterized images 4 y = t.ivector (' y ') # The labels is presented as 1D vector of 5 # [INT] Labels 6 7 # Construct the logistic regression Class 8 #
./theta (3)). * (Theta (2). *plot_x + theta (1)); plot ( Plot_x, plot_y) % Legend, specific for the exercise legend (' admitted ', ' not admitted ', ' decision boundary ') axis ([+, +, +]) else %x already mapfeature (with 28 features), call this part of the program % here is the grid range u = Linspace (-1, 1.5, 50); v = Linspace ( -1, 1.5,); z = zeros (Length (u), Length (v));% Evaluate z = theta*x over the gridFor i = 1:length (u)for j = 1:length (v)Z (i,j) = mapfeature (U
By the basic principle of logistic regression, we represent the probability of customer default as P, then the normal probability is 1-p. As a result, you can get: At this point, the probability p for a customer default can be expressed as: The score scale set by the Scorecard can be defined by a linear expression that represents a fraction of the ratio logarithm, which is represented as follows: wher
I. Linear Logistic Regression
The Code is as follows:
Import numpy as npimport pandas as pdimport matplotlib. pyplot as pltimport scipy. optimize as optimport Seaborn as SNS # Read the dataset Path = 'ex2data1.txt 'Data = PD. read_csv (path, header = none, names = ['expired', 'expired', 'admitted']) # Separate Positive and Negative datasets positive = data [DATA ['admitted']. ISIN ([1])] Negative = data [DA
Question address:
Exercise: Logistic Regression
Question summary:In a high school, there are 80 students, 40 of whom are admitted to the university, and 40 are not. X contains the scores of 80 students in two standard examinations, and y includes whether the students are admitted (1 indicates admission, 0 indicates not admission ).
Process:
1. Load Test DataAnd add an offset for the X input.
X = l
This chapter mainly explains the principle of logistic regression and its mathematical derivation, the logistic has 3 different forms of expression, and now I will unfold these different forms, and its effect in the classification.And compare these three kinds of forms. These three forms of loss function are written below:The following are the three kinds of loss
Regression: Assuming there are some data points, we use a straight line to fit these points (the line is called the best fit Line), the fitting process is called regression.
The purpose of Logistic regression is to find the best fitting parameters of a nonlinear function sigmoid, and the solving process can be accompl
Logistic regression is often used for classification problems, the simplest of which are two classification questions: Is it junk mail? Is the game winning or losing?For linear regression problems, Z = w0*x0+w1*x1+w2*x2+ ...Generally, through the least squares learning parameter w to predict the size of Z when given an X value, its value range (-∞,+∞), and for th
Forest In order to prevent overfitting, a random forest is equivalent to several decision trees.Four, KNN nearest neighborSince KNN has to traverse all the remaining points each time it looks for the next closest point to it, the algorithm is expensive.V. Naive BayesTo push the probability that the occurrence of event a occurs under B (where events A and B can be decomposed into multiple events), you can calculate the probability of event a occurring under the probability of event B, and then
going to say things like this:(1) The binary classification of Logistic regression is good, the kernel of SVM is good(2) I moved the kernel trick to logreg inside.First, a probabilistic SVM algorithm is given.The specific approach is in two steps:(1) using kernel Soft-margin SVM first to find out the W ' SVM and BSVM based on data(2) Introduction of A and b two variables into the Logreg (a Do size change,
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