http://blog.csdn.net/warmyellow/article/details/5454943Introduction to LDA algorithmA LDA Algorithm Overview:Linear discriminant Analysis (Linear discriminant, LDA), also called Fisher Linear discriminant (Fisher Linear discriminant, FLD), is a classical algorithm for pattern recognition, It was introduced in the field of pattern recognition and artificial intell
1. LDA Overview
LDA (latent Dirichlet allocation) is a document theme generation model , also known as a three-layer Bayesian probabilistic model , containing words , themes , and document Three-tier structure. The so-called generative model, that is, we think that every word in an article is obtained by " choosing a subject in a certain probability and choosing a word from the subject with a certain proba
discriminant thinking is based on the known classification of the data to calculate the various kinds of center of gravity, the unknown classification of the data, calculate its distance from all kinds of center of gravity, and a certain center of gravity distance is attributed to this class
Linear discriminant Analysis (Linear discriminant, LDA) is a classical algorithm for pattern recognition, which was introduced in the field of pattern recog
LDA was a mentor in the early October, and each time he picked up the "Lda math gossip" to see the formula deduced in front of it was a difficult problem, dragged until the end of October. This weekend took two days to finally understand the LDA, in fact, LDA is a very simple model, do not be frightened by the precedin
Http://www.52nlp.cn/lda-math-lda-%E6%96%87%E6%9C%AC%E5%BB%BA%E6%A8%A1Evaluation method of LDA thematic model--perplexityHttp://www.52nlp.cn/lda-math-lda-%E6%96%87%E6%9C%AC%E5%BB%BA%E6%A8%A1Lda-math-lda Text ModelingHttp://www.iyun
The LDA here refers to latent Dirichlet Allocation (hidden Dirichlet distribution), rather than linear discriminant analysis (linear discriminant analyses), which is a topic generation model, and the latter is a discriminant model, The discriminant model used in this experiment is not the latter, but the SVM discriminant model, which is a LIBSVM toolkit developed and designed by Professor Linzhiren (Lin Chih-jen) of Taiwan University. Experimental Flo
The main reference is the articleHttp://www.cnblogs.com/LeftNotEasy/archive/2011/01/08/lda-and-pca-machine-learning.htmlHttp://www.cnblogs.com/jerrylead/archive/2011/04/21/2024384.htmlHttp://www.cnblogs.com/jerrylead/archive/2011/04/21/2024389.htmlThe above three blogs have been summed up very well:Here we summarize the most important part:the principle of LDA is that The data that will be tagged (points) ,
LDA overall process
First, define the meaning of some letters:
Document Set D and topic set T
In D, each document D is considered as a word sequence Word bagIn fact, the location where each word appears isAlgorithmNo effect)
All the different words involved in D constitute a big collection Vocabulary (VOC)
LDA uses the document set D as the input (there will be cut words, deprecated wor
LDA (latent Dirichlet Allocation) is a document topic generation model that has recently seen a bit of data ready to be implemented using Python. As for the mathematical model of the relevant knowledge, a lot of some, here also gives a very detailed document previously referenced the LDA algorithm roaming guide
This post only speaks of the algorithm of the sampling method Python implementation.
Full
1. If you runProgramError:"Exception in thread "Main" Java. Lang. noclassdeffounderror: ORG/slf4j/loggerfactory", This is because the project lacks both the slf4j-api.jar and slf4j-log4j12.jar jar packages.
2. If an error occurs in the running program:"Java. Lang. noclassdeffounderror: ORG/Apache/log4j/logmanager", This is because the project lacks the jar package log4j. jar.
3. Error:"Exception in thre
Mahout as an open source software package, integrates a lot of machine learning and data mining algorithms, detailed visible mahout official website.About LDA, this is not said here, see the Great God's Lda math gossip. This is just about to puke. Mahout website LDA's documentation: there is no documentation at all!In mahout-0.9 and previous versions, only hadoop1.0 is supported. Support hadoop2.0 Mahout on
Gensim-LDA topic model evaluation
Evaluate the quality of the LDA topic model and determine the modeling capability of improved parameters or algorithms.
Perplexity is only a crude measure, it's helpful (when using LDA) to get 'close' to the appropriate number of topics in a corpus.
1. Perplexity Definition
Http://en.wikipedia.org/wiki/Perplexity
Perplexity is an
Feature Selection (Dimension Reduction) is an important step in data preprocessing. For classification, feature selection can select the features most important to classification from a large number of features to remove noise from the original data. Principal Component Analysis (PCA) and linear discriminant analysis (LDA) are two of the most common feature selection algorithms. For more information about PCA, see my other blog. Here we mainly introdu
(i) LDA role
The traditional way to judge the similarity of two documents is by looking at the number of words that appear together in two documents, such as TF-IDF, which does not take into account the semantic associations behind the text, which may appear in two documents with little or no words, but two documents are similar.
For example, there are two sentences as follows:
"Jobs left us. ”
"Will the price of apples fall?" ”
You can see that the a
Introduction to LDA algorithmA LDA Algorithm Overview:Linear discriminant Analysis (Linear discriminant, LDA), also called Fisher Linear discriminant (Fisher Linear discriminant, FLD), is a classical algorithm for pattern recognition, It was introduced in the field of pattern recognition and artificial intelligence in 1996 by Belhumeur. The basic idea of sexual d
About PCA and LDA used in face recognition and other classificationAlgorithmThere are many examples, but they areCode, Especially for C ++ code. Therefore, I can only build C ++ Based on the Matlab code. There are still some issues with the LDA algorithm. All core code will be provided in the past two weeks. In fact, PCA, Lda, and so on are just a tool. With good
Introduction to LDA algorithmA. LDA Algorithm Overview:Linear discriminant Analysis (Linear discriminant, LDA), also called Fisher Linear discriminant (Fisher Linear discriminant, FLD), is a classical algorithm for pattern recognition, It was introduced in the field of pattern recognition and artificial intelligence in 1996 by Belhumeur. The basic idea of sexual
Previously, LDA was used to classify, and PCA was used for dimensionality reduction. The dimensionality reduction of PCA is to reduce the amount of subsequent computations, and the ability to distinguish different classes is not improved. PCA is unsupervised, and LDA is able to project different classes in the best direction, so that the distance between the two categories is the largest, to achieve easy-to
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