Application of Naive Bayes algorithm in spam filtering, Bayesian Spam
I recently wrote a paper on Big Data Classification (SPAM: My tutor reminds me every day), so I borrowed several books on big data from the library. Today, I read spam in "New Internet Big Data Mining" (if you are interested, you can take a look), which reminds me that I saw a famous enterpris
Main ideas:
1. Have a corpus
2. Count the frequency of occurrence of each word and use it as a naive Bayes candidate.
3. Example:
The corpus contains phrases such as China, the people, the Chinese, and the republic.
Input: Chinese people love the People's Republic of China;
Use Max for word splitting (score obtained from various distributions );
For example: solution1: Chinese people _ all Chinese people _
Main ideas:
1. Have a corpus
2. Count the frequency of occurrence of each word and use it as a naive Bayes candidate.
3. Example:
The corpus contains phrases such as China, the people, the Chinese, and the republic.
Input: Chinese people love the People's Republic of China;
Use max for word splitting (score obtained from various distributions );
For example: solution1: Chinese people _ all Chinese people _
Example of Naive Bayes algorithm and Bayesian exampleApplication of Bayesian
The famous application of Bayesian classifier for spam filtering is spam filtering, if you want to learn more about this, you can go to hacker and painter or the corresponding chapter in the beauty of mathematics. For the basic implementation of Bayesian, see the dataset in two folders
user requests a request, we need to traverse the probability of each grid in the computed database and return the center point of the maximum probability grid. Assuming that our lattice is 10*10 meters in size, then all the grid in Beijing will have 160 million lattice, traverse computation overhead is very huge. A method to improve the computational efficiency is to solve the approximate spatial range based on the user's signal vectors, and then calculate the probability of each lattice in the
attributes.Compared with the decision tree model,Naive Bayes modelIt originated from classical mathematical theory and has a solid mathematical foundation.And stable classification efficiency. At the same time, the NBC model requires few parameters, which are not sensitive to missing data and the algorithm is relatively simple. Theoretically, the NBC model has a
Naive Bayes algorithm is an algorithm based on Bayesian theorem, Bayes theorem is as follows:\[p (y| x) = \frac{p (x, y)}{p (×)} = \frac{p (Y) \cdot P (x| Y)}{p (X)}\]Naive Bayes is exe
Naive Bayes (Naive Bayes) and Python implementationsHttp://www.cnblogs.com/sumai1. ModelIn Gda, we require that eigenvector x be a continuous real vector. If x is a discrete value, it is possible to consider the naive Bayes classi
Bayesian classifierThe Bayes classification principle is a priori probability of an object. The Bayesian posterior probability formula is calculated. In other words, the object belongs to a class of probabilities. Select the class that has the maximum posteriori probability as the generic of the object. Now more research Bayesian classifier, there are four, each: Naive
, takes the derivative to 0 extremum point, is wants to find the parameter value.(Note: This means that although naive Bayes has three characters in it, we can use naive Bayesian models rather than Bayesian methods.) )However, the maximum likelihood estimate is only suitable for the case of large data volume. If the amount of data is small, the result is likely t
generally has two implementation methods: one is based on the bernuoli model and the other is based on the polynomial model. The previous implementation method is used here. This implementation method does not consider the number of times a word appears in the document, but does not consider it. Therefore, it is equivalent to assuming that the word is of equal weight.
2.2 Naive Bayes scenario
An important
This paper mainly introduces the knowledge of how to use naive Bayesian algorithm in Python. Has a good reference value. Let's take a look at the little part here. Why the title is "using" instead of "implementing": First, the pros provide algorithms that are higher than the algorithms we write ourselves, both in terms of efficiency and accuracy. Secondly, for those who are not good at maths, it is very pai
, or K nearest neighbor (Knn,k-nearestneighbor) classification algorithm, is one of the simplest methods in data mining classification technology. The so-called K nearest neighbor is the meaning of K's closest neighbour, saying that each sample can be represented by its nearest K-neighbor.The core idea of the KNN algorithm is that if the majority of the k nearest samples in a feature space belong to a categ
Bayesian classifierThe classification principle of Bayesian classifier is based on the prior probability of an object, and the Bayesian formula is used to calculate the posteriori probability, that is, the probability of the object belonging to a certain class, and select the class with the maximum posteriori probability as the class to which the object belongs. At present, there are four kinds of Bayesian classifiers, each of which are: Naive
Bayesian classifierThe classification principle of Bayesian classifier is based on the prior probability of an object, and the Bayesian formula is used to calculate the posteriori probability, that is, the probability of the object belonging to a certain class, and select the class with the maximum posteriori probability as the class to which the object belongs. At present, there are four kinds of Bayesian classifiers, each of which are: Naive
Learning notes of machine learning practice: Classification Method Based on Naive Bayes,
Probability is the basis of many machine learning algorithms. A small part of probability knowledge is used in the decision tree generation process, that is, to count the number of times a feature obtains a specific value in a dataset, divide by the total number of instances in the dataset to obtain the probability tha
1. Preface:Naive Bayes (naive Bayesian) is a simple multi-class classification algorithm, the premise of which is to assume that each feature is independent of each other . Naive Bayes training is mainly for each characteristic, under the condition of a given label, calculat
, this technology is called smoothing technology.
Non-binary features
Simplicity of independence
Why is it simple? It is impractical to assume that all features are independent of each other.
Causes of double count
P (features, label) = w [label] × ∏ f ε features w [f, label] (considering the possible interaction between contribution of features in training)
Here, w [label] is the "Initial score" of a given tag. w [f, label] is the contribution of a given feature to the possibility of a ta
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