What is the principle of PageRank algorithm?
This article shows you what the principle of PageRank algorithm is, the content is concise and easy to understand, it can definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.
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Unexpected delight
When you stay on page B, you may not click on the two links inside, which means that we have to punish the coefficient of PR (B) by, for example, a penalty coefficient of 0.85, so PR (A) = 0.85*0.5*PR (B) + 0.85*1.0*PR (C), since you haven't found A through two internal links, but in the other corner of the world. An uncle typed a URL directly in the address bar and found the web page A directly, which was a pleasant surprise for A, so PR (A) had to consider this factor and further amend PR (A) to
PR (A) = 0.85 * 0.5 * PR (B) + 0.85 * 1.0 * PR (C) + (1-0.85) / 4
Where 4 is the total number of web pages
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Abstract the formula
In fact, the above formula is the final formula for finding the PR of a web page, but the total number of web pages is 4, and the link relationship of 4 web pages is assumed. In order not to lose generality, a general formula is deduced:
Among them
Mpi describes the collection of all web pages pointing to the web page Pi, L (Pj) is the number of outgoing links of the web page Pj, N is the total number of web pages, and an is the penalty factor.
According to the above formula, we can calculate the PR value of each web page, when the iteration tends to be stable, that is, the final result. For the Map-Reduce implementation code of the algorithm, please see the following push.
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