Entry
BBCBASIC: Windows: Algorithm: Search: Google: Link: Pagerank: Can you show a simple program?
Jul 16th, 2006 14:58
Knud van Eeden,
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--- Knud van Eeden --- 16 July 2006 - 11:15 pm -----------------------
BBCBASIC: Windows: Algorithm: Search: Google: Link: Pagerank: Can you
show a simple program?
===
Steps: Overview:
1. -E.g. create the following program
--- cut here: begin --------------------------------------------------
READ N%
:
IF N% <= 0 THEN PRINT "choose N% minimally 1" : STOP
:
DIM adjacencyMatrix$( N%, N% + 1 )
:
FOR I% = 1 TO N%
FOR J% = 1 TO N% + 1
READ adjacencyMatrix$( I%, J% )
NEXT J%
NEXT I%
:
DIM linkOutI%( N% )
:
FOR I% = 1 TO N%
FOR J% = 2 TO N% + 1
IF adjacencyMatrix$( I%, J% ) <> "" THEN
linkOutI%( I% ) = linkOutI%( I% ) + 1
ENDIF
NEXT J%
NEXT I%
:
FOR I% = 1 TO N%
page$ = adjacencyMatrix$( I%, 1 )
PRINT "page "; page$; ": ";
PRINT; linkOutI%( I% ); " outgoing links"
NEXT I%
:
DIM pageRankR( N% + 1 )
:
pageRankPageMaxR = 1 / N%
:
FOR columnI% = 2 TO N% + 1
FOR rowI% = 1 TO N%
linkOutI = linkOutI%( rowI% )
IF ( ( adjacencyMatrix$( rowI%, columnI% ) <> "" ) AND ( linkOutI
>= 1 ) ) THEN pageRankR( columnI% - 1 ) = pageRankR( columnI% - 1 ) +
( pageRankPageMaxR * ( 1 / linkOutI ) )
NEXT rowI%
NEXT columnI%
:
PRINT
:
FOR I% = 1 TO N%
page$ = adjacencyMatrix$( I%, 1 )
PRINT "page "; page$; ": ";
PRINT; pageRankR( I% ); " pagerank"
NEXT I%
:
PRINT
:
REM now the demping factor
dempingFactorR = 0.85
:
FOR I% = 1 TO N%
page$ = adjacencyMatrix$( I%, 1 )
PRINT "page "; page$; ": ";
PRINT; ( 1 - dempingFactorR ) / N% + dempingFactorR * pageRankR(
I% );
PRINT; " pagerank with demping factor"
NEXT I%
:
END
:
REM total pages (change this number to your total number of pages)
DATA 4
:
REM page A links to no pages
REM page B links to A and C
REM page C links to A
REM page D links to A, B and C
:
REM page, links to the following pages
DATA "A", "" , "", "", ""
DATA "B", "A", "", "C", ""
DATA "C", "A", "", "", ""
DATA "D", "A", "B", "C", ""
:
--- cut here: end ----------------------------------------------------
2. -Run the program
3. -That will show a screen output similar to the following:
--- cut here: begin --------------------------------------------------
page A: 0 outgoing links
page B: 2 outgoing links
page C: 1 outgoing links
page D: 3 outgoing links
page A: 0.458333333 pagerank
page B: 0.0833333334 pagerank
page C: 0.208333333 pagerank
page D: 0 pagerank
page A: 0.427083333 pagerank with demping factor
page B: 0.108333333 pagerank with demping factor
page C: 0.214583333 pagerank with demping factor
page D: 0.0375 pagerank with demping factor
--- cut here: end ----------------------------------------------------
4. -If you want to test with the pages linking
where B, C and D link all to page A
replace the data with this
--- cut here: begin --------------------------------------------------
REM page A links to no pages
REM page B links to A
REM page C links to A
REM page D links to A
:
REM page, links to the following pages
DATA "A", "" , "", "", ""
DATA "B", "A", "", "", ""
DATA "C", "A", "", "", ""
DATA "D", "A", "", "", ""
:
--- cut here: end ----------------------------------------------------
5. -That will show a screen output similar to the following:
--- cut here: begin --------------------------------------------------
page A: 0 outgoing links
page B: 1 outgoing links
page C: 1 outgoing links
page D: 1 outgoing links
page A: 0.75 pagerank
page B: 0 pagerank
page C: 0 pagerank
page D: 0 pagerank
page A: 0.675 pagerank with demping factor
page B: 0.0375 pagerank with demping factor
page C: 0.0375 pagerank with demping factor
page D: 0.0375 pagerank with demping factor
--- cut here: end ----------------------------------------------------
===
Internet: see also:
---
Internet: Search Engine: Google: Algorithm: Search: Link: Pagerank:
Can you show a simple example?
http://www.faqts.com/knowledge_base/view.phtml/aid/41611/fid/828
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