How to compare two blocks of text, to Test for copied content?

**ksinclair** · 12-04-2009, 03:26 AM

I am looking for a tool that can compare two blocks of text
to see if they are the 'same' or different/unique content.
Is there such a tool? There must be.

Second question, how does google do this comparison?
How do they know when two pages have duplicate content?
Ideally, I want a tool that works equivalently to google's tool.

Thanks

**amplify** · 12-04-2009, 03:58 AM

For your first question, there is a tool for checking plagiarism. It's called CopyScape and can be found at: http://www.copyscape.com/

I don't understand your second question though. Sorry I couldn't be of more assistance.

**ksinclair** · 12-09-2009, 03:41 PM

I will try out copyscape. But copyscape is for text that is on a web page, I believe? What I want is to compare to blocks of text; maybe text I have just created in my word processor, for example.

**hina** · 12-09-2009, 04:21 PM

To compare two blocks of text:
Try a diff tool, there are some for Windows:
http://www.google.com/search?q=diff+windows

But I am sure that's not how Google detects "duplicate content". Their algorithm must be more sophisticated.

**amplify** · 12-09-2009, 06:47 PM

I believe you need CopyScape Premium to search blocks of text only.

It can be found: http://www.copyscape.com/signup.php?pro=1&o=f

**domaindot** · 12-09-2009, 09:17 PM

Originally Posted by ksinclair

I am looking for a tool that can compare two blocks of text
to see if they are the 'same' or different/unique content.
Is there such a tool? There must be.

Copyscape is there, like amplify said. You can always build your own tool.

Originally Posted by ksinclair

Second question, how does google do this comparison?
How do they know when two pages have duplicate content?
Ideally, I want a tool that works equivalently to google's tool.

Thanks

Google does much more than mere textual comparison. They analyze the sets for related words/phrases (LSA). They also do contextual analysis of the sets.

**amplify** · 12-09-2009, 10:37 PM

Originally Posted by domaindot

Google does much more than mere textual comparison. They analyze the sets for related words/phrases (LSA). They also do contextual analysis of the sets.

Do you mind to elaborate on that? It's way over my head.

**domaindot** · 12-10-2009, 11:01 AM

http://en.wikipedia.org/wiki/Latent_semantic_analysis

http://www.unl.edu/sbehrend/html/sbs...lAnalysis.html

Layman's language: you can build a tool like Google's algorithm (we're not talking about search here) for text comparison, but it will take a lot of time and effort.

There is always Copyscape.

**mannoo2005** · 03-22-2010, 01:02 PM

You can use this free tool: http://www.plagium.com

**ksinclair** · 03-22-2010, 02:01 PM

Originally Posted by mannoo2005

You can use this free tool: http://www.plagium.com

i dont understand it. a lot of colored boxes. I did a test
of content that is likely to be unique but it gave a lot of results.
maybe its not unique or is it searching every word input,
as 'or' for each word? it shoudl search it as a whole,
as a set string.

**mannoo2005** · 03-22-2010, 02:38 PM

when you put the text, it searches it and compares it to what found, to see its unique percentage (which is red circles). So, it's very useful if you purchased any content or articles, to see if it's spinned from other or original content.