How do you implement Related tags functionality as used in Stackoverflow.com?

Question

Hi everybody,

Good morning!

Have been trying to find an answer to this. How do you implement the 'related tags' functionality as used in many websites like our stackoverflow.com and http://tagexplorer.sandbox.yahoo.com/.

A user clicks on tag and he gets all the related tags connected to that.

Daksh

Answer 1

My guess is that it is a correlation between which tags are most often used together.

For example:

• Question A tagged with tag1, tag2
• Question B tagged with tag1, tag3
• Question C tagged with tag1, tag2

Then it's natural to assume that tag2 "is related to" tag1.

I would say the best place to learn would be O'Reilly's Programming Collective Intelligence book.

Answer 2

A couple of ways come to mind. You could just do a quick query to select related tag names:

SELECT * FROM tags WHERE tag_name LIKE '%$current_tag%'

Another way would be to actually setup your tag table to have a relations field, maybe related IDs separated by commas, but this seems hellish to maintain.

I'm sure someone will come up with a better answer, so I'm quite curious as well.

Answer 3

Hmm, I'm not very good at math :-), but sounds like you are looking for the correlation between two tags. My first instinct would be to set the expected value to 50% (expecting each tag to appear on 50% of the articles - this might be way off), calculate the correlation coefficient of tags in pairs and decide that if the correlation is above a certain value (which you must determine by experimenting), they are related.

Alternatively you might get by using a simple measure like (number of articles they co-appear) / (total number of articles where at least one tag appears).

Answer 4

IMHO, I thought it is a ready made script which is being used.

Answer 5

Maybe s.o. tracks how many time tags come together

1. I insert Q1 with tags A + B so relationWeight(A,B) = 1

2. I insert Q2 with tags A + B so relationWeight(A,B) = 2

3. Now I delete Q1 and Q2. I have to know the "relationWeight" to disassociate tags when relationWeight=0

Answer 6

using (DataAccessDataContext db = new DataAccessDataContext()) { Repeater1.DataSource = from rt in db.RelatedTags where st.ITEMID == itemid select new TagView() { ID = rt.Tag.ID, NAME = rt.Tag.NAME }; Repeater1.DataBind();
}

///:)