ideas for algorithm? sorting a list randomly with emphasis on variety

Posted by Steve Eisner on Stack Overflow See other posts from Stack Overflow or by Steve Eisner
Published on 2010-03-20T18:18:51Z Indexed on 2010/03/20 18:21 UTC
Read the original article Hit count: 296

Filed under:

random

|

sorting

|

algorithm

|

multivariate-partition

I have a table of items with [ID,ATTR1,ATTR2,ATTR3]. I'd like to select about half of the items, but try to get a random result set that is NOT clustered. In other words, there's a fairly even spread of ATTR1 values, ATTR2 values, and ATTR3 values. This does NOT necessarily represent the data as a whole, in other words, the total table may be generally concentrated on certain attribute values, but I'd like to select a subset with more variety. The attributes are not inter-related, so there's not really a correlation between ATTR1 and ATTR2.

Any ideas for an efficient algorithm? Thanks! I don't really even know how to search for this :)

© Stack Overflow or respective owner

Related posts about random

Text inside <p> shrinks on mobile devices while div does not [migrated]

as seen on Pro Webmasters - Search for 'Pro Webmasters'
I asked this question on stack overflow, but didn't get any answers, so I'm trying here. Does anybody know whats happening here? I tested on opera, dolphin and the factory android browser. (although it seems now to be working on opera) The div doesn't change size, but the text somehow is shrunk… >>> More
Random Movement for multiple entities

as seen on Game Development - Search for 'Game Development'
I have this code for a arraylist of entities. All the entities use the same random and so all of them move in the same direction. How can I change it so it generates a new random number for each entity? public void moveFemale() { for(int i = 0; i < 1000; i++){ random = rand.nextInt(99); … >>> More
Python: Random is barely random at all?

as seen on Stack Overflow - Search for 'Stack Overflow'
I did this to test the randomness of randint: >>> from random import randint >>> >>> uniques = [] >>> for i in range(4500): # You can see I optimistic. ... x = randint(500, 5000) ... if x in uniques: ... raise Exception('We duped ' + str(x) + '… >>> More
Why is Random class isn't really random?

as seen on Stack Overflow - Search for 'Stack Overflow'
I've read about it on a message board - Random class isn't really random. It is created with predictable fashion using a mathematical formula. Is it really true? If so, Random isn't really random?? >>> More
c++ generate a good random seed for psudo random number generators

as seen on Stack Overflow - Search for 'Stack Overflow'
I am trying to generate a good random seed for a psudo-random number generator. I thought I'd get the expert's opinions. let me know if this is a bad way of doing it or if there are much better ways. #include <iostream> #include <cstdlib> #include <fstream> #include <ctime> unsigned… >>> More

Related posts about sorting

Sorting eigenvectors by their eigenvalues (associated sorting)

as seen on Stack Overflow - Search for 'Stack Overflow'
I have an unsorted vector of eigenvalues and a related matrix of eigenvectors. I'd like to sort the columns of the matrix with respect to the sorted set of eigenvalues. (e.g., if eigenvalue[3] moves to eigenvalue[2], I want column 3 of the eigenvector matrix to move over to column 2.) I know I can… >>> More
Sorting in SSRS Reports overriding Group sorting

as seen on Stack Overflow - Search for 'Stack Overflow'
I am new to SSRS (2005) and am creating my first report. I need to create a group-based running value but is sorted or some other field. For example, from the data below |Employee| Day |Hours|Salary| |E1 | 1.1 | 5 | 5 | |E2 | 1.2 | 6 | 6 | |E3 | 1.3 | 7 | 7 | |E2 … >>> More
org-sort multi: date/time (?d ?t) | priority (?p) | title (?a)

as seen on Super User - Search for 'Super User'
Is anyone aware of an org-sort function / modification that can refile / organize a group of TODO so that it sorts them by three (3) criteria: first sort by due date, second sort by priority, and third sort by by title of the task? EDIT: I believe that org-sort by deadline (?d) has a bug that… >>> More
A Look at the GridView's New Sorting Styles in ASP.NET 4.0

as seen on Internet.com - Search for 'Internet.com'
Scott Mitchell looks at four new sorting-related style properties added to the GridView in ASP.NET 4.0. >>> More
A Look at the GridView's New Sorting Styles in ASP.NET 4.0

as seen on 4 Guys From Rolla - Search for '4 Guys From Rolla'
Like every Web control in the ASP.NET toolbox, the GridView includes a variety of style-related properties, including CssClass, Font, ForeColor, BackColor, Width, Height, and so on. The GridView also includes style properties that apply to certain classes of rows in the grid, such as RowStyle,… >>> More