Problem 1237. It's race time! Write a faster function than the test suite call of unique().

Created by Jeremy

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Write a function to get unique elements of a vector faster than unique()! Input will be a vector (of integers or floating point numbers) of any size. The order of the returned vector is unimportant.

Example: Input: x = [1 1 2 2 3 3]; Output: [1 2 3];

Input: x = [0.1 3.1 2.1 2.0 3.1]; Output: [0.1 3.1 2.1 2.0]; % or any order

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275 Solutions
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Last Solution submitted on Apr 23, 2020

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Jeremy on 1 Feb 2013

I'm sure some smarter person will find a faster method!

Muthu Annamalai on 2 Feb 2013

My solution passed on the third try; there's definitely some CPU timing mismatch going on!

Jeremy on 3 Feb 2013

Agreed, some of my solutions passed only part of the time.

Jeremy on 3 Feb 2013

Hi, just wondering whether someone could help me out here. I was expanding the testset, and I was trying x = [1:10 2:11] but I got an error "Error: Dimensions of matrices being concatenated are not consistent." I then tried x = [1 2 3 4], and x = 1:4; but got the same error. On my version of MATLAB all these statements work perfectly and I believe they are basic MATLAB syntax. x = [1; 2; 3; 4] worked fine however. In the end I had to transpose the matrices.

Jeremy

shen on 27 Dec 2013

it even cannot pass on my own computer, but....

Solution Comments

Solution 199391

3 Comments

3 Comments

Boris Huart on 1 Feb 2013

It was too tempting...

James on 1 Feb 2013

I thought I was being original by trying this. Guess not... :-(

Jeremy on 3 Feb 2013

Clever :), hadn't thought of that!

Solution 199338

1 Comment

1 Comment

Jeremy on 1 Feb 2013

thanks for the hint!

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fun matlab speed speed optimization tic toc unique

Problem 1237. It's race time! Write a faster function than the test suite call of unique().

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers48

Suggested Problems

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Problem Tags

Problem 1237. It's race time! Write a faster function than the test suite call of unique().

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers48

Suggested Problems

More from this Author7

Problem Tags

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