Problem 1686. Generate a melodic contour string matrix

Created by Ned Gulley

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<a href = "http://en.wikipedia.org/wiki/Parsons_code">Parsons code</a> is a surprisingly effective way to identify music by its melodic motion. That is, with each successive note, does the pitch go up, down, or stay the same. No effort is made to capture the length of the interval between notes. The result is a lossy but useful "thumbprint" of a musical piece.You will be given a string in Parsons code. By convention, the first note is denoted by *. Each note thereafter is either "u" for up, "d" for down, or "r" for repeat. The expected output is a string matrix showing the tune's contour. It can contain only space, star, dash, forward slash, and backward slash (ASCII values 32, 42, 45, 47, and 92 respectively). The output matrix should be the smallest possible bounding box that can contain all the nonspace characters. That is, there should be no empty rows or columns.Examples:<pre> str = '*rrr'
 melody = '*-*-*-*'</pre><pre> str = '*du'
 melody = ['* *'
 ' \ / '
 ' * ']</pre><pre> The "Happy Birthday" song!
 str = '*rududdrudud'
 melody = [' * * '
 ' / \ / \ '
 '*-* * * * * '
 ' \ / \ / \ '
 ' *-* * *']</pre>

<http://en.wikipedia.org/wiki/Parsons_code Parsons code> is a surprisingly effective way to identify music by its melodic motion. That is, with each successive note, does the pitch go up, down, or stay the same. No effort is made to capture the length of the interval between notes. The result is a lossy but useful "thumbprint" of a musical piece.

You will be given a string in Parsons code. By convention, the first note is denoted by *. Each note thereafter is either "u" for up, "d" for down, or "r" for repeat. The expected output is a string matrix showing the tune's contour. It can contain only space, star, dash, forward slash, and backward slash (ASCII values 32, 42, 45, 47, and 92 respectively). The output matrix should be the smallest possible bounding box that can contain all the nonspace characters. That is, there should be no empty rows or columns.

Examples:

str = '*rrr'
 melody = '*-*-*-*'

str = '*du'
 melody = ['*   *'
           ' \ / '
           '  *  ']

The "Happy Birthday" song!
 str = '*rududdrudud'
 melody = ['    *   *              '
           '   / \ / \             '
           '*-*   *   *     *   *  '
           '           \   / \ / \ '
           '            *-*   *   *']

Solve

Solution Stats

172 Solutions
44 Solvers

Last Solution submitted on Nov 06, 2021

Last 200 Solutions

Problem Comments

5 Comments

5 Comments

Show 2 older comments

Michael C. on 28 Jun 2013

There is an error in the second problem of the test suite (also in the example) with an extra "[" on the second line of the "correct" melody.

Ned Gulley on 28 Jun 2013

Amazing how hard it is to get your test suite right on the first try. Thanks, and it looks like you're in the lead!

Jean-Marie Sainthillier on 24 Jul 2017

The last 3 tests are incorrect.

Jean-Marie Sainthillier on 24 Jul 2017

Dimensions of matrices being concatenated are not consistent.

Ned Gulley on 25 Jul 2017

I admit they look wrong, but the actual text in the MATLAB code runs properly. I just re-scored some answers and they worked fine. It must be some kind of HTML display problem. I'll check into it.

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music strings

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