Problem 1048. Detect a number and replace with two NaN's

Created by Praveen Suvarna

Solve Later

{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","targetMode":"","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","targetMode":"","relationshipId":"rId2","target":"/matlab/output.xml"}],"parts":[{"partUri":"/matlab/document.xml","relationship":[],"contentType":"application/vnd.mathworks.matlab.code.document+xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<w:document xmlns:w=\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\"><w:body><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Write code which replaces the number 1 with two NaNs.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Example</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[ X = [ 1   2   NaN   4   1   3   7   NaN   1   4   NaN   2]]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Answer Y is</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[     [ NaN  NaN  2  NaN   4   NaN  NaN   3   7   NaN  NaN  NaN  4   NaN  2]]]></w:t></w:r></w:p></w:body></w:document>"},{"partUri":"/matlab/output.xml","contentType":"text/xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?><embeddedOutputs><metaData><evaluationState>manual</evaluationState><layoutState>code</layoutState><outputStatus>ready</outputStatus></metaData><outputArray type=\"array\"/><regionArray type=\"array\"/></embeddedOutputs>"}]}

Solve

Solution Stats

456 Solutions
201 Solvers

Last Solution submitted on Aug 19, 2020

Last 200 Solutions

Problem Comments

13 Comments

13 Comments

Show 10 older comments

J-G van der Toorn on 22 Nov 2012

The test-suite is incorrectly programmed. Isequal does not work for nan's:
isequal(nan,nan) is never true.

Furthermore, the line "if n=1" is an incorrect statement.

J.R.! Menzinger on 22 Nov 2012

J.G. is right!! please correct it!

Praveen Suvarna on 22 Nov 2012

Dear all,
You can make use of 'isnan'
Try.
It can be solved...

Andrei Bobrov on 22 Nov 2012

use 'isequaln'

James on 23 Nov 2012

NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN...

Batman?

@bmtran (Bryant Tran) on 23 Nov 2012

the other commenters are right. see: http://www.mathworks.com/help/matlab/ref/isequalwithequalnans.html

David on 24 Nov 2012

Still, the open "if" statement in the test suite will not pass any solutions. Consider making "n" an argument?

nyancat on 26 Nov 2012

the problem can be solved, but the test suite has bugs like everyone else commented. please fix the open "if" and isequal on NaN's i.e. assert(isequal(y_correct, y_correct)) does not pass in the second test.

Praveen Suvarna on 26 Nov 2012

Is it fine now?

David on 26 Nov 2012

Not quite. You will still need to use "isequalwithequalnans" (or "isequaln" in newer versions) instead of "isequal".

Ned Gulley on 27 Nov 2012

I updated the test suite with the suggestions made here. I believe it works now.

Jean-Marie Sainthillier on 29 Nov 2012

The particular number is 1

Andrew Newell on 19 Jun 2013

This problem would be much better if the "particular number" was one of the arguments to the function.

Solution Comments

Solution 168227

1 Comment

1 Comment

James on 27 Nov 2012

I wrote this solution when there were multiple problems with the test suite. It's an ugly hack, and not a "real" solution. Now that the test suite is working, please ignore this solution.

Problem Recent Solvers201

Problem Tags

tricky