Remove the nth column from input matrix A and return the resulting matrix in output B.
So if
A = [1 2 3; 4 5 6];
and
n = 2
then B is
[ 1 3 4 6 ]
Solution Stats
Problem Comments
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10 older comments
Jon
on 13 Nov 2013
All solutions with score 11 or 12 use the regexp cheat.
Len
on 11 Sep 2014
Is there somewhere to go to receive advice on how to improve your code?
Sneha
on 30 Oct 2014
Is there somewhere to go to receive advice on how to improve your code?
Salil Goel
on 17 Mar 2015
i can't think of a better solution having size less than 19!
Nicholas Hind
on 21 Apr 2015
why isn't B = (A(:,n)=[]); working? thanks
Jyotsna mallela
on 8 Jun 2015
How to improvise this code?
Noriko Hounoki
on 7 Dec 2016
It's very MATLAB!
Raynald Belmont
on 18 Dec 2016
this was actually not that difficult :)
Rasheed Abid
on 31 Jan 2017
a good way to learn
David Verrelli
on 19 Mar 2017
There should be a single-column input matrix in the test suite.
Mohsen Khodadadi
on 29 Mar 2017
This was fun! Not difficult, but kind of challenging!
cqut
on 22 Dec 2017
A(n,:)=[]; B = A; it works,but I'm wrong,who tell me the reason?
Varun Garg
on 7 May 2018
Better test cases could be provided for edge cases.
Solution Comments
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1 Comment
Carlos Castillo
on 14 Nov 2018
B = horzcat(A(1:end,1:n-1), A(1:end,n+1:end)); gives size 35.
How can we know the real leading solution sizes if there are those "message solutions" that are not real solutions?
1 player likes this solution
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1 Comment
Yanni Wang
on 3 Mar 2018
woooooooow! good job
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1 Comment
Aamod Garg
on 20 Feb 2018
I really need to learn to code better. I say this because I keep on getting size which is atleast 2-3 times the size of the leading solution.
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1 Comment
John Badawi
on 15 Jun 2017
larger size but will work for n=1
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1 Comment
John Badawi
on 15 Jun 2017
This would fail for n=1
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2 Comments
SIVAPRAKASH DANABALASINGAM
on 10 Jan 2017
VERY EASY
Josiah Swim
on 29 Mar 2017
good stuff
1 player likes this solution
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1 Comment
Eqin Azlan
on 29 Dec 2016
B(n)=A[] ?
1 player likes this solution
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1 Comment
Coen Beeksma
on 29 Sep 2016
What am I doing wrong? Im new btw. Learning the basics.
1 player likes this solution
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1 Comment
Mohit Verma
on 2 Sep 2016
What is the best optimized solution for this particular problem? Could someone with size 19 or smaller please indicate their solutions. Thanks
1 player likes this solution
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1 Comment
Gunvor Røkke
on 19 Nov 2015
My code solves the problem, yet I get incorrect answer
2 players like this solution
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1 Comment
Ruchika Soni
on 19 Aug 2015
Good one.
1 player likes this solution
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1 Comment
Hiroki Fujiwara
on 25 Feb 2015
no need to use for loop or anything.
it's just this.
2 players like this solution
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2 Comments
Stephen
on 4 Dec 2014
nice, I wish I had thought of it this way
VOXEL INFOTECH Chennai-IND
on 4 Dec 2014
nice
1 player likes this solution
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2 Comments
VIVEK RUHELA
on 25 Nov 2014
can anybody tell me why this solution is not working:"[a,b] = qr(A);
[a1,b1] = qrdelete(a,b,n);
y = a1*b1;"
Although it gives right answers to all test Suits in the software.Plz
Zikobrelli
on 27 Nov 2014
because of rounding errors.
B = round(a1*b1);
it should work in this case as all numbers are integers.
1 player likes this solution
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2 Comments
Christopher Zerafa
on 24 Nov 2014
B=A(:,1:end-1);
What is wrong here?
Tanguy
on 28 Jan 2015
you are just removing the "last" column, not the "n-th" column.
2 players like this solution
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1 Comment
VIVEK RUHELA
on 13 Nov 2014
I've checked this coding:"[a,b] = qr(A);
[a1,b1] = qrdelete(a,b,n);
B = a1*b1;" Why this not working??? Can anybody check this....
2 players like this solution
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1 Comment
Pascal COMBES
on 26 Jul 2013
Why the following solution doesn't work? It does on my MATLAB 2011a :
function B = column_removal(A,n)
if((n < 1) || (n > size(A, 2)))
B = A;
return;
end
if(n > 1)
l = A(:, 1:(n-1));
else
l = [];
end
if(n < size(A, 2))
r = A(:, (n+1):size(A, 2));
else
r = [];
end
B = [l,r];
end
5 players like this solution
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2 Comments
2 players like this solution
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1 Comment
Adrian Dronca
on 7 Mar 2013
oops ! didn't read the requirements right
2 players like this solution
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1 Comment
Adrian Dronca
on 8 Mar 2013
i`m not really sure [] is faster than '' but is good to know
1 player likes this solution
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1 Comment
sea knowledge
on 12 Dec 2012
it seems that A(:,n)='' is a bit faster than A(:,n)=[]; but usually we use the latter one,
3 players like this solution
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5 Comments
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2 older comments
Sadid
on 15 Aug 2012
Dear Oscar,
in comparison to your code, the below implementation is much faster but your style of code is a crack to cody system, well done.
function A = column_removal(A,n)
A(:,n) = '';
end
Óscar
on 16 Aug 2012
Dear Sadid, I agree with you that my implementation is completely stupid and a waste of time in real life and that's why I don't like the current evaluation metric of Cody. A (time and/or memory)-based evaluation would be much more interesting. With the current evaluation metric, Cody promotes hacking and cracking (which is also fine), but players don't learn good manners for developing efficient code.
ahmed bilal
on 16 Oct 2012
NICE ONE BUT BIT DIFFICULT
HaveF
on 17 Dec 2012
@Óscar yes, you are right. the player can't study the one with well written style
PARTH PATEL
on 16 Sep 2014
agreed with Oscar
1 player likes this solution
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1 Comment
tomio wakasugi
on 5 Apr 2012
My MATLAB 2012a worked for #2
6 players like this solution
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6 Comments
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3 older comments
Craig
on 13 May 2012
What happened to "and return the resulting matrix in output B"?
Dirk Engel
on 22 Jun 2012
Strange: A(:,n) = [] has size 15 but is basically the same?
Andrew
on 16 Jul 2012
How safe is this to do?
Mechatrobrnotronik
on 2 Mar 2013
function ans = column_removal(A,n)
A(:, n) = ''
end
Why doesn't this code work? :/
Florian M. Faessler
on 27 Oct 2013
@Mechatrobrnotronik: I tested your code.
function ans = test_fkt(A,n)
A(:,n) = ''
end
Works for me. Returning A with removed column n.
Nonetheless I am interested in what '' actually does. I couldn't find it in the command reference.
Kristin Foster
on 3 Dec 2017
fun
3 players like this solution
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2 Comments
Yi Cao
on 25 Jan 2012
Can the server provide more information on failed solution?
Ninetrees
on 9 Feb 2012
For those who wonder how such low scores are being reported in Cody, it is because many players are changing the actual function call. The result is obvious to those of us who have solved many of these challenges.
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