I have a matrix and I am actually interested in obtaining a vector that will consist of the first column in each row that has values lower certain value.

2 Ansichten (letzte 30 Tage)
I have a matrix and I am actually interested in obtaining a vector that will consist of the first column in each row that has values lower 3. e.g if I have A=[ 5 7 8 3 2 ;6 2 1 4 4;1 2 3 4 5; 4 5 2 1 3]. I expect an Ans: [5;2;1;4]

Akzeptierte Antwort

Saint
Saint am 29 Mai 2017
Bearbeitet: Saint am 29 Mai 2017
Thanks Star Strider and MathsReallyWork. I kind of figure it out.Ans: [5;2;1;3]
dmax=3
Nrows=4
A=[5 7 8 3 2 ;6 2 1 4 4;1 2 3 4 5; 4 5 2 1 3]
for i=1:Nrows
B=A(i,:)';
a(i)=find(B<dmax,1,'first') ;
end
b=a'
  1 Kommentar
Stephen23
Stephen23 am 29 Mai 2017
Bearbeitet: Stephen23 am 29 Mai 2017
It is simpler and more efficient to process the whole array at once, rather than using a loop:
>> C = A.';
>> idx = C<dmax;
>> [col,row] = find(idx & cumsum(idx,1)==1)
col =
5
2
1
3
row =
1
2
3
4

Melden Sie sich an, um zu kommentieren.

Weitere Antworten (1)

MathReallyWorks
MathReallyWorks am 27 Mai 2017
Hello saint,
Your question is not clear. Please edit it.
By the description of your question I can guess that you want first column of each row provided that entry is less than 3. In that case this code works well:
A = [ 5 7 8 3 2 ;6 2 1 4 4;1 2 3 4 5; 4 5 2 1 3];
newA = A(A(:,1)<3,1)
But, then you said you are expecting [5;2;1;4] which is contradictory to your question.
[5;6;1;4] is possible as it contains all first element.

Kategorien

Mehr zu Creating and Concatenating Matrices finden Sie in Help Center und File Exchange

Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by