How can I create a matrix out of a matrix?

1 Ansicht (letzte 30 Tage)
Rengin
Rengin am 17 Feb. 2015
Bearbeitet: Mischa Kim am 19 Feb. 2015
Hello,
% I have a matrix as below:
A=[0 0 0;5 2 4;0 0 0;4 1 8;9 5 6;0 0 0]
% My 2.,4. and 5. rows are different than '0'. As a result I wanna have a matrix as below including the number of rows different than '0':
B=[2 5 2 4;4 4 1 8;5 9 5 6];
However, I have a bigger matrix in my real problem. It is just an example
Thx

Antworten (3)

Elias Gule
Elias Gule am 17 Feb. 2015
indices = find(any(A,2)); B = [indices A(indices,:)];

Mat
Mat am 17 Feb. 2015
B=sum(A,2)
C=find(B~=0)
D=[C A(C,:)]
??

Mischa Kim
Mischa Kim am 17 Feb. 2015
Rengin, you could use, e.g.
B = [(1:size(A,1))' A];
B(~any(B(:,2:end),2),:) = []
  12 Kommentare
Rengin
Rengin am 19 Feb. 2015
Hi Mischa,
I just wanted to make some regulations on my code and send it today. Actually I had another question, if you have time to take a look at my code. I create Ibestfirst matrix in 173th row and put it in two for loops. However, at the end, my matrix size changes to 5x500, although it has to be 1x500. I am not a programmer btw. I am just trying to write some basic codes to test some algorithms :(
thx
Mischa Kim
Mischa Kim am 19 Feb. 2015
Bearbeitet: Mischa Kim am 19 Feb. 2015
After computing Xs add
B = [(1:size(Xs,1))' Xs];
B(~any(B(:,2:end),2),:) = []
to get
B =
1.0e+02 *
0.190000000000000 1.387778103306779 0.343814253001248
0.250000000000000 0.208481799046993 0.176385990188109
1.170000000000000 0.458209269814333 3.910781553669295
1.280000000000000 0.483323512292465 0.264376184324426
1.820000000000000 0.684481966455650 0.795152138548950
3.240000000000000 0.846839613465022 1.292539618758099
3.610000000000000 0.568404629169297 0.577528050340383
4.340000000000000 0.190023379731620 0.466716273193995
4.770000000000000 1.018698679681144 2.434206303256232
The first column contains the row numbers: 19, 25, 117, etc.
To your second question: the variable iter is set to 5 when you enter the for-loop, most likely because it is set to that value in one of the other scripts. Simply use a different (new) variable name, e.g. my_iter, and it'll work.

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