how to extract n elements from a vector and store them in a matrix

Hi,

I have a matrix with 3 variables:

a = [3 6 0 3 8 4 9 1 2 4 9 3 2 5 7 0 1 2.....]

b = [5 6 5 3 1 3 8 2 2 3 5 7 1 2 6 1 6 7.....]

c = [0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0.......]

I want to write a for loop that every time that c == 1 goes to the corresponding position of a and b, cuts 5 elements from each vector and stores them in two different matrices that would look something like this:

matrix a

a1 8 4 9 1 2

a2 2 5 7 0 1

a3 ....

matrix b

b1 1 3 8 2 2

b2 1 2 6 1 6

b3 .....

any idea on how to do it?

Answer 1

[Image Analyst]

Try this:

a = [3 6 0 3 8 4 9 1 2 4 9 3 2 5 7 0 1 2];
b = [5 6 5 3 1 3 8 2 2 3 5 7 1 2 6 1 6 7];
c = [0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0];
locations1 = find(c == 1);
aMatrix = zeros(numel(locations1), 5);
bMatrix = zeros(numel(locations1), 5);
for row = 1 : numel(locations1)
    thisIndex = locations1(row);
    aMatrix(row, :) = a(thisIndex : thisIndex + 4);
    bMatrix(row, :) = b(thisIndex : thisIndex + 4);
end
aMatrix % Show in command window.

aMatrix = 2×5

8 4 9 1 2 2 5 7 0 1

bMatrix % Show in command window.

bMatrix = 2×5

1 3 8 2 2 1 2 6 1 6

and this:

MATLAB Academy - Free 2 hour training

Answer 2

[Fangjun Jiang]

a = [3 6 0 3 8 4 9 1 2 4 9 3 2 5 7 0 1 2];
b = [5 6 5 3 1 3 8 2 2 3 5 7 1 2 6 1 6 7];
c = [0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0];
in1=find(c);
in2=in1'+[0:4];
NewA=a(in2)

NewA = 2×5

8 4 9 1 2 2 5 7 0 1

NewB=b(in2)

NewB = 2×5

1 3 8 2 2 1 2 6 1 6

[Hernia Baby]

This solution is amazing! I like it!

Answer 3

[Hernia Baby]

a = [3 6 0 3 8 4 9 1 2 4 9 3 2 5 7 0 1 2];
b = [5 6 5 3 1 3 8 2 2 3 5 7 1 2 6 1 6 7];
c = [0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0];

temp = cumsum(c)

temp = 1×18

0 0 0 0 1 1 1 1 1 1 1 1 2 2 2 2 2 2

for ii = 1:max(temp)
    ta = a;
    tb = b;
    ta(temp~=ii)=[];
    tb(temp~=ii)=[];
    A{ii,1}=ta(1:5);
    B{ii,1}=tb(1:5);
end
A=cell2mat(A)

A = 2×5

8 4 9 1 2 2 5 7 0 1

B=cell2mat(B)

B = 2×5

1 3 8 2 2 1 2 6 1 6