Sum row 2 and stop when 1 is reached in row 1

Hi,

I have a array of two rows with the following numbers:

Row1: [0,0,1,0,0,0,1,0,0,1,0]

Row2: [0.0220,0.3110,0.0230,1.0550,0.0230,0.0456,0.1120,0.0400,0.0660,0.3690]

I want to take the sum of row 2: until row 1 contains 1.

for example: 0.0220+0.3110, 0.0230 + 1.0550 + 0.0230 +0.0456

I tried to do this with a loop but it doesn't give me want I want.

for i = Row1

if(i == 0)

sum(Row2)

break;

end

if(i == 1)

break;

end

end

can anyone help me with this?

Thanks a lot!

Answer 1

[Image Analyst]

Try using find():

Row1 =[0,0,1,0,0,0,1,0,0,1,0];
Row2 = [0.0220,0.3110,0.0230,1.0550,0.0230,0.0456,0.1120,0.0400,0.0660,0.3690];
oneIndexes = find(Row1 == 1)

oneIndexes = 1×3

3 7 10

% Find out where each stretch starts and stops.
startIndexes = [1, oneIndexes]

startIndexes = 1×4

1 3 7 10

stopIndexes = [oneIndexes - 1, length(Row2)]

stopIndexes = 1×4

2 6 9 10

% Loop over each stretch, computing the sum in that stretch.
for k = 1 : length(startIndexes)
	index1 = startIndexes(k);
	index2 = stopIndexes(k);
	theSums(k) = sum(Row2(index1 : index2));
end
theSums % Show in command window

theSums = 1×4

0.3330 1.1466 0.2180 0.3690

[Iris Willaert]

Briliant that did the job for me!

Thanks!

[Image Analyst]

You're welcome. Can you click the "Accept this answer" link for the best answer and click the Vote icon for both answers. 🙂

Answer 2

[David Hill]

m=  [0,0,1,0,0,0,1,0,0,1;0.0220,0.3110,0.0230,1.0550,0.0230,0.0456,0.1120,0.0400,0.0660,0.3690];
%rows of the same matrix must be the same size

f=[1,find(m(1,:))];
for k=2:length(f)
  s(k-1)=sum(m(2,f(k-1):f(k)-1));
end

[Iris Willaert]

Great! thanks a lot!!!