How to add values in coloumn with corresponding of logical array?

I have a matrix which is shown in following snipped table.

I have to add the value in colomn no 7 when the logical value as per in last coloumn is 1 with the previous value of coloumn 7.

For example: In 3rd row of last coloumn I have logical value 1 so I can add corresponding value of coloumn 7 i.e, 7.6079 with previous value 4.1703 and replace the 4.1703 with output 11.7782.

For that wrote following code:

% Event is the Matrix as shown in the image.
    St = find(Event(:,10));  % Index of ones in last coloumn
    m = length(St);          % No of instance
         
    n = length(Event);
    for i = 1:n-m
        if Event(i,10) == 1
            s = Event(i,7) + Event(i-1,7);
            Event(i-1,7)=s;
            Event(i,:)=[];
        end
    end

This worked for all the cases where logical 1 in last coloumn is followed by 0. But, problem encountered when there are consecutive 1 in last coloumn. The above code is adding the corresponding value of 7th coloumn with respect to last coloumn.

The output should be 77.8971(5.0724+12.730+10.910+19.562+24.285+5.3377). i.e, all the corresponding values of all consecutive 1 should be added with previous 0.

But I'm geting 17.8024 (5.0724+12.730).

Answer 1

[Jan]

Start from the end:

s = 0;
for k = size(Event, 1):-1:1
    if Event(k, 10)  % You can omit the == 1
        s = s + Event(k, 7);
    elseif s ~= 0
        Event(k, 7) = Event(k, 7) + s;
        s           = 0;
    end
end

% Remove the rows with 1 in column 10 afterwards:
Event(Event(:, 10) == 1, :) = [];

With your approach deleting the i.th row causes troubles, because then the former i+1.th row becomes the new i.th row. But in the next iteration i is increased and the former i+1.th row is not considered ever.

[Pritam Daundkar]

Thanks for your response.

But still the issue is not resolved same answer is coming.

[Jan]

@Pritam Daundkar: It is very unlikely that my code produces the same result as yours. It would be very useful, if you provide some small inputs such that they can be copy&paste'd. Then I could check your observation.

[Pritam Daundkar]

% Input

Event = [ 0 0 0 0 0 0 5.0724 4 305 0

0 0 0 0 0 0 12.7300 9 2 1

0 0 0 0 0 0 10.9100 7 3 1

0 0 0 0 0 0 19.5620 14 2 1

0 0 0 0 0 0 24.2850 16 3 1

0 0 0 0 0 0 5.3377 4 2 1

0 0 0 0 0 0 4.9985 4 1461 0 ]

Output using your code

Event = [ 0 0 0 0 0 0 17.8024 4 305 0

0 0 0 0 0 0 4.9985 4 1461 0 ]

Which is similar answer with the my previous code.

Just adding 1st logical 1 with previous 0.

[Jan]

@Pritam Daundkar: Nope, I definitely get a different result:

Event = [  0     0     0     0    0     0     5.0724     4	305	0; ...
           0     0     0     0    0     0	12.7300    9	2	1; ...
           0     0     0     0    0     0	10.9100    7	3	1; ...
           0     0     0     0    0     0	19.5620    14	2	1; ...
           0     0     0     0    0     0	24.2850    16	3	1; ...
           0     0     0     0    0     0	5.3377      4	2	1; ...
           0     0     0     0    0     0	4.9985      4	1461    0 ];
s = 0;
for k = size(Event, 1):-1:1
    if Event(k, 10)  % You can omit the == 1
        s = s + Event(k, 7);
    elseif s ~= 0
        Event(k, 7) = Event(k, 7) + s;
        s           = 0;
    end
end
% Remove the rows with 1 in column 10 afterwards:
Event(Event(:, 10) == 1, :) = [];
Event(:, 7)

ans = 2×1

77.8971 4.9985

So if you get another result, you do not use my code.

A sorter version:

for k = size(Event, 1) - 1:-1:1
    Event(k, 7) = Event(k, 7) + Event(k+1, 7) * Event(k+1, 10);
end
Event(Event(:, 10) == 1, :) = [];