Cumulative Summation down a matrix in loop

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IDN
IDN 2022-2-9
评论： Adam Danz 2022-2-10
Hello!
I have 2 matrix, I would like to sum Matrix B values cummulative given condition. The condition is that it starts to sum once Matrix A = -1 and stops when Matrix A = 1 and it goes on and on all the way down to the end of the data set. Thanks for the help!
Matrix A Matrix B CumSum
0
0
0
-1 0
-1 0.02
-1 -12.09
-1 6.61
1 1.1 -4.36 CumSum
0 0
-1 0
-1 -6.8
-1 -26.87
-1 2.67
-1 -9.99
-1 9.28
-1 -3.17
1 8.6 7.39 CumSum
0
0
0
  2 个评论
IDN
IDN 2022-2-9
编辑：IDN 2022-2-9
those are the totals when cumum runs by summing values in Matrix B. So -4.36 and -26.28 is the expected answer when all set an done. Thanks for helping!

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采纳的回答

Adam Danz
Adam Danz 2022-2-9
编辑：Adam Danz 2022-2-9
Ran in:
If and only if the groups marked by A=-1 to A=1 are not interruped by any other values in A and a 1 does not appear before the first -1, the solution is,
T = readtable('Sum Sample.xlsx')
Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.
T = 20×3 table
MatrixA MatrixB CumSum _______ _______ ______ 0 NaN NaN 0 NaN NaN 0 NaN NaN -1 0 NaN -1 0.02 NaN -1 -12.09 NaN -1 6.61 NaN 1 1.1 -4.36 0 0 NaN -1 0 NaN -1 -6.8 NaN -1 -26.87 NaN -1 2.67 NaN -1 -9.99 NaN -1 9.28 NaN -1 -3.17 NaN
startIdx = find([false;diff(T.MatrixA==-1)==1]);
stopIdx = find([false;diff(T.MatrixA==1)==1]);
groupSums = arrayfun(@(start,stop)sum(T.MatrixB(start:stop)),startIdx,stopIdx)
groupSums = 2×1
-4.3600 -26.2800
Or perhaps you want,
T.CumSum(stopIdx) = groupSums
T = 20×3 table
MatrixA MatrixB CumSum _______ _______ ______ 0 NaN NaN 0 NaN NaN 0 NaN NaN -1 0 NaN -1 0.02 NaN -1 -12.09 NaN -1 6.61 NaN 1 1.1 -4.36 0 0 NaN -1 0 NaN -1 -6.8 NaN -1 -26.87 NaN -1 2.67 NaN -1 -9.99 NaN -1 9.28 NaN -1 -3.17 NaN
  4 个评论
显示 2更早的评论
Adam Danz
Adam Danz 2022-2-10
Just saw your message now. Glad you worked it out. That line merely places data within the table T so nothing should be coming out horizontally.

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更多回答（1 个）

Highphi
Highphi 2022-2-9
Ran in:
matrixA = [0 0 0 -1 -1 -1 -1 1 0 -1 -1 -1 -1 -1 -1 -1 1 0 0 0]'; % for ref
matrixB = [0 0 0 0 0.02 -12.09 6.61 1.1 0 0 -6.8 -26.87 2.67 -9-99 9.28 -3.17 8.6 0 0 0]'; % for ref
state = 0;
matrixSums = zeros(size(matrixA,1), 1);
for i = 1:size(matrixA, 1)
temp = matrixA(i);
if (temp == -1) && (state == 0)
state = 1;
cumSum = matrixB(i);
elseif (state == 1) && (temp ~= 1)
cumSum = cumSum + matrixB(i);
elseif (state == 1) && (temp == 1)
cumSum = cumSum + matrixB(i);
matrixSums(i) = cumSum;
state = 0;
end
end
outMat = [matrixA, matrixB, matrixSums]
outMat = 20×3
0 0 0 0 0 0 0 0 0 -1.0000 0 0 -1.0000 0.0200 0 -1.0000 -12.0900 0 -1.0000 6.6100 0 1.0000 1.1000 -4.3600 0 0 0 -1.0000 0 0
  2 个评论
IDN
IDN 2022-2-9
Thanks, this looks good as well...i just dont have the toolbox required for the "state" functionality
Highphi
Highphi 2022-2-9
you shouldn't need a toolbox, it's just a variable to indicate your status

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