Calculation of summation with filtering positive and negative values
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Hi
I have one matrix with u(i,j,t).
I need calculate sum of the variable like this in each time step.i,j have not folloed an approprate pattern for example the same i or j
sum(t)= u(167,148,t)+u(167,139,t)+u(167,165,t)+u(167,164,t)+u(167,163,t)+..
But,I need an algorithm to seperate positive and negative values.
for example in each time step check the u: if u is positive: sumpositive(t)=u(167,158,t)+u(167,159,t)+u(167,160,t)+u(167,161,t)+u(167,162,t)
if u is negative : sumnegative(t)=iu(167,158,t)+u(167,159,t)+u(167,160,t)+u(167,161,t)+u(167,162,t)
Thanks
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回答(1 个)
the cyclist
2023-4-24
% Set seed for reproducibility
rng default
% Some pretend data
u = randn(4,4,3);
% Identify positive u
uIsPos = u >= 0;
% Sum the positive u
sumpositive = sum(u.*uIsPos,3)
% Sum the negative u
sumnegative = sum(u.*~uIsPos,3)
4 个评论
the cyclist
2023-4-25
for t = 1:length(time)
sumpositive(t) = (u(167,158,t).*(u(167,158,t)>0)) + (u(167,159,t).*(u(167,159,t)>0)) + (u(167,160,t).*(u(167,160,t)>0));
sumnegative(t) = (u(167,158,t).*(u(167,158,t)<0)) + (u(167,159,t).*(u(167,159,t)<0)) + (u(167,160,t).*(u(167,160,t)<0));
end
which can be simplified to
for t = 1:length(time)
sumpositive(t) = sum(u(167,158:160,t).*(u(167,158:160,t)>0));
sumnegative(t) = sum(u(167,158:160,t).*(u(167,158:160,t)<0));
end
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