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loop to identify new particles

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C.G.
C.G. on 26 Jan 2021
Commented: C.G. on 29 Jan 2021
I have the particle Id and y coordinates for every particle in my model over 3000s.
My loop currently tells me how many grains in each second have y coordinates <-0.13 and sums this in the variable 'grains'. This loop includes all the grains <-0.13, even if they have already been included in prevoius time steps.
I want the loop to only include new grains to get mass efflux per second that is not cumulative, and I want it to use the particle ID to do this. For example if particle 2 was included in time step 2, do not include in time step 2.
Can anybody help?
ymax = -0.13;
for b = 1:length(particledata)
%save all the rows in the 1st and 6th column (ID and y-coordinates) of each cell as a new variable y
y{b} = particledata{b}(:,[1 6]);
%use the function table2array to turn the format of the data from a table to an array
y_array{b} = table2array(y{b});
%sum the total number of grains with y coordinate <-0.13 in each cell, and save into a new variable 'grains'
grains{b} = sum(y_array{b}(:,2)<ymax);
fprintf('A total of %d grains left the rice pile\n',grains{b});
end

Answers (1)

Anmol Dhiman
Anmol Dhiman on 28 Jan 2021
Edited: Anmol Dhiman on 28 Jan 2021
Hi Chloe,
Assuming you have all the data in an array format. Follow the below instructions
% outside the loop
temp = [];
% Inside the loop after y_array{b} = table2array(y{b}); statement
temp2 = setdiff(y_Array{b}(:,2),temp);
grains{b} = sum(temp2<ymax);
temp = [temp temp2];
Hope it helps
  5 Comments
C.G.
C.G. on 29 Jan 2021
Thank you for your response, the code does work but I am not entirely sure it is what I need it to do. Could you explain it a bit for me?
I need the code to find and save all the rows in the array where column 2 is <-0.13. Then I want it too look through the rows and if the number in the first column (particle ID) and only save the row where the first occurenence of this number occurs. I have recently adapted the code above to this.
for b = 1:length(particledata)
%get the particle ID (:,1) and coordinates (:,6) and save them in an array
y{b} = table2array(particledata{b}(:,[1 6]));
%find and save all the rows in the array where column 2 is <-0.13
grains{b} = y{b}(y{b}(:,2) <= ymax, :);
%if the number in the first column of each cell is in any of the previous columns,delete the row
end

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