for loop to go through a cell array

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C.G. 2020-11-25

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https://ww2.mathworks.cn/matlabcentral/answers/661843-for-loop-to-go-through-a-cell-array

评论： C.G. 2020-11-25

I have written a code which tells me how many particles go past a certain x-coordinate for a single time step. The code accesses one cell of a 710x1 cell array currently, but now I want to tell it to do this for all the cells in the array, so i can plot a particles vs. time graph.

I know I need another for loop to do this, but I am unsure how to tell it to go through all the cells in the array.

%% particles leaving the rice pile
%for each cell in the array (timestep), calculate the number of particles after a certain x coordinate 
%access the {nth} cell of the cell array, and save all the rows in the 5th column (x-coordinates) as a new variable 
xc = particledata{212}(:,5);
%use the function table2array to turn the format of the data from a table to an array
xc_array = table2array(xc);
%for all the rows in the array, if the x coordinate goes beyond the outlet
%of the rice pile, display 'grain left rice pile'
%-0.15 is the x coordinate for the outlet
ricepileoutlet = -0.15
for b = 1:size(xc_array,1)
    if xc_array(b,1)< ricepileoutlet
    disp('grain left rice pile')
    end 
end
%display how many grains in total left the rice pile in the time step
%add up the number of times the x coordinate is >0.188 and save this in a new variable 'grains'
grains=sum(xc_array(:,1)< ricepileoutlet);
fprintf('A total of %d grains left the rice pile\n',grains);

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Answer 1

KALYAN ACHARJYA 2020-11-25

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https://ww2.mathworks.cn/matlabcentral/answers/661843-for-loop-to-go-through-a-cell-array#answer_555678

编辑：KALYAN ACHARJYA 2020-11-25

在 MATLAB Online 中打开

No loop needed here

% FOllowing result counts the total grain left rice pile

result=sum(xc_array>ricepileoutlet)

Note: Assumed that xc_array is an 1D array

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C.G. 2020-11-25

在 MATLAB Online 中打开

I will share my whole code below.

I started with 710 .csv files which I inputted to matlab. Each one of these .csv files has 1 second of data in it.

%% input
%input data from each .csv file into matlab 
%need particle id, velocity and coordinates stored
files = dir('*.csv'); %dir lists the files in a folder. In the specified folder, recognise all the .csv files
num_files = length(files); %specify how many files have been found and call it num_files
particledata = cell(length(files), 1); %create a cell array the same length as the number of files in one column
%for all the files found in the specified folder, read the tables of data and fill the empty cell array 'results' with the data in each .csv file
for a = 1:num_files
  particledata{a} = readtable(files(a).name);
end 
%% time steps
%number of excel files = number of time steps the model is run for (seconds)
totalruntime = num_files;
%% particles leaving the rice pile
%for each cell in the array (timestep), calculate the number of particles after a certain x coordinate 
%access the {nth} cell of the cell array, and save all the rows in the 5th column (x-coordinates) as a new variable 
xc = particledata{600}(:,5);
%use the function table2array to turn the format of the data from a table to an array
xc_array = table2array(xc);
%for all the rows in the array, if the x coordinate goes beyond the outlet
%of the rice pile, display 'grain left rice pile'
%-0.125 is the x coordinate for the end of the box on the mfix model 
ricepileoutlet = -0.15;
for c = 1:size(xc_array,1)
    if xc_array(c,1)< ricepileoutlet
    disp('grain left rice pile')
    end 
end
%display how many grains in total left the rice pile in the time step
%add up the number of times the x coordinate is >0.188 and save this in a new variable 'grains'
grains=sum(xc_array(:,1)< ricepileoutlet);
fprintf('A total of %d grains left the rice pile\n',grains);

KALYAN ACHARJYA 2020-11-25

在 MATLAB Online 中打开

Have you tried this example?

grain_num=zeros(1,size(xc_array,1));
for i=1:size(xc_array,1)
data=xc_array{i};
grain_num(i)=sum(data>ricepileoutlet);
end
bar(grain_num);

C.G. 2020-11-25

as you said above, xc_array is not a cell array.

my cell array containing all my 710 .csv files is 'particledata'

what I want to do overall is:

go through each cell of particledata and look at the data in column 5
for each of the cells in particle data, tell me if any of the rows in column 5 have values <-0.15, if so how many.
create a new variable called 'grains', which tells me how many rows have values <0.15 for each cell
plot a bar chart of grains vs. time

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for loop to go through a cell array

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for loop to go through a cell array

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