Pad a matrix with additional rows and concatenate another column

Hello, all!

I've included a sample of the code I'm using to pad a matrix with additional rows, then concatenate another column to that matrix. I can get the code to work for the first row of the matrix, but I'm not sure how to scale it for all six rows. I've tried using a for-loop but then get an error that the dimensions are not consistent.

    mu = 398600.4415;

    test_data = [6778.14 0 20 60 90 60; 6778.14 0 20 60 90 60; 7178.14 0 40 60 90 60; ...
        7178.14 0 40 60 90 60; 7578.17 0 60 60 90 60; 7578.17 0 60 60 90 60];

    % Calculate time in minutes
    C = unique(test_data(:,1));
    for i = 1:length(C)
        if C(i) == 6778.14
            T(i) = (sqrt((4*pi.^2)/(mu) * C(i).^3))/60;
        elseif C(i) == 7178.14
            T(i) = (sqrt((4*pi.^2)/(mu) * C(i).^3))/60;
        else
            T(i) = (sqrt((4*pi.^2)/(mu) * C(i).^3))/60;
        end
    end

    % Divide the orbital period into 6 equal time steps
    T_step = zeros(length(T), 6);
    T_step(1,:) = [0:T(1)/5:T(1)];
    T_step(2,:) = [0:T(2)/5:T(2)];
    T_step(3,:) = [0:T(3)/5:T(3)];
    T_step = T_step';

    [m n] = size(T_step);

    temp = padarray(test_data(1,:), [m-1 0], 'replicate','pre');
    test_data = [temp, T_step(:,1)]

In the end, if the value in the first column of test_data is 6778.14, I need to concatenate the first column of T_step. Likewise the second column of T_step for 7178.14 and the third column for 7578.14.

I hope this is clear enough but if you need more detail, please let me know. I'd appreciate any help you can provide.

Answer 1

[Aref Majdara]

Hi Bill, I'm trying to understand your question. So, for this specific test data that you have provided, what are the dimensions of the matrix that you expect to get at the end? Is it 36x7 ?

[Aref Majdara]

If yes, here is one way to do that:

mu = 398600.4415;

test_data = [6778.14 0 20 60 90 60; 6778.14 0 20 60 90 60; 7178.14 0 40 60 90 60; ...
    7178.14 0 40 60 90 60; 7578.17 0 60 60 90 60; 7578.17 0 60 60 90 60]

% Calculate time in minutes
C = unique(test_data(:,1));
for i = 1:length(C)
    if C(i) == 6778.14
        T(i) = (sqrt((4*pi.^2)/(mu) * C(i).^3))/60;
    elseif C(i) == 7178.14
        T(i) = (sqrt((4*pi.^2)/(mu) * C(i).^3))/60;
    else
        T(i) = (sqrt((4*pi.^2)/(mu) * C(i).^3))/60;
    end
end
% Divide the orbital period into 6 equal time steps
T_step = zeros(length(T), 6);
T_step(1,:) = [0:T(1)/5:T(1)];
T_step(2,:) = [0:T(2)/5:T(2)];
T_step(3,:) = [0:T(3)/5:T(3)];
T_step = T_step';
[m n] = size(T_step);
R=length(test_data);

for i=1:R
    temp = padarray(test_data(i,:), [m-1 0], 'replicate','pre');

      if (test_data(i,1)==6778.14)
          temp = [temp, T_step(:,1)];
      elseif (test_data(i,1)==7178.14)
          temp = [temp, T_step(:,2)];
      elseif (test_data(i,1)== 7578.17)
          temp = [temp, T_step(:,3)];
      end

      if(i==1)
          M=temp;
      else
          M=[M; temp];
      end
  end

M

[Bill Symolon]

Aref, that's exactly what I was looking for. Thanks!

[Bill Symolon]

Aref,

I hope I can impose on you one more time. I've scaled the code you provided to include my entire dataset, but I'm still missing something. Here's the full code I'm using:

    %%Define a range of orbital parameters as initial conditions
    mu = 398600.4415;           % Stnd grav parameter 

    % Set Altitude 
    Alt = 400:400:1200;

    % Convert Altitude to Semi-major Axis 
    Ree = 6378;         % Equatorial radius of Earth in km
    a = Alt + Ree;

    % Set Eccentricity
    e = 1.7E-16;    % Near zero

    % Set Inclination
    i = 20:20:60;

    % Set Right Ascension of Ascending Node 
    RAAN = 0:60:300;

    % Set Argument of Perigee
    omega = 0:60:180;

    % Set True Anomaly
    nu = 0:60:300;

    %%Calculate the orbital period in minutes
    C = unique(a);
    for z = 1:length(C)
        if C(z) == 6778.14
            T(z) = (sqrt((4*pi.^2)/(mu) * C(z).^3))/60;
        elseif C(z) == 7178.14
            T(z) = (sqrt((4*pi.^2)/(mu) * C(z).^3))/60;
        else
            T(z) = (sqrt((4*pi.^2)/(mu) * C(z).^3))/60;
        end
    end

    %%Divide the orbital period into 6 equal time steps
    T_step = zeros(length(T), 6);
    T_step(1,:) = [0:T(1)/5:T(1)];
    T_step(2,:) = [0:T(2)/5:T(2)];
    T_step(3,:) = [0:T(3)/5:T(3)];
    T_step = T_step';
    [m n] = size(T_step);

    %%Use nested for-loops to build matrix
    index = 1;
    for j = 1:length(a)
        for k = 1:length(i)
            for l = 1:length(RAAN)
                for o = 1:length(omega)
                    for p = 1:length(nu)
                        parameters(index,:) = [a(j) e i(k) RAAN(l) omega(o) nu(p)];
                        index = index + 1;
                    end
                end
            end
        end
    end    

    %%Add the time steps to the parameters matrix
    R=length(parameters);

    for index=1:R
        temp = padarray(parameters(index,:), [m-1 0], 'replicate','pre');

    if parameters(index,1) == 6778.14
        temp = [temp, T_step(:,1)];
    elseif parameters(index,1) == 7178.14
        temp = [temp, T_step(:,2)];
    elseif parameters(index,1) == 7578.17
        temp = [temp, T_step(:,3)];
    end

    if(index == 1)
        M = temp;
    else
        M = [M; temp];
    end
    end
    parameters = M;

Everything is working great, except the code doesn't add the time steps as the 7th column. When it's all said and done, I should end up with a 7776x7 matrix. Currently, I'm getting 7776x6.

I'd appreciate your thoughts. Thanks!