How to concatenate columns of varying lengths, generated by a for loop, into a matrix?

How to concatenate columns vectors of varying lengths, generated by a for loop, into a matrix?

num_sim = 1000;      %1000 monte carlo simulations


%~~~~~~~~~~Coalesce data from Obs_Node.out files~~~~~~~~~~~~
for i=1:num_sim
    Obs_Node = fopen(["/Users/apple/Dropbox/My Mac (apple’s MacBook Pro)/Desktop/Simulations/MC_"+num2str(i)+'/Obs_Node.out']);   % Open monte carlo output file in Path (i) 
    
    skip_lines=11;   %skip all the lines until the output data of interest
    
    for k=1:(skip_lines)
        x=fgetl(Obs_Node);
    end

    temp1 = fscanf(Obs_Node,'%f',[5,Inf]);        %scan the matrix of data
    TEMP1 = temp1';       % transpose data
    
    theta_ObsNode = TEMP1(:,3);      % Isolate the Hydraulic Conductivity column
    THETA_ObsNode(:,i) = theta_ObsNode(:);  %add column from this loop to past loops to make matrix of data
    
    flux_ObsNode = TEMP1(:,4);      % Isolate the Water Flux column
    FLUX_ObsNode(:,i) = flux_ObsNode(:);   %add column from this loop to past loops to make matrix of data
    
    Conc_ObsNode = TEMP1(:,5);      % Isolate the Concentration g/cm3 column
    CONC_ObsNode(:,i) = Conc_ObsNode(:);    %add column from this loop to past loops to make matrix of data 
    
    fclose(Obs_Node);
end

[David Hill]

You will have to pad the columns with zeros or nan to make them the same length or you will have to use a cell array.

[Wesser]

I fond this function that can pad a vector with NAN or zeros...but is there another way to do this? Would I call the function after

num_sim = 1000;      %1000 monte carlo simulations
%~~~~~Preallocation~~~~~~~~~~`
%Obs_Node.out
Node_CONC=zeros(200000,num_sim);
THETA_ObsNode = zeros(200000,num_sim);
FLUX_ObsNode = zeros(200000,num_sim);
CONC_ObsNode = zeros(200000,num_sim);

%~~~~~~~~~~Coalesce data from Obs_Node.out files~~~~~~~~~~~~
for i=1:num_sim
    Obs_Node = fopen(["/Users/apple/Dropbox/My Mac (apple’s MacBook Pro)/Desktop/Simulations/MC_"+num2str(i)+'/Obs_Node.out']);   % Open monte carlo output file in Path (i) 
    
    skip_lines=11;   %skip all the lines until the output data of interest
    
    for k=1:(skip_lines)
        x=fgetl(Obs_Node);
    end

    temp1 = fscanf(Obs_Node,'%f',[5,Inf]);        %scan the matrix of data
    TEMP1 = temp1';       % transpose data
    
    theta_ObsNode = TEMP1(:,3);      % Isolate the Hydraulic Conductivity column
    %pad theta_ObsNode with NAN to 200000, but how? 
    THETA_ObsNode(:,i) = theta_ObsNode(:);  %add column from this loop to past loops to make matrix of data
    
    flux_ObsNode = TEMP1(:,4);      % Isolate the Water Flux column
    %pad flux_ObsNode with NAN to 200000, but how?
    FLUX_ObsNode(:,i) = flux_ObsNode(:);   %add column from this loop to past loops to make matrix of data
    
    Conc_ObsNode = TEMP1(:,5);      % Isolate the Concentration g/cm3 column
    %pad Conc_ObsNode with NAN to 200000, but how?
    CONC_ObsNode(:,i) = Conc_ObsNode(:);    %add column from this loop to past loops to make matrix of data 
    
    fclose(Obs_Node);
end

Answer 1

[Jan]

Maybe all you need is:

Node_CONC     = nan(200000,num_sim);
THETA_ObsNode = nan(200000,num_sim);
FLUX_ObsNode  = nan(200000,num_sim);
CONC_ObsNode  = nan(200000,num_sim);

...
TEMP1 = temp1';       % transpose data
s = size(TEMP1, 1);

THETA_ObsNode(1:s, i) = TEMP1(:,3);
FLUX_ObsNode(1:s,  i) = TEMP1(:,4);
CONC_ObsNode(1:s,  i) = TEMP1(:,5);

[Wesser]

This set me on the right track. Thanks to all for the continued guidance! This is what I ended up with:

%~~~~~Preallocation~~~~~~~~~~`
%Obs_Node.out

THETA_ObsNode = nan(300000,num_sim);

%~~~~~~~~~~Coalesce data from Obs_Node.out files~~~~~~~~~~~~
for i=1:num_sim
    Obs_Node = fopen("/Users/apple//Simulations/MC_"+i+"/Obs_Node.out");   % Open monte carlo output file in Path (i) 
              
    skip_lines=11;   %skip all the lines until the output data of interest
    
    for k=1:(skip_lines)
        x=fgetl(Obs_Node);
    end
    
    temp1 = fscanf(Obs_Node,'%f',[5,Inf]);        %scan the matrix of data
    TEMP1 = temp1';       % transpose data
   
    theta_ObsNode = TEMP1(:,3);      % Hydraulic Conductivity
    theta_ObsNode(end+1:300000)=nan;
    THETA_ObsNode(:,i) = theta_ObsNode(:);      
    
    fclose(Obs_Node);
end

[Jan]

This is faster:

    THETA_ObsNode(1:height(TEMP1), i) = TEMP1(:,3);    

With your code you overwrite a lot of NaNs by NaNs.