Creating multiple plots in one graph from multiple .txt files

Hi,

i need help to create code that allows me to read data from multiple .txt files, then do some math on it and from calculated values create plots on one graph from all of those .txt. I'am struggling with it because of my lack of knowledge in matlab.

I have to take WF/dLogM colum, find max of it and then divide every value of that column by found max value. Then just plot Molecular Weight as x and calculated values as y.

I need any sugestions what functions/commands I should use.

[Rik]

If you have trouble with Matlab basics you may consider doing the Onramp tutorial (which is provided for free by Mathworks).

What have you tried for each step?

Answer 1

[Mathieu NOE]

hello

try this :

d = dir('NW*.txt'); % d is a structure array that contains the list of all txt files starting with NW

% create figure and use "hold on" to overlay multiple results 
figure(1)
hold on

% main loop

for k = 1:numel(d)
    FileName=d(k).name;
    fprintf(1,'Now reading %s\n',FileName);
    data = readmatrix(FileName,"NumHeaderLines",40,"DecimalSeparator",","); % read the data and skip the first 40 lines
    % data has 20 columns :
    % Ret. Vol.	RI	UV	RALS	LALS	IV - DP	IV -  IP	Adjusted RI	Adjusted UV	Adjusted RALS	Adjusted LALS	Adjusted IV - DP	Adjusted IV -  IP	
    %Molecular Weight	Cumulative Weight Fraction	Normalized Wt Fr	Normalized Mole Fraction	Conc.	WF/dLogM
    
%     I have to take WF/dLogM colum, find max of it and then divide every value of that column
%     by found max value.
    [m,n] = size(data);
    WF_dLogM = data(:,n); % could be done also with = data(:,end) but we need anyway "n" again below 
    Molecular_Weight = data(:,n-5);
    
    % remove NaN values due to missing data in file
    ind_nan = isnan(WF_dLogM);
    WF_dLogM(ind_nan) = []; % NaN values are removed
    Molecular_Weight(ind_nan) = []; % values are removed

    % remove very large negative values (bug ?) like -1,00000e+005
    ind_neg = (WF_dLogM<0);
    WF_dLogM(ind_neg) = []; % very large negative values are removed
    Molecular_Weight(ind_neg) = []; % values are removed

    % normalize data
    WF_dLogM_normalized = WF_dLogM./max(WF_dLogM); % 
    
    %plot Molecular Weight as x and calculated values as y
    leg_str{k} = ['File : ' FileName ];
    plot(Molecular_Weight,WF_dLogM_normalized);
    
end

% plot legend
legend(leg_str);

[Gabriel]

Hello, this works perfectly, but I just figured out that every file (NW2003D also) has 2 rows of WFdLogM (NaN,data1,NaN,data2). Its because of 2 peaks (data1=peak1, data2=peak2). I am only intrested in peak1 (peak2 comes from reference).

And here is the problem. max(WFdLogM) is much bigger for peak2 than peak1. Is that possible to find max just for the peak1? (data2 can be deleted, it is not usable for me).

[Mathieu NOE]

hello again Gabriel

sorry I don't see where are supposed to be these 2 rows of WFdLogM (NaN,data1,NaN,data2) ?

in the NW2003D file you provided (attached here again) , I see the is a first block of data with only 7 columns, then at row index = 1702, you have 20 columns of data (with one single row WFdLogM) , then again at row index = 3114 we come back to 7 columns of data

so for me there is one single row of WFdLogM data that you can capture between rows 1702 and 3113

where do you see WFdLogM (NaN,data1,NaN,data2) ?

cheers

[Gabriel]

Hi, you're right, i haven't noticed that, the file i attached before has just 1 row. But every another file that i own has 2 rows. For example that one.

[Mathieu NOE]

hello again

try this :

d = dir('2023*.txt'); % d is a structure array that contains the list of all txt files starting with 2023
% d = dir('NW*.txt'); % d is a structure array that contains the list of all txt files starting with NW

% create figure and use "hold on" to overlay multiple results 
figure(1)
hold on

% main loop

for k = 1:numel(d)
    FileName=d(k).name;
    fprintf(1,'Now reading %s\n',FileName);
    data = readmatrix(FileName,"NumHeaderLines",40,"DecimalSeparator",","); % read the data and skip the first 40 lines
    % data has 20 columns :
    % Ret. Vol.	RI	UV	RALS	LALS	IV - DP	IV -  IP	Adjusted RI	Adjusted UV	Adjusted RALS	Adjusted LALS	Adjusted IV - DP	Adjusted IV -  IP	
    %Molecular Weight	Cumulative Weight Fraction	Normalized Wt Fr	Normalized Mole Fraction	Conc.	WF/dLogM
    
%     I have to take WF/dLogM colum, find max of it and then divide every  value of that column      by found max value.
    [m,n] = size(data);
    WF_dLogM = data(:,n); % could be done also with = data(:,end) but we need anyway "n" again below 
    Molecular_Weight = data(:,n-5);
    
    % find NaN index
    ind_nan = isnan(WF_dLogM);
    [begin,ends] = find_start_end_group(~ind_nan);
    % we want only the first group of data
    ind = (begin(1):ends(1));
    WF_dLogM = WF_dLogM(ind);
    Molecular_Weight = Molecular_Weight(ind);
    
%     WF_dLogM(ind_nan) = []; % NaN values are removed
%     Molecular_Weight(ind_nan) = []; % values are removed

    % remove very large negative values (bug ?) like -1,00000e+005
    ind_neg = (WF_dLogM<0);
    WF_dLogM(ind_neg) = []; % very large negative values are removed
    Molecular_Weight(ind_neg) = []; % values are removed

    % normalize data
    WF_dLogM_normalized = WF_dLogM./max(WF_dLogM); % 
    
    %plot Molecular Weight as x and calculated values as y
    FileName = strrep(FileName,'_',' ');
    leg_str{k} = ['File : ' FileName ];
    plot(Molecular_Weight,WF_dLogM_normalized);
    
end

% plot legend
legend(leg_str);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function [begin,ends] = find_start_end_group(ind)
% This locates the beginning /ending points of data groups
% Important : ind must be a LOGICAL array

    D = diff([0;ind(:);0]);
    begin = find(D == 1);
    ends = find(D == -1) - 1;
end

[Mathieu NOE]

small improvement to combine both data files in one plot

% d = dir('2023*.txt'); % d is a structure array that contains the list of all txt files starting with 2023
% d = dir(['NW*.txt'); % d is a structure array that contains the list of all txt files starting with NW

% You can save the output of DIR as a structured array, or in your case two structured arrays that can then be combined:
d1 = dir('NW*.txt');
d2 = dir('2023*.txt');
d = [d1;d2];


% create figure and use "hold on" to overlay multiple results 
figure(1)
hold on

% main loop

for k = 1:numel(d)
    FileName=d(k).name;
    fprintf(1,'Now reading %s\n',FileName);
    data = readmatrix(FileName,"NumHeaderLines",40,"DecimalSeparator",","); % read the data and skip the first 40 lines
    % data has 20 columns :
    % Ret. Vol.	RI	UV	RALS	LALS	IV - DP	IV -  IP	Adjusted RI	Adjusted UV	Adjusted RALS	Adjusted LALS	Adjusted IV - DP	Adjusted IV -  IP	
    %Molecular Weight	Cumulative Weight Fraction	Normalized Wt Fr	Normalized Mole Fraction	Conc.	WF/dLogM
    
%     I have to take WF/dLogM colum, find max of it and then divide every  value of that column      by found max value.
    [m,n] = size(data);
    WF_dLogM = data(:,n); % could be done also with = data(:,end) but we need anyway "n" again below 
    Molecular_Weight = data(:,n-5);
    
    % find NaN index
    ind_nan = isnan(WF_dLogM);
    [begin,ends] = find_start_end_group(~ind_nan);
    % we want only the first group of data
    ind = (begin(1):ends(1));
    WF_dLogM = WF_dLogM(ind);
    Molecular_Weight = Molecular_Weight(ind);
    
%     WF_dLogM(ind_nan) = []; % NaN values are removed
%     Molecular_Weight(ind_nan) = []; % values are removed

    % remove very large negative values (bug ?) like -1,00000e+005
    ind_neg = (WF_dLogM<0);
    WF_dLogM(ind_neg) = []; % very large negative values are removed
    Molecular_Weight(ind_neg) = []; % values are removed

    % normalize data
    WF_dLogM_normalized = WF_dLogM./max(WF_dLogM); % 
    
    %plot Molecular Weight as x and calculated values as y
    FileName = strrep(FileName,'_',' ');
    leg_str{k} = ['File : ' FileName ];
    plot(Molecular_Weight,WF_dLogM_normalized);
    
end

% plot legend
legend(leg_str);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function [begin,ends] = find_start_end_group(ind)
% This locates the beginning /ending points of data groups
% Important : ind must be a LOGICAL array

    D = diff([0;ind(:);0]);
    begin = find(D == 1);
    ends = find(D == -1) - 1;
end

[Mathieu NOE]

hello again @Gabriel

do you mind accepting my answer (if it has fullfiled your expectations ) ? tx