I plotted this and i want to measure the length and analyze the section of this plot

This is the part that i want to analyze and measure,its just an example

Is there a way to analyze this?

thank you for your attention

[Firas Guechchati]

Answer 1

[Ameer Hamza]

Do you have x and y values of the line and the x values of the end-points? If yes, you can use logical indexing

x; % vector of all x-values
y; % vector of all y-values
x1; % left en-point
x2; % right end-point

idx = (x1 < x) & (x < x2);
x_vals = x(idx);
y_vals = y(idx); % x and y values you want

[Firas Guechchati]

but if i dont know the x and y values of the turning point ?

[Ameer Hamza]

How are turing point decided?

[Firas Guechchati]

%% Plot Einstellungen: Eingabe 

offset_y = 0.05;                 % Offset in y-Richtung von der x-Achse und zwischen zwei Graphen
offset_x = 0;                    % Offset in x-Richtung von der y-Achse 

        

%% Sensitivit�t: Eingabe

% Gl�ttung der Werte
h = 0.25;                   % h = 0,8
fitting = 1;                %  close fit: 1;  normal fit: 2;  and some satisfactory smoothing with: 3 

eck = 2000;                 % Eckenkorrekturfaktor -> Radius (bzgl. Messpunkte) an den Grenzstellen (Ecken) um �berschwinger zu gl�tten

% Sensitivit�t zur Bestimmung der Grenzwerte
range_grad = 500;            % "Reichweite" der Gradienten:  
delta_rel = 1;            % relative Abweichung die �berschritten werden muss um Grenzwerte zu setzen


%% 
% Datei-Import: Eingabe

number = 1;                                 % Anzahl der Messungen, Anzahl der Graphen in einem figure. 
%path = 'C:\Users\tobi9\Desktop\Hiwi Temp\VSP\BH\kontur\';   %Dateipfad, exclusive Dateinamen z.B. '\\C\...\Kontur\Daten\'
%dataname = 'BH-3-0grad';            %'NA_49_32_1_WK_1_P';    % Name der Datei, ohne nummeriert bsp: 'AR'
%type = 'txt';                               % Dateiformat z.B. 'hfm'  oder  'txt'
%head_jump = 1;                              % Anzahl Kopfzeilen !! zum �berspringen !! (iMSE -> Hommel)

[filename,filepath]=uigetfile({'*.txt','Result file (*.txt)'},'Choose result file'); %Dateiauswahl �ffnen und zugelassene Dateien festlegen
if isequal (filename,0) % Abbruch wenn keine Datei ausgew�hlt
    disp('No file chosen, program is canceled.');
    return;
end

Newfile=comma2point([filepath '' filename]);
Konturdaten=dlmread(Newfile,'\t',2,0);
x=Konturdaten(:,1);
y=Konturdaten(:,2);


institut = 'imse';                          % 'imse', 'wzl', sonstige    (vorgespeicherte Institute...)

%% Vorbereitung
    % Grenzstellen
    pos_1 = nan;
    pos_2 = nan;
        
for n=1:number
    
    % Datei-Import:
%    name = dataname;           % Name der Datei, nummeriert mit n bsp: ['AR' n]
    
    %% Datei-Import
switch institut
    
    case 'imse'
    %fid =  fopen([path name '.' type],'r');
    %daten = textscan(fid,'%q %q %q','HeaderLines',2,'Delimiter', {';'});
    %fclose(fid);

    %x = daten{1,1};
    %y = daten{1,2};

    % x_10 = sprintf('%0.10f',x);
    % y_10 = sprintf('%0.10f',y);
    
    case 'wzl'
    fid =  fopen([path name '.' type],'r');
    daten_temp = textscan(fid,'%f %f %f %f %f %f ','HeaderLines',63,'Delimiter', {'=', ' '});
    fclose(fid);

    daten{1,1} = daten_temp{1,2};
    daten{1,2} = daten_temp{1,4};
    
    x = daten{1,1};
    y = daten{1,2};

    % x_10 = sprintf('%0.10f',x);
    % y_10 = sprintf('%0.10f',y);
    
end%switch
    
%% Eingrenzung der Messwerte (manuell)

% figure(1)
% plot(daten{1,1},daten{1,2});
% close(figure(1))
% 
% % %y1_links = find( -7.6<y,1);
% % %y1_rechts = find( -7.5<y,1);
%  x1_min = find( 3.45<x,1);
%  x1_max = find(9.8<x,1);
% % 
% % % y2_links = find( -7.8>y,1);
% % % y2_rechts = find( -7.4<y,1);
%  x2_min = find( 3.5<x,1);
%  x2_max = find( 9.75<x,1);
% % 
% % % y3_links = find( -7.3<y,1);
% % % y3_rechts = find( -7.05<y,1);
%  x3_min = find( 14.85<x,1);
%  x3_max = find( 22.1<x,1);
% % 
% % 
%  xn_min = ['x' num2str(n) '_min'];
%  xn_max = ['x' num2str(n) '_max'];
% % % yn_links = ['y' num2str(n) '_links'];
% % % yn_rechts = ['y' num2str(n) '_rechts'];
% % 
%  xn_min = eval(xn_min);
%  xn_max = eval(xn_max);
% % % yn_links = eval(yn_links);
% % % yn_rechts = eval(yn_rechts);
% % 
% % %lim_u = max(xn_min,yn_links);
% % %lim_o = min(xn_max,yn_rechts);
%  lim_u = xn_min;
%  lim_o = xn_max;
%  x = x(lim_u:lim_o);
%  y = y(lim_u:lim_o);
% 
% x_roh = x;
% y_roh = y;
% 
% daten{1,1} = x_roh;
% daten{1,2} = y_roh;

    %% Gl�tten der Messwerte
    switch fitting
        case 1 % close fit
            p = 1/(1 + h^3/60);
            
        case 2 % normal fit
            p = 1/(1 + h^3/6);
            
        case 3 % some satisfactory smoothing
            p = 1/(1 + h^3/0.6);
    end%switch
            
            
    glatt = csaps(x,y,p);       %Gl�tten der Werte.  0<=p<=1...   normal fit: p = 1/(1 + h^3/6);  close fit:  p = 1(1 + h^3/60); and some satisfactory smoothing with p = 1/(1 + h^3/0.6)...   
    
    y = glatt.coefs(:,4);       % y wird mit den gegl�tteten Werten �berschrieben (ein Eintrag geht "verloren"!)
    x = x(1:(length(x)-1));     % Anpassen der L�nge von x auf y
    
    %% Grenzwerte finden 

    finish = round((length(x)/2-1),0);
    gradient = nan(length(x),range_grad);
    gradient_mittel = nan(finish,1);
    
            
        
    
        for i=1:range_grad
            ii           = length(x)-i+1; 
            gradient(i)  = (y((i+range_grad))-y(i))   / (x(i+range_grad)-x(i));
            gradient(ii) = (y((ii))-y(ii-range_grad)) / (x(ii)-x(ii-range_grad));
        end%for
        
        for i=(1*range_grad+1):1:(finish)
            
            gradient(i)  = (y((i+range_grad))-y(i)) / (x(i+range_grad)-x(i));

            if abs(gradient(i)-gradient(i-range_grad)) >= delta_rel*gradient(i-range_grad)
                pos_1 = (i+range_grad/2);

            break%for  
            end%if
        end%for

        for ii=(length(x)-(range_grad+1)):-1:(finish)

            gradient(ii)  = (y((ii))-y(ii-range_grad)) / (x(ii)-x(ii-range_grad));

            if abs(gradient(ii)-gradient(ii+range_grad)) >= delta_rel*abs(gradient(ii+range_grad))
                pos_2 = (ii-range_grad/2);

            break%for
            end%if
        end%for


        if isnan(pos_1)
            pos_1 = 1+range_grad/1+0;
        end    
        if isnan(pos_2)
            pos_2 = length(x)-range_grad*1;
        end%if

        positionen(1,n) = pos_1;
        positionen(2,n) = pos_2;
%% manuelle Eingabe der Grenzwerte (falls ben�tigt)
    
%     if n == 3
%         pos_1 = 800;
%         pos_2 = 13000;
%     end%if
% 
%     if n == 2
%         pos_1 = 751-250;
%         pos_2 = 9248;
%    end%if
%     
%    if n == 1
%         pos_1 = 751-250;
%         pos_2 = 9248-7000;
%    end%if
    
    
    
    %% Eckenkorrektur
    

    
     fin_1 = length(x (1:pos_1));
     fin_2 = length(x (pos_2:end));
     
     fin = min([fin_1,fin_2])-5;
 
     glatt_links = csaps( x ((pos_1-fin):(pos_1+eck)) , y ((pos_1-fin):(pos_1+eck)),p);
     glatt_rechts = csaps( x ((pos_2-eck):(pos_2+fin)) , y((pos_2-eck):(pos_2+fin)),p);
     
     y(pos_1-fin:pos_1+eck-2) = glatt_links.coefs(1:end-1,4);
     y(pos_2-eck+2:pos_2+fin) = glatt_rechts.coefs(2:end,4);
     
     y(pos_1+eck-1) = (y(pos_1+eck-1)+glatt_links.coefs(end,4))/2;
     y(pos_2-eck) = (y(pos_2-eck)+glatt_rechts.coefs(1,4))/2;
     
  
    %%
    

    x_1 = x(pos_1);
    y_1 = y(pos_1);

    x_2 = x(pos_2);
    y_2 = y(pos_2);

  
    % plotten der Messwerte zur �berpr�fung der Grenzwerte
    figure(n);
    plot(x,y);
    hold on
    plot(x_1,y_1, 'x');
    hold on
    plot(x_2,y_2, 'x');
    hold on
    plot(daten{1,1},daten{1,2});      

[Firas Guechchati]

x and y are double arrays

i wanted to use the triangle threshold method of image analyst,but it didnt work is there a way to plot it and at the same time or after plotting to get the section that i want

[Firas Guechchati]

@ameer hamza sorry the turning point would be where its more curved and as i showed on the outline that would be the two red points

[Ameer Hamza]

more curved is a very subjective term. It needed to be defined in a mathematically precise wat.

[Firas Guechchati]

i have an idea

what if i determine the max slope and the min slope,and these are my values that i want