MATLAB: Lines Not Connecting In graph

external filesgraphsloops

I have the following code but i am not able to get the graph to join the points together:
a few of the files are attached.
for i = 1:62
    T=(i-1)*30;
   
    FTA=load(['XYpoints_timeFromDeparture_',num2str(T),'.txt']);
    FTA = fopen(['XYpoints_timeFromDeparture_',num2str(T),'.txt']);
  
    Xa=fscanf(FTA,'%f %*f %*f %*f',Inf);
    fclose(FTA);
    
    FTA = fopen(['XYpoints_timeFromDeparture_',num2str(T),'.txt']);
    Ya=fscanf(FTA,'%*f %f %*f %*f',Inf);
    fclose(FTA);
    FTA = fopen(['XYpoints_timeFromDeparture_',num2str(T),'.txt']);
    Xb=fscanf(FTA,'%*f %*f %f %*f',Inf);
    fclose(FTA);
    FTA = fopen(['XYpoints_timeFromDeparture_',num2str(T),'.txt']);
    Yb=fscanf(FTA,'%*f %*f %*f %f',Inf);
    fclose(FTA);
    
    Op=([Xa]-[Xb]);
    Ad=([Ya]-[Yb]);
    Angle = atand(Op./Ad);  
    A = (i*30);
    TTxt =sprintf('For Time At %.0f: ', A);
    disp(TTxt)
   
    AvgAngle = mean(Angle)*-1;
    
    AvgAngleDISP = sprintf("The Average Angle is: %.3f°",AvgAngle);
    disp(AvgAngleDISP)
    
    V_MPH = ((tand(AvgAngle)*10*cosd(30)-10*sind(30))*2.237);
   
    VT = sprintf("The Velocity is: %.3fmph",V_MPH);
    disp(VT)
    
    hold on
    figure(3);
    x = A/60;
    y = V_MPH;
    
    plot(x,y,'k-x')
    xlabel('Time (Minutes)')
    ylabel('Velocity (MPH)')
end

Best Answer

As you can see, x and y are 1x1, which indicates that for each file, you are just plotting a single point. If you want to draw a line, then you will need to move the plot() statement out of the for-loop and store the values of x and y in an array. Try the following code.
for i = 1:62
    T=(i-1)*30;
   
    FTA=load(['XYpoints_timeFromDeparture_',num2str(T),'.txt']);
    FTA = fopen(['XYpoints_timeFromDeparture_',num2str(T),'.txt']);
  
    Xa=fscanf(FTA,'%f %*f %*f %*f',Inf);
    fclose(FTA);
    
    FTA = fopen(['XYpoints_timeFromDeparture_',num2str(T),'.txt']);
    Ya=fscanf(FTA,'%*f %f %*f %*f',Inf);
    fclose(FTA);
    FTA = fopen(['XYpoints_timeFromDeparture_',num2str(T),'.txt']);
    Xb=fscanf(FTA,'%*f %*f %f %*f',Inf);
    fclose(FTA);
    FTA = fopen(['XYpoints_timeFromDeparture_',num2str(T),'.txt']);
    Yb=fscanf(FTA,'%*f %*f %*f %f',Inf);
    fclose(FTA);
    
    Op=([Xa]-[Xb]);
    Ad=([Ya]-[Yb]);
    Angle = atand(Op./Ad);  
    A = (i*30);
    TTxt =sprintf('For Time At %.0f: ', A);
    disp(TTxt)
   
    AvgAngle = mean(Angle)*-1;
    
    AvgAngleDISP = sprintf("The Average Angle is: %.3f°",AvgAngle);
    disp(AvgAngleDISP)
    
    V_MPH = ((tand(AvgAngle)*10*cosd(30)-10*sind(30))*2.237);
   
    VT = sprintf("The Velocity is: %.3fmph",V_MPH);
    disp(VT)
    
    x(i) = A/60;
    y(i) = V_MPH;
end
figure;
plot(x,y,'k-x')
xlabel('Time (Minutes)')
ylabel('Velocity (MPH)')
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