How to graph a patch that follows a line?

I'm trying to export my figure without background using the attached code. As you may see, I'm using a patch function to cover a very small area, I want to use a smaller patch that follows the red line (see line 91). Any ideas about how to do it?

The idea is tha my patch does follow only YL = ylim, but it follows the same tendency of red line line, and with a small thikness, maybe 1 unit or something like that.

clear;clc
A=[     -12.236     1417.575        3.629         0.2756         6.495
      -4.239     1416.849        1.700         0.5884        10.726
       3.764     1415.702        8.779         0.1139        18.386
      11.765     1414.657       19.057         0.0525         0.357
      19.767     1413.565       23.490         0.0426         1.128
      27.773     1412.141        6.767         0.1478         2.323
      35.778     1410.820        6.459         0.1548         0.816
      51.771     1409.493       13.318         0.0751         0.005
      67.743     1409.605        2.851         0.3507        19.542
      75.736     1409.051        4.407         0.2269         0.005
      83.685     1409.926        3.746         0.2670         6.940
      91.646     1410.386        6.075         0.1646        21.096
      99.640     1409.575        8.106         0.1234         5.910
     107.620     1409.047        7.330         0.1364        12.873
     123.623     1407.111       19.248         0.0520         4.626
     131.608     1406.459       19.462         0.0514         4.579
     155.748     1398.703       10.460         0.0956         4.238
     163.770     1396.466       10.020         0.0998         1.405
     171.768     1395.721        9.112         0.1097         0.925
     179.769     1394.702       10.088         0.0991         0.347
     187.762     1394.345       38.594         0.0259         1.539
     195.760     1393.510       33.104         0.0302         2.456
     203.770     1391.803       22.253         0.0449         4.501
     211.773     1390.669       18.235         0.0548         4.996
      -4.714     1412.787       11.198         0.0893        11.495
       3.294     1411.678       35.189         0.0284        19.953
      11.297     1410.652        1.944         0.5143         9.786
      19.302     1409.587       22.708         0.0440         2.563
      35.329     1406.982        2.800         0.3571        51.108
      43.336     1405.852        8.600         0.1163         1.075
      51.311     1405.562       24.378         0.0410         3.769
      59.264     1405.778        3.745         0.2670         0.405
      67.242     1405.315       27.800         0.0360        23.019
      75.225     1404.677       32.562         0.0307         0.161
      91.021     1405.037        2.033         0.4919        33.104
     106.966     1403.454        0.401           2.49        13.230
     114.978     1402.459        0.414           2.42        13.897
     130.941     1400.754        0.532           1.88         6.411
     138.998     1399.510        3.936         0.2540         2.818
     147.118     1397.609        6.552         0.1526         1.683
     155.255     1394.488       43.711         0.0229         4.206
     163.310     1392.528       36.826         0.0272         1.930
     171.305     1391.754       25.253         0.0396         1.071
     179.307     1390.750        9.461         0.1057         0.656
     187.288     1390.294        7.927         0.1261         1.636
     195.285     1389.441       26.961         0.0371         2.424
     203.310     1387.864       27.695         0.0361         4.414
     211.316     1386.764       15.058         0.0664         5.489];

X = A(:,1);
Y = A(:,2);
Z = A(:,3);

[xq,yq]=meshgrid(linspace(min(X),max(X),100),linspace(min(Y),max(Y),100));
zq=griddata(X,Y,Z,xq(:),yq(:),'cubic'); %cubic for smoother results

figure()
[c,h]=contourf(xq,yq,reshape(zq,100,100));
colormap(jet(5)) 
axis equal
hold on
cota=[     -12.236     1417.575        3.629         0.2756         6.495
      -4.239     1416.849        1.700         0.5884        10.726
       3.764     1415.702        8.779         0.1139        18.386
      11.765     1414.657       19.057         0.0525         0.357
      19.767     1413.565       23.490         0.0426         1.128
      27.773     1412.141        6.767         0.1478         2.323
      35.778     1410.820        6.459         0.1548         0.816
      51.771     1409.493       13.318         0.0751         0.005
      67.743     1409.605        2.851         0.3507        19.542
      75.736     1409.051        4.407         0.2269         0.005
      83.685     1409.926        3.746         0.2670         6.940
      91.646     1410.386        6.075         0.1646        21.096
      99.640     1409.575        8.106         0.1234         5.910
     107.620     1409.047        7.330         0.1364        12.873
     123.623     1407.111       19.248         0.0520         4.626
     131.608     1406.459       19.462         0.0514         4.579
     155.748     1398.703       10.460         0.0956         4.238
     163.770     1396.466       10.020         0.0998         1.405
     171.768     1395.721        9.112         0.1097         0.925
     179.769     1394.702       10.088         0.0991         0.347
     187.762     1394.345       38.594         0.0259         1.539
     195.760     1393.510       33.104         0.0302         2.456
     203.770     1391.803       22.253         0.0449         4.501
     211.773     1390.669       18.235         0.0548         4.996];

plot(cota(:,1),cota(:,2),'r', 'linewidth',2)
YL = ylim;
XL = xlim;
patch([XL, fliplr(cota(:,1)')], [[1 1]*YL(2), fliplr(cota(:,2)')], 'w')
 set(gca,'YTick',[])
 set(gca,'XTick',[])
 set(gca,'XColor', 'none','YColor','none')
 set(gca,'color','none')

[darova]

The question is unclear for me: what are trying to do?

Where is area you trying to cover?

[Philippe Corner]

I updated the question, please copy the code and comment this line "patch(shown in the second picture). I would like to create my patch following the red line and with a small thick.

Thanks for your kind help

[darova]

You want to extract those borders?

[Philippe Corner]

I want to cover the contour plot that appears above the red line, I already did that, as I showed you on the second figure, but what I want is that may patch does not go on that way, I want my patch to be following the upper border you drew in red, but with a small thickness. Please feel trae to ask again if I’m not being clear.. Cheers

Answer 1

[darova]

I found boundary points and moved them down a bit

zq(isnan(zq)) = 1000;           % replace NaN with big number
ix = find(diff(zq(:)) > 500);   % find border indexes
plot(xq(ix),yq(ix)-0.5,'*-r')

Here is what i get

[Philippe Corner]

Hi Darova, that is interesting, you are finding there the uppest limit of the contour plot. My request is to plot the patch until thos limits. Take a look of the complete contour plot without your code and with your code:

I'm not sure if you can see it in the image, but i plotted with your code a line that goes for all the uppest limit of the contour. I want my patch to go until that line, and then I can conver from

plot(cota(:,1),cota(:,2),'r', 'linewidth',2) (my code)

until

plot(xq(ix),yq(ix),'r', 'linewidth',2) (your code, I edited the position to be exaclty at yq(ix), color and line width)

Do you know how could i plot the patch until that line you found? thats the purpose of my question.

Thanks in advance

[darova]

Just concantenate data:

xc = [cota(:,1); flipud(xq(ix))];
yc = [cota(:,2); flipud(yq(ix))];
patch(xc,yc,'w')

Or you can just replace data with NaN in between those lines:

xc = [cota(:,1); flipud(xq(ix))];% just concantenate data
yc = [cota(:,2); flipud(yq(ix))];
in = inpolygon(xq(:),yq(:),xc,yc);
zq(in) = nan;
[c,h] = contourf(xq,yq,zq);

[Philippe Corner]

That's very nice, thanks a lot for the help!