Plot Heatmap from distinct coordinates and data array of floats

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Elinor Ginzburg
Elinor Ginzburg 2023 年 8 月 6 日
コメント済み: Elinor Ginzburg 2023 年 8 月 13 日
I have an array of floats of size 200x2 where each row is the (x,y) coordinate of a specific point on the heatmap (x=column 1 and y=column 2). I also have an array of floats of size 1x200, which is the data I want to plot, I'll denote it as z. At each row of the coordinates array, the point (x,y) is associated with the value in z at the same index. I want to create a heatmap using this data.
I tried creating a meashgrid from the two columns of the coordinate array, but then I have this problem that z doesn't have the proper dimantions. I believe I need to create an array filed with zeros, and fill it with z values at the adequate coordinates, but than I have the problem that the coordinates are floats.
This is the code I used (which is of course problematic):
coords = load('grid_points.mat').array;
accuracies = load('test_accuracies.mat').array;
xcoord = coords(:,1);
ycoord = coords(:,2);
[X,Y] = meshgrid(xcoord,ycoord);
x = X(:); % Your varaible x should something like this as a column vector
y = Y(:); % Similar for variable y
z = accuracies(:); % Similar for variable z
tbl = table(x,y,z); % Combine them in a table
h = heatmap(tbl,'x','y','ColorVariable','z'); % Generate heat map
patial view of the coordinates array:
patial view of the data array:
I'd appreciate it if anyone could help me understand how can I overcome the fact that the coordinates array has floats in it (I don't want to convert it into integers, I want to keep it as floats if possible).
Thank you very much for your time and attention


KSSV 2023 年 8 月 6 日
It depends on your data whether it is structured or unstructured. Let x, y, z be your column data vectors.
xi = unique(x) ; yi = unique(y) ;
[X,Y] = meshgrid(xi,yi) ;
Z = reshape(z,size(X)) ;
dt = delaunayTriangulation(x,y) ;
tri = dt.ConnectivityList ;
Also have a look on griddata and scatteredInterpolant
  5 件のコメント
KSSV 2023 年 8 月 7 日
load test_accuracies.mat
z = array' ;
load grid_points.mat ;
x = double(array(:,1)) ;
y = double(array(:,2)) ;
pgon = polyshape(x,y) ;
xp = pgon.Vertices(:,1) ;
yp = pgon.Vertices(:,2) ;
F = scatteredInterpolant(x,y,z) ;
zp = F(xp,yp) ;
x1 = x(1:100) ; y1 = y(1:100) ;
x2 = x(101:200) ; y2 = y(101:200) ;
xi = linspace(min(x),max(x),500) ;
yi = linspace(min(y),max(y),500) ;
[X,Y] = meshgrid(xi,yi) ;
idx = inpolygon(X,Y,xp,yp) ;
id = ~isnan(zp) ;
Z = griddata(xp(id),yp(id),zp(id),X,Y) ;
Z(~idx) = NaN ;
shading interp
Elinor Ginzburg
Elinor Ginzburg 2023 年 8 月 13 日
I'm sorry for the late reply. Thank you so much for your help!


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