how to solve "error using griddata" in order to plot an efficiency map

hello i'm trying to plot an efficiency map of a motor using vectors of torque and speed and their corresponding efficiencies obtained from some measurments is it possible to plot efficiency map with this?

ps: the vectors are loaded from an excel file

I'm trying to plot somthing similar with this script

x0=min(speedRPM);  x1=max(speedRPM); nx=100;
y0=min(TorqueNm);  y1=max(TorqueNm); ny=100;
x=linspace(x0,x1,nx);
y=linspace(y0,y1,ny);
[X,Y]=meshgrid(x,y);
Z=griddata(speedRPM,TorqueNm,EffeciencyPer,X,Y);
contourf(X,Y,Z);
colorbar;

But when i run it it shows me this error

>> efficiencymap

Error using griddata (line 110)

X and Y must be same length as Z or the lengths of X and Y must match the size of Z.

could you help ?

[DGM]

The error message says there's a problem with the size or orientation of arrays, but nobody can know how your arrays are sized or oriented unless you tell us.

% test arrays have corresponding size
speedRPM = 1:200; % 1x200
TorqueNm = 1:100; % 1x100
EffeciencyPer = speedRPM + TorqueNm'; % 100x200

% all this code runs just fine with test arrays
x0=min(speedRPM);  x1=max(speedRPM); nx=100;
y0=min(TorqueNm);  y1=max(TorqueNm); ny=100;
x=linspace(x0,x1,nx);
y=linspace(y0,y1,ny);
[X,Y]=meshgrid(x,y);
Z=griddata(speedRPM,TorqueNm,EffeciencyPer,X,Y);
contourf(X,Y,Z);
colorbar;

[wafa mezzi]

HI i'm atteching the excel files here could you check them please ?

Answer 1

[Walter Roberson]

% test arrays have corresponding size
speedRPM = 1:200; % 1x200
TorqueNm = 1:100; % 1x100
EffeciencyPer = speedRPM + TorqueNm'; % 100x200
% all this code runs just fine with test arrays
x0=min(speedRPM);  x1=max(speedRPM); nx=100;
y0=min(TorqueNm);  y1=max(TorqueNm); ny=100;
x=linspace(x0,x1,nx);
y=linspace(y0,y1,ny);
[X,Y] = meshgrid(x,y);
F = scatteredInterpolant(speedRPM, TorqueNm, EfficiencyPer);
Z = F(X, Y);

contourf(X, Y, Z.');   %probably Z.', perhaps Z instead

[DGM]

To be honest, I don't know what to make of these curves. (Z.' on left)

[Walter Roberson]

speedRPM = readmatrix('https://www.mathworks.com/matlabcentral/answers/uploaded_files/615045/speedRPM.xlsx');
TorqueNm = readmatrix('https://www.mathworks.com/matlabcentral/answers/uploaded_files/615040/TorqueNm.xlsx');
EffeciencyPer = readmatrix('https://www.mathworks.com/matlabcentral/answers/uploaded_files/615035/EffeciencyPer.xlsx');

x0 = min(speedRPM);  x1=max(speedRPM); nx=100;
y0 = min(TorqueNm);  y1=max(TorqueNm); ny=101;
x = linspace(x0,x1,nx);
y = linspace(y0,y1,ny);
[X,Y] = meshgrid(x,y);

F = scatteredInterpolant(speedRPM, TorqueNm, EffeciencyPer);
Z = F(X, Y);
contourf(X, Y, Z);   %probably Z.', perhaps Z instead

figure();
plot3(speedRPM, TorqueNm, EffeciencyPer)
xlabel('speed')
ylabel('torque')
zlabel('efficiency')

The data is not really representative enough to establish a contour.

[wafa mezzi]

thank you so much !

but could you explain how you solved this issue please just in case i get new arrays for new measurments how to determine their sizes in order to avoid this error repeating

[Walter Roberson]

You do not need to determine their size. nx and ny are arbitrary; the higher they are, the smoother the plot will be, but the longer it will take to compute.