how to plot a contour plot with excel data??

I have to plot a contour plot for excel data. I have two variables x and y , and the individual variables contain 50 data ponts

i defined the data for the variables x and y

contour(x,y) ...i have written code but it is showing the error .can someone tell me where i did mistake ?

[VBBV]

What is the error? Attach your data file if possible

[sunitha]

Error is Z should be atleast 2*2 matrix

Ks=xlsread('contour gr.xlsx','A:A');

N=xlsread('contour gr.xlsx','B:B');

contour(Ks, N )

This is the code that i have written

[VBBV]

K = readmatrix('contour gr.xlsx');
F = K(:,1)+ 2*K(:,2); % your example matrix which specifies function in terms of X and Y
Z =  repmat(F,1,49); % your example Z matrix 
contour(K(:,1),K(:,2),Z)  % your contour plot 

Try above

[sunitha]

i have already calculated the output values and imported it in the excel .i have non linear equations from that i have calculated the variables

X=((bt*Qo*(1+R)*Xo)+(Y*a*V(i)*1000*J*bs))./(bt*((Qo*(1+R))-((V(i)*Y*k*N)/((Kn(i)*1000)+N))+(V(i)*kd)));

eqn1=(Qo*(1+R)*(No-N))-(V(i)*((a*J*1000)+((X*k*N)/((Kn(i)*1000)+N))));

eqn2=(sqrt((Lstar(i)^1.76)+(5.2*(Nstar-Nstar_min))-(Lstar(i)^0.88))/2.6)==jstar^0.88;

soln(i)=vpasolve([eqn1,eqn2],[N,J]);

i have these equations , now i varied the Kn parameter ,has 49 inputs corresponding to that i have calculated N, J variables.

now how i can plot contours for this non linear equation

??

[sunitha]

should i vary the parameters two at a time and corresponding to that i have to plot this contours ??

Answer 1

[LO]

from the folder containing your excel file run

the error about Z may be related to the fact that contour is waiting for a missing variable. But a turnaround is to give to the function an array directly (2D in this case).

Please edit the path to your file (remove the square brackets and put your file location).

%% Import the data
[~, ~, raw] = xlsread('[path to your file here]\contour gr.xlsx','Sheet1');
raw = raw(2:end,:);
%% Create output variable
data = reshape([raw{:}],size(raw));
%% Create table
contourgr = table;
%% Allocate imported array to column variable names
contourgr.ksmgcm3 = data(:,1);
contourgr.SmgL = data(:,2);
%% Clear temporary variables
clearvars data raw;

contour(table2array(contourgr)); 

Answer 2

[Star Strider]

I cannot see how to do a contour plot of two vectors that do not represent gridded data, since that does not make sense.

However one option could be:

D = readmatrix('contour gr.xlsx');
x = D(:,1);
y = D(:,2);

figure
contourf(x*y.')

.