How to convert the graph below in to heatmap?

I have the graph below. It was plotted using the code below:

%% matrix (:,4) is the weight of the corresponding matrix(:1:2) branches. Ignore matrix(:,3).               
                nodes = [];
                for i = 1:1:size(matrix,1)
                   if matrix(i,4) <= 10000
                       nodes = [nodes,matrix(i,1:2)];
                   end    
                end
                nodes_cellarray{:} = nodes;
                set(figure, 'Visible', 'on');
                Graph = graph(matrix(:,1),matrix(:,2));
                plot_array = plot(Graph, 'layout', 'auto');
%               plot_array.EdgeColor = 'red';
                highlight(plot_array,nodes_cellarray{:},'EdgeColor','r','NodeColor','r','LineWidth',4);
                

I have attached the matrix23.xlsx file that has the matrix 'matrix' used above.

[Jay Vaidya]

Can anyone suggest a solution? I was trying to convert it into the adjacency matrix and then make a heatmap from that. But that was giving me some weird adjacency matrix with many 0 values and hence a wrong heatmap as well. Since I am new to MATLAB, I would appreciate it if you have any ideas. Thank you.

[Deepak Kumar]

Refer the below MATLAB documentation link to get more insight about "heatmap" function

https://in.mathworks.com/help/matlab/ref/heatmap.html

Answer 1

[Walter Roberson]

t = readtable('matrix23.xlsx');
mask = t{:,3} == 65535 | t{:,4} == 65535;
t(mask,:) = [];

figure(1)
h = heatmap(t, 'Var1', 'Var2', 'ColorVariable', 'Var3');
h.GridVisible = false;

figure(2)
subplot(1,3,1);
scatter(t{:,1}, t{:,2}, [], t{:,3});
title('scatter');

A = sparse(t{:,1}, t{:,2}, t{:,3}, 2600, 2600);
subplot(1,3,2)
spy(A);
title('normal spy');
subplot(1,3,3)
r = symrcm(A);
spy(A(r,r));
title('spy symrcm');

[Jay Vaidya]

I used this, and put Var1 = x1 and Var2 = x52, what should I put in the ColorVariable and Var3? This is the error that is giving otherwise.

[Walter Roberson]

Add the option

'readvariablenames', false

To the readtable call. Then the four variables will be Var1 Var2 Var3 Var4. You can reassign the variable names by changing

t.Properties.VariableNames

I assumed that the first column correeponds to x values and the second corresponds to y values and the third corresponds to z values with the fourth being unknown purpose.

You got the x1 and x52 variables because readtable() did not notice that the first row was purely numeric and assumed that the first row was a header line giving the variable names. In sufficiently new versions of MATLAB, readtable() does recognize that the first line is completely numeric and does not create variable names from the data, equivalent to having specified 'readvariablenames', false

[Jay Vaidya]

Thank you. The code worked fine after adding 'ReadVariableNames', false. But I don't know what to make out of the results. The heatmap I need is nothing but an image like a color map that I was asking in this thread. I have added the extra explanation there as well. https://www.mathworks.com/matlabcentral/answers/498629-how-to-color-a-graph-that-is-shown-below?s_tid=mlc_ans_email_view#comment_782675 Thank you.

Answer 2

[Jay Vaidya]

I wrote a for loop to convert the graph into a matrix that represents the weights of the edges.

See below (left: heatmap and the right one is the older graph)

clc
clear all
close all

% A= data imported
% A = xlsread('data.xlsx');

A = xlsread('matrix22.xlsx');

A(isnan(A)) = inf;
matrix = A;

nodes_x = 51;
nodes_y = nodes_x;

% A = A(:,:);
[r_A,c_A]= size(A); %getting row and column dimension of A

%max_A=max(A,[],2).'; %column vector of maximum node number to get max node number
%max_A(3)= max_A(4)= 0; %3,4 column is garbage
%max_A=max(max_A); %gives you the maximum node number

%dim_res= sqrt(max_A); %getting  dimension of matrix C
dim_res=nodes_x;
B = zeros(r_A,4); % B will be the direction matrix ie B[;,1]= row number of each point B[;,2]= column number of each point B[;,3]= difference number of each point B[;,4]= weight value of each point   

for i=1:r_A
    B(i,1)=2*floor(A(i,1)/dim_res)+1; %row of each point cells are left to fill in edges 
    B(i,2)=2*mod(A(i,1),dim_res)+1; %column of each point cells are left to fill in edges
    B(i,3)=A(i,2)-A(i,1); % direction vector of each point
    B(i,4)=A(i,4);%assuming column 4 is the required column
end

C=zeros(101,99);
for i=1:r_A
    if B(i,3)==1
        C(B(i,1),B(i,2)+1)=B(i,4);% if the node is the next node, it should put the value in the adjacent cell in the same row
    elseif B(i,3) == nodes_x
        C(B(i,1)+1,B(i,2))=B(i,4);
    end
end

%%
C(1,:) = [];
C(size(C,1)-1:size(C,1),:) = [];
C(:,1:2) = [];

%5 heatmap
h  = heatmap(C,'Colormap', winter);
h.Colormap = parula;
h.ColorScaling = 'scaled';
h.ColorLimits = [0 10000];
h.GridVisible = 'off';
h.MissingDataColor = [0.8 0.8 0.8];
h.Title = 'Phase matrixs';
h.XLabel = '';
h.YLabel = '';
% caxis(h,[0 1]);

%% graph plot
% 
nodes = [];
                for i = 1:1:size(matrix,1)
                   if matrix(i,4) <= 10000
                       nodes = [nodes,matrix(i,1:2)];
                   end    
                end
                nodes_cellarray{:} = nodes;
                set(figure, 'Visible', 'on');
                Graph = graph(matrix(:,1),matrix(:,2));
                plot_array = plot(Graph, 'layout', 'auto');
                highlight(plot_array,nodes_cellarray{:},'EdgeColor','r','NodeColor','r','LineWidth',4);
%