MATLAB Answers

How to convert the graph below in to heatmap?

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Jay Vaidya
Jay Vaidya on 31 Dec 2019
Answered: Jay Vaidya on 5 Jan 2020
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.
figure23.jpg
  2 Comments
Deepak Kumar
Deepak Kumar on 3 Jan 2020
Refer the below MATLAB documentation link to get more insight about "heatmap" function

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Accepted Answer

Walter Roberson
Walter Roberson on 3 Jan 2020
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');
  3 Comments
Jay Vaidya
Jay Vaidya on 3 Jan 2020
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.

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More Answers (1)

Jay Vaidya
Jay Vaidya on 5 Jan 2020
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);
%

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