Find min value of each column of 2D lattice and plot

Question

James Kosiol 2023-3-16

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1929615-find-min-value-of-each-column-of-2d-lattice-and-plot

评论： Dyuman Joshi 2023-3-16

Hey everyone,

I am looking to create a 10 x 10 lattice with randomly assigned values for each coordinate then find the minimum value of each column of the lattice and finally plotting the lattice with the lowest number of each column coloured to show visually.

so far all I have is this:

clc
clear
P = randi(10, 10, 10);
for i = 1:1:10
    [row(i), column(i)] = min(P(:,i));
    [x,y] = meshgrid(1:10,1:10);
    xlim([1,10])
    ylim([0,10])
    axis equal
    x_l = reshape(x,[],1);
    y_l = reshape(y,[],1);
    figure; scatter(x_l,y_l)
    hold on
    scatter(x_l(row(i)),y_l(column(i)), 'R', 'filled')
end

but as you can tell, it doesn't work.

I hope this makes sense!

Thanks

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Dyuman Joshi 2023-3-16

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1929615-find-min-value-of-each-column-of-2d-lattice-and-plot#answer_1194135

编辑：Dyuman Joshi 2023-3-16

在 MATLAB Online 中打开

It is better to define variables not varying with the loop index, out of the loop. Moreso, as you are using figure().

It's not clear to me, if you want to color the minimum value or the index of the minimum value in each column. The code below corresponds to coloring the minimum value of each column.

Edit - Clarification below in the comments to color the index (first occurance) of the minimum value.

n=10;

P = randi(n, n, n)

P = 10×10

4 4 5 10 6 1 8 1 9 5 9 10 6 7 3 10 10 1 4 1 5 10 4 7 6 10 3 7 1 10 1 7 4 1 8 3 3 8 8 10 6 8 1 1 2 1 6 1 10 8 4 1 7 9 10 6 6 9 8 7 7 5 6 4 5 2 4 7 1 4 2 10 9 2 1 6 6 1 7 3 7 2 4 3 4 4 10 1 8 5 10 5 6 10 7 10 2 1 7 5

[x,y] = meshgrid(1:n);

x_l = reshape(x,[],1);

y_l = reshape(y,[],1);

figure; scatter(x_l,y_l)

xlim([1,n])

ylim([0,n])

axis equal

xticks(1:n)

for i = 1:n

[~,idx] = min(P(:,i));

hold on

scatter(i,n+1-idx, 'R', 'filled')

end

You can achieve the result without the loop as well (As Rik mentioned below)

figure

scatter(x_l,y_l)

xlim([1,n])

ylim([0,n])

axis equal

xticks(1:n)

hold on

%directly obtain the indices

[~,ctr]=min(P)

ctr = 1×10

4 6 5 4 8 1 10 1 3 2

scatter(1:n,n+1-ctr,'G','filled')

5 个评论
显示 3更早的评论隐藏 3更早的评论

James Kosiol 2023-3-16

Excellent work! exactly what I was after. Many thanks.

Dyuman Joshi 2023-3-16

You are Welcome!

请先登录，再进行评论。

Answer 2

Mathieu NOE 2023-3-16

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1929615-find-min-value-of-each-column-of-2d-lattice-and-plot#answer_1194155

在 MATLAB Online 中打开

not sure if I understood really what you want to do

maybe this ?

clc
clear
N = 10;
[x,y] = meshgrid(1:N,1:N);
xlim([1,N])
ylim([0,N])
axis equal
x_l = reshape(x,[],1);
y_l = reshape(y,[],1);
figure(1); scatter(x_l,y_l)
for i = 1:N
    P = randi(N, N);
    [m, ind] = min(P,[],'all','linear');
    [r,c] = ind2sub(size(P),ind);
    hold on
    pause(0.4)
    scatter(r,c, 'R', 'filled')
end