How to plot vertical line when hitting the range?

Hello, I would like to plot four red lines on the figure.

which is on the edge of yellow block.

But, I don't know how to find and plot it.

Attachment is new.mat , included fx, dy, new value.

The blue blocks are all zero and the yellow blocks are all 1.

Thanks.

load new.mat
contourf(fx,dy,new,'linestyle','none');
ylabel('Range Cell','FontSize',15,'Fontname','Times');
xlabel('Radial Velocity (m/s)','FontSize',15,'Fontname','Times')
set(gca,'FontSize',15,'Fontname','Times');

[KSSV]

You can insert lines manually or get the points and plot line...this is one of the option.

[Chen yuru]

I would like to automatically select the yellow region.

Thanks.

Answer 1

[Michael Madelaire]

%% Init
clear all; close all; clc;
cd 'C:\Users\s144117\Desktop\mathworks'
%% Load
load('new')

%% Find boarders
boarders = [];
for i=2:length(new(:,1))-1
    column_before = new(i-1, :);
    column = new(i, :);
    column_after = new(i+1, :);
    flag_before = sum(column_before == 1) > 0;
    flag = sum(column == 1) > 0;
    flag_after = sum(column_after == 1) > 0;
    
    if flag_before == 0 && flag == 1
        boarders = [boarders, i-1];
    elseif flag == 1 && flag_after == 0
        boarders = [boarders, i+1];
    end
end

%% Plot
contourf(fx,dy,new,'linestyle','none');
ylim = get(gca, 'ylim');
hold on;
for i=1:length(boarders)
    plot([1,1]*fx(boarders(i)), ylim, '-', 'Color', 'red')
end
ylabel('Range Cell','FontSize',15,'Fontname','Times');
xlabel('Radial Velocity (m/s)','FontSize',15,'Fontname','Times')
set(gca,'FontSize',15,'Fontname','Times');

[Chen yuru]

Thank you so much!

[Michelle Hirsch]

Here's a small simplification for releases since 18b - you can call xline to draw the vertical lines instead of having to use the clever plot([1,1]* ...) trick.