Put arrow and its value in a plot

Hello there,

I want to show a row and its value in a plot. Please find attached the data. My intended plot should be like this:

load('data_ask_MLD')
figure;
plot(PTn,z);
set(gca,'ydir','reverse')

Thank you!

Answer 1

[Mathieu NOE]

hello

this is a simple example , based on the fex submission :

arrow - File Exchange - MATLAB Central

load('data_ask_MLD')
figure;
plot(PTn,z);
set(gca,'ydir','reverse')

% define which row for display
r = 100;
x = PTn(r);
y = z(r);
al = 1; % arrow length (in x direction)

arrow([x-al,y],[x,y]); % Fex : https://fr.mathworks.com/matlabcentral/fileexchange/278-arrow
text(x-4*al, y, ['MLD = ' sprintf('%0.5g', y)])

Answer 2

[Pramil]

Hi Adi,

You can use the "text" function available in MATLAB to create plot shown in your image. Here is the documentation link for the same for your reference:

https://www.mathworks.com/help/releases/R2022a/matlab/ref/text.html

And here is the updated code:

load('data_ask_MLD')
figure;
plot(PTn,z);
set(gca,'ydir','reverse')

[~, idx] = min(abs(z - MLD));
x_value = PTn(idx);
text(x_value, MLD, 'MLD = 24.7\rightarrow ','HorizontalAlignment','right');

Answer 3

[Star Strider]

The 'textarrow' coordinates have to adapt to the data and then correct for the reversed y-axis direction.

Try this —

load('data_ask_MLD')
figure;
plot(PTn,z);
set(gca,'ydir','reverse')
xlabel('PTn')
ylabel('z')
xapf = @(x,pos,xl) pos(3)*(x-min(xl))/diff(xl)+pos(1);                % 'x' Annotation Position Function
yapf = @(y,pos,yl) pos(4)*(y-min(yl))/diff(yl)+pos(2);                % 'y' Annotation Position Function
xl = xlim;
yl = ylim;
pos = gca().Position;
MLDval = 24.7;
PTnval = interp1(z, PTn, MLDval)                                      % X-Coordinate Value (Derived From Data) Right End Of The Arrow

PTnval = 27.2905

zval = interp1(PTn, z, PTnval)                                        % Y-Coordinate Value (Derived From Data)

zval = 24.7000

annotation('textarrow', xapf(PTnval+[-2.25 -0.25],pos,xl), 1-yapf([1 1]*zval,pos,yl), String=("MLD = "+MLDval)+" m ", HeadStyle='vback3')

EDIT — (23 Nov 2024 at 12:45)

Changed 'HeadStyle'.

.