2-D Plot with two y-axis and only ONE funktion

hello,

what i have:

I have a funktion (temperature-profil) which gives me the temperature related to the depth of the ocean.

y-axis: the depth of the ocean
x-axis : temperature

my database: my ocean is 100 km deep and i know the temperature at almost every km, so the pressure

my problem: I would like to add a second y-axis which shows me the pressure at every km. I tried it with plotyy, but i dont want that second graph, i just want the axis. so i tried just to add an axis, that worked. But i dont know how to give there my database instead of "ylim" , i would like that its related to the km of the ocean

my code:

version 1

    daten=xlsread('T_profile.xls','sheet4');
    figure;
    [ax,h1,h2] = plotyy(daten(1:49,2), daten(1:49,1), daten(1:49,1), daten(1:49,4) ); %Temperaturprofil
    title('Rp: 1 Ts: 280');
    set(ax(1),'YDir','reverse');
    set(ax(2),'YDir','reverse');
    xlabel('Temperatur in K');
    ylabel('Ozeantiefe in km');

version 2

    daten=xlsread('T_profile.xls','sheet4');  
    figure;
    plot(daten(1:49,2), daten(1:49,1)); %Temperaturprofil
    title('Rp: 1 Ts: 280');
    set(gca,'YDir','reverse');
    xlabel('Temperatur in K');
    ylabel('Ozeantiefe in km');
    set(gca,'Box','off'); 
    axesPosition = get(gca,'Position');          %# Get the current axes position
    hNewAxes = axes('Position',axesPosition,...  %# Place a new axes on top...
                    'Color','none',...           %#   ... with no background color
                    'YLim',[0 10],...            %#   ... and a different scale
                    'YAxisLocation','right',...  %#   ... located on the right
                    'XTick',[],...               %#   ... with no x tick marks
                    'Box','off');                %#   ... and no surrounding box
    ylabel(hNewAxes,'scale 2');  %# Add a label to the right y axis

i uploaded a picture how it looks right now (ignore the red line) and i would like to have an y axis on the right with the related pressure (the code for that is:

 figure;
    plot(daten(1:49,2), daten(1:49,1)); %Temperaturprofil
    title('Rp: 2 Ts: 280');
    set(gca,'YDir','reverse');
    xlabel('Temperatur in K');
    ylabel('Ozeantiefe in km');

    hold on;
    plot(daten(1:49,3), daten(1:49,1),'r');%Schmelztemperatur
    set(gca,'YDir','reverse');
    legend({'Temperaturprofil','Schmelztemperatur'},'Location','southwest')
)

thank you for your help!!

Answer 1

[Christiaan]

Hello,

If I understand you correctly, you would like to plot one figure where at the y axis is the depth, and at the x axis the temperature and the pressure. (also with two axes)

In this example I have made a code for you, that illustrates how this can be achieved.

clc;clear all;close all;

depth   =   linspace(-120000,0,120001);
temp    =   280-60*depth/120000;
pres    =   1-depth/10;

x1 = temp;
y1 = depth;
x2 = pres;
y2 = depth;

figure
line(x1,y1/1000,'Color','r');
xlabel('temperature [K]');
ylabel('depth [km]');
legend('temperature [K]','Location','northeast')
set(gca,'xgrid','on','ygrid','on')

ax1 = gca; % current axes
ax1.XColor = 'r';
ax1.YColor = 'k';

ax1_pos = ax1.Position; % position of first axes
ax2 = axes('Position',ax1_pos,...
    'XAxisLocation','top',...
    'YAxisLocation','left',...
    'Color','none','XColor','b');

line(x2,y2/1000,'Parent',ax2,'Color','b')
xlabel('Pressure [Bar]');
ylabel('depth [km]');

set(gca,'xgrid','on','ygrid','on')

legend('pressure (Bar)','Location','northwest')

Good Luck! Christiaan

[Mademoiselle_Opossum]

Hello Christian!

Thank you very much that you took the time! But I think you understood it wrong - maybe I havent write it clear enouth!

I would like the graph like it is in my attached file, but with the correspondet pressure on the right hand side.

There wouldnt be a second funktion or something - I would like a plot, that when i look at it I see : "oh ok, at 50 km the tempereture is at 295 K and what pressure i have at 50 km?" (that would be on the right hand side - where is nothing right now) is that possible? (so there are to diffrent y-ranges but the second (pressure) would do nothing - just give me the information what pressure i have at a possible depth (the depth is right now on the left hend side y-axis)

[Christiaan]

Hello !

You can use the MATLAB function plotyy to plot one x variable (i.e. temperature) vs. two y variables (i.e. depth & pressure). A small example is shown below:

clc;clear all; close all;

depth   =   linspace(-120000,0,120001);
temp    =   280-60*depth/120000;
pres    =   1-depth/10;

%temp_depth_pressure = [depth;temp;pres];

[hAx,hLine1,hLine2] = plotyy(temp,depth/1000,temp,pres);grid on;
title('temperature vs. depth & pressure')
xlabel('temperature (K)')

ylabel(hAx(1),'Depth (km)') % left y-axis
ylabel(hAx(2),'Pressure (bar)') % right y-axis

Good Luck! Christiaan