[Reddit Cross Post] Problems with a contour diagram for a caogulation diagram

I need someting simila to this

But I only can get this

I do not know how to use the program, so all is from AI

Can someone help me?

my code

% Diagrama de coagulación: parte 1

% Log[Al] vs pH con especies de aluminio

clear; clc; close all;

% ==== DATOS ====
pH_contour = [7.9,7.6,7.4,7.1,6.8,6.3,6.8,5.7,4.9,4.4,4.3,4.2,4.2];
log_Al = [-3.3,-3.0,-2.9,-2.6,-2.5,-2.3,-2.2,-2.0,-1.9,-1.9,-1.8,-1.7,-1.7];
Al2SO4_3 = [0.00001,0.00003,0.00004,0.00006,0.00009,0.00013,0.00019,0.00025,0.00031,0.00038,0.00044,0.00050,0.00056];
Z = [6.4,79.5,97.8,98.9,98.1,99.1,99.1,96.6,94.2,93.5,94.9,97.1,92.8];

% ==== MALLA REGULAR PARA INTERPOLACIÓN ====
xi = linspace(min(pH_contour), max(pH_contour), 50);
yi = linspace(min(log_Al), max(log_Al), 50);

[XI, YI] = meshgrid(xi, yi);

ZI = griddata(pH_contour, log_Al, Z, XI, YI, 'cubic');

Warning: Duplicate x-y data points detected: using average values for duplicate points.

% ==== CREAR FIGURA ÚNICA ====
figure('Position', [100, 100, 1200, 800]);
hold on; grid on; box on;

% ==== CONTORNO ====

contourf(XI, YI, ZI, 15, 'LineWidth', 0.5); % sin clabel

colormap(jet);
c = colorbar;
caxis([0 100]);
ylabel(c, 'Porcentaje de Remoción (%)', 'FontSize', 12);
c = colorbar;
caxis([0 100]);
ylabel(c, 'Porcentaje de Remoción (%)', 'FontSize', 12);

% === MOVER LA BARRA DE COLOR A LA DERECHA ===
c.Position(1) = 0.8; % mueve horizontalmente (más a la derecha)
c.Position(3) = 0.02; % ajusta el ancho de la barra

ylabel(c, 'Porcentaje de Remoción (%)', 'FontSize', 12, 'Rotation', 270, ...
    'VerticalAlignment', 'bottom', 'HorizontalAlignment', 'center');

% ==== LÍNEAS DE ESPECIES ====
pH = linspace(0, 14, 200);

y_Al3 = -3.5294 .* pH + 13.176; % Al3+
y_AlOH2 = -2.3077 .* pH + 6.0769; % Al(OH)2+
y_AlOH4 = pH - 12.4; % Al(OH)4-

plot(pH, y_Al3, 'r', 'LineWidth', 1.8, 'DisplayName', 'Al^{3+}');
plot(pH, y_AlOH2, 'b', 'LineWidth', 1.8, 'DisplayName', 'Al(OH)^{2+}');
plot(pH, y_AlOH4, 'g', 'LineWidth', 1.8, 'DisplayName', 'Al(OH)_4^-');

% ==== CONFIGURAR EJES ====
xlabel('pH', 'FontSize', 14, 'FontWeight', 'bold');
ylabel('log [Al]', 'FontSize', 14, 'FontWeight', 'bold');
xlim([0 14]);
ylim([min(log_Al)-0.2, max(log_Al)+0.2]);
set(gca, 'FontSize', 12, 'LineWidth', 1.2);

% ==== SEGUNDO EJE (DERECHO) PARA [Al2(SO4)3] ====
ax1 = gca;
ax2 = axes('Position', get(ax1, 'Position'), ...
    'YAxisLocation', 'right', ...
    'Color', 'none', ...
    'XColor', 'none', ...
    'YColor', 'r');

set(ax2, 'YLim', [min(Al2SO4_3) max(Al2SO4_3)], ...
    'YTick', linspace(min(Al2SO4_3), max(Al2SO4_3), 6), ...
    'YTickLabel', arrayfun(@(x) sprintf('%.5f', x), ...
    linspace(min(Al2SO4_3), max(Al2SO4_3), 6), 'UniformOutput', false), ...
    'FontSize', 12, 'LineWidth', 1.2);

ylabel(ax2, 'Concentración Al_2(SO_4)_3 (M)', ...
    'FontSize', 14, 'FontWeight', 'bold', 'Color', 'r');

% ==== TÍTULO Y LEYENDA ====
title('Diagrama de Coagulación - Contorno de Remoción', ...
    'FontSize', 16, 'FontWeight', 'bold');

legend('Location', 'southwest', 'FontSize', 12, ...
    'EdgeColor', 'black', 'Color', 'white');

% ==== GRID Y ESTILO ====
grid on;
hold off;

●

Source: https://www.reddit.com/r/matlab/comments/1od1onr/problems_with_a_contour_diagram_for_a_caogulation/

[Cris LaPierre]

You need a 2D dataset for Z. This approach is trying to turn vector inputs for X,Y, and Z into matrices.

[Mathieu NOE]

the x,y,z data represent a narrow band - not interpolation method is able to create data from nothing.

You need to add more points to cover the area you want.

pH_contour = [7.9,7.6,7.4,7.1,6.8,6.3,6.8,5.7,4.9,4.4,4.3,4.2,4.2];
log_Al = [-3.3,-3.0,-2.9,-2.6,-2.5,-2.3,-2.2,-2.0,-1.9,-1.9,-1.8,-1.7,-1.7];
Al2SO4_3 = [0.00001,0.00003,0.00004,0.00006,0.00009,0.00013,0.00019,0.00025,0.00031,0.00038,0.00044,0.00050,0.00056];
Z = [6.4,79.5,97.8,98.9,98.1,99.1,99.1,96.6,94.2,93.5,94.9,97.1,92.8];
colormap('jet')
scatter3(pH_contour, log_Al, Z,50,Z,'filled')
colorbar
view(2)
hold on
plot(pH_contour, log_Al,'-')
xlabel('pH')
ylabel('log Al')

●

Answer 1

[Cris LaPierre]

Assuming you had the matrix of data used to create the contourf plot, somethink like this might work.

% Axes 1 - contour plot
f = figure;
ax1 = axes(f, 'NextPlot', 'add', 'YAxisLocation', 'right', 'Box', 'on');
x = linspace(4.1,8.2,20);
startValue = 1.7; % Starting value for logspace
endValue = 171.3; % Ending value for logspace
y = logspace(log10(startValue), log10(endValue));

[X,Y] = meshgrid(x,y);
ZI = rand(size(X))*120-10; % a matrix of random numbers

contourf(x,y,ZI)

% format axes 1
xlim([3 10])
xticks([])
ylim([1.7 171.3])
ylabel('concentration AI_2(SO_4),14 H_2O')
set(ax1, 'YScale', 'log');
yticks([1.7 17.1 171.3])

% Set colors and colorbar
C = hsv(25);
colormap(ax1,[0 0 0; C(1:9,:)])
clim([-11.2, 110.8])
c = colorbar(ax1);
c.Ticks = -11.2:12.2:110.8;
c.TickLabels = ["" 1:12.2:110.8];

% Axes 2 - line plots (drawn on top of contourf plot)
ax2 = axes(f, 'NextPlot', 'add', 'Color', 'none');
linkprop([ax1,ax2],{"Position"});

pH = linspace(0, 14, 200);

y_Al3 = -3.5294 .* pH + 13.176; % Al3+
y_AlOH2 = -2.3077 .* pH + 6.0769; % Al(OH)2+
y_AlOH4 = pH - 12.4; % Al(OH)4-

plot(pH, y_Al3, 'g-', 'LineWidth', 1.8, 'DisplayName', 'Al^{3+}');
hold on
plot(pH, y_AlOH2, 'b-', 'LineWidth', 1.8, 'DisplayName', 'Al(OH)^{2+}');
plot(pH, y_AlOH4, 'm-', 'LineWidth', 1.8, 'DisplayName', 'Al(OH)_4^-');
hold off

% Format axes2
xlabel('pH');
xlim([3 10])
ylabel('log [Al]');
ylim([-5 -3]);

legend(ax2,'Orientation','horizontal','Location','northoutside')

I would have used yyaxis left/right, but there appears to be a bug with that. Or at least with uistack with yyaxis axes as input.