How to change my y-axis?

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cindyawati cindyawati 2025-1-24

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评论： Ishaan 2025-1-28

I want to change my y-axis so in the below from 0 to 100, and why my result give me the square (like grid) in the middle

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cindyawati cindyawati 2025-1-27

在 MATLAB Online 中打开

hello @Samar this is my code

% Hyperthermia Simulation with an Improved Biological Model

clear; clc; close all;

%% Parameter Model

alpha = 0.5; % thermal conductivity (cm^2/s)

Q = 0.1; % hot source (W/cm^3)

r0 = 0.03; % cancer growth (1/s)

beta = 0.02; % temperature sensitivity

Topt = 37; % temperarature for cancer growth (Celsius)

K = 1e6; % capacity of cancer

N0 = 1e4; % amount of cancer at the begining

omega_b = 0.01; % blood cooling (1/s)

T_blood = 37; % temperatur of blood (Celsius)

death_threshold = 45; % the boundary temperature above which cells die(Celsius)

death_rate = 0.05; % The rate of cell death if the temperature is too high

time = 0:0.1:100; % time simulation(second)

x = 0:0.1:5; % spatial position (cm)

[X, T] = meshgrid(x, time); % grid 2D

%% Temperature Initialization

T_t = zeros(length(time), length(x)); % temperature at t

T_t(:, 1) = T_blood; % temperature initial

%% Iteration Time for Temperature Distribution

for t = 2:length(time)

for i = 2:length(x)-1

% Equation of heat with cooling of blood

T_t(t, i) = T_t(t-1, i) + alpha * (T_t(t-1, i+1) - 2 * T_t(t-1, i) + T_t(t-1, i-1)) ...

- omega_b * (T_t(t-1, i) - T_blood) + Q;

end

% Set boundary conditions

T_t(t, 1) = T_t(t, 2); % limit left

T_t(t, end) = T_t(t, end-1); % limit right

end

%% Tumor Growth Model

N = zeros(length(time), 1); % Number of tumor cells

N(1) = N0; % Initial cell number

for t = 2:length(time)

% Tissue center temperature

T_mid = T_t(t, ceil(length(x)/2));

% Correction of tumor growth rate with temperature

r_t = r0 * exp(-beta * (T_mid - Topt)^2);

% If the temperature exceeds the threshold for cell death

if T_mid > death_threshold

r_t = r_t - death_rate;

end

% Tumor cell growth model

N(t) = N(t-1) + r_t * N(t-1) * (1 - N(t-1)/K);

end

%% Plot result

figure;

% temperature distribution

subplot(1, 2, 1);

imagesc(x, time, T_t);

xlabel('Position (cm)');

ylabel('Time (s)');

title('Temperature Distribution in Tissue');

colorbar;

caxis([T_blood 45]); % Range temperature

%colormap('hot');

% cancer growth

subplot(1, 2, 2);

plot(time, N, 'LineWidth', 2);

xlabel('Time (s)');

ylabel('Number of Tumor Cells');

title('Tumor Growth vs Time');

%grid on;

%% result

fprintf('Simulasi selesai. \n');

Simulasi selesai.

fprintf('Jumlah sel tumor awal: %.2f\n', N0);

Jumlah sel tumor awal: 10000.00

fprintf('Jumlah sel tumor akhir: %.2f\n', N(end));

Jumlah sel tumor akhir: 0.00

fprintf('Suhu akhir di tengah jaringan: %.2f °C\n', T_t(end, ceil(length(x)/2)));

Suhu akhir di tengah jaringan: -18.68 °C

cindyawati cindyawati 2025-1-27

hi @Torsten. Yes I want to reverse it such that 0 is at the bottom and 100 is at the top. Thank you

Voss 2025-1-27

在 MATLAB Online 中打开

% Hyperthermia Simulation with an Improved Biological Model

clear; clc; close all;

%% Parameter Model

alpha = 0.5; % thermal conductivity (cm^2/s)

Q = 0.1; % hot source (W/cm^3)

r0 = 0.03; % cancer growth (1/s)

beta = 0.02; % temperature sensitivity

Topt = 37; % temperarature for cancer growth (Celsius)

K = 1e6; % capacity of cancer

N0 = 1e4; % amount of cancer at the begining

omega_b = 0.01; % blood cooling (1/s)

T_blood = 37; % temperatur of blood (Celsius)

death_threshold = 45; % the boundary temperature above which cells die(Celsius)

death_rate = 0.05; % The rate of cell death if the temperature is too high

time = 0:0.1:100; % time simulation(second)

x = 0:0.1:5; % spatial position (cm)

[X, T] = meshgrid(x, time); % grid 2D

%% Temperature Initialization

T_t = zeros(length(time), length(x)); % temperature at t

T_t(:, 1) = T_blood; % temperature initial

%% Iteration Time for Temperature Distribution

for t = 2:length(time)

for i = 2:length(x)-1

% Equation of heat with cooling of blood

T_t(t, i) = T_t(t-1, i) + alpha * (T_t(t-1, i+1) - 2 * T_t(t-1, i) + T_t(t-1, i-1)) ...

- omega_b * (T_t(t-1, i) - T_blood) + Q;

end

% Set boundary conditions

T_t(t, 1) = T_t(t, 2); % limit left

T_t(t, end) = T_t(t, end-1); % limit right

end

%% Tumor Growth Model

N = zeros(length(time), 1); % Number of tumor cells

N(1) = N0; % Initial cell number

for t = 2:length(time)

% Tissue center temperature

T_mid = T_t(t, ceil(length(x)/2));

% Correction of tumor growth rate with temperature

r_t = r0 * exp(-beta * (T_mid - Topt)^2);

% If the temperature exceeds the threshold for cell death

if T_mid > death_threshold

r_t = r_t - death_rate;

end

% Tumor cell growth model

N(t) = N(t-1) + r_t * N(t-1) * (1 - N(t-1)/K);

end

%% Plot result

figure;

% temperature distribution

subplot(1, 2, 1);

imagesc(x, time, T_t);

set(gca, 'YDir', 'normal');

xlabel('Position (cm)');

ylabel('Time (s)');

title('Temperature Distribution in Tissue');

colorbar;

caxis([T_blood 45]); % Range temperature

%colormap('hot');

% cancer growth

subplot(1, 2, 2);

plot(time, N, 'LineWidth', 2);

xlabel('Time (s)');

ylabel('Number of Tumor Cells');

title('Tumor Growth vs Time');

%grid on;

%% result

fprintf('Simulasi selesai. \n');

Simulasi selesai.

fprintf('Jumlah sel tumor awal: %.2f\n', N0);

Jumlah sel tumor awal: 10000.00

fprintf('Jumlah sel tumor akhir: %.2f\n', N(end));

Jumlah sel tumor akhir: 0.00

fprintf('Suhu akhir di tengah jaringan: %.2f °C\n', T_t(end, ceil(length(x)/2)));

Suhu akhir di tengah jaringan: -18.68 °C

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Answer 1

Malay Agarwal 2025-1-27

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2173279-how-to-change-my-y-axis#answer_1558275

编辑：Malay Agarwal 2025-1-27

在 MATLAB Online 中打开

tmp.m

Hi @cindyawati cindyawati,

To reverse the direction of the y-axis, you can use the following command:

set(gca, 'YDir', 'normal');

By default, the imagesc function changes the y-axis direction to "reverse", which is why 0 is at the top and 100 is at the bottom. The above command changes the direction back to "normal". I have attached your code with this modification. Here is the result:

tmp

Simulasi selesai. Jumlah sel tumor awal: 10000.00 Jumlah sel tumor akhir: 0.00 Suhu akhir di tengah jaringan: -18.68 °C

Refer to the following answer from MathWorks Support team for more details: https://www.mathworks.com/matlabcentral/answers/94170-how-can-i-reverse-the-y-axis-when-i-use-the-image-or-imagesc-function-to-display-an-image-in-matlab

Hope this helps!

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Malay Agarwal 2025-1-27

You can call the command again for the second plot and it should reverse that as well.

Voss 2025-1-27

在 MATLAB Online 中打开

Or just avoid calling

set(gca, 'YDir', 'reverse');

on the second subplot.

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Answer 2

Ishaan 2025-1-28

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2173279-how-to-change-my-y-axis#answer_1558352

在 MATLAB Online 中打开

Hello @cindyawati cindyawati,

I understand that you intend to flip the y-axis ticks and fix the grid like pattern towards the (current) bottom of the plot. To reproduce the plot, I isolated the code snippet that generated the figure you provided.

alpha = 0.5; % thermal conductivity (cm^2/s) 
Q = 0.1; % hot source (W/cm^3) 
omega_b = 0.01; % blood cooling (1/s) 
T_blood = 37; % temperatur of blood (Celsius) 
time = 0:0.1:100; % time simulation(second) 
x = 0:0.1:5; % spatial position (cm) 
%% Temperature Initialization 
T_t = zeros(length(time), length(x)); % temperature at t 
T_t(:, 1) = T_blood; % temperature initial 
%% Iteration Time for Temperature Distribution 
for t = 2:length(time) 
    for i = 2:length(x)-1 
        % Equation of heat with cooling of blood 
        T_t(t, i) = T_t(t-1, i) + alpha * (T_t(t-1, i+1) - 2 * T_t(t-1, i) + T_t(t-1, i-1)) ... 
            - omega_b * (T_t(t-1, i) - T_blood) + Q; 
    end 
    % Set boundary conditions 
    T_t(t, 1) = T_t(t, 2); % limit left 
    T_t(t, end) = T_t(t, end-1); % limit right 
end 
imagesc(x, time, T_t); 
colorbar; 
caxis([T_blood 45]); % Range temperature 

Firstly, to change your y-axis order, you can flip the time variable like this.

time = 100:-0.1:0;

NOTE: This will flip the plot generated as well.

Alternatively, you can use the other methods mentioned to flip the y-axis.

Upon inspecting the image ”matrix (T_t)”, near the square (like grid) I notice that adjacent values have large differences.

T_t(970:979, 18:24)

This is leading to the grid like output. I also noticed that the top row of `T_t` is initialized to 0 and is never modified in the loop.

Hence, you will need to cross-check the equation of heat with cooling of blood as that is generating the “T_t” matrix.

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cindyawati cindyawati 2025-1-28

thank you @Ishaan I already try but the image still like grid. I still confused why give like a grid. For y-axis its already solved

Ishaan 2025-1-28

Hello @cindyawati cindyawati,

I suggest you to check some sections of the "T_t" matrix and verify if the values are as you expect. As the graph is plotted according to the matrix data.

To clarify, "T_t(412:414, 9:11)" is:

Notice that there is very less difference in adjacent values. This is the yellow area of the graph.

For the values in the bell bottom, the difference between adjacent values is large, "99.2591" and "-4.8532". Hence the grid like pattern of alternate blue and yellow values.

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How to change my y-axis?

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