How to properly set ticks, numbers and the their decimal places on colorbar?

Question

Giuseppe 2022-10-6

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1818910-how-to-properly-set-ticks-numbers-and-the-their-decimal-places-on-colorbar

评论： Star Strider 2022-10-6

I want to show on the colorbar 50 ticks but visualize only 11 or 10 numbers asscoiated to them and then set 6 decimal places for each number. Can you help me?

Here is my attempt code but only one number seems to appear on the bar.

load JC_L1

load PLOs_filt

fig = figure;

color_map_L1 = flip(turbo(numel(JC_L1))); % I prefer to associate the red to high-energy level

for k1 = 1:50

plot([PLOs_filt(1).prop(k1).orbits.x],[PLOs_filt(1).prop(k1).orbits.y],...

"Color",color_map_L1(k1,:)); hold on

end

axis equal

colormap(color_map_L1);

% Colorbar settings

cb = colorbar;

ticks = flip(JC_L1)'; %Specify how many numbers show on the colorbar

set(cb,'ytick', ticks/max(ticks));

set(cb,'yticklabel',ticks);

tix = cb.Ticks; % Get Tick Values

cb.TickLabels = compose('%9.6f',tix);

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Answer 1

Star Strider 2022-10-6

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1818910-how-to-properly-set-ticks-numbers-and-the-their-decimal-places-on-colorbar#answer_1068180

在 MATLAB Online 中打开

Try something like this —

[X,Y,Z] = peaks(50);

figure

surf(X, Y, Z)

grid on

colormap(turbo)

hcb = colorbar;

% get(hcb)

tix = hcb.Ticks; % Get Tick Values

hcb.TickLabels = compose('%9.6f',tix); % Set Tick Labels

The format descriptor '%9.6f' allows for the decimal and sign position so all the tick labels are aligned appropriately.

.

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Star Strider 2022-10-6

在 MATLAB Online 中打开

One problem is that your code wants to force 50 tick labels onto the colorbar. That can easily be done, however fewer would be easier to see.

Try this —

LD1 = load(websave('JC_L1','https://www.mathworks.com/matlabcentral/answers/uploaded_files/1147800/JC_L1.mat'));

JC_L1 = LD1.JC_L1;

LD2 = load(websave('PLOs_filt','https://www.mathworks.com/matlabcentral/answers/uploaded_files/1147805/PLOs_filt.mat'));

PLOs_filt = LD2.PLOs_filt;

fig = figure;

color_map_L1 = flip(turbo(numel(JC_L1))); % I prefer to associate the red to high-energy level

for k1 = 1:50

plot([PLOs_filt(1).prop(k1).orbits.x],[PLOs_filt(1).prop(k1).orbits.y],...

"Color",color_map_L1(k1,:)); hold on

end

axis equal

colormap(color_map_L1);

% Colorbar settings

cb = colorbar;

ticks = flip(JC_L1)'; %Specify how many numbers show on the colorbar

ticklims = [min(ticks); max(ticks); min(ticks)/max(ticks); numel(ticks)] % Interest Only - Not Required For Code (Delete If Desired)

ticklims = 4×1

3.0006 3.0009 0.9999 50.0000

% set(cb,'ytick', ticks/max(ticks));

% set(cb,'yticklabel',ticks);

tix = cb.Ticks; % Get Tick Values

tikpos = linspace(min(tix), max(tix), numel(ticks)); % Tick Positions On 'colorbar'

cb.Ticks = tikpos; % Set Tick Positions

% tix = cb.Ticks; % Get Tick Values

cb.TickLabels = compose('%9.6f',ticks/max(ticks)); % Set & Format Tick Labels

% cb.FontSize = 5;

The tick positions must be in the range of the current ticks, so the ‘tickpos’ vector creates 50 of them in that range. After that, the compose call creates and formats the labels. They are automatically positioned on the previously set ticks.

To make the tick labels easier to read, I suggest creating fewer elements of the ‘ticks’ vector to begin with. The rest of the code will automatically accommodate them.

.

Star Strider 2022-10-6

在 MATLAB Online 中打开

I do not understand.

I am using the ‘ticks’ vector (derived from the ‘JC_L1’ array) to create the tick labels, because that is apparently what you use, and then divide them by the maximum (apparently to scale them). Choose whatever you want to use for the tick labels, providing that there are enough of them to create the arrays.

Creating 11 tick labels while displaying all 50 ticks is relatively straightforward, and this revised code does that. Change the values in ‘tiklblidx’ to control the tick values displayed, and where they are displayed. They are indices, so they must be integers greater than 0 and between 1 and 50.

Try this —

LD1 = load(websave('JC_L1','https://www.mathworks.com/matlabcentral/answers/uploaded_files/1147800/JC_L1.mat'));

JC_L1 = LD1.JC_L1;

LD2 = load(websave('PLOs_filt','https://www.mathworks.com/matlabcentral/answers/uploaded_files/1147805/PLOs_filt.mat'));

PLOs_filt = LD2.PLOs_filt;

fig = figure;

color_map_L1 = flip(turbo(numel(JC_L1))); % I prefer to associate the red to high-energy level

for k1 = 1:50

plot([PLOs_filt(1).prop(k1).orbits.x],[PLOs_filt(1).prop(k1).orbits.y],...

"Color",color_map_L1(k1,:)); hold on

end

axis equal

colormap(color_map_L1);

% Colorbar settings

cb = colorbar;

ticks = flip(JC_L1)'; %Specify how many numbers show on the colorbar

% ticklims = [min(ticks); max(ticks); min(ticks)/max(ticks); numel(ticks)] % Interest Only - Not Required For Code (Delete If Desired)

% set(cb,'ytick', ticks/max(ticks));

% set(cb,'yticklabel',ticks);

tix = cb.Ticks; % Get Tick Values

tikpos = linspace(min(tix), max(tix), numel(ticks)); % Tick Positions On 'colorbar'

cb.Ticks = tikpos; % Set Tick Positions

% tix = cb.Ticks; % Get Tick Values

cb.TickLabels = cell(50,1);

tiklblidx = [1 5 10 15 20 25 30 35 40 45 50];

cb.TickLabels(tiklblidx) = compose('%9.6f',ticks(tiklblidx)/max(ticks)); % Set & Format Tick Labels

.

Giuseppe 2022-10-6

编辑：Giuseppe 2022-10-6

在 MATLAB Online 中打开

JC_L1.mat

Ok, last thing: Can you reverse the colorbar colors (from blue to red) and show the numbers containend in JC_L1 with six decimal places?

load JC_L1
format long
JC_L1'
ans = 50×1
000900891023230
000894276927840
000887643313580
000881028967010
000874419173230
000867791975870
000861196034850
000854592397690
000847948043080
000841330136040

So I need to start from the bottom of colorbar with the value 3.000577 (blue color) up to the last value 3.000901 (red color)

Star Strider 2022-10-6

在 MATLAB Online 中打开

Reversing the colorbar is straightforward. This also reverses the tick labels, however if you want them as they were before the colorbar was reversed, change the relevant assignment to:

cb.TickLabels(tiklblidx) = compose('%9.6f', JC_L1(flip(tiklblidx))); % Set & Format Tick Labels

That will reverse the order of the tick labels without re-flipping the colorbar. In my code they are unchanged (unflipped), so flip the index if you want to.

This now uses a select subset of ‘JC_L1’ for the colorbar tick labels.

Try this —

LD1 = load(websave('JC_L1','https://www.mathworks.com/matlabcentral/answers/uploaded_files/1147800/JC_L1.mat'));

JC_L1 = LD1.JC_L1;

LD2 = load(websave('PLOs_filt','https://www.mathworks.com/matlabcentral/answers/uploaded_files/1147805/PLOs_filt.mat'));

PLOs_filt = LD2.PLOs_filt;

fig = figure;

color_map_L1 = flip(turbo(numel(JC_L1))); % I prefer to associate the red to high-energy level

for k1 = 1:50

plot([PLOs_filt(1).prop(k1).orbits.x],[PLOs_filt(1).prop(k1).orbits.y],...

"Color",color_map_L1(k1,:)); hold on

end

axis equal

colormap(color_map_L1);

% Colorbar settings

cb = colorbar;

ticks = flip(JC_L1)'; %Specify how many numbers show on the colorbar

% ticklims = [min(ticks); max(ticks); min(ticks)/max(ticks); numel(ticks)] % Interest Only - Not Required For Code (Delete If Desired)

% set(cb,'ytick', ticks/max(ticks));

% set(cb,'yticklabel',ticks);

tix = cb.Ticks; % Get Tick Values

tikpos = linspace(min(tix), max(tix), numel(ticks)); % Tick Positions On 'colorbar'

cb.Ticks = tikpos; % Set Tick Positions

% tix = cb.Ticks; % Get Tick Values

cb.Direction = 'reverse';

cb.TickLabels = cell(50,1);

tiklblidx = [1 5 10 15 20 25 30 35 40 45 50];

cb.TickLabels(tiklblidx) = compose('%9.6f', JC_L1(tiklblidx)); % Set & Format Tick Labels

.

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