Different color scale?

Dear all,

I have two different dataset one in txt format (ROTI output) and another in xlsx format(S4 output).I wanted to plot different scalebar with different color so that I can recognize these two data set. Would you please tell me the command of it?

Thank you,

Aramesh

[Rik]

What did you try so far?

[Ara]

Thank you for your reply.

I tries thi sfor S4:

colormap jet;

c1 = colorbar('Location', 'eastoutside');

c1.Label.String = 'S4';

caxis([0 0.3]);

and this for ROTI.

c2 = colorbar('Location', 'westoutside');

c2.Label.String = 'ROTI (TECU/min)';

caxis([0 0.5]);

but both are jet like eachother.

[Mathieu NOE]

hello @Ara

it would help us (and you BTW) if you could share a working code and the data

all the best

[Ara]

Hi Mathieu NOE,

Thank you for your comment. Unfortunately, I cannot share the data.

Best wishes,

Answer 1

[Image Analyst]

You need to use the colormap function to set the colormap for each axes independently. So display one image, set the colormap, then display the other and call colormap again with the other colormap. If you're plotting line curves instead of displaying images, there is a 'Color' (or maybe 'LineColor' option in plot to let you set the specific color of each curve.

help colormap

 colormap - View and set current colormap
    This MATLAB function sets the colormap for the current figure to the
    specified predefined colormap.

    Set Colormap
      colormap map
      colormap(map)
      colormap(target,map)
      cmap = colormap(___)

    Get Current Colormap
      cmap = colormap
      cmap = colormap(target)

    Input Arguments
      map - Colormap for new color scheme
        colormap name | three-column matrix of RGB triplets | 'default'
      target - Target
        Figure object | Axes object | PolarAxes object |
        GeographicAxes object | standalone visualization

    Output Arguments
      cmap - Colormap values
        three-column matrix of RGB triplets

    Examples
      openExample('graphics2/ChangeColormapUsedForPlotExample')
      openExample('graphics2/ChangeColormapThenSetItBackToDefaultExample')
      openExample('graphics/ColormapSpecifyAxesTiledLayoutExample')
      openExample('graphics2/SpecifyNumberOfColorsForColormapExample')
      openExample('graphics2/CreateCustomColormapExample')
      openExample('graphics2/ReturnColormapValuesUsedInPlotExample')
      openExample('graphics/ColormapReturnFromTiledLayoutExample')
      openExample('graphics2/ChangeColormapForFigureWithImageExample')

    See also colorbar, ind2rgb, hsv2rgb, rgbplot, Colormap Editor

    Introduced in MATLAB before R2006a
    Documentation for colormap
       doc colormap

If you have any more questions, then attach your data and code to read it in with the paperclip icon after you read this:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

[Ara]

Dear Image analysis,

Thank you for your response. I did this but still same color bar. And, please see atatched the figure.

I would appreciate if you help me to modefy the code?

Best.

% Add colorbar for S4
colormap(ax1, jet);
c1 = colorbar('Location', 'eastoutside');
c1.Label.String = 'S4';
caxis(ax1, [0 0.3]);  % Set color axis limits for S4
% Create another map for ROTI
ax2 = worldmap(latlim, lonlim); % Axis for ROTI
setm(ax2, 'FFaceColor', 'none'); % Make the background transparent
load coastlines
geoshow(coastlat, coastlon, 'DisplayType', 'polygon', 'FaceColor', [0.6 0.8 0.6]);

hold on; % Allow overlay of ROTI data

% Plot ROTI data
idx = filtered_time_hours_all >= (i-1)*5/60 & filtered_time_hours_all < i*5/60;
if any(idx)
    scatterm(all_lat(idx), all_lon(idx), 10, all_roti(idx), 'filled', 'Marker', 's');
    
    % Add colorbar for ROTI
    c2 = colorbar('Location', 'westoutside');
    c2.Label.String = 'ROTI (TECU/min)';
    caxis(ax2, [0 0.5]);  % Set color axis limits for ROTI
end

[Image Analyst]

I don't know what you want. What color ranges do you want for the left colorbar and right colorbar, and what numerical data values do the top and bottom of the colorbars represent?

[Ara]

Dear Image Analysis,

I want to show different threshold for ROTI (0-0.5) and S4 (0-0.3) in one map. ALso, show different color bar. I set "jet" for one of them and "hot" for another one but it does not appear on the plot.

Answer 2

[Walter Roberson]

    caxis([0 0.3]);

That is affecting the current axis.

    caxis([0 0.5]);

That too is affecting the current axis. Which appears to be the same axis as before.

Each axis has only one CLim axis property, so only one caxis() can be in effect at the same time in each axis.

If you need two different caxis() then you need two different axes.

[Ara]

Hi Walter,

Thank you for your response.

Exactly, I am facing this problem it set both threshould in 0.5 only. Would you please explain more how set two different axes?

I am attaching the figure.

Best,

Aramesh

[Ara]

please see atatched the editted code (part of it) that i wrote.

% Add colorbar for S4
colormap(ax1, jet);
c1 = colorbar('Location', 'eastoutside');
c1.Label.String = 'S4';
caxis(ax1, [0 0.3]);  % Set color axis limits for S4
% Create another map for ROTI
ax2 = worldmap(latlim, lonlim); % Axis for ROTI
setm(ax2, 'FFaceColor', 'none'); % Make the background transparent
load coastlines
geoshow(coastlat, coastlon, 'DisplayType', 'polygon', 'FaceColor', [0.6 0.8 0.6]);

hold on; % Allow overlay of ROTI data

% Plot ROTI data
idx = filtered_time_hours_all >= (i-1)*5/60 & filtered_time_hours_all < i*5/60;
if any(idx)
    scatterm(all_lat(idx), all_lon(idx), 10, all_roti(idx), 'filled', 'Marker', 's');
    
    % Add colorbar for ROTI
    c2 = colorbar('Location', 'westoutside');
    c2.Label.String = 'ROTI (TECU/min)';
    caxis(ax2, [0 0.5]);  % Set color axis limits for ROTI
end

[Rik]

You're aware you didn't set a colormap for ax2?

[Ara]

It means that I need to add it here like this. What to write instaed of "jet" to make a difference between them?

% Add colorbar for ROTI
colormap(ax2, jet);  
c2 = colorbar('Location', 'westoutside');
c2.Label.String = 'ROTI (TECU/min)';
caxis(ax2, [0 0.5]);  % Set color axis limits for ROTI
end

[Ara]

Hi Walter,

I make two different caxis but again it shows both threshould in 0.5. Do you have any clue what to do?

I would greatly appreciate your help.

Aramesh

here is my code but it still shows 0.5 for both of them.

colormap(ax, parula);
    caxis([0 0.3]); % S4 range
    c1 = colorbar('Location', 'eastoutside');
    c1.Label.String = 'S4';
    
    % Plot ROTI data
    idx = filtered_time_hours_all >= (i-1)*5/60 & filtered_time_hours_all < i*5/60;
    if any(idx)
        scatterm(all_lat(idx), all_lon(idx), ...
                 10, all_roti(idx), ...
                 'filled', 'Marker', 's', 'MarkerFaceAlpha', 0.6);
        colormap(ax, parula);
        caxis([0 0.5]); % ROTI range
        c2 = colorbar('Location', 'westoutside');
        c2.Label.String = 'ROTI (TECU/min)';

[DGM]

If you're dealing with multiple axes, you should be explicitly specifying which axes colormap()/clim() are operating on. You had that before, but I don't know why you don't have it specified now.

[Ara]

I did this but again it does not works. Show both in 0.5.

colormap(ax1, parula);

Unrecognized function or variable 'ax1'.

caxis(ax1, [0 0.3]);
c1 = colorbar('Location', 'eastoutside');
c1.Label.String = 'S4';
% Create world map for ROTI
ax2 = worldmap(latlim, lonlim);
setm(ax2, 'FFaceColor', 'none'); % Keep background transparent
hold on;
idx = filtered_time_hours_all >= (i-1)*5/60 & filtered_time_hours_all < i*5/60;
if any(idx)
    scatterm(ax2, all_lat(idx), all_lon(idx), ...
        10, all_roti(idx), ...
        'filled', 'Marker', 's', 'MarkerFaceAlpha', 0.6);
end
colormap(ax2, parula);
caxis(ax2, [0 0.5]);
c2 = colorbar('Location', 'westoutside');
c2.Label.String = 'ROTI (TECU/min)';

[Image Analyst]

It would be easier for us to reproduce and debug if you gave us a small working example, instead of an unrunnable snippet. And include screenshots of what you are getting, and if possible (mock something up in Photoshop), what you'd like to get.

[Ara]

Thank you Image Analyst. Unfortunately, I cannot share my data so the code is useless without the data. I am attaching one photo of it.I just want right bar show scale from 0-0.3 (circles in the figure) and left bar show scales from 0-0.5 (dots in this figures). Is that possible to show two different scale in one map?

[Walter Roberson]

colormap(ax1, parula);
caxis(ax1, [0 0.3]);
c1 = colorbar(ax1, 'Location', 'eastoutside');
c1.Label.String = 'S4';
% Create world map for ROTI
ax2 = worldmap(latlim, lonlim);
setm(ax2, 'FFaceColor', 'none'); % Keep background transparent
hold on;
idx = filtered_time_hours_all >= (i-1)*5/60 & filtered_time_hours_all < i*5/60;
if any(idx)
    scatterm(ax2, all_lat(idx), all_lon(idx), ...
        10, all_roti(idx), ...
        'filled', 'Marker', 's', 'MarkerFaceAlpha', 0.6);
end
colormap(ax2, parula);
caxis(ax2, [0 0.5]);
c2 = colorbar(ax2, 'Location', 'westoutside');
c2.Label.String = 'ROTI (TECU/min)';

[Ara]

thanks Walter. It shows both in scale of 0.5 again.

Here is my full code. Can you please modify it here to make sure that I am doing right?

% Create a VideoWriter object for the output video
video_filename = 'Combined_S4_and_ROTI_Video_average_Parula_axes.mp4';
v = VideoWriter(video_filename, 'MPEG-4');
v.FrameRate = 2; % Adjust frame rate
open(v);

% Latitude and longitude limits for Europe
latlim = [20 90];
lonlim = [-30 60];

% Define the time range (5-minute intervals for a full day)
start_time = datetime(2023, 4, 24, 0, 0, 0);
end_time = datetime(2023, 4, 24, 23, 59, 59);
time_bins = start_time:minutes(5):end_time;

% Initialize variables for ROTI data
all_lat = [];
all_lon = [];
all_roti = [];
filtered_time_hours_all = [];

% List of ROTI data files
fileNames = {'Dataajac.txt', 'Dataasky.txt', 'Dataflrs.txt', 'Datafunc.txt', ...
             'Datahamd.txt', 'Datahrmn.txt', 'Datalamp.txt', ...
             'Datalpal.txt', 'Datalyns.txt', 'Datamdvj.txt', 'Datametg.txt', ...
             'Datanklg.txt', 'Dataorid.txt', 'Datapolv.txt', 'Datareyk.txt', ...
             'Datariga.txt', 'Datarink.txt', 'Datascor.txt', 'Datasenu.txt', ...
             'Datasulp.txt', 'Datatro1.txt'};

% Process ROTI data files
for f = 1:length(fileNames)
    fileName = fileNames{f};
    try
        % Try reading ROTI data
        data = readmatrix(fileName);
        time_mjd = data(:, 1); % MJD time
        ROTI = data(:, 8);     % ROTI values
        IPP_lon = data(:, 10); % Longitude
        IPP_lat = data(:, 11); % Latitude
        
        % Convert MJD to hours since start of the day
        mjd_start = floor(min(time_mjd));
        time_hours = (time_mjd - mjd_start) * 24;
        
        % Filter for specific time range (20 to 44 hours)
        time_filter = time_hours >= 20 & time_hours < 44;
        filtered_time_hours = time_hours(time_filter) - 20; 
        
        % Filtered data
        all_lat = [all_lat; IPP_lat(time_filter)];
        all_lon = [all_lon; IPP_lon(time_filter)];
        all_roti = [all_roti; ROTI(time_filter)];
        filtered_time_hours_all = [filtered_time_hours_all; filtered_time_hours];
    catch
        disp(['Skipping file: ', fileName, ' due to an error.']);
    end
end

% Initialize variables for S4 data
all_S4_data = struct('time_dt', {}, 'S4', {}, 'Lon_IPP', {}, 'Lat_IPP', {});

% Process S4 data from station files
for station_num = 1:29
    filename = sprintf('Station%d.xlsx', station_num);
    try
        % Read S4 data
        data = readmatrix(filename, 'OutputType', 'string');
        time_str = data(:, 1); % Time strings
        S4 = str2double(data(:, 3)); % S4 values
        Lon_IPP = str2double(data(:, 15)); % Longitude
        Lat_IPP = str2double(data(:, 16)); % Latitude
        elevation = str2double(data(:, 5)); % Elevation angle
        
        % Convert time strings to datetime format
        time_dt = datetime(time_str, 'InputFormat', 'yyyy-MM-dd''T''HH:mm:ss.SSS');
        
        % Apply filters
        date_filter = (time_dt >= start_time) & (time_dt <= end_time) & (elevation >= 30);
        if any(date_filter)
            all_S4_data(station_num).time_dt = time_dt(date_filter);
            all_S4_data(station_num).S4 = S4(date_filter);
            all_S4_data(station_num).Lon_IPP = Lon_IPP(date_filter);
            all_S4_data(station_num).Lat_IPP = Lat_IPP(date_filter);
        end
    catch
        disp(['Error processing Station ', num2str(station_num)]);
    end
end

% Create figure for plotting
figure('Position', [100, 100, 1200, 800]); % Larger figure

% Loop through each 5-minute interval and create frames
for i = 1:length(time_bins) - 1
    % Initialize map for the current time interval
    ax = worldmap(latlim, lonlim);
    setm(ax, 'FFaceColor', [0.5 0.7 0.9]);
    load coastlines;
    geoshow(coastlat, coastlon, 'DisplayType', 'polygon', 'FaceColor', [0.6 0.8 0.6]);
    
    % Calculate and display the average S4 value
    avg_S4 = [];
    for station_num = 1:length(all_S4_data)
        if ~isempty(all_S4_data(station_num).time_dt)
            current_interval = (all_S4_data(station_num).time_dt >= time_bins(i)) & ...
                               (all_S4_data(station_num).time_dt < time_bins(i + 1));
            if any(current_interval)
                avg_S4 = [avg_S4; all_S4_data(station_num).S4(current_interval)];
            end
        end
    end
    if ~isempty(avg_S4)
        avg_S4_value = mean(avg_S4, 'omitnan');
        disp(['Average S4 for time ', datestr(time_bins(i)), ': ', num2str(avg_S4_value)]);
    else
        avg_S4_value = NaN;
    end
    
    % Plot S4 data
    for station_num = 1:length(all_S4_data)
        if ~isempty(all_S4_data(station_num).time_dt)
            current_interval = (all_S4_data(station_num).time_dt >= time_bins(i)) & ...
                               (all_S4_data(station_num).time_dt < time_bins(i + 1));
            if any(current_interval)
                scatterm(all_S4_data(station_num).Lat_IPP(current_interval), ...
                         all_S4_data(station_num).Lon_IPP(current_interval), ...
                         40, all_S4_data(station_num).S4(current_interval), ...
                         'filled', 'MarkerEdgeColor', 'k', 'MarkerFaceAlpha', 0.6);
            end
        end
    end
    colormap(ax, parula);
    caxis([0 0.3]);
    c1 = colorbar('Location', 'eastoutside');
    c1.Label.String = 'S4';
    
    % Plot ROTI data
    idx = filtered_time_hours_all >= (i-1)*5/60 & filtered_time_hours_all < i*5/60;
    if any(idx)
        scatterm(all_lat(idx), all_lon(idx), ...
                 10, all_roti(idx), ...
                 'filled', 'Marker', 's', 'MarkerFaceAlpha', 0.6);
        colormap(ax, parula);
        caxis([0 0.5]);
        c2 = colorbar('Location', 'westoutside');
        c2.Label.String = 'ROTI (TECU/min)';
    end
    
    % Add title and subtitle
    title('Combined S4 and ROTI Data for All Stations');
    subtitle(['Time: ', datestr(time_bins(i), 'HH:MM'), ', Average S4: ', num2str(avg_S4_value, '%.3f')]);
    
    % Capture the current frame
    frame = getframe(gcf);
    writeVideo(v, frame);
end

% Close the video writer
close(v);
disp(['Video saved as ', video_filename]);

 

[Ara]

when I run your code I got an error?

Unrecognized function or variable 'ax1'

[Ara]

here is with different axex but again only show 0.5 for both.

% Create a VideoWriter object for the output video
video_filename = 'S4_and_ROTI_SingleMap_Axes.mp4';
v = VideoWriter(video_filename, 'MPEG-4');
v.FrameRate = 2; % Adjust frame rate
open(v);

% Latitude and longitude limits for Europe
latlim = [20 90];
lonlim = [-30 60];

% Define the time range (5-minute intervals for a full day)
start_time = datetime(2023, 4, 24, 0, 0, 0);
end_time = datetime(2023, 4, 24, 23, 59, 59);
time_bins = start_time:minutes(5):end_time;

% Initialize variables for ROTI data
all_lat = [];
all_lon = [];
all_roti = [];
filtered_time_hours_all = [];

% List of ROTI data files
fileNames = {'Dataajac.txt', 'Dataasky.txt', 'Dataflrs.txt', 'Datafunc.txt', ...
             'Datahamd.txt', 'Datahrmn.txt', 'Datalamp.txt', ...
             'Datalpal.txt', 'Datalyns.txt', 'Datamdvj.txt', 'Datametg.txt', ...
             'Datanklg.txt', 'Dataorid.txt', 'Datapolv.txt', 'Datareyk.txt', ...
             'Datariga.txt', 'Datarink.txt', 'Datascor.txt', 'Datasenu.txt', ...
             'Datasulp.txt', 'Datatro1.txt'};

% Process ROTI data files
for f = 1:length(fileNames)
    fileName = fileNames{f};
    try
        % Read ROTI data
        data = readmatrix(fileName);
        time_mjd = data(:, 1); % MJD time
        ROTI = data(:, 8);     % ROTI values
        IPP_lon = data(:, 10); % Longitude
        IPP_lat = data(:, 11); % Latitude
        
        % Convert MJD to hours since start of the day
        mjd_start = floor(min(time_mjd));
        time_hours = (time_mjd - mjd_start) * 24;
        
        % Filter for specific time range (20 to 44 hours)
        time_filter = time_hours >= 20 & time_hours < 44;
        filtered_time_hours = time_hours(time_filter) - 20; 
        
        % Append filtered data
        all_lat = [all_lat; IPP_lat(time_filter)];
        all_lon = [all_lon; IPP_lon(time_filter)];
        all_roti = [all_roti; ROTI(time_filter)];
        filtered_time_hours_all = [filtered_time_hours_all; filtered_time_hours];
    catch
        disp(['Skipping file: ', fileName, ' due to an error.']);
    end
end

% Initialize variables for S4 data
all_S4_data = struct('time_dt', {}, 'S4', {}, 'Lon_IPP', {}, 'Lat_IPP', {});

% Process S4 data from station files
for station_num = 1:29
    filename = sprintf('Station%d.xlsx', station_num);
    try
        % Read S4 data
        data = readmatrix(filename, 'OutputType', 'string');
        time_str = data(:, 1); % Time strings
        S4 = str2double(data(:, 3)); % S4 values
        Lon_IPP = str2double(data(:, 15)); % Longitude
        Lat_IPP = str2double(data(:, 16)); % Latitude
        elevation = str2double(data(:, 5)); % Elevation angle
        
        % Convert time strings to datetime format
        time_dt = datetime(time_str, 'InputFormat', 'yyyy-MM-dd''T''HH:mm:ss.SSS');
        
        % Apply filters
        date_filter = (time_dt >= start_time) & (time_dt <= end_time) & (elevation >= 30);
        if any(date_filter)
            all_S4_data(station_num).time_dt = time_dt(date_filter);
            all_S4_data(station_num).S4 = S4(date_filter);
            all_S4_data(station_num).Lon_IPP = Lon_IPP(date_filter);
            all_S4_data(station_num).Lat_IPP = Lat_IPP(date_filter);
        end
    catch
        disp(['Error processing Station ', num2str(station_num)]);
    end
end

% Create figure for plotting
figure('Position', [100, 100, 1200, 800]); % Larger figure

% Loop through each 5-minute interval and create frames
for i = 1:length(time_bins) - 1
    clf; % Clear the figure
    
    % Create world map
    ax1 = worldmap(latlim, lonlim);
    setm(ax1, 'FFaceColor', [0.5 0.7 0.9]);
    load coastlines;
    geoshow(coastlat, coastlon, 'DisplayType', 'polygon', 'FaceColor', [0.6 0.8 0.6]);
    
    % Plot S4 data
    for station_num = 1:length(all_S4_data)
        if ~isempty(all_S4_data(station_num).time_dt)
            current_interval = (all_S4_data(station_num).time_dt >= time_bins(i)) & ...
                               (all_S4_data(station_num).time_dt < time_bins(i + 1));
            if any(current_interval)
                scatterm(all_S4_data(station_num).Lat_IPP(current_interval), ...
                         all_S4_data(station_num).Lon_IPP(current_interval), ...
                         40, all_S4_data(station_num).S4(current_interval), ...
                         'filled', 'MarkerEdgeColor', 'k', 'MarkerFaceAlpha', 0.6);
            end
        end
    end
    % Add colorbar for S4
colormap(ax1, jet);
c1 = colorbar('Location', 'eastoutside');
c1.Label.String = 'S4';
caxis(ax1, [0 0.3]);  % Set color axis limits for S4
% Create another map for ROTI
ax2 = worldmap(latlim, lonlim); % Axis for ROTI
setm(ax2, 'FFaceColor', 'none'); % Make the background transparent
load coastlines
geoshow(coastlat, coastlon, 'DisplayType', 'polygon', 'FaceColor', [0.6 0.8 0.6]);

hold on; % Allow overlay of ROTI data

% Plot ROTI data
idx = filtered_time_hours_all >= (i-1)*5/60 & filtered_time_hours_all < i*5/60;
if any(idx)
    scatterm(all_lat(idx), all_lon(idx), 10, all_roti(idx), 'filled', 'Marker', 's');
    
    % Add colorbar for ROTI
    c2 = colorbar('Location', 'westoutside');
    c2.Label.String = 'ROTI (TECU/min)';
    caxis(ax2, [0 0.5]);  % Set color axis limits for ROTI
end
    
    % Add title
    title(['S4 and ROTI Data at ', datestr(time_bins(i), 'HH:MM')]);
    
    % Capture frame for video
    frame = getframe(gcf);
    writeVideo(v, frame);
end

% Close the video writer
close(v);
disp(['Video saved as ', video_filename]);

[Ara]

Hi Walter,

Sorry for bothering you again. But, I got the same problem after set different axes. It still shows both colorbar for 0.5 only. Do you have any suggestions?

Thank you.