create specific color map and save it
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how do i create my own color map for 2D-scatter plot.
such that all the values of z
- z <= 10 ------- take green color
- 10 < z <= 25 ----- yellow color
- 25 < z <= 50 ----- orange color
- z > 50 ----- red color
i want to create a color map obeying such condition and save it , so that i can use with whatever z i obtain in future.
as an example i have attached x,y,z
scatter(x,y,[],z,'filled','o')
1 个评论
KSSV
2020-5-28
Same question you have asked multiple times...
采纳的回答
Ameer Hamza
2020-5-28
Try this
val_z = (10:51).';
idx = 1*(val_z<=10) + ...
2*((10<val_z) & (val_z<=25)) + ...
3*((25<val_z) & (val_z<=50)) + ...
4*(val_z>50);
colors = [0 1 0; % green
1 1 0; % yellow
1 0.5 0; % orange
1 0 0]; % red
cmap = colors(idx, :);
scatter(x,y,[],z,'filled','o')
colormap(cmap)
set(gca, 'CLim', [10 51]);
12 个评论
Sajid Afaque
2020-5-28
Ameer Hamza
2020-5-28
This uses basic indexing operations available in MATLAB. It is difficult to summarize everything in one comment. I suggest running this code line by line and see the output of each step. Also, read about the indexing from the following links
Sajid Afaque
2020-5-28
First of al thank you for your help.
i am getting the colors according to my conditions.
but my color bar is showing up weird.
why is orange color repeating itself to the position of its value. and why don't green and yellow show up in color bar.
Additionally ,what should to i do to have increase in the darkness of color as value increases.( for example value > 50 we have red color, how can we acheive such that 51 has light red compared to 55 which should again be light red compared 60 and so on, my max value should be dark red)
Ameer Hamza
2020-5-28
Try this
val_z = (10:max(z)).';
cmap = zeros(numel(val_z), 3);
mask = val_z<=10;
cmap(mask, :) = repmat([0 1 0], sum(mask), 1); % green
mask = (10<val_z) & (val_z<=25);
cmap(mask, :) = repmat([1 1 0], sum(mask), 1); % yellow
mask = (25<val_z) & (val_z<=50);
cmap(mask, :) = repmat([1 0.5 0], sum(mask), 1); % orange
mask = val_z>50;
n = sum(mask);
t = linspace(0, 1, n).';
red = [1 0 0];
dark_red = [0.3 0 0];
cmap(mask, :) = (1-t).*red + t.*dark_red;
scatter(x,y,[],z,'filled','o')
set(gca, 'CLim', [10 max(z)]);
colormap(cmap)
colorbar
Sajid Afaque
2020-5-28
I am getting this error
Ameer Hamza
2020-5-28
Which MATLAB version are you using?
Sajid Afaque
2020-5-28
Ameer Hamza
2020-5-28
You can try this
val_z = (10:max(z)).';
cmap = zeros(numel(val_z), 3);
mask = val_z<=10;
cmap(mask, :) = repmat([0 1 0], sum(mask), 1); % green
mask = (10<val_z) & (val_z<=25);
cmap(mask, :) = repmat([1 1 0], sum(mask), 1); % yellow
mask = (25<val_z) & (val_z<=50);
cmap(mask, :) = repmat([1 0.5 0], sum(mask), 1); % orange
mask = val_z>50;
n = sum(mask);
t = linspace(0, 1, n).';
red = [1 0 0];
dark_red = [0.3 0 0];
cmap(mask, :) = interp1([0 1], [red; dark_red], t);
scatter(x,y,[],z,'filled','o')
set(gca, 'CLim', [10 max(z)]);
colormap(cmap)
colorbar
Sajid Afaque
2020-5-28
again my colorbar shows green at higher values whereas it should have been limited to trange 0-10
Ameer Hamza
2020-5-28
There seems to be some difference in the working of colormap in R2013b. In R2020a, it looks fine
Sajid Afaque
2020-5-28
Ameer Hamza
2020-5-28
I don't have any idea about this. Maybe something is mentioned in archived documentation, but the reason is not obvious.
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