How can I plot circular colormap for 0-24 hour phase?

I am plotting 24 hour phase figure where I want a circular colormap i.e. 0th hour and 24th hour should have same same but with smooth transition of color.

I was using following lines to generate the plot:

jet_wrap = vertcat(jet,flipud(jet));
colormap(jet_wrap);

In the figure the main problem is I can differentiate between the area shade 6th hour and 18th hour viz.

Also, whenever i am running my code "jet_wrap" sizes doubles every single time and even if I clear it's value before running it. Why it's happening?

[dpb]

jet_wrap = vertcat(jet,flipud(jet));

says to take one copy of the colormap and paste a second (reversed) copy of it on the bottom. This will, indeed, be twice the size of the original colormap.

To keep the final result the same size as the original would require decimating by a factor of two -- with some issues of being precisely symmetric.

[UTKARSH VERMA]

If i run the above line then it should be twice the size of the colormap but when I was running it again then it again become the double of size which it gain from the previous execution.

[DGM]

When called without any arguments, jet() will return a color table with either 64 or 256 entries (depending on version). If the size of jet_wrap grows beyond length 128 (or 512), then either you have a variable called "jet", or you have some other thing changing the size of jet_wrap that you're not showing.

jet_wrap = vertcat(jet,flipud(jet));
size(jet_wrap,1)

ans = 512

jet_wrap = vertcat(jet,flipud(jet));
size(jet_wrap,1)

ans = 512

jet_wrap = vertcat(jet,flipud(jet));
size(jet_wrap,1)

ans = 512

Answer 1

[DGM]

If you want a circular colormap, why are you using jet?

Just use hsv().

imshow(repmat(permute(hsv(64),[1 3 2]),[1 64 1]))

Or you could concoct your own map using any closed path that does not intersect itself. Those are really the only two requirements.

% a similar constant-luma sweep in HSYn
cc = [0.9612 0.4459 0.4459;0.9475 0.4615 0.4019;0.9305 0.4783 0.3598;0.9102 0.4963 0.3201;0.887 0.5154 0.283;0.8611 0.5352 0.2489;0.8326 0.5557 0.2183;0.8019 0.5765 0.1913;0.7692 0.5977 0.1683;0.7349 0.6188 0.1494;0.6993 0.6397 0.1348;0.6628 0.6603 0.1248;0.6256 0.6803 0.1193;0.5882 0.6995 0.1184;0.5509 0.7178 0.1222;0.5141 0.7349 0.1306;0.4781 0.7507 0.1435;0.4433 0.7651 0.1608;0.41 0.7779 0.1823;0.3785 0.789 0.2079;0.3492 0.7982 0.2372;0.3222 0.8056 0.27;0.298 0.8109 0.306;0.2766 0.8143 0.3449;0.2584 0.8155 0.3861;0.2435 0.8147 0.4295;0.232 0.8118 0.4745;0.224 0.8069 0.5207;0.2197 0.8 0.5676;0.219 0.7912 0.6149;0.222 0.7805 0.662;0.2286 0.7681 0.7086;0.2388 0.7541 0.7541;0.2525 0.7385 0.7981;0.2695 0.7217 0.8402;0.2898 0.7037 0.8799;0.313 0.6846 0.917;0.3389 0.6648 0.9511;0.3674 0.6443 0.9817;0.4024 0.623 1;0.4432 0.6022 1;0.4802 0.5833 1;0.5146 0.5658 1;0.5472 0.5492 1;0.5787 0.5332 1;0.6098 0.5173 1;0.6411 0.5014 1;0.6732 0.485 1;0.7068 0.4679 1;0.7427 0.4496 1;0.782 0.4296 1;0.8215 0.411 0.9921;0.8508 0.4018 0.9628;0.8778 0.3944 0.93;0.902 0.3891 0.894;0.9234 0.3857 0.8551;0.9416 0.3845 0.8139;0.9565 0.3853 0.7705;0.968 0.3882 0.7255;0.976 0.3931 0.6793;0.9803 0.4 0.6324;0.981 0.4088 0.5851;0.978 0.4195 0.538;0.9714 0.4319 0.4914];
imshow(repmat(permute(cc,[1 3 2]),[1 64 1]))

% another HSYn sweep with PWL hue and luma
cc = [0.006539 0.4252 0.4252;0.02025 0.427 0.4844;0.03879 0.4261 0.5446;0.06235 0.4227 0.605;0.09104 0.4167 0.6648;0.1249 0.4084 0.723;0.1638 0.398 0.7789;0.2077 0.3858 0.8316;0.2562 0.3719 0.8801;0.3091 0.3568 0.9237;0.3658 0.3408 0.9617;0.426 0.3243 0.9933;0.4876 0.3119 1;0.5482 0.3013 1;0.6091 0.2906 1;0.6716 0.279 1;0.7376 0.2657 1;0.8093 0.2494 1;0.8622 0.2498 0.9639;0.9023 0.2593 0.914;0.9359 0.2726 0.8619;0.9631 0.2894 0.8086;0.9838 0.3095 0.7552;0.9983 0.3326 0.7026;1 0.3621 0.6506;1 0.3916 0.6033;1 0.4203 0.5595;1 0.4487 0.5178;0.9892 0.4815 0.4815;0.9744 0.5154 0.4506;0.9566 0.5497 0.4252;0.9364 0.584 0.4056;0.9146 0.618 0.3921;0.8917 0.6514 0.3847;0.8685 0.6838 0.3834;0.8455 0.7149 0.388;0.8233 0.7445 0.3982;0.8025 0.7723 0.4137;0.7836 0.7983 0.4342;0.767 0.8222 0.4591;0.7531 0.844 0.4879;0.7422 0.8636 0.52;0.7345 0.881 0.5547;0.7345 0.881 0.5547;0.6844 0.8732 0.5071;0.6312 0.8662 0.4633;0.5751 0.8599 0.4235;0.5166 0.854 0.3884;0.4559 0.8481 0.3581;0.3936 0.8421 0.3332;0.3301 0.8356 0.3139;0.2658 0.8284 0.3004;0.2012 0.8202 0.2928;0.1369 0.8106 0.2914;0.07338 0.7995 0.2961;0.01112 0.7865 0.3069;0 0.7436 0.338;0 0.6954 0.3665;0 0.6485 0.3888;0 0.6026 0.4057;0 0.5577 0.4177;0 0.5137 0.4252;0 0.4704 0.4285;0.006539 0.4252 0.4252];
imshow(repmat(permute(cc,[1 3 2]),[1 64 1]))

I'm sure there are countless other colormaps on the File Exchange if you want something different.

[UTKARSH VERMA]

Hi DGM,

Thanks for addressing my question, hsv() gives what I require and also thanks for suggesting some self designed colormap.