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

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UTKARSH VERMA on 29 Aug 2021
Commented: UTKARSH VERMA on 30 Aug 2021
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?
DGM on 30 Aug 2021
Edited: DGM on 30 Aug 2021
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

DGM on 29 Aug 2021
Edited: DGM on 29 Aug 2021
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 on 30 Aug 2021
Hi DGM,
Thanks for addressing my question, hsv() gives what I require and also thanks for suggesting some self designed colormap.

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