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tlambert03

opened on Dec 3, 2023

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Hey @kushalkolar et al,

great package! i was just looking around the image utils here and noticed that you require matplotlib to generate colormaps but, understandably, don't include matplotlib in your dependencies.

when working on napari and other related image libs, I also wanted to use colormaps without having to depend on matplotlib, and made cmap, a lib that only depends on numpy and provides all the matplotlib colormaps (and many more) and basic mapping functionality. the lib exports to many third-party colormap objects. Would you be interested in looking at a PR that uses cmap here?

Reacted by Ivo Flipse, Kushal Kolar and Eric Thomson

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1. kushalkolar commented on Dec 4, 2023

   

   kushalkolar

   on Dec 4, 2023

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   Hi @tlambert03 I like this idea, thanks for posting! 😄

   I really like this feature which seems like it lets you make custom arbitrary cmaps?

   In [2]: cmap1 = cmap.Colormap(["red", "green", "blue"])
   
   In [3]: cmap1(np.linspace(0,1,5))
   Out[3]:
   array([[1.        , 0.        , 0.        , 1.        ],
          [0.50393701, 0.24900417, 0.        , 1.        ],
          [0.        , 0.50196078, 0.        , 1.        ],
          [0.        , 0.24900417, 0.50393701, 1.        ],
          [0.        , 0.        , 1.        , 1.        ]])

   It would make it possible to have things like this in fastplotlib:

   # already exists
   line.cmap = "jet"
   
   # with your cmap lib :D 
   line.cmap = ["red", "blue", "violet"]
   
   # would apply to line collections as well
   line_collection.cmap = ["red", "blue", "violet"]

   In fastplotlib "Graphic Feature" classes are used to manage the buffers that represent various aspects of a graphic/plot item (such as the underlying data, colors, cmaps, etc.).

   For lines and scatter we use CmapFeature

   For images we use ImageCmapFeature

   For LineCollection it's implemented within the Graphic class itself, in the constructor and cmap.setter .

   I think that for lines, scatter and line collections it should be possible to just use your cmap package in utils.functions.parse_cmap_values()

   And also replace get_cmap()

   And have an updated list of qualitative cmaps because they behave differently: https://github.com/fastplotlib/fastplotlib/blob/main/fastplotlib/utils/functions.py#L12-L25

   There might be other things in utils.functions that can be replaced with your cmap library, or other places as well! :)
2. tlambert03 commented on Dec 4, 2023

   

   tlambert03

   on Dec 4, 2023

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   I really like this feature which seems like it lets you make custom arbitrary cmaps?

   yep! you can express custom color maps many different ways

   For lines and scatter we use CmapFeature
   For images we use ImageCmapFeature

   thanks for the tips! i'll have a look soon
3. kushalkolar commented on Aug 30, 2024

   

   kushalkolar

   on Aug 30, 2024

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   done in #390
4. kushalkolar

   closed this as completedon Aug 30, 2024

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