## matplotlib-users

 [Matplotlib-users] Selecting a color from a given color map. From: Daniel Welling - 2012-02-16 21:14:29 ```Greetings. I have a series of lines that I would like to plot on the same axis, but I would like to set the color of each such that the range of colors used progresses through a given color map (e.g. the default Jet map.) For example, if I have 7 lines, the first would use the first most color from the Jet color map (blue.) The next line would use the color that is 1/7 the way up the map, e.g. green or so. This would continue until the last line was red. How would I go about doing this (that is, loading a color map and pulling a specific color from it that could be handed to plot as an rgba tuple)? Thanks! -dw ```
 Re: [Matplotlib-users] Selecting a color from a given color map. From: Tony Yu - 2012-02-16 21:27:23 Attachments: Message as HTML ```On Thu, Feb 16, 2012 at 4:14 PM, Daniel Welling wrote: > Greetings. > > I have a series of lines that I would like to plot on the same axis, > but I would like to set the color of each such that the range of > colors used progresses through a given color map (e.g. the default Jet > map.) For example, if I have 7 lines, the first would use the first > most color from the Jet color map (blue.) The next line would use the > color that is 1/7 the way up the map, e.g. green or so. This would > continue until the last line was red. > > How would I go about doing this (that is, loading a color map and > pulling a specific color from it that could be handed to plot as an > rgba tuple)? > > Thanks! > -dw > > Hi Daniel, You can just pass values to a colormap. If those values are evenly spaced between 0 and 1, you'll get the result you desire. Example: #~~~~~ import numpy as np import matplotlib.pyplot as plt n_lines = 10 x = np.linspace(0, 10) phase_shift = np.linspace(0, np.pi, n_lines) color_idx = np.linspace(0, 1, n_lines) for i, shift in zip(color_idx, phase_shift): plt.plot(x, np.sin(x - shift), color=plt.cm.jet(i)) plt.show() #~~~~~ Coincidentally, this past weekend, I started wrapping up random code like this into a utility package. See `cycle_cmap` in this package: https://github.com/tonysyu/mpltools/blob/master/mpltools/color.py. The package is still in the early stages, and function names could easily change, so use with caution. Best, -Tony ```