Re: [Matplotlib-users] basemap: how to plot "toothed" curves

[Phil C. <phi...@an...>]

Wow, that's fantastic Ben. Thanks so much for finding that, it's just 
what I need!
Regards,

- Phil

Benjamin Root wrote:
> Looks like someone else figured out a creative solution using quiver: 
> http://stackoverflow.com/questions/19918502/sawtooth-line-style-in-matplotlib
>
> Here it is (slightly cleaned up):
>
> |import  matplotlib.pyplotas  plt
> import  numpyas  np
>
> x=  np.linspace(0,  2*np.pi,  100)
> y=  np.sin(x)
>
> dx=  np.diff(x)
> dy=  np.diff(y)
>
> x2=  np.linspace(0,  2*np.pi,  10)
> y2=  np.sin(x2)
>
> dx=  np.zeros_like(x2)  +  1e-12
> dy=  np.sin(x2+dx)  -  y2
>
> length=  np.hypot(dx,dy)
> dx/=  length
> dy/=  length
>
> fig,  ax=  plt.subplots()
> ax.set_aspect("equal")
> ax.plot(x,  y,  lw=4)
>
> size=  20
> ax.quiver(x2,  y2,  -dy,  dx,  headaxislength=size,  headlength=size,  headwidth=size,  color="blue")
> plt.margins(0.2)|
>
> I don't know yet how to get rounded heads, though. Now I am looking to 
> see how the text box styles of "sawtooth" and "roundtooth" are handled 
> in the code to see if that could be exploited, instead.
>
> Cheers!
> Ben Root
>
>
>
> On Fri, Oct 16, 2015 at 10:24 AM, Benjamin Root <ben...@gm... 
> <mailto:ben...@gm...>> wrote:
>
>     Hmmm, this is actually an interesting problem. I am also a
>     meteorologist, so this is interesting to me.
>
>     I haven't figured it out yet, but here are my thoughts:
>
>     1) There are the "^" triangle markers as well as "2" tri_up
>     markers:
>     http://nbviewer.ipython.org/github/WeatherGod/AnatomyOfMatplotlib/blob/master/AnatomyOfMatplotlib-Part3-HowToSpeakMPL.ipynb#Markers
>     2) The markevery property should be set to a float value to have
>     the markers spaced out evenly along the line regardless of aspect
>     ratios and zooming (note, this assumes that the line is defined
>     with many vertices to give a smooth appearance).
>
>     Problem:
>     Using markers and markevery in a Line2D object has an inherent
>     limitation: all of the markers will be drawn in the same
>     orientation. So, we can't orient the markers along the normal of
>     the line.
>     Also, there is no pre-defined marker for half-circles, so this
>     approach wouldn't work well for warm-fronts/dry-lines/etc.
>
>     I'll have to see if a PolygonCollection + Line2D might be the
>     right approach here...
>
>     Ben Root
>
>
>
>
>     On Fri, Oct 16, 2015 at 7:22 AM, Phil Cummins
>     <phi...@an... <mailto:phi...@an...>> wrote:
>
>         Hi,
>
>         I would like to plot "toothed" curves using basemap. These are
>         curves with triangles on one side, that are used to plot
>         pressure fronts in meteorology or thrust faults in geology.
>         You need to be able to say which side of the curve the
>         triangles should appear on. Does anyone know whether such
>         curves can be plotted using mtplotlib/basemap?
>
>         Thanks,
>
>         - Phil
>
>         Australian National University
>
>
>
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-- 

Phil Cummins
Prof. Natural Hazards
Research School of Earth Sciences
Australian National University