Most of the plots I need to make for work have very different x and y axis scales, and under these conditions, the pyplot.arrow function (which I think is a FancyArrow) makes arrows where the heads are pretty distorted. (MPL version 0.99.1 -- Windows; version 0.99.1.1-r1 -- Gentoo)
I've spent quite a bit of time learning about the different arrow classes -- FancyArrow, YAArrow, FancyArrowPatch -- and I've found that the FancyArrowPatch gives arrows that do not look distorted under these conditions. For examples: import matplotlib.pyplot as plt import matplotlib.patches as mpp fig = plt.figure() ax=fig.add_subplot(111) ax.axis([520,580, 0,0.2]) a = plt.arrow(550,0.06,15,0.1, width=0.01, head_length=1.) ax.add_patch(a) b = mpp.YAArrow(fig, (555,0.16), (540,0.06), width=0.01, headwidth=0.03) ax.add_patch(b) c = mpp.FancyArrowPatch((530,0.06), (545,0.16), arrowstyle='-|>', lw=2, mutation_scale=50) ax.add_patch(c) plt.show() However, this leads to my questions: 1) Are there any plans or would it make sense to add another keyword to the pyplot.arrow function that allows you to choose the arrow class you would like to use? The default could be FancyArrow so that the original usage of pyplot.arrow will not be affected. The axes.arrow function - which it looks like it gets called by the pyplot.arrow function - could then convert the input arguments into the form necessary for the class you choose. 2) Or... Is there a simple way that you can call the arrow function with start and end points in data coordinates, but have the arrow parameters calculated in normalized figure coordinates? I think FancyArrow calculates the head and body points using a line perpendicular to the line of the arrow in data coordinates, which I think is the source of my problem (? -- at least that is what I found doing some test calculations on my own). However, if I call the pyplot.arrow function with the following keywords, 'trasform=fig.transFigure, figure=fig' (as per the Artist tutorial, see below), then the arrow looks okay, but it needs to be positioned in normalized figure coordinates and it does not move when you zoom or translate the plot. d = plt.arrow(0.15, 0.3, 0.15, 0.4, head_width=0.05, transform=fig.transFigure, figure=fig) ax.add_patch(d) For me, this is not a really big concern now that I figured it out, but I'm trying to teach my coworkers how to use Python/Matplotlib, and although they are interested in learning both, most of them are not and probably never will be really strong Python programmers. As a consequence, I think that all of the different arrow options and usages outside of pyplot.arrow will be a bit confusing for them... (I know it was for me at first...) Sorry for the long question message. I hope it was clear. Ryan P.S. As this is my first message to the list, I wanted to thank everyone who contributes to this great project. I'm a fairly new Python and Matplotlib user (only about 7 or 8 months for Python, less for MPL), and the combination of Python/Numpy/Scipy/Matplotlib is by far the most useful tool that I've learned in quite a long time. Hopefully, someday I'll be skilled enough to contribute something back. -- View this message in context: http://old.nabble.com/Arrow-question-request-tp27590334p27590334.html Sent from the matplotlib - users mailing list archive at Nabble.com. ------------------------------------------------------------------------------ SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
