Re: [Matplotlib-users] How to use 'arrow'?

[Jessica Lu <jl...@as...>]

I usually use the following to make single arrows:

plot([0,1], 'k.')
arr1 = pylab.Arrow(0.5, 0.5, 0.1, 0.0, width=0.02)
fig = pylab.gca()
fig.add_patch(arr1)


If in "ipython -pylab" you need to savefig or send another command  
(e.g. xlabel) or reload/refresh the plot (I can't remember the  
command) for the new patch to display. I use this rather than arrow()  
because I can control the arrow width and other properties. There is  
also the quiver command which lets you draw many arrows:

quiver([[0, 1, 2]], [[0, 1, 2]], [[0.0, 0.0, 0.0]], [[0.1, 0.1,  
0.1]], 0.2)

Cheers,
Jessica

On Jul 20, 2007, at 6:32 AM, Alexander Dietz wrote:

> Hi,
>
> How is the syntax for the matplotlib command 'arrow'? There is not  
> very much to take from the help (see below). An example would be nice.
>
> Thanks
>   Alex
>
> In [46]: arrow?
> Type:           function
> Base Class:     <type 'function'>
> String Form:    <function arrow at 0xb77f8a3c>
> Namespace:      Interactive
> File:           /usr/lib/python2.4/site-packages/matplotlib/pylab.py
> Definition:     arrow(*args, **kwargs)
> Docstring:
>     Draws arrow on specified axis from (x,y) to (x+dx,y+dy).
>     Optional kwargs control the arrow properties:
>             alpha: float
>             animated: [True | False]
>             antialiased or aa: [True | False]
>             axes: an axes instance
>             clip_box: a matplotlib.transform.Bbox instance
>             clip_on: [True | False]
>             clip_path: an agg.path_storage instance
>             edgecolor or ec: any matplotlib color
>             facecolor or fc: any matplotlib color
>             figure: a matplotlib.figure.Figure instance
>             fill: [True | False]
>             hatch: unknown
>             label: any string
>             linewidth or lw: float
>             lod: [True | False]
>             picker: [None|float|boolean|callable]
>             transform: a matplotlib.transform transformation instance
>             visible: [True | False]
>             zorder: any number
>
>     Addition kwargs: hold = [True|False] overrides default hold state
>
> ---------------------------------------------------------------------- 
> ---
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2005.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ 
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users