Re: [matplotlib-devel] Re: collection initializer color handling vs quiver

I did a tiny bit of work on this over the weekend too and decided to try 
to use a LineCollection instead of patches inspired by Chris Barker's 
code, but removing his polar coordinate stuff. Lines seemed a more 
promising way to go for the arrows, although the width should scale down 
when the arrows get small so that they're never wider than their length. 
Using a line collection may not permit this. I also haven't got it 
working yet. FWIW, Jordan's explanations of expected behaviour have been 
spot on so far. Also, I'd be happy to see the API fixed up a bit.

Gary R.

Jordan Dawe wrote:
> 
>> The length of that proposed keyword is a warning flag that it may also 
>> be a bad design.  Again, I would say either eliminate built-in support 
>> for color-by-length, or implement it via "color='length'", and then 
>> intercept that non-standard 'length' specification inside quiver so 
>> that it never gets passed to the standard color-handling routines.
>>
>> Now that you have explained it, I am inclined to either do a quick-fix 
>> of the present quiver so that it works again roughly as-is, or change 
>> the example so that it does not use the undocumented(?) "color=True" 
>> syntax; is one of these alternatives OK with you?   Do you have a 
>> preference?  Or do you already have an improved version that we can 
>> substitute now?  One way or another, I don't want to leave a 
>> non-functioning demo in svn.
> I would remove it; if we want a quiver function with color as length, we 
> could create a wrapper function to do that.  I would lean towards making 
> people generate their own color array based on the array length.  I'm 
> not going to have a new quiver anytime soon I think--a friend of mine 
> today pointed out that matlab distorts quiver arrows just like 
> matplotlib does.  In matlab it isn't as noticable, however, since matlab 
> impliments quiver as lines instead of as polygons.  In the short term, 
> I'm seriously tempted to just make matplotlib do the same.
> 
> Jordan