Thread: [Matplotlib-users] A collection of axvspan ?

All,
I need to plot stripes of different widths at different locations along the x 
axis, but spanning the whole range of y data. Using axvspan in a loop works 
quite fine. However, I was wondering whether it wouldn't be more efficient to 
build a PatchCollection. 
BrokenBarHCollection could be a candidate, but I have trouble figuring how to 
force the bars to span the whole range of y: is it possible to force the 
ordinates to axes coordinates ?
Thanks a lot in advance for any idea/comment
P.

On 6/21/07, Pierre GM <pgm...@gm...> wrote:
> All,
> I need to plot stripes of different widths at different locations along the x
> axis, but spanning the whole range of y data. Using axvspan in a loop works
> quite fine. However, I was wondering whether it wouldn't be more efficient to
> build a PatchCollection.
> BrokenBarHCollection could be a candidate, but I have trouble figuring how to
> force the bars to span the whole range of y: is it possible to force the
> ordinates to axes coordinates ?
> Thanks a lot in advance for any idea/comment

You could use this if you pass in a custom blended transform -- see
the src for axhspan and axvspan to see how it creates the blended
transform (blend of xaxis and yaxis transform) and just pass this off
to the bar collection.

Let me know if you need any help.

JDH

Pierre GM wrote:
> All,
> I need to plot stripes of different widths at different locations along the x 
> axis, but spanning the whole range of y data. Using axvspan in a loop works 
> quite fine. However, I was wondering whether it wouldn't be more efficient to 
> build a PatchCollection. 
> BrokenBarHCollection could be a candidate, but I have trouble figuring how to 
> force the bars to span the whole range of y: is it possible to force the 
> ordinates to axes coordinates ?
> Thanks a lot in advance for any idea/comment

I haven't tried it, but I think you can use the same trick that axvspan 
uses:

  trans = blend_xy_sep_transform( self.transData, self.transAxes )

where "self" in this case is the axes instance, so you would use "ax" or 
whatever.  Then, since the collection is an artist, you can use its 
inherited set_transform(trans) method, and specify your x coordinates in 
data units and your y as 0 and 1 to span the whole vertical extent. 
This is assuming you want the width of your bars to be in data 
coordinates, not just the x-positions of their centers.

Eric

> P.
> 
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On Thursday 21 June 2007 17:15:01 Eric Firing wrote:
>   trans = blend_xy_sep_transform( self.transData, self.transAxes )
>
> where "self" in this case is the axes instance, so you would use "ax" or
> whatever.  Then, since the collection is an artist, you can use its
> inherited set_transform(trans) method, 

John, Eric,
That works like a charm ! Thanks a lot !