Improvement in Plotting methods.

[sushobhana]

added as_patch for annulus.

In [15]: reg3 = CircleAnnulusPixelRegion(PixCoord(.4,.5), .2 , .3)

In [16]: reg3.plot()
Out[16]: <matplotlib.axes._subplots.AxesSubplot at 0x7efd8f016390>

In [17]: plt.show()

Now, also uses visual meta data for plotting:

In [3]: st = 'image\npoint(1.3,1.5) # point=arrow 14 color=magenta'

In [4]: reg = DS9Parser(st)

In [5]: reg = reg.shapes.to_regions()[0]

In [6]: reg.plot()
Out[6]: <matplotlib.axes._subplots.AxesSubplot at 0x7fdd8e37a2e8>

In [7]: plt.show()

In [3]: st = 'image\ncircle(1.4,1.5,.3) # color=pink width=3 font="times 10 normal roman" text={Circle} tag={foo} tag={foo bar} This is a Comment'

In [4]: reg = DS9Parser(st)

In [5]: reg = reg.shapes.to_regions()[0]

In [6]: ax = reg.plot()

In [7]: ax.legend()
Out[7]: <matplotlib.legend.Legend at 0x7f7e4c1aa358>

In [8]: plt.show()

In [3]: a = 'image\ntext(1315,1041) # color=magenta font="helvetica 14 bold roman" text={Region}'

In [4]: reg = DS9Parser(a).shapes.to_regions()[0]

In [5]: ax = reg.plot()

In [6]: ax.set_xlim(0,2000)
Out[6]: (0, 2000)

In [7]: ax.set_ylim(0,2000)
Out[7]: (0, 2000)

In [8]: plt.show()
/home/sushobhana/anaconda3/lib/python3.6/site-packages/matplotlib/font_manager.py:1320: UserWarning: findfont: Font family ['helvetica'] not found. Falling back to DejaVu Sans
  (prop.get_family(), self.defaultFamily[fontext]))

In [7]: from regions import *

In [8]: from matplotlib import pyplot as plt

In [9]: reg3 = RectangleAnnulusPixelRegion(PixCoord(.4,.5), .2 , .3, .4, .5)

In [10]: ax =  reg3.plot()

In [11]: plt.show()

Also, implemented the __eq__ for PixCoord.

[keflavich]

This is looking really good. I'm not sure I caught everything in this review; there's a lot changed here.

Could you add an example to the docs with these improved plots? Something like the images on the frontpage of the pyregion docs. That might be best as the topic of another PR, but we should show off these changes somewhere!

[keflavich]

Is this supposed to be reachable? If not, see if you can add a message that might help the user figure out what went wrong. I don't believe non-concentric annuli should be possible to declare.

[sushobhana]

yes, it's reachable. It is the CompoundPixelRegion class and not CircleAnnulusPixelRegion

[keflavich]

can we maybe use more descriptive variable names than x and y here? That might be the subject of a different PR, I just realize now looking at this code that it's hard to understand where those come from with these names.

[keflavich]

Why? I don't mind, just wondering if there's a reason. Does that make it look more like ds9?

[sushobhana]

It does not look like a line with width one. This Arrow patch seems ugly.Also, there is a line meta in DS9 decides which end of the line would be arrow like. I will work on that.

[keflavich]

whitespace (indentation isn't consistent here)

[sushobhana]

There are a lot of big and small changes made here, and I don't want to push things further in the PR here.
There is still more to be done to make this more DS9 though.
Up for a final review!
@keflavich

[keflavich]

I'm happy with this, so I'm merging it. Could you link to the Issues with the next steps? For one, we want a documentation page analogous to pyregion's frontpage showing all the graphical tools in action; it can pretty much be the RST version of the original issue posted here.

You also left a to-do item of having some of the internals of the plot method put into an as_patch method.