Re: [Matplotlib-users] line width adjustments

[John H. <jdh...@ac...>]

>>>>> "James" == James Boyle <bo...@ll...> writes:

    James> I would like to be able to change the width of a line.  If
    James> I just use B/W the use of line widths and styles can
    James> differentiate a number of lines. Currently, I do this: p =
    James> plot(datar,-1.0*(pr),'b') p.extend(
    James> plot(datac,-1.0*(pc),'r--')) p[0].set_linewidth(2)
    James> p[1].set_linewidth(3)

    James> Is this the way to do this? or is there something more
    James> elegant. 

I guess beauty is in the eye of the beholder, but I find this more
elegant

   liner, linec = plot(datar, -1.0*pr, 'b', 
                       datac, -1.0*pc, 'r--')
   liner.set_linewidth(2)
   linec.set_linewidth(3)  

    James> It might be useful for the third argument to have color,
    James> style and width.

It's certainly doable, but my hesitancy in doing this is that there
are a lot of properties of a line that one could make an argument for
putting in the format string.  matthew suggested allowing a label as
in 'r--;red line' (ala octave).  Should the alpha property be in
there?  My inclination is to follow the python design philosophy of
"one obvious way to do it".  

Perhaps a better solution is to allow keyword args to the plot command

  plot(datar, -1.0*pr, 'b', 
       linewidth=0.2, label='a red line', alpha=0.2)

This could be extended to handle plot multiple plots with one command
as follows

  plot(x1, y1, 'b', x2, y2, 'r--', 
       linewidth=(2,3), label=('a blue line', 'a red line'), 
       alpha=(1.0,0.5), antialiased = (True,False))      

legend can be altered to use line labels if they exist, so you could
build the legend of this plot just by callinging

  legend()

I find this the kwargs approach a little cleaner than having a
mother-of-all-format-strings.

    James> I have not been able to figure out how to change the line
    James> thickness of the axis frame, i.e. the x and y axis
    James> themselves. There are examples for the grid, if one is
    James> used, and the tick marks but not the frame itself.

Just an oversight on my part - I've been adding these neglected
accessor methods as people need them.  The axes border is a
patches.Rectangle instance.  If you add the following accessor method
to class Axes (on or around line 598) 

    def get_frame(self):
        "Return the axes Rectangle frame"
        return self._axesPatch

I just added it to the src tree.  You can then control the axes
rectangle as well, as in this example

    from matplotlib.matlab import *
    ax = subplot(111)
    plot([1,2,3])
    frame = ax.get_frame()
    frame.set_linewidth(3.0)
    frame.set_facecolor('r')
    frame.set_edgecolor('y')
    show()

Hope this helps,
JDH