Re: [Matplotlib-users] Getting started with bar charts

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

>>>>> "Jouni" =3D=3D Jouni K Sepp=E4nen <jk...@ik...> writes:

    Jouni> How I came up with this: I knew that I wanted to make some
    Jouni> of the xticklines invisible, so I looked at the list of
    Jouni> line objects for clues as to what differs between
    Jouni> them. They seem to have xdata and ydata properties, and
    Jouni> ydata is (0,) for half of the lines and (1,) for the other
    Jouni> half, so it looks like it is the vertical position in axis
    Jouni> coordinates. (xdata seems to be in data coordinates.)

Off the top of my head, I didn't remember the answer either.  Here's
how I answered it: I opened up lib/matplotlib/axis.py in my local copy
of the mpl src distro and searched for Tick (you could have done the
same by pointing your browser to
http://matplotlib.sourceforge.net/matplotlib.axis.html#Tick) and saw
the following attributes in the docstring

    Publicly accessible attributes

      tick1line  : a Line2D instance
      tick2line  : a Line2D instance
      gridline   : a Line2D instance
      label1     : a Text instance
      label2     : a Text instance
      gridOn     : a boolean which determines whether to draw the ticklin=
e
      tick1On    : a boolean which determines whether to draw the 1st tic=
kline
      tick2On    : a boolean which determines whether to draw the 2nd tic=
kline
      label1On   : a boolean which determines whether to draw tick label
      label2On   : a boolean which determines whether to draw tick label


I know, and it should be better documented, that for the x-axis, the
tick1 and label1 designations are for the lower axis, and the tick2
and label2 are for the upper (ditto for left/right for the y-axis).
So tick.tick1line controls the properties for the lower tick, etc.

Thus one can do

for tick in ax.xaxis.get_major_ticks():
    tick.tick1line.set_visible(False)
    tick.label2.set_color('darkslategray')

As Jouni notes, the documentation could and should be better, but the
underlying concepts are pretty simple.  A Figure contains multiple
Axes, each of which contains an XAxis and YAxis.  The XAxis and Yaxis
contains XTicks and YTicks, and these contains tick lines (Line2D
instances) and tick labels (Text instances).  Each of these upper-case
thingies is a well-documented matplotlib class (this class containment
hierarchy is also documented in the user's guide).  For future
reference, the links to the class documentation for each of these is

Figure       : http://matplotlib.sourceforge.net/matplotlib.figure.html
Axes/Subplot : http://matplotlib.sourceforge.net/matplotlib.axes.html
XAxis/YAxis  : http://matplotlib.sourceforge.net/matplotlib.axis.html
XTick/YTick  : http://matplotlib.sourceforge.net/matplotlib.axis.html
Line2D       : http://matplotlib.sourceforge.net/matplotlib.lines.html
Text         : http://matplotlib.sourceforge.net/matplotlib.text.html

As Jouni notes, setp and getp are a nice way to get quick interactive
access to the configurable properties, but they are also documented in
the class documentation in the links above.

JDH