Re: [Matplotlib-users] default tick behaviour

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

>>>>> "matthew" == matthew arnison <ma...@ca...> writes:

    matthew> Hi again, I'm having more trouble with matplotlib ticks
    matthew> today. I wrote a little demo script that illustrates some
    matthew> of the problems:

Hi Matthew,

Thanks for sending me these example scripts - it really helps to have
complete examples when working on these problems.  I've made a few
changes to the tickval formatter.  The relevant function is
matplotlib.axis.format_tickval and is pretty simple conceptually.

Try replacing the default format_tickval with this one.  The d
variable gives the max-min distance of the view limits.  I use
different format strings depending on the size of the distance. 

    def format_tickval(self, x):
        'Format the number x as a string'
        d = self.viewlim.interval()
        if self._scale == 'log':
            # only label the decades
            fx = self.transData.func(x)
            isdecade = abs(fx-int(fx))<1e-10
            if self._ticklabelStrings is None and not isdecade: return ''

        #if the number is not too big and it's an int, format it as an
        #int
        if abs(x)<1e4 and x==int(x): return '%d' % x

        # if the value is just a fraction off an int, use the int
        if abs(x-int(x))<0.0001*d: return '%d' % int(x)

        # use exponential formatting for really big or small numbers,
        # else use float
        if d < 1e-2   : fmt = '%1.2e'
        elif d < 1e-1 : fmt = '%1.2f'
        elif d > 1e5  : fmt = '%1.3e'
        elif d > 10   : fmt = '%1.1f'
        elif d > 1    : fmt = '%1.2f'
        else          : fmt = '%1.3f'
        s =  fmt % x
        #print d, fmt, x, s
        # strip trailing zeros, remove '+', and handle exponential formatting
        m = self._zerorgx.match(s)
        if m:
            s = m.group(1)
            if m.group(2) is not None: s += m.group(2)
        s = s.replace('+', '')
        return s

And then feed it some more of your sadistic examples <wink>.  If you
don't like what you see, try tweaking the formats and the distance
values until you get sensible results.  Or feel free to provide more
comments and send more examples.

JDH