Re: [Matplotlib-users] Define minimum precision for tick labels

[Stan W. <sta...@nr...>]

import numpy as np
import matplotlib.ticker as mticker

class RStripScalarFormatter(mticker.ScalarFormatter):
    """
    Formats as ScalarFormatter but without trailing zeros.

    The 'format' attribute of ScalarFormatter instances contains the basic
    number formatting as well as the formatting for TeX or MathText.  Here we
    separate those into the 'format' and 'wrapformat' attributes, respectively.
    """
    # Code adapted from mticker.ScalarFormatter.

    def __init__(self, useOffset=True, useMathText=False):
        mticker.ScalarFormatter.__init__( self, useOffset=useOffset,
                                          useMathText=useMathText )
        if self._usetex:
            self.wrapformat = '$%s$'
        elif self._useMathText:
            self.wrapformat = '$\mathdefault{%s}$'
        else:
            self.wrapformat = '%s'

    def _set_format(self):
        # set the format string to format all the ticklabels
        # The floating point black magic (adding 1e-15 and formatting
        # to 8 digits) may warrant review and cleanup.
        locs = ( (np.asarray(self.locs) - self.offset) /
                 10**self.orderOfMagnitude ) + 1e-15
        maxsigfigs = max( len(str('%1.8f' % loc).split('.')[1].rstrip('0'))
                          for loc in locs )
        self.format = '%1.' + str(maxsigfigs) + 'f'

    def pprint_val(self, x):
        xp = (x - self.offset) / 10**self.orderOfMagnitude
        if np.absolute(xp) < 1e-8:
            xp = 0
        xpstr = ( (self.format % xp).rstrip('0').rstrip('.')
                  or '0' )  # If nothing is left, it must've been zero.
        return self.wrapformat % xpstr

if __name__ == '__main__':

    import matplotlib.pyplot as plt

    plt.plot([-0.005, 0.02])
    axes = plt.gca()
    axes.yaxis.set_major_formatter(RStripScalarFormatter())
    plt.show()