home built tick formatter to use with FuncFormatter():
        x     value to be formatted
        type  'x' or 'y' or 'y2' to set which list of ticks to get

        also sets self._yfmt/self._xfmt for statusbar

def __format(self, x, type='x'):
        """ home built tick formatter to use with FuncFormatter():
        x     value to be formatted
        type  'x' or 'y' or 'y2' to set which list of ticks to get

        also sets self._yfmt/self._xfmt for statusbar
        """
        fmt, v = '%1.5g','%1.5g'
        if type == 'y':
            ax = self.axes.yaxis
        elif type == 'y2' and len(self.fig.get_axes()) > 1:
            ax =  self.fig.get_axes()[1].yaxis
        else:
            ax = self.axes.xaxis

        try:
            dtick = 0.1 * ax.get_view_interval().span()
        except:
            dtick = 0.2
        try:
            ticks = ax.get_major_locator()()
            dtick = abs(ticks[1] - ticks[0])
        except:
            pass
        if dtick > 89999:
            fmt, v = ('%.1e',  '%1.6g')
        elif dtick > 1.99:
            fmt, v = ('%1.0f', '%1.2f')
        elif dtick > 0.099:
            fmt, v = ('%1.1f', '%1.3f')
        elif dtick > 0.0099:
            fmt, v = ('%1.2f', '%1.4f')
        elif dtick > 0.00099:
            fmt, v = ('%1.3f', '%1.5f')
        elif dtick > 0.000099:
            fmt, v = ('%1.4f', '%1.6e')
        elif dtick > 0.0000099:
            fmt, v = ('%1.5f', '%1.6e')

        s =  fmt % x
        s.strip()
        s = s.replace('+', '')
        while s.find('e0')>0:
            s = s.replace('e0','e')
        while s.find('-0')>0:
            s = s.replace('-0','-')
        if type == 'y':
            self._yfmt = v
        if type == 'y2':
            self._y2fmt = v
        if type == 'x':
            self._xfmt = v
        return s