manual_axis.py

00001 """
matplotlib is fairly rigid about how and where it draws it xaxis and
yaxis, and it is a frequent request to be able to place these in other
locations.  While it is not possible to customize matplotlib's
internal axis objects in this way, it is not too hard to simply turn
them off and draw your own axis lines, tick lines, and tick labels
where and how you want them
"""

import numpy as np
from pylab import figure, show
import matplotlib.lines as lines

def make_xaxis(ax, yloc, offset=0.05, **props):
    xmin, xmax = ax.get_xlim()
    locs = [loc for loc in ax.xaxis.get_majorticklocs()
            if loc>=xmin and loc<=xmax]
    tickline, = ax.plot(locs, [yloc]*len(locs),linestyle='',
            marker=lines.TICKDOWN, **props)
    axline, = ax.plot([xmin, xmax], [yloc, yloc], **props)
    tickline.set_clip_on(False)
    axline.set_clip_on(False)
    for loc in locs:
        ax.text(loc, yloc-offset, '%1.1f'%loc,
                horizontalalignment='center',
                verticalalignment='top')

def make_yaxis(ax, xloc=0, offset=0.05, **props):
    ymin, ymax = ax.get_ylim()
    locs = [loc for loc in ax.yaxis.get_majorticklocs()
            if loc>=ymin and loc<=ymax]
    tickline, = ax.plot([xloc]*len(locs), locs, linestyle='',
            marker=lines.TICKLEFT, **props)
    axline, = ax.plot([xloc, xloc], [ymin, ymax], **props)
    tickline.set_clip_on(False)
    axline.set_clip_on(False)

    for loc in locs:
        ax.text(xloc-offset, loc, '%1.1f'%loc,
                verticalalignment='center',
                horizontalalignment='right')


props = dict(color='black', linewidth=2, markeredgewidth=2)
x = np.arange(200.)
y = np.sin(2*np.pi*x/200.) + np.random.rand(200)-0.5
fig = figure(facecolor='white')
ax = fig.add_subplot(111, frame_on=False)
ax.axison = False
ax.plot(x, y, 'd', markersize=8, markerfacecolor='blue')
ax.set_xlim(0, 200)
ax.set_ylim(-1.5, 1.5)
make_xaxis(ax, 0, offset=0.1, **props)
make_yaxis(ax, 0, offset=5, **props)

show()