Have a lot of data, and when looking at full view I'd
> like no markers, but when zoom in to see individual
> points I'd like to place markers on the graph. Planing
> on attaching some code to events to toggle markers on my
> line. Is there a way to change the markers a line uses
> after it has been plotted, or do I have to clear the plot
> and replot?
Here is some example code that changes the marker style based on zoom
level. I wrote the example initially to show how to clip data from a
line based on zoom, but it also changes the marker style based on
number of points in the view window
"""
Clip a line according to the current xlimits, and change the marker
style when zoomed in
"""
from matplotlib.lines import Line2D
import matplotlib.numerix as nx
from pylab import figure, show
class ClippedLine(Line2D):
"""
Clip the xlimits to the axes view limits -- this example assumes x is sorted
"""
def __init__(self, ax, *args, **kwargs):
Line2D.__init__(self, *args, **kwargs)
self.ax = ax
def set_data(self, *args, **kwargs):
Line2D.set_data(self, *args, **kwargs)
self.xorig = nx.array(self._x)
self.yorig = nx.array(self._y)
def draw(self, renderer):
xlim = self.ax.get_xlim()
ind0, ind1 = nx.searchsorted(self.xorig, xlim)
self._x = self.xorig[ind0:ind1]
self._y = self.yorig[ind0:ind1]
N = len(self._x)
if N<1000:
self._marker = 's'
self._linestyle = '-'
else:
self._marker = None
self._linestyle = '-'
Line2D.draw(self, renderer)
fig = figure()
ax = fig.add_subplot(111, autoscale_on=False)
t = nx.arange(0.0, 100.0, 0.01)
s = nx.sin(2*nx.pi*t)
line = ClippedLine(ax, t, s, color='g', ls='-', lw=2)
ax.add_line(line)
ax.set_xlim(10,30)
ax.set_ylim(-1.1,1.1)
show()