Hello users,
I wish to repeatedly re-plot labels and contour data on a figure since
redrawing the figure is temporally expensive. The attached script (I
apologize for its length), hopefully, illustrates a simplified version
of what I'm trying to do -- contour temporally-varying data on a map
projection.
I do not understand how to erase the plot label each time the figure is
to be reused. I also do not know how to erase the contour-fill
although, based on the generated PNG files, it does not, for unknown
reasons , appear to be necessary. From some postings, it seems that I
have to employ collections attributes, but I have not been able to find
documentation or examples that illustrate this.
My system:
* matplotlib.__version__: '0.91.2'
* sys.version: '2.5.1 (r251:54863, Apr 18 2007, 08:51:08) [MSC
v.1310 32 bit (Intel)]'
Thanks,
-- jv
'''
PURPOSE
Discover a procedure for eliminating the need to redraw each map projection
from scratch each there is new data to be plotted.
Redrawing each map is time-consuming!
AUTHOR
[EMAIL PROTECTED]
'''
import pylab
from matplotlib.toolkits.basemap import Basemap
import numpy
import os
parameters = dict(projection='merc', llcrnrlon=-180,urcrnrlon=180,
llcrnrlat=-80,urcrnrlat=85, lon_0=100,lat_ts=20, resolution='c')
map = Basemap(**parameters)
map.drawcoastlines()
map.drawmapboundary()
map.drawmeridians(pylab.arange(0,360,30))
map.drawparallels(pylab.arange(-90,90,30))
parameters = dict(num=1, figsize=(8, 8), dpi=80, facecolor='w', edgecolor='k',
frameon=False)
figure = pylab.figure(**parameters)
pylab.title('Figure-reuse Trial')
def render(data):
timestamp, longitudes, latitudes, values = data['timestamp'],
data['longitudes'], data['latitudes'], data['values']
longitudes, latitudes = pylab.meshgrid(longitudes, latitudes)
pylab.figure(num=1) # set current figure
parameters = dict(alpha=1, color='white', fontsize=12, fontweight='heavy',
horizontalalignment='left', verticalalignment='center',
transform=pylab.gca().transAxes)
pylab.text(0.01,0.98, timestamp, **parameters)
x, y = map(longitudes, latitudes)
map.contourf(x, y, values)
filename = os.extsep.join(('Reuse-trial',str(data['timestamp'])[:10],'png'))
pylab.savefig(filename)
##pylab.show()
#~ _restore_(figure) TBD: how to erase current label and contour fill colors
although the latter erasure surprisingly does not seem to be required !
def timeline():
''' a generator for fabricated, planet-wide, data for testing purposes '''
data = dict()
delta_x, delta_y = 1.0, 0.5
data['longitudes'] = numpy.arange(-180.0, 180.0+delta_x, delta_x)
data['latitudes'] = numpy.arange(-90.0, 90.0+delta_y, delta_y)
computations = dict(yesterday=horizontal(data['longitudes'],
data['latitudes']), today=vertical(data['longitudes'], data['latitudes']))
for timestamp,values in computations.items():
data['timestamp'] = timestamp
data['values'] = values
yield data
def horizontal(longitudes,latitudes):
data = numpy.empty(shape=(longitudes.size, latitudes.size), dtype=float,
order='C')
for index,longitude in enumerate(longitudes):
data[index] = longitude
return data
def vertical(longitudes,latitudes):
data = numpy.empty(shape=(longitudes.size, latitudes.size), dtype=float,
order='C')
for index,latitude in enumerate(latitudes):
data[:,index] = latitude
return data
for data in timeline():
render(data)
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