Jesper Larsen wrote:
> Hi matplotlib users,
>
> I have a small web application for calculating tsunami travel times
> (http://ocean.dmi.dk/apps/tsunami). The application uses matplotlib/basemap
> for producing contour maps of the tsunami travel times.
>
> To speed up the response time of the application I made a version in which
> the
> calculations are performed for every second integer longitude and latitude
> for calculation windows of 60x60 degrees lon x lat, 90x90, 180x180 and
> global. This is a lot of plots for which I am making a new Basemap instances
> for each plot since:
>
> llcrnrlon
> llcrnrlat
> urcrnrlon
> urcrnrlat
>
> differs for each plot. The initialization of the Basemap instances are
> responsible for the vast majority of the CPU usage in the application.
>
> In converting the application to numpy (from numarray) I was wondering
> whether
> I could reduce the plotting time as well. Is it possible to reuse a Basemap
> instance somehow in my case or is that out of the question?
>
> Regards,
> Jesper
>
>
Jesper: As long as you are using the cylindrical equidistant
projection, something like this might work:
from matplotlib.toolkits.basemap import Basemap
import pylab as p
map = Basemap()
map.fillcontinents(color='coral')
map.drawparallels(p.arange(-90,91,30))
map.drawmeridians(p.arange(-180,181,30))
p.savefig('fig1.png')
ax = p.gca()
llcrnrlat = 20
llcrnrlon = -140
urcrnrlat = 55
urcrnrlon = -65
corners = ((llcrnrlon,llcrnrlat), (urcrnrlon,urcrnrlat))
ax.update_datalim( corners )
ax.set_xlim((llcrnrlon, urcrnrlon))
ax.set_ylim((llcrnrlat, urcrnrlat))
p.savefig('fig2.png')
llcrnrlat = 30
llcrnrlon = -20
urcrnrlat = 80
urcrnrlon = 50
corners = ((llcrnrlon,llcrnrlat), (urcrnrlon,urcrnrlat))
ax.update_datalim( corners )
ax.set_xlim((llcrnrlon, urcrnrlon))
ax.set_ylim((llcrnrlat, urcrnrlat))
p.savefig('fig3.png')
You might not be able to get labels on the meridians and parallels with
this approach though.
-Jeff
--
Jeffrey S. Whitaker Phone : (303)497-6313
NOAA/OAR/CDC R/PSD1 FAX : (303)497-6449
325 Broadway Boulder, CO, USA 80305-3328
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