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Basemap readshapefile should read shapefile for the long/lat specified in the Basemap instance. #5993
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I think the difficulty with this request is that Basemap uses the pyshp On Fri, Feb 12, 2016 at 11:21 AM, wxguy notifications@github.com wrote:
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Thanks for the clarification. Is it not possible to pickle the shapefile and use it again. At least this would improve the plotting speed. Also is it possible to use |
It would be great and highly appreciated if this request is accepted. |
This should be moved to the basemap issue tracker. matplotlib/basemap#263 |
I need to plot more than 100 images for a specific area which are not included in default Basemap. I have read lot of documentation regarding speeding up the matplotlib/basemap plotting examples. Most of them lead to this example https://github.com/matplotlib/basemap/blob/master/examples/hires.py . I agree that
picklling
does improve the code for Basemap instance. However, I also required to read the shape file once the Basemap instance is created like following:-south = 0
north = 5
west = 70
east = 85
following is a global instance and read once only
m = Basemap(projection='merc', llcrnrlat=south, urcrnrlat=north,
llcrnrlon=west, urcrnrlon=east, resolution='c')
the following line a part of plotting function and not a continuous line from above
m.readshapefile('data/gis-data/world_countries/ne_10m_admin_0_countries_lakes', 'ne_10m_admin_0_countries_lakes', linewidth=0.7)
Please see that I am reading shape file from NE 10 resolution file (~ 8 mb). When I read this shape file it takes about 10-15 sec which is too much for just map. This is a big problem as the code (m.readshapefile) reside inside the map plotting function and it has to be called to plot boundaries each time.
I have a question and a proposal (sort of) here.
Question:-
How to improve the plotting time by reducing the reading time of shape file using the default
m.readshapefile
code. There could be some solution similar to pickle which I am not aware. Best people can share their experience here (with some example code).Proposal (sort of):-
The major problem with the reading shape file which I think is basemap reading the entire shapefile. Why should it read all the data from shapefile if you the lat/lon which are already specified in the basemap instance. Therefore,
readshapefile
should only read data within the lon/lat specified from the basemap instance. I hope that this way shapefile read time may be reduced greatly.I may or may not be correct somewhere above. Forgive my ignorance. I hopr that some one may help me on reading shapefile/ plotting the map faster.
Note ::: Please don't suggest me to use lower resolution basemap/shapefile.
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