[Numpy-discussion] subdivide array
On 30 November 2010 17:58, Pierre GM wrote: > On Nov 30, 2010, at 5:40 PM, John wrote: >> I have an array of data for a global grid at 1 degree resolution. It's >> filled with 1s and 0s, and it is just a land sea mask (not only, but >> as an example). I want to be able to regrid the data to higher or >> lower resolutions (i.e. 0.5 or 2 degrees). But if I try to use any >> standard interp functions, such as mpl_toolkits.basemap.interp it >> fails -- I assume due to the data being binary. >> >> I guess there may be a fairly easy routine to do this?? Does someone >> have an example? > > Just a random idea: have you tried to convert your input data to float? > Hopefully you could get some values between 0 and 1 for your interpolated > values, that you'll have to transform back to integers following a scheme of > your choosing... I would argue that some float between 0 and 1 is an excellent representation when regridding a binary land-sea-mask onto a higher resolution. After all, this information is not there. Why should a land-sea mask be binary anyway? As if a grid-cell can only be fully ocean or fully land... BTW, I just realised Pythons convention that negative indices count from the end of the array is perfect when using a 180x360 land-sea-mask, as lon[-30] and lon[330] mean and should mean the same :) Gerrit. -- Gerrit Holl PhD student at Department of Space Science, Luleå University of Technology, Kiruna, Sweden http://www.sat.ltu.se/members/gerrit/ ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] subdivide array
On Nov 30, 2010, at 5:40 PM, John wrote: > Hello, > > I have an array of data for a global grid at 1 degree resolution. It's > filled with 1s and 0s, and it is just a land sea mask (not only, but > as an example). I want to be able to regrid the data to higher or > lower resolutions (i.e. 0.5 or 2 degrees). But if I try to use any > standard interp functions, such as mpl_toolkits.basemap.interp it > fails -- I assume due to the data being binary. > > I guess there may be a fairly easy routine to do this?? Does someone > have an example? Just a random idea: have you tried to convert your input data to float? Hopefully you could get some values between 0 and 1 for your interpolated values, that you'll have to transform back to integers following a scheme of your choosing... ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] subdivide array
> I have an array of data for a global grid at 1 degree resolution. It's > filled with 1s and 0s, and it is just a land sea mask (not only, but > as an example). I want to be able to regrid the data to higher or > lower resolutions (i.e. 0.5 or 2 degrees). But if I try to use any > standard interp functions, such as mpl_toolkits.basemap.interp it > fails -- I assume due to the data being binary. > > I guess there may be a fairly easy routine to do this?? Does someone > have an example? > When I've had to do this, I typically set Basemap's interp to do nearest-neighbor interpolation (by setting order=0). It defaults to order=1, which is bilinear interpolation, which will destroy the binary nature of your data (as you perhaps noticed). Tim ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
[Numpy-discussion] subdivide array
Hello, I have an array of data for a global grid at 1 degree resolution. It's filled with 1s and 0s, and it is just a land sea mask (not only, but as an example). I want to be able to regrid the data to higher or lower resolutions (i.e. 0.5 or 2 degrees). But if I try to use any standard interp functions, such as mpl_toolkits.basemap.interp it fails -- I assume due to the data being binary. I guess there may be a fairly easy routine to do this?? Does someone have an example? Thanks! ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
