Re: [Matplotlib-users] draw track across the Dateline in Basemap

[Eric F. <ef...@ha...>]

On 07/03/2012 08:21 AM, Jeff Whitaker wrote:
> On 7/3/12 11:39 AM, fatuheeva wrote:
>> Hello,
>> I am wondering if Basemap has the ability to plot a track across the
>> Dateline? Plotting longitudes that go across the Dateline (e.g.,
>> [175,177,179,-179,-176]) wraps the track back around the globe when it
>> goes from 179 to -179. Instead, I want them directly connected. My
>> Basemap instance looks like:
>>
>> m = Basemap(projection='merc',llcrnrlat = 10,urcrnrlat = 30,llcrnrlon
>> = 160,\
>>                 urcrnrlon = -160,lat_ts = 20,resolution = 'l',lon_0 = 180)
>>
>> Am I screwed on this one?
>> Thanks,
>>
>> Mike
>
> Mike:  There's no automagical way to do this. You either have to shift
> your map so the dateline is in the middle, or split you track into two
> segments.
>
> -Jeff

If I am reading the original message correctly, what is needed is for 
the longitudes that are to be plotted to be unwrapped as well, as in the 
unwrap_lon (and unwrap) function here:

http://currents.soest.hawaii.edu/hg/pycurrents/file/2851d48cd865/data/navcalc.py

Eric

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