draw track across the Dateline in Basemap

Community matplotlib-users
1

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

2

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

···

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

-- Jeffrey S. Whitaker Phone : (303)497-6313
Meteorologist FAX : (303)497-6449
NOAA/OAR/PSD R/PSD1 Email : 325 Broadway Office : Skaggs Research Cntr 1D-113
Boulder, CO, USA 80303-3328 Web :

Jeffrey.S.Whitaker@…259…http://tinyurl.com/5telg

3

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

···

On 07/03/2012 08:21 AM, Jeff Whitaker wrote:

On 7/3/12 11:39 AM, fatuheeva wrote:

--
Jeffrey S. Whitaker Phone : (303)497-6313
Meteorologist FAX : (303)497-6449
NOAA/OAR/PSD R/PSD1 Email :Jeffrey.S.Whitaker@...259...
325 Broadway Office : Skaggs Research Cntr 1D-113
Boulder, CO, USA 80303-3328 Web :Jeffrey S. Whitaker: NOAA Physical Sciences Laboratory

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4

Thanks Jeff. I’ll explore those options and see what I can do.

Mike

···

From: Jeff Whitaker <jeffrey.s.whitaker@…259…>
To: matplotlib-users@…712…orge.net; fatuheeva@…9…
Sent: Tuesday, July 3, 2012 11:21 AM
Subject: Re: [Matplotlib-users] draw track across the Dateline in
Basemap

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

-- Jeffrey S. Whitaker Phone : (303)497-6313
Meteorologist FAX : (303)497-6449
NOAA/OAR/PSD R/PSD1 Email : Jeffrey.S.Whitaker@...259...
325 Broadway Office : Skaggs Research Cntr 1D-113
Boulder, CO, USA 80303-3328 Web : http://tinyurl.com/5telg