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I am trying to prepare a plot on the UK national grid.  This is a =
transverse mercator projection centred on the UK with a false origin =
offset from the projection origin (lat_0, lon_0).

The Basemap coordinate system origin (0 Easting and Northing) always =
seems to be set in the lower-left corner of the plot.  The plot I need =
includes data either side of the origin so I need the origin within the =
plot area.

Is there a general way of setting the origin somewhere other than the =
lower-left corner?

I can either get basemap to plot the correct data region, in which case =
the origin is in the wrong place or I can fool Basemap by adjusting the =
axes bounds later.  However, if I do this some of the coastline isn't =
plotted because Basemap decides it isn't on the map.

Cheers,
Stephen.

sidimok wrote:
>>> I would venture a guess that the problem is how to update the plot.

There are issues with calling Show() more than once - you may be able to 
set the interactive mode and get it to work.

the other option is to write a very simple app with a GUI toolkit -- see 
the embedding in ** examples.

If you want to do wxPython, you can use wxmpl to wrap MPL, and building 
a little app with wxTimer and a stop button would be really easy.

-Chris



-- 
Christopher Barker, Ph.D.
Oceanographer

Emergency Response Division
NOAA/NOS/OR&R            (206) 526-6959   voice
7600 Sand Point Way NE   (206) 526-6329   fax
Seattle, WA  98115       (206) 526-6317   main reception

Chr...@no...

>> I would venture a guess that the problem is how to update the plot.

That's it!
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On Oct 10, 2007, at 12:53 PM, massimo sandal wrote:

> sidimok ha scritto:
>> I would write down an MPL script that loads a block data,  
>> generated on the
>> fly (in a file) by another computing program, at a regular time  
>> rate, let's
>> say every 30". The script may have an "exit button" to stop it,  
>> and it might
>> proceed this way:
>> 1. time = time_old
>> 2. Load the "data" from lines 0 to -1(EOF)
>> 3. Save "data" length: N = len(data)
>> 4. plot
>> 5. After time_new-time_old = time_step
>>    5a. load "data_tmp" from lines N to -1
>>    5b. extend "data" with "data_tmp"
>>    5c. plot
>>    5d. Go back to step 5, or press "Stop" button
>> Does anyone have an idea how to encode this purpose?
>
> I don't really understand what the problem is. If you don't you  
> know how
> to wait a definite time between loading the file, have a look at the
> time module:
>
> http://docs.python.org/lib/module-time.html
>
> especially time.sleep()
>
> m.

I would venture a guess that the problem is how to update the plot.
I have not investigated this problem, but I have a hard time figuring
out how matplotlib deals with updating plots after plot.show() has
been called to plot to the screen the first time.

Cheers
   Tommy 

sidimok ha scritto:
> I would write down an MPL script that loads a block data, generated on the
> fly (in a file) by another computing program, at a regular time rate, let's
> say every 30". The script may have an "exit button" to stop it, and it might
> proceed this way:
> 
> 1. time = time_old
> 2. Load the "data" from lines 0 to -1(EOF)
> 3. Save "data" length: N = len(data)
> 4. plot
> 5. After time_new-time_old = time_step
>    5a. load "data_tmp" from lines N to -1
>    5b. extend "data" with "data_tmp"
>    5c. plot
>    5d. Go back to step 5, or press "Stop" button
> 
> Does anyone have an idea how to encode this purpose?

I don't really understand what the problem is. If you don't you know how
to wait a definite time between loading the file, have a look at the
time module:

http://docs.python.org/lib/module-time.html

especially time.sleep()

m.

-- 
Massimo Sandal
University of Bologna
Department of Biochemistry "G.Moruzzi"

snail mail:
Via Irnerio 48, 40126 Bologna, Italy

email:
mas...@un...

tel: +39-051-2094388
fax: +39-051-2094387

Hi everyone!

I would write down an MPL script that loads a block data, generated on the
fly (in a file) by another computing program, at a regular time rate, let's
say every 30". The script may have an "exit button" to stop it, and it might
proceed this way:

1. time = time_old
2. Load the "data" from lines 0 to -1(EOF)
3. Save "data" length: N = len(data)
4. plot
5. After time_new-time_old = time_step
   5a. load "data_tmp" from lines N to -1
   5b. extend "data" with "data_tmp"
   5c. plot
   5d. Go back to step 5, or press "Stop" button

Does anyone have an idea how to encode this purpose?

Thanks.



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Great!  Glad to know I wasn't going crazy ;)

Cheers,
Mike

Wayne E. Harlan wrote:
> By the time I did the update it was at 3931 but it works just fine.  I 
> inserted the 6"x8" picture into swriter and it shows up at 6"x8".   
> Thank you very much !
> 
> Wayne
> 
> Michael Droettboom wrote:
>> Wayne E. Harlan wrote:
>>> Michael:
>>>
>>> Both r3927 and r3929 resulted in the smaller png file that's just 
>>> transparent background.
>>
>> The point of interest is r3926, before this change.  r3927 and r3929 
>> are identical on the trunk.
>>
>> It turns out there was a peculiarity with how image files are saved in 
>> the GtkAgg backend that was triggering this bug.  That should now be 
>> fixed in r3930.  Please try that and let me know how that works for you.
>>
>>> It's roughly 20% of the size of the file I get with the latest 
>>> release, 0.90.1, which opens fine (but has the wrong dpi).  That 
>>> tells me that on my system, some stuff just isn't getting written to 
>>> the file.  I have attached my matplotlibrc and will read the docs to 
>>> see how to save a raw image and attach that, too.  I don't have 
>>> ImageMagick, but can download and compile it later today.  I tried a 
>>> 300 dpi jpg with r3929 and the image saves OK but has the wrong dpi 
>>> (72).  The .raw image is also attached.  It was over 17 MB so I 
>>> bzipped it.  I'm surprised it ended up at 700 bytes !
>>
>> That raw file is fully white and transparent also.
>>
>> Hope that helps,
>> Mike
>>
>>> Wayne
>>>
>>> Michael Droettboom wrote:
>>>> Unfortunately, I'm not able to reproduce this here with the .py you 
>>>> attached.  Both SVN r3926 (before the PNG resolution change) and SVN 
>>>> r3927 (after the PNG resolution change) work for me.  Are you 
>>>> comparing those two SVN revisions, or SVN vs. 0.90.1?
>>>>
>>>> I can confirm that the PNG you attached is all white and fully 
>>>> transparent.
>>>>
>>>> Just for information, my machine (RHEL4) has libpng 1.2.7.
>>>>
>>>> Can you send a copy of your matplotlibrc?  Also, can you save out a 
>>>> .raw image?  (If you rename it to foo.rgba, you can display these 
>>>> images with the ImageMagick command "display -size 1800x1200 -depth 
>>>> 8 foo.rgba") That would help determine whether the problem is in the 
>>>> PNG-writing code or something higher up.
>>>>
>>>> Cheers,
>>>> Mike
>>>>
>>>> Wayne E. Harlan wrote:
>>>>> Michael:
>>>>>
>>>>> I tried a complete checkout for comparison (3929).  In the 
>>>>> meantime, my libpng is 1.2.18 (installed from source as is 
>>>>> everything - this is an LFS/BLFS system.)  Yes, the plot was 
>>>>> working before the change and I can send you some png's from that 
>>>>> if you need to see them, or I can backtrack to 0.90.1 and repeat 
>>>>> this.  Please bear in mind that the plot displays (and always has) 
>>>>> quite correctly on screen - it's just the saved file that consists 
>>>>> of just background.  I have attached the script, the resulting png 
>>>>> and a saved screenshot from the Gimp.  Attachments are gzipped.
>>>>>
>>>>> Wayne
>>>>>
>>>>> Michael Droettboom wrote:
>>>>>> Hmmm.  I'm very surprised that this change could cause that.  All 
>>>>>> it does is add an additional metadata chunk to the PNG file, which 
>>>>>> shouldn't have any affect on the image data itself.  
>>>>>> simple_plot.py works fine for me in GIMP 2.0.5 both before and 
>>>>>> after this change.  Can you verify that this plot was working 
>>>>>> before the change to save the resolution in the PNG file?  If so, 
>>>>>> can you send me the source for your plot and the PNG file?  Also, 
>>>>>> what version of libpng are you using? (pkg-config --version libpng 
>>>>>> should display this on most recent Linux distros).
>>>>>>   
>>>>
>>

-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Adam Mercer wrote:
> On 09/10/2007, Jeff Whitaker <js...@fa...> wrote:
>
>   
>> Adam:  If you can convert your coordinates into latitudes and
>> longitudes, then you can plot the data with the basemap tookit on your
>> choice of map projection (see
>> http://www.scipy.org/Cookbook/Matplotlib/Maps for an example).
>>     
>
> Following that example I'm running into a few problems, this is the code I have:
>
> map = Basemap(projection='ortho',lat_0=50,lon_0=-100,resolution='l',area_thresh=1000.)
> map.drawmeridians(pylab.arange(0,360,30))
> map.drawparallels(pylab.arange(-90,90,30))
> map.contour(lat, lon, values)
>
> where lat is an array of the latitude, lon the corresponding latitude
> and values the value of the quantity I want to plot, this results in
> the error:
>
> Traceback (most recent call last):
>   File "./plot_skymap.py", line 54, in ?
>     map.contour(lat, lon, values)
>   File "/opt/local/lib/python2.4/site-packages/matplotlib/toolkits/basemap/basemap.py",
> line 2484, in contour
>     xx = x[x.shape[0]/2,:]
> IndexError: too many indices
>
> Can anyone give me any pointers, on what the problem is here?
>
> Cheers
>
> Adam
>   
Adam:  If lat and lon are 2D arrays containing the lats and lons of the 
grid in degrees, you first need to convert to map projection coordinates 
using the map instance:

x,y = map(lons, lats)

(if lons and lats are 1D, you can use pylab.meshgrid to make them 2D first)

Then you pass contour the x, y values

map.contour(x,y,values)

For filled contours use contourf.

Are you sure you want an orthographic projection?  I thought sky maps 
used a stereographic projection 
(http://www.progonos.com/furuti/MapProj/Normal/ProjAppl/projAppl.html).

-Jeff

-- 
Jeffrey S. Whitaker         Phone : (303)497-6313
NOAA/OAR/CDC  R/PSD1        FAX   : (303)497-6449
325 Broadway                Boulder, CO, USA 80305-3328

On Tuesday 09 October 2007 20:08:29 Adam Mercer wrote:
> On 09/10/2007, Jeff Whitaker <js...@fa...> wrote:
> > Adam:  If you can convert your coordinates into latitudes and
> > longitudes, then you can plot the data with the basemap tookit on your
> > choice of map projection (see
> > http://www.scipy.org/Cookbook/Matplotlib/Maps for an example).
>
> Following that example I'm running into a few problems, this is the code I
> have:

Gonna assume that values is a 1D array, right ? I'm pretty sure that you need 
a 2D array for contours to work.

http://www.scipy.org/Cookbook/Matplotlib/Gridding_irregularly_spaced_data

On 09/10/2007, Jeff Whitaker <js...@fa...> wrote:

> Adam:  If you can convert your coordinates into latitudes and
> longitudes, then you can plot the data with the basemap tookit on your
> choice of map projection (see
> http://www.scipy.org/Cookbook/Matplotlib/Maps for an example).

Following that example I'm running into a few problems, this is the code I have:

map = Basemap(projection='ortho',lat_0=50,lon_0=-100,resolution='l',area_thresh=1000.)
map.drawmeridians(pylab.arange(0,360,30))
map.drawparallels(pylab.arange(-90,90,30))
map.contour(lat, lon, values)

where lat is an array of the latitude, lon the corresponding latitude
and values the value of the quantity I want to plot, this results in
the error:

Traceback (most recent call last):
  File "./plot_skymap.py", line 54, in ?
    map.contour(lat, lon, values)
  File "/opt/local/lib/python2.4/site-packages/matplotlib/toolkits/basemap/basemap.py",
line 2484, in contour
    xx = x[x.shape[0]/2,:]
IndexError: too many indices

Can anyone give me any pointers, on what the problem is here?

Cheers

Adam