matplotlib-users Mailing List for matplotlib (Page 6)

I would like to use a higher resolution coastline than the high resolution
coastline optionally provided with (specifically, I would like to use the
NOAA/NOS Medium Resolution Coastline). I can see two ways to do this:

Option 1) Create a coastline file using the in the NOAA/NOS data in the same
format as the data files used by the basemap toolkit. I couldn't find a
description of this format, but it appears that it is partially explained by
the code snippet:

if line.startswith('P'):
                area = float(linesplit[5])
                west,east,south,north =
float(linesplit[6]),float(linesplit[7]),float(linesplit[8]),float(linesplit[9])
                typ = int(linesplit[3])

So the first line of the existing high resolution coastline is:
P      0  169598 1 W 79866900.000 -17.53378 190.35911 -34.83044  77.71958

Which should be interpreted as 
typ = 1
area = 79866900.000
west = -17.53378 
east = 190.35911 
south = -34.83044  
north = 77.71958

area is used to control whether this segment of coastline is displayed
the directions are the bounding box for the coastline segment
I am not clear on how typ is used (I see it getting manipulated, but I don't
see it ever getting used), or what its acceptable values are. I am also not
clear what the first, second and fourth values of the line are (not counting
the initial 'P'). Any help with this format would be appreciated.

Option 2) Load a coastline by whatever means I choose as a list of lists of
touples (or some other format?) and then transform those values using the
basemap object. If the coastline were easily expressed as a pair of lists or
arrays lon,lat, then I could simply use 

b=basemap(...) 
coastx,coasty = b(lcoastlon,coastlat)

but the coastline is made up of multiple segments (islands, etc). Is the
best way to transform a collection of segments simply to loop over the
segments?

coast = [ [(x11,y11),... (x1n,y1n)], [(x21,y21),... (x2n,y2n)],...
[(xn1,yn1),...(xnn,ynn)] ]
newcoast = []
for c in coast:
  ln,lt = map(list,zip(*c))
  x,y = m(ln,lt)
  newcoast.append(zip(x,y))

Once I have a transformed list of lists of touples, I can replace the
basemap objects coastsegs
b.coastsegs = newcoast

and then draw the coastline using the built-in 
b.drawcoastlines()

Or is there some method that I am missing?


-- 
View this message in context: http://www.nabble.com/coastlines-in-matplotlib.toolkits.basemap-tf4617110.html#a13186210
Sent from the matplotlib - users mailing list archive at Nabble.com.

Do you know if there is a reason why I cannot succeed in generating a
pick_event using wxmpl?
I know I could use EVT_POINT but I need the picker event to return the event.ind

thanks!

Hi, I am trying to install matplotlib 0.90.1.  I have python 2.5 on a fresh
Mandriva 2007.1 installation.  I have installed numpy and scipy - I think
these are ok, they both import and the tests were largely successful.  I
believe I have all the background packages installed -

   - matplotlib core: zlib, zlib-devel, libpng, libpng-devel, freetype,
   freetype-devel, freetype-utils
   - gtk/gtkagg backend: gtk2-devel, gtk+-devel, pygtk2, glib-devel,
   pygtk2-devel, gnome-libs-devel, pygtk2-libglade
   - tk backend: tcl, tk, tkinter
   - wx/wxagg backends - the wxpython rpms from
wxpython<http://wxpython.org%3c/a>

apart from freetype-utils which I have not been able to find.


With mpl I get the following, having set the path like this:

In [2]: sys.path
Out[2]:
['',
 '/usr/bin',
 '/home/emason',
 '/usr/lib/python2.5/site-packages/numpy/lib',
 '/usr/lib/python2.5/site-packages/scipy/lib',
 '/usr/lib/python25.zip',
 '/usr/lib/python2.5',
 '/usr/lib/python2.5/plat-linux2',
 '/usr/lib/python2.5/lib-tk',
 '/usr/lib/python2.5/lib-dynload',
 '/usr/lib/python2.5/site-packages',
 '/usr/lib/python2.5/site-packages/Numeric',
 '/usr/lib/python2.5/site-packages/PIL',
 '/usr/lib/python2.5/site-packages/gtk-2.0',
 '/usr/lib/python2.5/site-packages/wx-2.6-gtk2-unicode',
 '/usr/lib/python2.5/site-packages/IPython/Extensions',
 '/home/emason/.ipython']
[for PYTHONPATH in .bashrc I defined the paths to numpy/lib and scipy/lib; I
don't know if this is necessary, in any event it made no difference with
these not defined]

When I then try to build I get:

[root@msasa matplotlib-0.90.1]# python setup.py build
running build
running build_py
copying lib/matplotlib/mpl-data/matplotlibrc -> build/lib.linux-i686-2.5
/matplotlib/mpl-data
running build_ext
building 'matplotlib._nc_transforms' extension
gcc -pthread -fno-strict-aliasing -DNDEBUG -O2 -g -pipe
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fomit-frame-pointer -march=i586
-mtune=generic -fasynchronous-unwind-tables -g -fPIC -Isrc -I.
-I/usr/local/include -I/usr/include -I. -I/usr/include/python2.5 -c
src/_nc_transforms.cpp -o build/temp.linux-i686-2.5/src/_nc_transforms.o
-DNUMERIC=1 -DVERBOSE
src/_nc_transforms.cpp:13:40: error: Numeric/arrayobject.h: No such file or
directory
src/_nc_transforms.cpp: In member function 'Py::Object
Bbox::update_numerix_xy(const Py::Tuple&)':
src/_nc_transforms.cpp:517: error: 'PyArrayObject' was not declared in this
scope
src/_nc_transforms.cpp:517: error: 'xyin' was not declared in this scope
src/_nc_transforms.cpp:517: error: expected primary-expression before ')'
token
src/_nc_transforms.cpp:517: error: expected `;' before 'PyArray_FromObject'
src/_nc_transforms.cpp: In member function 'Py::Object
Bbox::update_numerix(const Py::Tuple&)':
src/_nc_transforms.cpp:586: error: 'PyArrayObject' was not declared in this
scope

[snip]

src/_nc_transforms.cpp:1275: error: 'retmask' was not declared in this scope
src/_nc_transforms.cpp:1278: error: expected primary-expression before ')'
token
src/_nc_transforms.cpp:1278: error: expected `;' before 'PyArray_FromDims'
src/_nc_transforms.cpp: In function 'void init_nc_transforms()':
src/_nc_transforms.cpp:2428: error: 'import_array' was not declared in this
scope
error: command 'gcc' failed with exit status 1
[root@msasa matplotlib-0.90.1]#


It seems to trip up when expecting a file 'arrayobject.h' in the /Numeric
directory; indeed that file is not there, though Numeric is on the path.
Numeric came as part of the Mandriva install.

I'd be grateful for any help with this, thanks in advance, Evan

Pascoe, S (Stephen) wrote:
> Thanks Jeff,
>
> Unfortunately another issue is with plotting the axes tick labels.  This
> output is for a public service where the users expect to see eastings
> and northings displayed from the official UK national grid origin.  I
> can use standard matplotlib axes to produce eastings/northings but with
> your solution the origin would be shown as in the wrong place.
>
> I can envisage solving this by creating a tick Formatter object that
> offsets the axes.  Maybe that is my solution but I was hoping for a
> simpler way.
>
> Cheers,
> Stephen.
>   

Stephen: Using a TickFormatter is probably the best solution.  -Jeff

P.S.  Could you send me an example when you're done - perhaps to include 
in the examples directory?
> ---
> Stephen Pascoe  +44 (0)1235 445980
> British Atmospheric Data Centre
> Rutherford Appleton Laboratory
>
> -----Original Message-----
> From: Jeff Whitaker [mailto:js...@fa...] 
> Sent: 12 October 2007 13:11
> To: Pascoe, S (Stephen)
> Cc: mat...@li...
> Subject: Re: [Matplotlib-users] Basemap with origin within the plot
>
> Pascoe, S (Stephen) wrote:
>   
>> 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.
>>
>>
>>   
>>     
> Stephen:  There's no way to change the coordinate system Basemap uses.  
> To get you data to plot in the correct place, just add an offset
>
> xoffset, yoffset = map(lon_0, lat_0)
>
> to the UK national grid coordinates of the data you are plotting.
>
> HTH,
>
> -Jeff
>
>   


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

Pascoe, S (Stephen) wrote:
> 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.
>
>
>   
Stephen:  There's no way to change the coordinate system Basemap uses.  
To get you data to plot in the correct place, just add an offset

xoffset, yoffset = map(lon_0, lat_0)

to the UK national grid coordinates of the data you are plotting.

HTH,

-Jeff

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

Hi,

I have some time series data of server CPU usage (user, system, WIO,  
free, etc) and would like to plot this as a stacked bar chart, with  
dates / times on the x axis (as per plot_date for x, y series data).

Is this possible?

Cheers,
James.

On 10/10/2007, Pascoe, S (Stephen) <S.P...@rl...> wrote:

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

I've just had to deal with a similar problem, you need to use the
basemap.shiftgrid() method to shift the co-ordinate grid accordingly.

Cheers

Adam

Hi Joshua,

> As you can see from the attached graph, there is a break the in graph 
> somewhere around 7 AM or so.  This is the data I am graphing for that red 
> line:
>
> "2007-10-09 00:00:00",0.015
> "2007-10-09 01:00:00",0.015
> "2007-10-09 02:00:00",0.014
> "2007-10-09 03:00:00",0.012
> "2007-10-09 04:00:00",0.008
> "2007-10-09 05:00:00",0.002
> "2007-10-09 06:00:00",-0.006
>   
<snip>
> If I change the -0.006 at 6:00AM to 0.006, it graphs with no break in the 
> line. 
Can not comment on Matplotlib, ... but what method are you using the
process your input?
RegEx or other ?, can it handle negative input?

The attached script has missing data points where the data point in None

Don't know if that helps
Steve

John,

I would prefer to be able to use the power and flexibility of datestr2num
and the underlying dateutil.parser, rather than writing my own parser.
However, looking further at dateutil.parser.parse, it takes an argument
tzinfos, which allows timezone names other than the local timezone and
UTC/GMT/Z to be understood within parse. I haven't worked out the full range
of functionality for the tzinfos argument, but a simple example would be:

> tzlibrary = {'EST':-5*60*60,'EDT':-4*60*60,'EST':-6*60*60,
> 'CDT':-5*60*60,'PST':-8*60*60,'PDT':-7*60*60}
> matplotlib.dates.date2num(dateutil.parser.parse('jan 1, 2007 12:00
> PST',tzinfos=tzlibrary))
732677.83333333337
> matplotlib.dates.date2num(dateutil.parser.parse('jan 1, 2007 12:00
> PDT',tzinfos=tzlibrary))
732677.79166666663
> matplotlib.dates.date2num(dateutil.parser.parse('jan 1, 2007 12:00
> EDT',tzinfos=tzlibrary))
732677.66666666663 

Actually, I can just duplicate datestr2num, but pass a tzinfos dictionary as
well, e.g.:

def datestr2num(d,tzinfos=None):
    """
    Convert a date string to a datenum using dateutil.parser.parse
    d can be a single string or a sequence of strings
    """
    if is_string_like(d):
        dt = dateutil.parser.parse(d,tzinfos=tzinfos)
        return date2num(dt)
    else:
        return date2num([dateutil.parser.parse(s,tzinfos=tzinfos) for s in
d])

explicitly passing a tzinfos of None does not cause any problems for
dateutil.parser.parse.

thanks,

Charles


John Hunter-4 wrote:
> 
> On 10/11/07, Charles Seaton <cs...@st...> wrote:
> 
>> Any suggestions on how to get either matplotlib.dates.datestr2num or
>> dateutil.parser.parse to properly handle timezone information in the
>> datestring would be greatly appreciated.
> 
> Not sure how to answer this question vis-a-vid dateutil.parser, but
> you may want to consider creating your own datestr -> datetime
> converter using time.strptime and then allowing mpl to convert to
> numbers using date2num.  I think you can use the %Z format code for
> timezones.
> 
> JDH
> 
> 

-- 
View this message in context: http://www.nabble.com/datestr2num%2C-dateutil.parse-and-timezone-problems-tf4609462.html#a13167297
Sent from the matplotlib - users mailing list archive at Nabble.com.

On 11/10/2007, Jeff Whitaker <js...@fa...> wrote:

> but I think you want
>
> values, lon = basemap.shiftgrid(180, values, lon, start=False)

Thats it! Thanks a lot!

Cheers

Adam

Disclaimer: I do know Python, but am not terribly familiar with Matplotlib as 
I'm taking over the maintenance of our graphing libraries.  This post is 
likely to leave out details that you need to help diagnose the problem, but I 
didn't think posting all 1500 or so lines of our graphing routines would be 
that helpful at this point. :)

As you can see from the attached graph, there is a break the in graph 
somewhere around 7 AM or so.  This is the data I am graphing for that red 
line:

"2007-10-09 00:00:00",0.015
"2007-10-09 01:00:00",0.015
"2007-10-09 02:00:00",0.014
"2007-10-09 03:00:00",0.012
"2007-10-09 04:00:00",0.008
"2007-10-09 05:00:00",0.002
"2007-10-09 06:00:00",-0.006
"2007-10-09 07:00:00",1.068
"2007-10-09 08:00:00",12.8
"2007-10-09 09:00:00",15.21
"2007-10-09 10:00:00",20.13
"2007-10-09 11:00:00",20.94
"2007-10-09 12:00:00",21.15
"2007-10-09 13:00:00",21.13
"2007-10-09 14:00:00",20.88
"2007-10-09 15:00:00",20.72
"2007-10-09 16:00:00",20.55
"2007-10-09 17:00:00",16.28
"2007-10-09 18:00:00",13.18
"2007-10-09 19:00:00",4.342
"2007-10-09 20:00:00",0.016
"2007-10-09 21:00:00",0.015
"2007-10-09 22:00:00",0.015
"2007-10-09 23:00:00",0.015

If I change the -0.006 at 6:00AM to 0.006, it graphs with no break in the 
line.  This is not a big deal to me, but it is a big deal to the consumer of 
these graphs.  Could this be a bug in matplotlib, or is it more likely a bug 
in what we're doing with the data (almost nothing) before it gets to the 
matplotlib graphing routines?

Thanks for any insight you can give.

j

-- 
Joshua Kugler                           
Lead System Admin -- Senior Programmer
http://www.eeinternet.com
PGP Key: http://pgp.mit.edu/  ID 0xDB26D7CE
PO Box 80086 -- Fairbanks, AK 99708 -- Ph: 907-456-5581 Fax: 907-456-3111

Adam Mercer wrote:
> On 11/10/2007, Jeff Whitaker <js...@fa...> wrote:
>
>   
>> Adam:  I assume your data is on a latitude-longitude grid?  You've asked
>> for a mollweide projection centered on the Greenwich meridian.  Your
>> data is not centered on Greenwich - but the error message is trying to
>> say that you can shift your grid (with the shiftgrid function) so that
>> is has the same orientation as the map projection region.  This only
>> comes into play with global projections that 'wrap-around' at the edges,
>> like the mollweide and mercator projections.  The orthographic
>> projection does not 'wrap around' - hence you don't get the error message.
>>     
>
> Looking at the shiftmap function it looks like I should shift the
> co-ordinate grid so that my longitude runs from -180 to 180 instead of
> 0 to 360, therefore the following shiftgrid call should do this
>
> values, lon = basemap.shiftgrid(180, values, lon)
>
> However I still get the same error and the corruption in the resulting
> plot.  I feel like I'm missing something obvious here but can't find
> it.
>
> Cheers
>
> Adam
>   
Adam:

 From the basemap docs;

shiftgrid(lon0, datain, lonsin, start=True)
    shift global lat/lon grid east or west.
    assumes wraparound (or cyclic point) is included.
     
    lon0:  starting longitude for shifted grid
           (ending longitude if start=False). lon0 must be on
           input grid (within the range of lonsin).
    datain:  original data.
    lonsin:  original longitudes.
    start[True]: if True, lon0 represents the starting longitude
    of the new grid. if False, lon0 is the ending longitude.
     
    returns dataout,lonsout (data and longitudes on shifted grid).


You did

values, lon = basemap.shiftgrid(180, values, lon)

but I think you want

values, lon = basemap.shiftgrid(180, values, lon, start=False)

HTH,

-Jeff

-- 
Jeffrey S. Whitaker         Phone  : (303)497-6313
Meteorologist               FAX    : (303)497-6449
NOAA/OAR/PSD  R/PSD1        Email  : Jef...@no...
325 Broadway                Office : Skaggs Research Cntr 1D-124
Boulder, CO, USA 80303-3328 Web    : http://tinyurl.com/5telg

On 10/11/07, Alexander Schmolck <a.s...@gm...> wrote:
> Hi,
>
> I'm using matplotlib in a C++ app (with a qt4 gui), by embedding python with
> boost::python. The C++ app calls Py_Initialize(), init_myplottingmodule(), and
> boost::python::import("matplotlib.pylab") once on startup and certain GUI
> events then fire up a matplotlib window via calls like this one:
>
> // simplified version
> void plotCurve(){
>     clf();
>     title("Diagonal line plot");
>     double O1[] = {0,1};
>     plot(std::vector<double>(O1,O1+2), std::vector<double>(O1,O1+2), "b:");
>     show();

Eeeeew, that looks really dangerous.  For starters, I would never try
to do this using pylab, but rather follow the lead of
examples/embedding_in_qt.py.  Then you won't be competing for the
mainloop....

JDH

On 10/11/07, Charles Seaton <cs...@st...> wrote:

> Any suggestions on how to get either matplotlib.dates.datestr2num or
> dateutil.parser.parse to properly handle timezone information in the
> datestring would be greatly appreciated.

Not sure how to answer this question vis-a-vid dateutil.parser, but
you may want to consider creating your own datestr -> datetime
converter using time.strptime and then allowing mpl to convert to
numbers using date2num.  I think you can use the %Z format code for
timezones.

JDH

I am having some problems getting matplotlib.dates.datestr2num to handle
timezones in the datestring.

>import matplotlib
>matplotlib.dates.datestr2num('Jan 1, 2007 12:00 PDT')
732677.83333333337
>matplotlib.dates.datestr2num('Jan 1, 2007 12:00 PST')
732677.83333333337
>matplotlib.dates.datestr2num('Jan 1, 2007 12:00-08')
732677.83333333337
>matplotlib.dates.datestr2num('Jan 1, 2007 12:00 UTC')
732677.5
>matplotlib.dates.datestr2num('Jan 1, 2007 12:00 EST')
732677.5
>matplotlib.dates.datestr2num('Jan 1, 2007 12:00-07')
732677.79166666663

The problem appears to lie with dateutil, as direct use of the
dateutil.parser.parse function shows the same problem:

> import dateutil.parser
> dateutil.parser.parse('Jan 1, 2007 12:00 EST')
datetime.datetime(2007, 1, 1, 12, 0)
> dateutil.parser.parse('Jan 1, 2007 12:00 PDT')
datetime.datetime(2007, 1, 1, 12, 0, tzinfo=tzlocal())
> dateutil.parser.parse('Jan 1, 2007 12:00 PST')
datetime.datetime(2007, 1, 1, 12, 0, tzinfo=tzlocal())

I am using dateutil version 1.2.

Any suggestions on how to get either matplotlib.dates.datestr2num or
dateutil.parser.parse to properly handle timezone information in the
datestring would be greatly appreciated.

Charles Seaton
OHSU/CMOP
-- 
View this message in context: http://www.nabble.com/datestr2num%2C-dateutil.parse-and-timezone-problems-tf4609462.html#a13162968
Sent from the matplotlib - users mailing list archive at Nabble.com.

Hi Yadin,

I am a simple user, but I already faced this problem. The idea I used is 
to plot the data as an image, with magnitudes being converted in color 
levels.

To do that, you have to define an array (let's say 'Z', Z(x,y) with dims 
len(X) and len(Y) and fill it with tour magnitudes. Then you have a two 
dimensional array that you display as an image using :

im = pylab.Imshow(Z)

Imshow has a lot of options you can use to customize your display, and 
you can add a colorbar with :
pylab.colorbar()

I have some examples of such scripts, but commented in French, so 
perhaps not very useful for you.

See the user's guide to begin, p 38 for example.

Regards,
Alain

yadin Bocuma Rivas a écrit :
>
> I i have tree lists or array of values
> list x of 100... values
> list y of 100.. values
> list mag of 100.. values
> list x and y are coordiantes of points
> and list Mag is magnitude of something at that point
>
> how can i plot this quantities using matplotlib, any function please?
>
> my code starts as.....i need to plot the points vhat can i use?
>
> from __future__ import division
> from matplotlib.patches import Patch
> from pylab import *
>
> def func3(x,y):
>     return (1- x/2 + x**5 + y**3)*exp(-x**2-y**2)
>
>
> # make these smaller to increase the resolution
> dx, dy = 0.5, 0.5
>
> X = arange(-3.0, 3.0001, dx)
>
> Y = arange(-3.0, 3.0001, dy)
>
> Mag= X**2+Y**2
>
> ?????(X, Y, Mag)
> colorbar()
> axis([-3,3,-3,3])
> savefig('three d plot of points making a surface')
> show()
>
>
> ------------------------------------------------------------------------
>
> ¡Sé un mejor ambientalista!
> Encuentra consejos para cuidar el lugar donde vivimos en:
> http://telemundo.yahoo.com/promos/mejorambientalista.html
>
>
> ------------------------------------------------------------------------
>
> ¡Sé un mejor besador!
> Comparte todo lo que sabes sobre besos en:
> http://telemundo.yahoo.com/promos/mejorbesador.html
> ------------------------------------------------------------------------
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Splunk Inc.
> Still grepping through log files to find problems?  Stop.
> Now Search log events and configuration files using AJAX and a browser.
> Download your FREE copy of Splunk now >> http://get.splunk.com/
> ------------------------------------------------------------------------
>
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>   

On 11/10/2007, Jeff Whitaker <js...@fa...> wrote:

> Adam:  I assume your data is on a latitude-longitude grid?  You've asked
> for a mollweide projection centered on the Greenwich meridian.  Your
> data is not centered on Greenwich - but the error message is trying to
> say that you can shift your grid (with the shiftgrid function) so that
> is has the same orientation as the map projection region.  This only
> comes into play with global projections that 'wrap-around' at the edges,
> like the mollweide and mercator projections.  The orthographic
> projection does not 'wrap around' - hence you don't get the error message.

Looking at the shiftmap function it looks like I should shift the
co-ordinate grid so that my longitude runs from -180 to 180 instead of
0 to 360, therefore the following shiftgrid call should do this

values, lon = basemap.shiftgrid(180, values, lon)

However I still get the same error and the corruption in the resulting
plot.  I feel like I'm missing something obvious here but can't find
it.

Cheers

Adam

On 11/10/2007, Jeff Whitaker <js...@fa...> wrote:

> Adam:  I assume your data is on a latitude-longitude grid?  You've asked
> for a mollweide projection centered on the Greenwich meridian.  Your
> data is not centered on Greenwich - but the error message is trying to
> say that you can shift your grid (with the shiftgrid function) so that
> is has the same orientation as the map projection region.  This only
> comes into play with global projections that 'wrap-around' at the edges,
> like the mollweide and mercator projections.  The orthographic
> projection does not 'wrap around' - hence you don't get the error message.

Thanks, that makes sense now.

Cheers

Adam

Adam Mercer wrote:
> Hi
>
> I'm running into a problem using the mollweide projection, with the
> following simplified code, my actual code doesn't use random data for
> values but this is a clearer example to the problem I'm experiencing:
>
> lon = numpy.arange(0, 361, 1)
> lat = numpy.arange(-90, 91, 1)
> x, y = numpy.meshgrid(lon, lat)
> values = numpy.random.random((181, 361))
>
> map = basemap.Basemap(projection='moll', lon_0=0, resolution='c')
> map.drawcoastlines()
> map.drawcountries()
> map.drawmapboundary()
> map.drawmeridians(numpy.arange(0,360,30))
> map.drawparallels(numpy.arange(-90,90,30))
>
> X, Y = map(x, y)
>
> map.contourf(X, Y, values)
>
> I get the following error:
>
>  WARNING: x coordinate not montonically increasing - contour plot
>  may not be what you expect.  If it looks odd, your can either
>  adjust the map projection region to be consistent with your data, or
>  (if your data is on a global lat/lon grid) use the shiftgrid
>  function to adjust the data to be consistent with the map projection
>  region (see examples/contour_demo.py).
>
> And the resulting map is incorrect due to the horizontal trends, see
> http://tier2.ihepa.ufl.edu/~ram/files/moll.jpg
>
>
> but if I use the orthographic projection ie:
>
> map = basemap.Basemap(projection='ortho', lat_0=-20, lon_0=-30, resolution='c')
>
> Then there are no errors, and the map is displayed as expected, see
> http://tier2.ihepa.ufl.edu/~ram/files/ortho.jpg
>
> I am unsure as to why I am receiving this error for the mollweide
> projection, as my coordinate grid is covering the entire surface.  I
> am clearly doing something wring here but I don't know what - does
> anyone know what is causing this issue?
>
> Cheers
>
> Adam
>   

Adam:  I assume your data is on a latitude-longitude grid?  You've asked 
for a mollweide projection centered on the Greenwich meridian.  Your 
data is not centered on Greenwich - but the error message is trying to 
say that you can shift your grid (with the shiftgrid function) so that 
is has the same orientation as the map projection region.  This only 
comes into play with global projections that 'wrap-around' at the edges, 
like the mollweide and mercator projections.  The orthographic 
projection does not 'wrap around' - hence you don't get the error message.


-Jeff

-- 
Jeffrey S. Whitaker         Phone  : (303)497-6313
Meteorologist               FAX    : (303)497-6449
NOAA/OAR/PSD  R/PSD1        Email  : Jef...@no...
325 Broadway                Office : Skaggs Research Cntr 1D-124
Boulder, CO, USA 80303-3328 Web    : http://tinyurl.com/5telg

=0AI i have tree lists or array of values=0Alist x of 100... values=0Alist =
y of 100.. values=0Alist mag of 100.. values=0Alist x and y are coordiantes=
 of points =0Aand list Mag is magnitude of something at that point=0A=0Ahow=
 can i plot this quantities using matplotlib, any function please?=0A=0Amy =
code starts as.....i need to plot the points vhat can i use?=0A=0Afrom __fu=
ture__ import division=0Afrom matplotlib.patches import Patch=0Afrom pylab =
import *=0A=0Adef func3(x,y):=0A    return (1- x/2 + x**5 + y**3)*exp(-x**2=
-y**2)=0A=0A=0A# make these smaller to increase the resolution=0Adx, dy =3D=
 0.5, 0.5=0A=0AX =3D arange(-3.0, 3.0001, dx)=0A=0AY =3D arange(-3.0, 3.000=
1, dy)=0A=0AMag=3D X**2+Y**2=0A=0A?????(X, Y, Mag)=0Acolorbar()=0Aaxis([-3,=
3,-3,3])=0Asavefig('three d plot of points making a surface')=0Ashow()=0A=
=0A=0A=0A=0A=0A=0A      =0A=A1S=E9 un mejor ambientalista!=0AEncuentra cons=
ejos para cuidar el lugar donde vivimos en:=0A=0Ahttp://telemundo.yahoo.com=
/promos/mejorambientalista.html=0A=0A=0A=0A=0A=0A      ____________________=
________________________________________________________________=0A=A1S=E9 =
un mejor fot=F3grafo!=0APerfecciona tu t=E9cnica y encuentra las mejores fo=
tos.                       =0Ahttp://telemundo.yahoo.com/promos/mejorfotogr=
afo.html

>
> Can this be changed?  Is there a better approach I should take in
> getting my students started using scipy and pylab together?
>

Teaching them what is a module and a namespace is a good think, why don't
telling them to do :

import pylab as pl
import numpy as npy

for instance so that they have a feeling it's almost like MAtlab, but better
structured ?

Matthieu

Hi,

I'm using matplotlib in a C++ app (with a qt4 gui), by embedding python with
boost::python. The C++ app calls Py_Initialize(), init_myplottingmodule(), and
boost::python::import("matplotlib.pylab") once on startup and certain GUI
events then fire up a matplotlib window via calls like this one:

// simplified version
void plotCurve(){
    clf();
    title("Diagonal line plot");
    double O1[] = {0,1};
    plot(std::vector<double>(O1,O1+2), std::vector<double>(O1,O1+2), "b:");
    show();
}

Although this does sort of work, it doesn't work quite right. Specifically on
clicking on the close button of the window, bad things frequently happen. For
example, the first close seems to work, but subsequent attempts to close newly
opened plots just zombify the window (it no longer repaints automatically but
stays open; replots happen to that same window, i.e. the one that was opened
second).

Now I'm somewhat aware of all the nastiness of different event loops, the
heroic efforts of ipython to make matplotlib work nicely interactively without
blocking the REPL, but somehow I would have (naively) thought that all that
work was just needed to avoid blocking. For the code above, blocking till the
window would be closed is perfectly fine. Indeed that's what happens if I try
something equivalent in the plain python shell (outside the C++ app).

Any idea about the likely cause of the problem and what might be the simplest
way to get it to work as expected (similar symptoms appear w/ matplotlib
0.87.7 and 0.91 under linux and osx)?

cheers,

'as

Hi

I'm running into a problem using the mollweide projection, with the
following simplified code, my actual code doesn't use random data for
values but this is a clearer example to the problem I'm experiencing:

lon = numpy.arange(0, 361, 1)
lat = numpy.arange(-90, 91, 1)
x, y = numpy.meshgrid(lon, lat)
values = numpy.random.random((181, 361))

map = basemap.Basemap(projection='moll', lon_0=0, resolution='c')
map.drawcoastlines()
map.drawcountries()
map.drawmapboundary()
map.drawmeridians(numpy.arange(0,360,30))
map.drawparallels(numpy.arange(-90,90,30))

X, Y = map(x, y)

map.contourf(X, Y, values)

I get the following error:

 WARNING: x coordinate not montonically increasing - contour plot
 may not be what you expect.  If it looks odd, your can either
 adjust the map projection region to be consistent with your data, or
 (if your data is on a global lat/lon grid) use the shiftgrid
 function to adjust the data to be consistent with the map projection
 region (see examples/contour_demo.py).

And the resulting map is incorrect due to the horizontal trends, see
http://tier2.ihepa.ufl.edu/~ram/files/moll.jpg


but if I use the orthographic projection ie:

map = basemap.Basemap(projection='ortho', lat_0=-20, lon_0=-30, resolution='c')

Then there are no errors, and the map is displayed as expected, see
http://tier2.ihepa.ufl.edu/~ram/files/ortho.jpg

I am unsure as to why I am receiving this error for the mollweide
projection, as my coordinate grid is covering the entire surface.  I
am clearly doing something wring here but I don't know what - does
anyone know what is causing this issue?

Cheers

Adam

On 10/11/07, Ryan Krauss <rya...@gm...> wrote:

> Can this be changed?  Is there a better approach I should take in
> getting my students started using scipy and pylab together?

Yes, this was left in initially for backward compatibility but I think
we should strive for maximal numpy compatibility going forward.  In
svn, we now have pyplot ehich is like pylab but minus the numpy stuff.
 Thus if you are using svn (or future releases) you can encourage your
students to

from scipy import *
from matplotlib.pyplot import *

I have successfully (I think) coerced my students into using
Scipy/Numpy for signal processing and dynamic system modeling.  They
are mechanical engineering coming from a Matlab background.  In order
to make using Python easy and have it feel like Matlab,  I teach them
to put

from scipy import *
from pylab import *

at the beginning of every script.  One problem with this is that the
zeros and ones functions of pylab default to integers while those from
scipy default to floating point numbers.  I have had several students
this week beating there heads against problems that turned out to be
trying to put floating point values in an array that was created using
pylab.zeros.

Can this be changed?  Is there a better approach I should take in
getting my students started using scipy and pylab together?

Thanks,

Ryan