#=======================================================================
# Examples for Testing Function curl_2d in Module curl_2d.
# (Using CCM3 output.)
#
# I assume that this script is run on a system that has the module 
# sphere installed.
#
# Copyright (c) 2004 by Johnny Lin.  For licensing, distribution
# conditions, contact information, and additional documentation see
# the URL http://www.johnny-lin.com/py_pkgs/gemath/doc/.
#=======================================================================


#- Import modules:

try:  execfile('/home/jlin/.pythonrc.py')
except:  print "test_curl_2d.py:  Ignore Johnny Lin's path settings."

import cdms, os, MV
import Numeric as N
import gemath
from gemath.curl_2d import curl_2d
import IaGraph
from IaGraph import *


#- Data:  From CCM3 output.  u and v are in m/s and x and y are in
#  deg (except for the final example, when we take x and y as being
#  in m):

f = cdms.open('uv_501hPa_ccm3.nc')
u = f('U')
v = f('V')
x = MV.filled( u.getAxis(-1)[:] )
y = MV.filled( u.getAxis(-2)[:] )
u = MV.filled( u[:,:] )
v = MV.filled( v[:,:] )


#- Set system variables for lon/lat axes tick labels:

sysvar = IaGraph.Sysvar()
sysvar.__class__.x_tickvalues = \
    {0:'0', 90:'90E', 180:'180E', 270:'270E', 360:'360E'}
sysvar.__class__.y_tickvalues = \
    {-90:'90S', -45:'45S', 0:'EQ', 45:'45N', 90:'90N'}


#- Plot u and v data:

base_fn = 'test_curl_2d_ccm3_udata'
contour(u, x, y, title=base_fn)
active2gif(base_fn+'.gif')
os.system('convert -verbose -trim -border 8x8 -bordercolor white ' \
         +'-mattecolor black -frame 2x2 ' \
         +base_fn+'.gif gem_'+base_fn+'.jpg')

base_fn = 'test_curl_2d_ccm3_vdata'
contour(v, x, y, title=base_fn)
active2gif(base_fn+'.gif')
os.system('convert -verbose -trim -border 8x8 -bordercolor white ' \
         +'-mattecolor black -frame 2x2 ' \
         +base_fn+'.gif gem_'+base_fn+'.jpg')


#- Use order 1 spherical algorithm:  x and y are in deg and u and v 
#  are in m/s.  The curl is in 1/s.  Note that these results should
#  be nearly identical to those from SPHEREPACK:

curl = curl_2d(x, y, u, v, algorithm='order1_spherical')

base_fn = 'test_curl_2d_ccm3_o1sph'
contour(curl, x, y, continents=1, title=base_fn)
active2gif(base_fn+'.gif')
os.system('convert -verbose -trim -border 8x8 -bordercolor white ' \
         +'-mattecolor black -frame 2x2 ' \
         +base_fn+'.gif gem_'+base_fn+'.jpg')


#- Use spectral method from SPHEREPACK.  Here we take x and y in deg, 
#  while u and v are in m/s.  If so the curl is in 1/s:

curl = curl_2d(x, y, u, v, algorithm='spherepack')

base_fn = 'test_curl_2d_ccm3_sphpk'
contour(curl, x, y, continents=1, title=base_fn)
active2gif(base_fn+'.gif')
os.system('convert -verbose -trim -border 8x8 -bordercolor white ' \
         +'-mattecolor black -frame 2x2 ' \
         +base_fn+'.gif gem_'+base_fn+'.jpg')


#- Add some missing values in the middle of the plot, use the
#  "default_spherical" algorithm.  The order 1 spherical algorithm 
#  will be chosen:

u[30:41,20:37] = 1e+20

curl = curl_2d(x, y, u, v, algorithm='default_spherical')

base_fn = 'test_curl_2d_ccm3_defsph'
contour(MA.masked_values(curl, 1e+20), x, y, continents=1, title=base_fn)
active2gif(base_fn+'.gif')
os.system('convert -verbose -trim -border 8x8 -bordercolor white ' \
         +'-mattecolor black -frame 2x2 ' \
         +base_fn+'.gif gem_'+base_fn+'.jpg')




#- Close data file:

f.close()




# ===== end file =====