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balto_plot.py
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"""
This module defines some plotting functions that are used by the
BALTO GUI app. It should be included in the same directory as
"balto_gui.py" and the corresponding Jupyter notebook.
"""
#------------------------------------------------------------------------
#
# Copyright (C) 2020. Scott D. Peckham
#
# Added use of cartopy in 2020-11 to 2020-12.
#
#------------------------------------------------------------------------
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature
import numpy as np
#------------------------------------------------------------------------
#
# plot_data() # for x vs. y plots
#-----------------
# hist_equal()
# power_stretch1()
# power_stretch2()
# power_stretch3()
# log_stretch()
# stretch_grid()
# show_grid_as_image() (used for balto_gui.show_grid() method)
#
#------------------------------------------------------------------------
def plot_data( x, y, xmin=None, xmax=None, ymin=None, ymax=None,
x_name='x', x_units='', marker=',',
y_name='y', y_units='',
x_size=8, y_size=4):
figure = plt.figure(1, figsize=(x_size, y_size))
# fig, ax = plt.subplots( figsize=(x_size, y_size))
# Set the plot point marker
# https://matplotlib.org/3.1.1/api/markers_api.html
# marker = ',' # pixel
# marker = '.' # point (small circle)
# marker = 'o' # circle
# marker = '+'
# marker = 'x'
#if (ymin is None):
# ymin = y.min()
#if (ymax is None):
# ymax = y.max()
#if (ymax - ymin < 0.1):
# ymin = ymin - 0.5
# ymax = ymin + 0.5
# x_name2 = x_name.replace('_', ' ').title()
# y_name2 = y_name.replace('_', ' ').title()
plt.plot( x, y, marker=marker)
plt.xlabel( x_name + ' [' + x_units + ']' )
plt.ylabel( y_name + ' [' + y_units + ']' )
plt.ylim( ymin, ymax )
plt.xlim( xmin, xmax )
#-------------------------------------
# This may be necessary depending on
# the data type of ymin, ymax
#-------------------------------------
## plt.ylim( np.array([ymin, ymax]) )
## plt.xlim( np.array([xmin, xmax]) )
plt.show()
# plot_data()
#------------------------------------------------------------------------
def histogram_equalize( grid, PLOT_NCS=False):
# https://docs.scipy.org/doc/numpy/reference/generated/numpy.histogram.html
(hist, bin_edges) = np.histogram( grid, bins=256)
# hmin = hist.min()
# hmax = hist.max()
cs = hist.cumsum()
ncs = (cs - cs.min()) / (cs.max() - cs.min())
ncs.astype('uint8');
############## ncs.astype('uint8') # no semi-colon at end ??????????
if (PLOT_NCS):
plt.plot( ncs )
flat = grid.flatten()
flat2 = np.uint8( 255 * (flat - flat.min()) / (flat.max() - flat.min()) )
grid2 = ncs[ flat2 ].reshape( grid.shape )
return grid2
# histogram_equalize()
#------------------------------------------------------------------------
def power_stretch1( grid, p ):
return grid**p
# power_stretch1()
#------------------------------------------------------------------------
def power_stretch2( grid, a=1000, b=0.5):
# Note: Try a=1000 and b=0.5
gmin = grid.min()
gmax = grid.max()
norm = (grid - gmin) / (gmax - gmin)
return (1 - (1 + a * norm)**(-b))
# power_stretch2()
#------------------------------------------------------------------------
def power_stretch3( grid, a=1, b=2):
# Note: Try a=1, b=2 (shape of a quarter circle)
gmin = grid.min()
gmax = grid.max()
norm = (grid - gmin) / (gmax - gmin)
return (1 - (1 - norm**a)**b)**(1/b)
# power_stretch3()
#------------------------------------------------------------------------
def log_stretch( grid, a=1 ):
return np.log( (a * grid) + 1 )
# log_stretch()
#------------------------------------------------------------------------
def stretch_grid( grid, stretch, a=1, b=2, p=0.5 ):
if (stretch == 'power_stretch1'):
# Try: p = 0.3
grid2 = power_stretch1( grid, p)
elif (stretch == 'power_stretch2'):
# Try: a=1000, b=0.5.
grid2 = power_stretch2( grid, a=a, b=b )
elif (stretch == 'power_stretch3'):
# Try: a=1, b=2.
grid2 = power_stretch3( grid, a=a, b=b)
elif (stretch == 'log_stretch'):
grid2 = log_stretch( grid, a=a )
elif (stretch == 'hist_equal'):
grid2 = histogram_equalize( grid, PLOT_NCS=False)
else:
print('SORRY, Unknown stretch =', stretch)
return None
return grid2
# stretch_grid()
#------------------------------------------------------------------------
def get_map_projection( proj_name,
central_longitude=0.0, central_latitude=0.0,
false_easting=0.0, false_northing=0.0, globe=None,
standard_parallels=(20.0, 50.0),
scale_factor=None,
min_latitude=-80.0, max_latitude=84.0,
true_scale_latitude=None, latitude_true_scale=None, ### BOTH
secant_latitudes=None,
pole_longitude=0.0, pole_latitude=90.0,
central_rotated_longitude=0.0, sweep_axis='y',
satellite_height=35785831, cutoff=-30, approx=None,
southern_hemisphere=False, zone=15): #### numeric UTM zone
proj_name = proj_name.lower()
if (proj_name == 'albersequalarea'):
proj = ccrs.AlbersEqualArea(central_longitude=central_longitude,
central_latitude=central_latitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe,
standard_parallels=standard_parallels)
elif (proj_name == 'azimuthalequidistant'):
proj = ccrs.AzimuthalEquidistant(central_longitude=central_longitude,
central_latitude=central_latitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'equidistantconic'):
proj = ccrs.EquidistantConic(central_longitude=central_longitude,
central_latitude=central_latitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe,
standard_parallels=standard_parallels)
elif (proj_name == 'lambertconformal'):
proj = ccrs.LambertConformal(central_longitude=-96.0, ##########
central_latitude=39.0, ##########
false_easting=false_easting,
false_northing=false_northing, globe=globe,
secant_latitudes=None,
standard_parallels=None, ## default: (33,45)
cutoff=cutoff)
elif (proj_name == 'lambertcylindrical'):
proj = ccrs.LambertCylindrical(central_longitude=central_longitude)
elif (proj_name == 'mercator'):
proj = ccrs.Mercator(central_longitude=central_longitude,
min_latitude=min_latitude, max_latitude=max_latitude,
latitude_true_scale=latitude_true_scale,
false_easting=false_easting,
false_northing=false_northing, globe=globe,
scale_factor=None) #########
elif (proj_name == 'miller'):
proj = ccrs.Miller(central_longitude=central_longitude, globe=globe)
elif (proj_name == 'mollweide'):
proj = ccrs.Mollweide(central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'orthographic'):
proj = ccrs.Orthographic(central_longitude=central_longitude,
central_latitude=central_latitude, globe=globe)
elif (proj_name == 'robinson'):
proj = ccrs.Robinson(central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'sinusoidal'):
proj = ccrs.Sinusoidal(central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'stereographic'):
proj = ccrs.Stereographic(central_latitude=central_latitude,
central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe,
true_scale_latitude=true_scale_latitude,
scale_factor=scale_factor)
elif (proj_name == 'transversemercator'):
proj = ccrs.TransverseMercator(central_longitude=central_longitude,
central_latitude=central_latitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe,
scale_factor=1.0, ##########
approx=approx)
elif (proj_name == 'utm'):
proj = ccrs.UTM(zone, southern_hemisphere=southern_hemisphere, globe=globe)
elif (proj_name == 'interruptedgoodehomolosine'):
proj = ccrs.InterruptedGoodeHomolosine(central_longitude=central_longitude,
globe=globe)
elif (proj_name == 'rotatedpole'):
proj = ccrs.RotatedPole(pole_longitude=pole_longitude,
pole_latitude=pole_latitude, globe=globe,
central_rotated_longitude=central_rotated_longitude)
elif (proj_name == 'osgb'):
proj = ccrs.OSGB(approx=approx)
elif (proj_name == 'europp'):
proj = ccrs.EuroPP
elif (proj_name == 'geostationary'):
proj = ccrs.Geostationary(central_longitude=central_longitude,
satellite_height=satellite_height,
false_easting=false_easting,
false_northing=false_northing, globe=globe,
sweep_axis=sweep_axis)
elif (proj_name == 'nearsideperspective'):
proj = ccrs.NearsidePerspective(central_longitude=central_longitude,
central_latitude=central_latitude,
satellite_height=satellite_height,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'eckerti'):
proj = ccrs.EckertI(central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'eckertii'):
proj = ccrs.EckertII(central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'eckertiii'):
proj = ccrs.EckertIII(central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'eckertiv'):
proj = ccrs.EckertIV(central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'eckertv'):
proj = ccrs.EckertV(central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'eckertvi'):
proj = ccrs.EckertVI(central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'equalearth'):
proj = ccrs.EqualEarth(central_longitude=central_longitude,
false_easting=false_easting,
false_northing=false_northing, globe=globe)
elif (proj_name == 'gnomonic'):
proj = ccrs.Gnomonic(central_latitude=central_latitude,
central_longitude=central_longitude, globe=globe)
elif (proj_name == 'lambertazimuthalequalarea'):
proj = ccrs.LambertAzimuthalEqualArea(central_longitude=central_longitude,
central_latitude=central_latitude, globe=globe,
false_easting=false_easting,
false_northing=false_northing)
elif (proj_name == 'northpolarstereo'):
proj = ccrs.NorthPolarStereo(central_longitude=central_longitude,
true_scale_latitude=true_scale_latitude, globe=globe)
elif (proj_name == 'osni'):
proj = ccrs.OSNI(approx=approx)
elif (proj_name == 'southpolarstereo'):
proj = ccrs.SouthPolarStereo(central_longitude=central_longitude,
true_scale_latitude=true_scale_latitude, globe=globe)
else:
# This is same as "Geographic coordinates"
proj = ccrs.PlateCarree(central_longitude=central_longitude,
globe=globe)
return proj
# get_map_projection()
#------------------------------------------------------------------------
def show_grid_as_image( grid, long_name, extent=None,
cmap='rainbow',
stretch_name='hist_equal',
stretch_a = 1.0,
stretch_b = 1.0,
stretch_p = 1.0,
nodata_value=None,
interp_method='nearest',
## crs='platecarree', # for Geographic coordinates
proj_name='mercator',
projection=None,
NO_SHOW=False, im_file=None,
## stretch='power_stretch3',
xsize=8, ysize=8, dpi=None):
# Note: extent = [minlon, maxlon, minlat, maxlat]
# See get_map_bounds() in balto_gui.py.
#-------------------------
# Other color map names
#--------------------------------------------
# hsv, jet, gist_rainbow (reverse rainbow),
# gist_ncar, gist_stern
#--------------------------------------------
#------------------------------------------
# Replace nodata value before the stretch
#------------------------------------------
grid2 = grid.copy()
if (nodata_value is not None):
w1 = (grid2 == nodata_value)
w2 = np.invert( w1 )
gmin = min(grid2[w2])
grid2[ w1 ] = gmin
#---------------------------------------------
# Apply stretch function to enhance contrast
#---------------------------------------------
# grid2 = stretch_grid( grid, stretch='power_stretch1', p=0.4)
# grid2 = stretch_grid( grid, stretch='power_stretch2', a=1000, b=0.5)
# grid2 = stretch_grid( grid, stretch='power_stretch3', a=1, b=2)
# grid2 = stretch_grid( grid, stretch='log_stretch', a=1)
grid2 = stretch_grid( grid2, stretch=stretch_name, a=stretch_a,
b=stretch_b, p=stretch_p)
#-----------------------------------------------
# Get new min and max, before replacing nodata
#-----------------------------------------------
gmin = grid2.min()
gmax = grid2.max()
# print('gmin =', gmin)
# print('gmax =', gmax)
# print('shape =', grid2.shape)
#------------------------------------------
# Replace the nodata values after stretch
#------------------------------------------
if (nodata_value is not None):
grid2[ w1 ] = np.nan # 2020-12-11
### grid2[ w1 ] = nodata_value
#-------------------------------------------
# Create figure and axes (without cartopy)
#--------------------------------------------
# balto_crs = None
# fig, ax = plt.subplots( figsize=(xsize, ysize), dpi=dpi )
#----------------------------------------------------------
# balto_crs = None
# balto_proj = None
# fig = plt.figure( figsize=(xsize, ysize), dpi=dpi )
# ax = fig.add_subplot(1,1,1, projection=balto_proj)
## ax.set_extent( extent, crs=balto_crs ) ##### NOT WORKING
#--------------------------------------------
# Set the CRS (Coordinate Reference System)
#-------------------------------------------------------
# See: https://scitools.org.uk/cartopy/docs/latest/
# tutorials/understanding_transform.html
#-------------------------------------------------------
use_cartopy = False
if (use_cartopy):
balto_crs = ccrs.PlateCarree() # For Geographic lon/lat coordinates.
#-------------------------
# Set the map projection
#--------------------------------------------
# extent = [minlon, maxlon, minlat, maxlat]
#--------------------------------------------
center_lon = (extent[0] + extent[1]) / 2.0
center_lat = (extent[2] + extent[3]) / 2.0
min_lat = extent[2]
max_lat = extent[3]
print('Extent =', extent )
if (projection is not None):
balto_proj = projection
else:
#------------------------------------------------
# This option requires using parameter defaults
#------------------------------------------------
proj_name = proj_name.lower()
balto_proj = get_map_projection(proj_name, globe=None,
central_longitude=center_lon,
central_latitude=center_lat,
false_easting=0.0, false_northing=0.0,
standard_parallels=(20.0, 50.0), scale_factor=None,
min_latitude=-80.0, max_latitude=84.0,
true_scale_latitude=None, latitude_true_scale=None, ### BOTH
secant_latitudes=None,
pole_longitude=0.0, pole_latitude=90.0,
central_rotated_longitude=0.0, sweep_axis='y',
satellite_height=35785831, cutoff=-30, approx=None,
southern_hemisphere=False, zone=15) ######
#------------------------------------------------
# Create figure and axes (matplotlib + cartopy)
#------------------------------------------------
# First 3 args to subplot: ncols, nrows, index for the subplots
fig = plt.figure( figsize=(xsize, ysize), dpi=dpi )
ax = fig.add_subplot(1,1,1, projection=balto_proj)
ax.set_extent( extent, crs=balto_crs )
## ax.set_xlim([extent[0], extent[1]])
## ax.set_ylim([extent[2], extent[3]])
else:
#------------------------------------------------
# Create figure and axes (matplotlib + cartopy)
#------------------------------------------------
# First 3 args to subplot: ncols, nrows, index for the subplots
fig = plt.figure( figsize=(xsize, ysize), dpi=dpi )
ax = fig.add_subplot(1,1,1)
## ax.set_extent( extent)
ax.set_xlim([extent[0], extent[1]])
ax.set_ylim([extent[2], extent[3]])
GRIDLINES = use_cartopy ######
if (GRIDLINES):
## DRAW_LABELS = (projection == 'platecarree') # (unsupported otherwise)
DRAW_LABELS = False # Now done by other means
gl = ax.gridlines(crs=balto_crs, draw_labels=DRAW_LABELS, linewidth=2,
color='gray', alpha=0.5, linestyle='--')
# ax.add_feature(cfeature.COASTLINE) # placed wrong ###########
# ax.add_feature(cfeature.COASTLINE, extent=extent) # no extent keyword
# ax.add_feature(cfeature.BORDERS)
# ax.add_feature(cfeature.RIVERS)
# ax.add_feature(cfeature.LAND) # (raster?)
# ax.add_feature(cfeature.OCEAN) # (raster?)
# ax.add_feature(cfeature.LAKES) # (raster?)
#----------------------------
# Set title and axis labels
#----------------------------
im_title = long_name.replace('_', ' ').title()
ax.set_title( im_title )
ax.set_xlabel('Longitude [deg]')
ax.set_ylabel('Latitude [deg]')
#----------------------------------------------------
# Need next 2 lines as work-around for cartopy bug
# that prevents axis labels from showing.
# https://stackoverflow.com/questions/35479508/
# cartopy-set-xlabel-set-ylabel-not-ticklabels
#----------------------------------------------------
ax.set_xticks(ax.get_xticks())
ax.set_yticks(ax.get_yticks())
## ax.set_xticks(ax.get_xticks()[abs(ax.get_xticks())<=360])
## ax.set_yticks(ax.get_yticks()[abs(ax.get_yticks())<=90])
#------------------------------------
# New code to use cartopy (2020-11)
#------------------------------------
## balto_crs = ccrs.PlateCarree()
## balto_crs = ccrs.PlateCarree(central_longitude=center_lon)
# im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
# vmin=gmin, vmax=gmax, extent=extent)
#------------------------------------------------------------------------------
# USE THIS BLOCK
# if (use_cartopy):
# im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
# vmin=gmin, vmax=gmax, extent=extent, transform=balto_crs)
#------------------------------------------------------------------------------
# im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
# vmin=gmin, vmax=gmax, transform=balto_crs)
#----------------------------------
# Old code, before use of cartopy
#----------------------------------
# im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
# vmin=gmin, vmax=gmax)
# im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
# vmin=gmin, vmax=gmax, extent=extent)
if (use_cartopy):
im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
vmin=gmin, vmax=gmax, extent=extent, transform=balto_crs)
else:
im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
vmin=gmin, vmax=gmax, extent=extent)
#--------------------------------------------------------
# NOTE! Must save before "showing" or get blank image.
# File format is inferred from extension.
# e.g. TMP_Image.png, TMP_Image.jpg.
#--------------------------------------------------------
if (im_file is not None):
plt.savefig( im_file )
if not(NO_SHOW):
plt.show()
plt.close()
# show_grid_as_image()
#------------------------------------------------------------------------
def show_grid_as_image_OLD( grid, long_name, extent=None,
cmap='rainbow',
stretch_name='hist_equal',
stretch_a = 1.0,
stretch_b = 1.0,
stretch_p = 1.0,
nodata_value=None,
interp_method='nearest',
## crs='platecarree', # for Geographic coordinates
proj_name='mercator',
projection=None,
NO_SHOW=False, im_file=None,
## stretch='power_stretch3',
xsize=8, ysize=8, dpi=None):
# Note: extent = [minlon, maxlon, minlat, maxlat]
# See get_map_bounds() in balto_gui.py.
#-------------------------
# Other color map names
#--------------------------------------------
# hsv, jet, gist_rainbow (reverse rainbow),
# gist_ncar, gist_stern
#--------------------------------------------
#------------------------------------------
# Replace nodata value before the stretch
#------------------------------------------
grid2 = grid.copy()
if (nodata_value is not None):
w1 = (grid2 == nodata_value)
w2 = np.invert( w1 )
gmin = min(grid2[w2])
grid2[ w1 ] = gmin
#---------------------------------------------
# Apply stretch function to enhance contrast
#---------------------------------------------
# grid2 = stretch_grid( grid, stretch='power_stretch1', p=0.4)
# grid2 = stretch_grid( grid, stretch='power_stretch2', a=1000, b=0.5)
# grid2 = stretch_grid( grid, stretch='power_stretch3', a=1, b=2)
# grid2 = stretch_grid( grid, stretch='log_stretch', a=1)
grid2 = stretch_grid( grid2, stretch=stretch_name, a=stretch_a,
b=stretch_b, p=stretch_p)
#-----------------------------------------------
# Get new min and max, before replacing nodata
#-----------------------------------------------
gmin = grid2.min()
gmax = grid2.max()
#------------------------------------------
# Replace the nodata values after stretch
#------------------------------------------
if (nodata_value is not None):
grid2[ w1 ] = np.nan # 2020-12-11
### grid2[ w1 ] = nodata_value
#-------------------------------------------
# Create figure and axes (without cartopy)
#--------------------------------------------
# balto_crs = None
# fig, ax = plt.subplots( figsize=(xsize, ysize), dpi=dpi )
#----------------------------------------------------------
# balto_crs = None
# balto_proj = None
# fig = plt.figure( figsize=(xsize, ysize), dpi=dpi )
# ax = fig.add_subplot(1,1,1, projection=balto_proj)
## ax.set_extent( extent, crs=balto_crs ) ##### NOT WORKING
#--------------------------------------------
# Set the CRS (Coordinate Reference System)
#-------------------------------------------------------
# See: https://scitools.org.uk/cartopy/docs/latest/
# tutorials/understanding_transform.html
#-------------------------------------------------------
balto_crs = ccrs.PlateCarree() # For Geographic lon/lat coordinates.
#-------------------------
# Set the map projection
#--------------------------------------------
# extent = [minlon, maxlon, minlat, maxlat]
#--------------------------------------------
center_lon = (extent[0] + extent[1]) / 2.0
center_lat = (extent[2] + extent[3]) / 2.0
min_lat = extent[2]
max_lat = extent[3]
print('Extent =', extent )
if (projection is not None):
balto_proj = projection
else:
#------------------------------------------------
# This option requires using parameter defaults
#------------------------------------------------
proj_name = proj_name.lower()
balto_proj = get_map_projection(proj_name, globe=None,
central_longitude=center_lon,
central_latitude=center_lat,
false_easting=0.0, false_northing=0.0,
standard_parallels=(20.0, 50.0), scale_factor=None,
min_latitude=-80.0, max_latitude=84.0,
true_scale_latitude=None, latitude_true_scale=None, ### BOTH
secant_latitudes=None,
pole_longitude=0.0, pole_latitude=90.0,
central_rotated_longitude=0.0, sweep_axis='y',
satellite_height=35785831, cutoff=-30, approx=None,
southern_hemisphere=False, zone=15) ######
#------------------------------------------------
# Create figure and axes (matplotlib + cartopy)
#------------------------------------------------
# First 3 args to subplot: ncols, nrows, index for the subplots
fig = plt.figure( figsize=(xsize, ysize), dpi=dpi )
ax = fig.add_subplot(1,1,1, projection=balto_proj)
ax.set_extent( extent, crs=balto_crs )
## ax.set_xlim([extent[0], extent[1]])
## ax.set_ylim([extent[2], extent[3]])
GRIDLINES = True ######
if (GRIDLINES):
## DRAW_LABELS = (projection == 'platecarree') # (unsupported otherwise)
DRAW_LABELS = False # Now done by other means
gl = ax.gridlines(crs=balto_crs, draw_labels=DRAW_LABELS, linewidth=2,
color='gray', alpha=0.5, linestyle='--')
# ax.add_feature(cfeature.COASTLINE) # placed wrong ###########
# ax.add_feature(cfeature.COASTLINE, extent=extent) # no extent keyword
# ax.add_feature(cfeature.BORDERS)
# ax.add_feature(cfeature.RIVERS)
# ax.add_feature(cfeature.LAND) # (raster?)
# ax.add_feature(cfeature.OCEAN) # (raster?)
# ax.add_feature(cfeature.LAKES) # (raster?)
#----------------------------
# Set title and axis labels
#----------------------------
im_title = long_name.replace('_', ' ').title()
ax.set_title( im_title )
ax.set_xlabel('Longitude [deg]')
ax.set_ylabel('Latitude [deg]')
#----------------------------------------------------
# Need next 2 lines as work-around for cartopy bug
# that prevents axis labels from showing.
# https://stackoverflow.com/questions/35479508/
# cartopy-set-xlabel-set-ylabel-not-ticklabels
#----------------------------------------------------
ax.set_xticks(ax.get_xticks())
ax.set_yticks(ax.get_yticks())
## ax.set_xticks(ax.get_xticks()[abs(ax.get_xticks())<=360])
## ax.set_yticks(ax.get_yticks()[abs(ax.get_yticks())<=90])
#------------------------------------
# New code to use cartopy (2020-11)
#------------------------------------
## balto_crs = ccrs.PlateCarree()
## balto_crs = ccrs.PlateCarree(central_longitude=center_lon)
# im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
# vmin=gmin, vmax=gmax, extent=extent)
#------------------------------------------------------------------------------
# im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
# vmin=gmin, vmax=gmax, extent=extent, transform=balto_crs)
#------------------------------------------------------------------------------
# im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
# vmin=gmin, vmax=gmax, transform=balto_crs)
#----------------------------------
# Old code, before use of cartopy
#----------------------------------
# im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
# vmin=gmin, vmax=gmax)
im = ax.imshow(grid2, interpolation=interp_method, cmap=cmap,
vmin=gmin, vmax=gmax, extent=extent)
#--------------------------------------------------------
# NOTE! Must save before "showing" or get blank image.
# File format is inferred from extension.
# e.g. TMP_Image.png, TMP_Image.jpg.
#--------------------------------------------------------
if (im_file is not None):
plt.savefig( im_file )
if not(NO_SHOW):
plt.show()
plt.close()
# show_grid_as_image_OLD()
#------------------------------------------------------------------------