def write_raster_data(data, projection, geotransform, filename):
"""Write array to raster file with specified metadata and one data layer
Input:
data: Numpy array containing grid data
projection: WKT projection information
geotransform: 6 digit vector
(top left x, w-e pixel resolution, rotation,
top left y, rotation, n-s pixel resolution).
See e.g. http://www.gdal.org/gdal_tutorial.html
filename: Output filename
Note: The only format implemented is GTiff and the extension must be .tif
"""
R = Raster(data, projection, geotransform)
R.write_to_file(filename)
def write_raster_data(data, projection, geotransform, filename, keywords=None):
"""Write array to raster file with specified metadata and one data layer
Input:
data: Numpy array containing grid data
projection: WKT projection information
geotransform: 6 digit vector
(top left x, w-e pixel resolution, rotation,
top left y, rotation, n-s pixel resolution).
See e.g. http://www.gdal.org/gdal_tutorial.html
filename: Output filename
keywords: Optional dictionary
Note: The only format implemented is GTiff and the extension must be .tif
"""
R = Raster(data, projection, geotransform, keywords=keywords)
R.write_to_file(filename)
def test_rasters_and_arrays(self):
"""Consistency of rasters and associated arrays
"""
# Create test data
lon_ul = 100 # Longitude of upper left corner
lat_ul = 10 # Latitude of upper left corner
numlon = 8 # Number of longitudes
numlat = 5 # Number of latitudes
dlon = 1
dlat = -1
# Define array where latitudes are rows and longitude columns
A1 = numpy.zeros((numlat, numlon))
# Establish coordinates for lower left corner
lat_ll = lat_ul - numlat
lon_ll = lon_ul
# Define pixel centers along each direction
lon = numpy.linspace(lon_ll + 0.5, lon_ll + numlon - 0.5, numlon)
lat = numpy.linspace(lat_ll + 0.5, lat_ll + numlat - 0.5, numlat)
# Define raster with latitudes going bottom-up (south to north).
# Longitudes go left-right (west to east)
for i in range(numlat):
for j in range(numlon):
A1[numlat - 1 - i, j] = linear_function(lon[j], lat[i])
# Upper left corner
assert A1[0, 0] == 105.25
assert A1[0, 0] == linear_function(lon[0], lat[4])
# Lower left corner
assert A1[4, 0] == 103.25
assert A1[4, 0] == linear_function(lon[0], lat[0])
# Upper right corner
assert A1[0, 7] == 112.25
assert A1[0, 7] == linear_function(lon[7], lat[4])
# Lower right corner
assert A1[4, 7] == 110.25
assert A1[4, 7] == linear_function(lon[7], lat[0])
# Generate raster object and write
projection = ('GEOGCS["WGS 84",'
'DATUM["WGS_1984",'
'SPHEROID["WGS 84",6378137,298.2572235630016,'
'AUTHORITY["EPSG","7030"]],'
'AUTHORITY["EPSG","6326"]],'
'PRIMEM["Greenwich",0],'
'UNIT["degree",0.0174532925199433],'
'AUTHORITY["EPSG","4326"]]')
geotransform = (lon_ul, dlon, 0, lat_ul, 0, dlat)
R1 = Raster(A1, projection, geotransform)
msg = ('Dimensions of raster array do not match those of '
'raster object')
assert numlat == R1.rows, msg
assert numlon == R1.columns, msg
# Write back to new (tif) file
out_filename = unique_filename(suffix='.tif')
R1.write_to_file(out_filename)
# Read again and check consistency
R2 = read_layer(out_filename)
msg = ('Dimensions of written raster array do not match those '
'of input raster file\n')
msg += (' Dimensions of input file '
'%s: (%s, %s)\n' % (R1.filename, numlat, numlon))
msg += (' Dimensions of output file %s: '
'(%s, %s)' % (R2.filename, R2.rows, R2.columns))
assert numlat == R2.rows, msg
assert numlon == R2.columns, msg
A2 = R2.get_data()
assert numpy.allclose(numpy.min(A1), numpy.min(A2))
assert numpy.allclose(numpy.max(A1), numpy.max(A2))
msg = 'Array values of written raster array were not as expected'
assert numpy.allclose(A1, A2), msg
msg = 'Geotransforms were different'
assert R1.get_geotransform() == R2.get_geotransform(), msg
p1 = R1.get_projection(proj4=True)
p2 = R2.get_projection(proj4=True)
msg = 'Projections were different: %s != %s' % (p1, p2)
assert p1 == p1, msg
# Exercise projection __eq__ method
assert R1.projection == R2.projection
# Check that equality raises exception when type is wrong
try:
R1.projection == 234
except TypeError:
pass
else:
msg = 'Should have raised TypeError'
raise Exception(msg)
