1.1.3.0 coordsys.setreferencevalue

1.1.3 Set the reference value
Description

Each axis associated with the Coordinate System has a reference value, reference pixel and an increment (per pixel). These are used in the mapping from pixel to world coordinate.

This function allows you to set a new reference value. You should not do this on ”stokes” axes unless you are an adept or a big risk taker.

You may supply the reference value in all of the formats described in the formatting discussion.

Note that the value argument should be one of the specified possibilitioes. Especially a measure will be accepted, but will have a null effect, due to the interpretation as a generic record.


Inputs
value	Reference value
	allowed:	any
	Default:	variant
type	Coordinate type: ”direction”, ”stokes”, ”spectral”, ”linear”, ”tabular” or leave empty for all.
	allowed:	string
	Default:

"""
#
print "\t----\t setreferencevalue Ex 1 \t----"
csys = cs.newcoordsys(direction=T, spectral=T)
rv = csys.referencevalue(format=’q’)
print rv
#{’quantity’: {’*1’: {’value’: 0.0, ’unit’: "’"},
# ’*2’: {’value’: 0.0, ’unit’: "’"}, ’*3’: {’value’: 1415000000.0, ’unit’: ’Hz’}}}
rv2 = rv[’quantity’][’*3’]
rv2[’value’] = 2.0e9
print rv2
#{’value’: 2000000000.0, ’unit’: ’Hz’}
csys.setreferencevalue(type=’spec’, value=rv2)
print csys.referencevalue(format=’n’)
#{’numeric’: array([  0.00000000e+00,   0.00000000e+00,   2.00000000e+09])}
#
# To set a new direction reference value, the easiest way, given a
# direction measure dr would be:
dr = me.direction(’j2000’,’30deg’,’40deg’)
# SHOULD BE SIMPLIFIED!!!
newrv=csys.referencevalue(format=’q’)
newrv[’quantity’][’*1’]=dr[’m0’]
newrv[’quantity’][’*2’]=dr[’m1’]
csys.setreferencevalue(value=newrv)
print csys.referencevalue(format=’q’)
#{’ar_type’: ’absolute’, ’pw_type’: ’world’,
# ’quantity’: {’*1’: {’value’: 1800.0, ’unit’: "’"},
#              ’*2’: {’value’: 2399.9999999999995, ’unit’: "’"},
#              ’*3’: {’value’: 1415000000.0, ’unit’: ’Hz’}}}
#
"""

coordsys.setreferencevalue - Function