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coordsys.setreferencecode - Function

1.1.3 Set new reference code


Description

This function sets the reference code for the specified coordinate type. Examples of reference codes are B1950 and J2000 for direction coordinates, or LSRK and BARY for spectral coordinates.

You must specify type, selecting from ’direction’, or ’spectral’ (the first two letters will do). If the Coordinate System does not contain a coordinate of the type you specify, an exception is generated.

Specify the new code with argument value. To see the list of possible codes, use the function referencecode (see example).

If adjust is T, then the reference value is recomputed. This is invariably the correct thing to do. If adjust is F, then the reference code is simply overwritten; do this very carefully.

Arguments





Inputs

value

Reference code

allowed:

string

Default:

type

Coordinate type: direction or spectral

allowed:

string

Default:

direction

adjust

Adjust reference value ?

allowed:

bool

Default:

true

Returns
bool

Example

 
 
"""  
#  
print "\t----\t Ex setreferencecode 1 \t----"  
csys = cs.newcoordsys(direction=T)  
clist = csys.referencecode(’dir’, T)      # See possibilities  
print clist  
#[’J2000’, ’JMEAN’, ’JTRUE’, ’APP’, ’B1950’, ’BMEAN’, ’BTRUE’, ’GALACTIC’,  
# ’HADEC’, ’AZEL’, ’AZELSW’, ’AZELNE’, ’AZELGEO’, ’AZELSWGEO’, ’AZELNEGEO’,  
# ’JNAT’, ’ECLIPTIC’, ’MECLIPTIC’, ’TECLIPTIC’, ’SUPERGAL’, ’ITRF’, ’TOPO’,  
# ’ICRS’, ’MERCURY’, ’VENUS’, ’MARS’, ’JUPITER’, ’SATURN’, ’URANUS’,  
# ’NEPTUNE’, ’PLUTO’, ’SUN’, ’MOON’, ’COMET’]  
print cs.referencecode(’dir’)  
#J2000  
cs.setreferencecode(’B1950’, ’dir’, T)  
#  
"""  
 
 
In this example we first get the list of all possible reference codes  
for a direction coordinate.  Then we set the actual reference code for the direction  
coordinate in our Coordinate System.  
 

Example

 
 
"""  
#  
print "\t----\t Ex setreferencecode 2 \t----"  
ia.maketestimage(’myimage.j2000’,overwrite=true)      # Open image  
csys = ia.coordsys()               # Get Coordinate System  
print csys.referencecode(’dir’, F)  
#J2000  
csys.setreferencecode(’B1950’, ’dir’, T)              # Set new direction system  
im2 = ia.regrid(outfile=’myimage.b1950’, csys=csys.torecord(),  
                overwrite=true)  # Regrid and make new image  
#  
"""  
 
 
In this example we show how to regrid an image from J2000  
to B1950.  First we recover the Coordinate System  into the Coordsys  
\tool\ called {\stf cs}.  We then set a new direction reference code,  
making sure we recompute the reference value.  Then the  
new Coordinate System is supplied in the regridding process  
(done with an Image \tool).  
 

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