1.1.3.0 coordsys.toabs

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coordsys.toabs - Function

1.1.3 Convert relative coordinate to absolute

Description

This function converts a relative coordinate to an absolute coordinate. The coordinate may be a pixel coordinate or a world coordinate.

If the coordinate is a pixel coordinate, it is supplied as a numeric vector. If the coordinate is a world coordinate, you may give it in all of the formats described in the formatting discussion.

If the coordinate value is supplied by a Coordsys tool function (e.g. toworld) then the coordinate ’knows’ whether it is world or pixel (and absolute or relative). However, you might supply the value from some other source as a numeric vector (which could be world or pixel) in which case you must specify whether it is a world or pixel coordinate via the isworld argument.

Arguments


Inputs
value	Relative coordinate
	allowed:	any
	Default:	variant
isworld	Is coordinate world or pixel? Default is unset.
	allowed:	int
	Default:	-1

Returns
record

Example

"""
#
print "\t----\t toabs Ex 1 \t----"
csys = cs.newcoordsys(direction=True, spectral=True)
aw = csys.toworld([100,100,24], ’s’)
rw = csys.torel(aw)
aw2 = csys.toabs(rw)
print aw
#{’ar_type’: ’absolute’, ’pw_type’: ’world’,
# ’string’: array([’23:53:19.77415678’, ’+01.40.00.84648186’,
#                  ’1.41502400e+09 Hz’], dtype=’|S19’)}
print rw
#{’ar_type’: ’relative’, ’pw_type’: ’world’,
# ’string’: array([’-6.00084720e+03 arcsec’, ’6.00084648e+03 arcsec’,
#                  ’2.40000000e+04 Hz’], dtype=’|S23’)}
print aw2
#{’ar_type’: ’absolute’, ’pw_type’: ’world’,
# ’string’: array([’23:53:19.77415672’, ’+01.40.00.84648000’,
#                  ’1.41502400e+09 Hz’], dtype=’|S19’)}
#
"""

This example uses world coordinates.

Example

"""
#
print "\t----\t toabs Ex 2 \t----"
csys = cs.newcoordsys(direction=True, spectral=True)
ap = csys.topixel()           # Reference value
rp = csys.torel(ap)
ap2 = csys.toabs(rp)
print ap
#{’ar_type’: ’absolute’, ’pw_type’: ’pixel’, ’numeric’: array([ 0.,  0.,  0.])}
print rp
#{’ar_type’: ’relative’, ’pw_type’: ’world’,
#     ’numeric’: array([  0.00000000e+00,   0.00000000e+00,  -1.41500000e+09])}
print ap2
#{’ar_type’: ’absolute’, ’pw_type’: ’world’, ’numeric’: array([ 0.,  0.,  0.])}
#
"""

This example uses pixel coordinates.

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