Class WCSAxis
source code
object --+
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WCSAxis
represents a single 1D WCS axis and allows easy metadata
discovery.
You'll usually use the fromHeader constructor.
The idea of using this rather than astropy.wcs or similar is that this
is simple and robust. It doesn't know many of the finer points of WCS,
though, and in particular it's 1D only.
However, for the purposes of cutouts it probably should do for the
overwhelming majority of non-spatial FITS axes.
The default pixel coordinates are handled in the FITS sense here,
i.e., the first pixel has the index 1. Three are methods that have pix0
in their names; these assume 0-based arrays. All the transforms return
Nones unchanged.
To retrieve the metadata shoved in, use the name, crval, crpix, cdelt,
ctype, cunit, and axisLength attributes.
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__init__(self,
name,
crval,
crpix,
cdelt,
ctype='UNKNOWN',
cunit='',
axisLength=1)
x.__init__(...) initializes x; see help(type(x)) for signature |
source code
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pixToPhys(self,
pixCoo)
returns the physical value for a 1-based pixel coordinate. |
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pix0ToPhys(self,
pix0Coo)
returns the physical value for a 0-based pixel coordinate. |
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physToPix(self,
physCoo)
returns a 1-based pixel coordinate for a physical value. |
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physToPix0(self,
physCoo)
returns a 0-based pixel coordinate for a physical value. |
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getLimits(self)
returns the minimal and maximal physical values this axis takes
within the image. |
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Inherited from object:
__delattr__,
__format__,
__getattribute__,
__hash__,
__new__,
__reduce__,
__reduce_ex__,
__repr__,
__setattr__,
__sizeof__,
__str__,
__subclasshook__
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fromHeader(cls,
header,
axisIndex,
forceSeparable=False)
returns a WCSAxis for the specified axis in header. |
source code
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Inherited from object:
__class__
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__init__(self,
name,
crval,
crpix,
cdelt,
ctype='UNKNOWN',
cunit='',
axisLength=1)
(Constructor)
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x.__init__(...) initializes x; see help(type(x)) for signature
- Overrides:
object.__init__
- (inherited documentation)
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fromHeader(cls,
header,
axisIndex,
forceSeparable=False)
Class Method
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returns a WCSAxis for the specified axis in header.
If the axis is mentioned in a transformation matrix (CD or PC), a
ValueError is raised; this is strictly for 1D coordinates.
The axisIndex is 1-based; to get a transform for the axis described by
CTYPE1, pass 1 here.
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