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NRAO Home > CASA > CASA Toolkit Reference Manual |
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image.newimagefromshape - Function
1.1.1 Construct an empty CASA image from a shape
Description
This function creates a CASA image file with the specified shape. All the
pixel values in the image are set to 0. Both float valued and complex valued
images are supported; the data type of the image is specified via the type
parameter.
If outfile is given, the image is written to the specified disk file. If outfile is unset, the on-the-fly Image tool returned by this function is associated with a temporary image. This temporary image may be in memory or on disk, depending on its size. When you destroy the on-the-fly Image tool (with the done function) this temporary image is deleted.
The Coordinate System, provided as a record describing a Coordsys tool (created via coordsys.torecord(), for instance), is optional. If you provide it, it must be dimensionally consistent with the pixels array you give (see also coordsys).
If you don’t provide the Coordinate System, a default Coordinate System is made for you. If linear=F (the default) then it is a standard RA/DEC/Stokes/Spectral Coordinate System depending exactly upon the shape (Stokes axis must be no longer than 4 pixels and you may find the spectral axis coming out before the Stokes axis if say, shape=[64,64,32,4]). Extra dimensions are given linear coordinates. If linear=T then you get a linear Coordinate System.
Arguments
Inputs |
| ||
outfile |
| Name of output image file. Default is unset.
| |
| allowed: | string |
|
| Default: |
| |
shape |
| Shape of image. Required.
| |
| allowed: | intArray |
|
| Default: | 0 | |
csys |
| Record describing Coordinate System. Default is unset.
| |
| allowed: | record | |
| Default: | ||
linear |
| Make a linear Coordinate System if csys not given?
| |
| allowed: | bool |
|
| Default: | false |
|
overwrite |
| Overwrite (unprompted) pre-existing output file?
| |
| allowed: | bool |
|
| Default: | false |
|
log |
| Write image creation messages to logger
| |
| allowed: | bool |
|
| Default: | true |
|
type |
| Type of image. ’f’ means Float, ’c’ means complex.
| |
| allowed: | string |
|
| Default: | f |
|
image
Example
"""
#
print "\t----\t newimagefromshape Ex 1 \t----"
im1=ia.newimagefromshape(’test2.data’, [64,64,128], overwrite=true)
cs1 = im1.coordsys(axes=[0,2])
im1.done()
im2 = ia.newimagefromshape(shape=[10, 20], csys=cs1.torecord())
cs1.done()
im2.done()
#
"""
The first example creates a zero-filled \imagefile\ named {\sff
test.data} of shape [64,64,128]. If you examine the header with
{\stff ia.summary()} you will see the RA/DEC/Spectral coordinate
information. In the second example, a Coordinate System describing
the first and third axes of the image {\sff test2.data} is created and
used to create a 2D temporary image.
__________________________________________________________________
More information about CASA may be found at the
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Copyright © 2016 Associated Universities Inc., Washington, D.C.
This code is available under the terms of the GNU General Public Lincense
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