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regionmanager.complement - Function

1.1.2 Create the complement of a world region


Description

This function (short-hand name comp) creates the complement of a world region(s).

The region parameter can be a single region record defining a simple or complex region or it can contain several region records in a Python dictionary. If multiple regions are given then the union of this set of regions is taken first, and the complement is found from the union.

NOTE: ia.statistics() is UNABLE to handle complement regions in CASA yet.

Arguments





Inputs

region

The world region

allowed:

any

Default:

variant

Region tool

comment

A comment stored with the region

allowed:

string

Default:

String

Returns
record

Example

 
 
- ia.open(’hcn’)  
- csys = ia.coordsys()  
- ia.shape()  
[155 178]  
-  
- blc = "17:42:29.303 -28.59.18.600"  
- trc = "17:42:28.303 -28.59.10.600"  
- r2 = rg.wbox(blc,trc,[1,2],csys.torecord())  
- r3 = rg.complement(r2);  
-  
- ia.statistics(region=r2)                          # Some output discarded  
Selected bounding box [90, 90] to [103, 98]  
No pts   = 126  
-  
- ia.statistics(region=r3)  
Selected bounding box [1, 1] to [155, 178]     # Some output discarded  
No pts   = 27464  
 
 
As expected,  the number of pixels in the complement  
is $(155*178)-126=27464$  

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