| Re: Copying a hash [message #81079 is a reply to message #81003] |
Thu, 09 August 2012 11:25   |
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Matt[3]
Messages: 23
Registered: April 2011
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Junior Member |
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On Tuesday, August 7, 2012 11:44:45 AM UTC-4, Matt wrote:
> On Monday, August 6, 2012 7:41:12 PM UTC-4, David Fanning wrote:
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>> Paul van Delst writes:
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>>> Bummer. To be honest, I'm not sure what the correct behaviour should be. Recursively copy all the components? I guess if
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>>> we think of the numbers and strings as objects also, then the answer should probably be yes.... ? Why duplicate one type
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>>> of object (int, float, or string) but not another (hash or list)? Still... it just doesn't seem right.
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>> I think this takes us back to the need for a "deep copy" in objects.
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>> http://www.idlcoyote.com/tips/copy_objects.html
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>> But, we have only been requesting it for 9 years, I see by
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>> the date on the article. I think the standard is 12 years
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>> before they either fix the problem or consign the requester
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>> to the loony bin. :-)
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>> Cheers,
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>> David
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>> --
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>> David Fanning, Ph.D.
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>> Fanning Software Consulting, Inc.
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>> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
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>> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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> Hi Guys,
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> Thanks for the help, and sorry for somehow missing that rather clear bit of documentation.
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> Yes, I'm not sure what the behavior should be either when there is a hash within a hash. The default behavior seems likely to cause trouble! Anyway, to copy down through one or two hash levels, the following lines seem to work:
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> copy=hash()
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> foreach variable, original, key do copy[key]=original[key, *]
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> I'm sure there's a smart way of doing this recursively for an indefinite number of levels, but this works for me, for now.
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> Cheers,
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> Matt
Probably no one cares about this but me, but the code I posted above doesn't copy arrays stored in a hash correctly (it turns multi-dimensional arrays into 1-D arrays). This works though:
copy=hash()
foreach variable, original, key do begin
if typeName(original[key]) eq 'HASH' then begin
copy[key]=original[key, *]
endif else begin
copy[key]=original[key]
endelse
endforeach
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