that's "rfits and wfits" -- missed an autocorrect...
(Mobile)
> On Apr 29, 2017, at 12:54 AM, Karl Glazebrook <[email protected]> wrote:
>
> Yes, the FITS standard allows these particular special case duplicate fields,
> but the PDL FITS readers has never supported them. It was done by hashes and
> of course hashes can only have one key. I imagine to get what you want you
> would have to modify Astro::FITS::Header either with special code our to use
> Tie::DxHash (which is probably overkill)
>
> Karl
>
>
>> On 29 Apr 2017, at 3:20 am, ejm <[email protected]> wrote:
>>
>> Hi all,
>>
>> I have a question about PDL::IO::FITS and in particular the methods hdr &
>> gethdr.
>>
>> I've got a Moose script that works fine with PDL::IO::FITS and adds fine the
>> usual FITS fields to a FITS
>> header. The resulting FITS file is read fine by SAOImage and the FITS fields
>> are in the order I want.
>>
>> The problem is with fields that are potential duplicates such as COMMENT and
>> HISTORY.
>>
>> I noticed that PDL::IO::FITS doesn't make use of Tie::DxHash which
>> specifically handles duplicate keys in tied hashes. Nor does
>> Astro::FITS::Header.
>>
>> I also don't see exported in PDL::IO::FITS the methods insert or index from
>> Astro::FITS::Header which might be the right methods to call for adding
>> COMMENT fields.
>>
>> When I create a tied hash using Tie::DxHash and copy over the data returned
>> by gethdr, I get a tied hash with duplicate COMMENT fields in the order I
>> want.
>>
>> I then save the resultant updated FITS header hash using sethdr.
>>
>> But when I view the FITS file in SAOImage for example I see the added fields
>> in alphabetical order, not the tied order they were saved in. I also don't
>> see any COMMENT fields.
>>
>> If I don't use Tie::DxHash, but just add the COMMENT field directly to the
>> tied hash returned by gethdr, I get only 1 COMMENT field in the header, with
>> the last value assigned to it, which makes sense since Tie::DxHash isn't
>> being used. Hence no duplicate keys allowed.
>>
>> What is the recommended way to add multiple COMMENT fields using
>> PDL::IO::FITS ?
>>
>> Thanks,
>>
>> --Ed
>>
>>
>>
>>
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>
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