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  1. Data Management
  2. DM-8100

Determine what astropy.io.fits does with FITS header cards for missing data

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    Details

    • Type: Improvement
    • Status: Done
    • Resolution: Done
    • Fix Version/s: None
    • Component/s: Third Party Software
    • Labels:
      None
    • Story Points:
      1
    • Sprint:
      Arch 2019-04-08
    • Team:
      Architecture

      Description

      As part of implementing RFC-239 determine how astropy.io.fits handles FITS header cards with missing (unknown) values. I am virtually certain it cannot write such cards, but what happens when it tries to read them?

      This will inform implementation of RFC-239.

        Attachments

          Issue Links

          is triggered by

          RFC - An issue whose primary purpose is to advertise an intent and allow stakeholders to comment. RFC-239 PropertyList should support missing values and possibly units

          • Implemented
          relates to

          Story - Created by Jira Software - do not edit or delete. Issue type for a user story. DM-9873 PropertySet does not support values of None

          • Done

          Improvement - An improvement or enhancement to an existing feature or task. DM-8101 Add support for missing values to PropertyList

          • Invalid
          links to

          Web Link Astropy issue discussing Undefined

          Web Link Astropy Pull Request

            Activity

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            tjenness Tim Jenness added a comment -

            Astropy does it by having a astropy.io.fits.card.Undefined special value. That strikes me as really unhelpful since it doesn't behave like any other value that you might expect. It also acts like it's True so you can't say if "FILTER" in header and header["FILTER"]: but have to have special code for dealing with is Undefined.

            Show
            tjenness Tim Jenness added a comment - Astropy does it by having a astropy.io.fits.card.Undefined special value. That strikes me as really unhelpful since it doesn't behave like any other value that you might expect. It also acts like it's True so you can't say if "FILTER" in header and header ["FILTER"] : but have to have special code for dealing with is Undefined .
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            tjenness Tim Jenness added a comment -

            I have filed a pull request on Astropy to change the behavior such that FITS undefined value maps to None in python: https://github.com/astropy/astropy/pull/8572

            Show
            tjenness Tim Jenness added a comment - I have filed a pull request on Astropy to change the behavior such that FITS undefined value maps to None in python: https://github.com/astropy/astropy/pull/8572
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            tjenness Tim Jenness added a comment -

            Astropy accepted my pull request. Now Astropy and PropertyList translate python None to FITS undefined and vice versa.

            Show
            tjenness Tim Jenness added a comment - Astropy accepted my pull request. Now Astropy and PropertyList translate python None to FITS undefined and vice versa.

              People

              Assignee:
              tjenness Tim Jenness
              Reporter:
              rowen Russell Owen
              Watchers:
              Fritz Mueller, Kian-Tat Lim, Russell Owen, Tim Jenness
              Votes:
              0 Vote for this issue
              Watchers:
              4 Start watching this issue

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                Updated:
                Resolved:

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