[Numpy-discussion] proposal: smaller representation of string arrays
peridot.faceted at gmail.com
Tue Apr 25 14:00:20 EDT 2017
On Tue, Apr 25, 2017 at 7:52 PM Phil Hodge <hodge at stsci.edu> wrote:
> On 04/25/2017 01:34 PM, Anne Archibald wrote:
> > I know they're not numpy-compatible, but FITS header values are
> > space-padded; does that occur elsewhere?
> Strings in FITS headers are delimited by single quotes. Some keywords
> (only a handful) are required to have values that are blank-padded (in
> the FITS file) if the value is less than eight characters. Whether you
> get trailing blanks when you read the header depends on the FITS
> reader. I use astropy.io.fits to read/write FITS files, and that
> interface strips trailing blanks from character strings:
> TARGPROP= 'UNKNOWN ' / Proposer's name for the target
> >>> fd = fits.open("test.fits")
> >>> s = fd.header['targprop']
> >>> len(s)
Actually, for what it's worth, the FITS spec says that in such values
trailing spaces are not significant, see page 7:
But they're not really relevant to numpy's situation, because as here you
need to do elaborate de-quoting before they can go into a data structure.
What I was wondering was whether people have data lying around with
fixed-width fields where the strings are space-padded, so that numpy needs
to support that.
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