I/O with AstroFITS

OnlineSampleStatistics provides FITS input/output for IndependentStatistic through an extension loaded when AstroFITS is available.

using OnlineSampleStatistics
using AstroFITS

Write an IndependentStatistic to a FITS file:

stat = IndependentStatistic(2, (3, 3))
fit!(stat, rand(3, 3))

fitsfile = openfits("myfile.fits", "w!")
write(fitsfile, FitsHeader(), stat)
close(fitsfile)

Read it back:

fitsfile = openfits("myfile.fits")
stat = read(IndependentStatistic, fitsfile)
close(fitsfile)

Each raw moment is stored in its own HDU, and weights (nobs) are stored in a dedicated HDU.

If you store multiple statistics in one file, use group IDs:

fitsfile = openfits("myfile.fits", "w!")

stat1 = IndependentStatistic(2, (3, 3))
fit!(stat1, rand(3, 3))
write(fitsfile, FitsHeader(), stat1, "ABC")

stat2 = IndependentStatistic(2, (3, 3))
fit!(stat2, rand(3, 3))
write(fitsfile, FitsHeader(), stat2, "DEF")

close(fitsfile)

fitsfile = openfits("myfile.fits")
stat1 = read(IndependentStatistic, fitsfile, "ABC")
stat2 = read(IndependentStatistic, fitsfile, "DEF")
close(fitsfile)

If no group ID is provided, one is generated automatically and checked for uniqueness in the file. If you provide a group ID that already exists, writing throws an ArgumentError.

To inspect available group IDs:

fitsfile = openfits("myfile.fits")
ids = OnlineSampleStatistics.find_stat_group_ids(fitsfile)
close(fitsfile)