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# A simple class for handling FITS images
# by Masahiro TANAKA 1999/12/19
# No document, sorry.
#
# Require: Ruby/NArray
# http://koala.astro.isas.ac.jp/~masa/ruby/
#
# Example:
# f = Fits.read('somthing.fits')
# f.data # => 2-dimentional NArray data
require 'narray'
class Fits
attr_accessor :data
attr_accessor :header
def initialize
@data = ""
@header = []
end
def data_to_narray(data,type,shape)
NArray.to_na( data, type, *shape ).ntoh
end
def read(fname)
f = File.open(fname, "r")
@header = []
nbytes = 0
foo = {}
while
line = f.read(80)
nbytes += 80;
@header.push line
name = line[0,8].strip!
break if name=="END"
rest = line[8..-1]
if rest =~ /^= +('[^']*')/ #'
foo[name] = $1
elsif rest =~ /^= +([^\s\/]+)/
foo[name] = $1
end
end
# skip extra space
nbytes %= 2880
f.read(2880-nbytes) if nbytes > 0
naxis = foo["NAXIS"].to_i
case foo["BITPIX"]
when "8"; elm_size = 1; type = NArray::BYTE
when "16"; elm_size = 2; type = NArray::SINT
when "32"; elm_size = 4; type = NArray::LINT
when "-32"; elm_size = 4; type = NArray::SFLOAT
when "-64"; elm_size = 8; type = NArray::DFLOAT
end
size = 1
dims = []
for i in 1..naxis
key = "NAXIS#{i}"
if foo.key? key
n = foo[key].to_i
size = size * n
dims.push n
#printf "%s=%i\n", key,n
end
end
@data = data_to_narray( f.read(size*elm_size), type, dims )
f.close
if foo.key? "BSCALE"
s = foo["BSCALE"].to_f
@data = @data.to_f.mul!(s) if s != 1
end
if foo.key? "BZERO"
s = foo["BZERO"].to_f
@data = @data.to_f.add!(s) if s != 0
end
self
end
end
def Fits.read(*a)
Fits.new.read(*a)
end
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