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import os
import tempfile
import numpy as np
import fitsio
def test_compression_nocompress():
with tempfile.TemporaryDirectory() as tmpdir:
fn = os.path.join(tmpdir, 'test.fits')
img = np.ones((20, 20))
with fitsio.FITS(fn, 'rw', clobber=True) as fits:
fits.write(img)
with fitsio.FITS(fn) as fits:
assert len(fits) == 1
def test_compression_diskfile_kwargs():
with tempfile.TemporaryDirectory() as tmpdir:
fn = os.path.join(tmpdir, 'test.fits')
img = np.ones((20, 20))
with fitsio.FITS(fn, 'rw', clobber=True) as fits:
fits.write(
img,
compress='RICE',
tile_dims=(10, 5),
qlevel=7.0,
qmethod='SUBTRACTIVE_DITHER_2',
dither_seed=42,
)
with fitsio.FITS(fn) as fits:
assert len(fits) == 2
hdr = fitsio.read_header(fn, ext=1)
for key, val in [
('ZTILE1', 5),
('ZTILE2', 10),
('ZQUANTIZ', 'SUBTRACTIVE_DITHER_2'),
('ZDITHER0', 42),
('ZCMPTYPE', 'RICE_ONE'),
]:
assert hdr[key] == val
def test_compression_efns():
with tempfile.TemporaryDirectory() as tmpdir:
fn = os.path.join(tmpdir, 'test.fits')
img = np.ones((20, 20))
with fitsio.FITS(fn + '[compress G]', 'rw', clobber=True) as fits:
fits.write(img)
hdr = fitsio.read_header(fn, ext=1)
for key, val in [
('ZTILE1', 20),
('ZTILE2', 1),
('ZQUANTIZ', 'SUBTRACTIVE_DITHER_1'),
('ZCMPTYPE', 'GZIP_1'),
]:
assert hdr[key] == val
def test_compression_efns_kwargs():
with tempfile.TemporaryDirectory() as tmpdir:
fn = os.path.join(tmpdir, 'test.fits')
img = np.ones((20, 20))
with fitsio.FITS(
fn + '[compress G 5 10; qz 8.0]', 'rw', clobber=True
) as fits:
fits.write(img, dither_seed=42)
hdr = fitsio.read_header(fn, ext=1)
for key, val in [
('ZTILE1', 5),
('ZTILE2', 10),
('ZQUANTIZ', 'SUBTRACTIVE_DITHER_2'),
('ZCMPTYPE', 'GZIP_1'),
('ZDITHER0', 42),
]:
assert hdr[key] == val
def test_compression_qlevels_none_zero():
default_kws = {
"compress": fitsio.GZIP_2,
"tile_dims": np.array([100, 100]),
"qmethod": fitsio.SUBTRACTIVE_DITHER_2,
}
with tempfile.TemporaryDirectory() as tmpdir:
fnpat = os.path.join(tmpdir, 'test-%i.fits')
H, W = 200, 200
bigimg = np.random.uniform(size=(H, W))
results = []
# None: don't even use compression at all
# 0: lossless gzip
for i, qlevel in enumerate([None, 0, 16, 4, 1]):
fn = fnpat % i
ql = qlevel
kw = {}
kw.update(default_kws)
if ql is None:
kw.update(compress=0)
ql = 0
kw["qlevel"] = ql
with fitsio.FITS(fn, 'rw', clobber=True) as fits:
fits.write(bigimg, dither_seed=42, **kw)
filesize = os.stat(fn).st_size
img2 = fitsio.read(fn)
rms = np.sqrt(np.mean((img2 - bigimg) ** 2))
results.append((qlevel, filesize, rms))
# No compression
q, sz, rms = results[0]
assert sz == 2880 * (1 + int(np.ceil(H * W * 8 / 2880.0)))
assert rms == 0.0
# GZIP lossless
q, sz, rms = results[1]
assert rms == 0.0
# Decreasing file size
for r1, r2 in zip(results, results[1:]):
q1, sz1, rms1 = r1
q2, sz2, rms2 = r2
assert sz1 > sz2
assert rms1 <= rms2
def test_compression_hcomp_args():
with tempfile.TemporaryDirectory() as tmpdir:
fn = os.path.join(tmpdir, 'test.fits')
img = np.ones((20, 20))
with fitsio.FITS(
fn + '[compress HS 10 10; s 2.0]', 'rw', clobber=True
) as fits:
fits.write(img, dither_seed=42)
hdr = fitsio.read_header(fn, ext=1)
for key, val in [
('ZTILE1', 10),
('ZTILE2', 10),
('ZQUANTIZ', 'SUBTRACTIVE_DITHER_1'),
('ZCMPTYPE', 'HCOMPRESS_1'),
('ZDITHER0', 42),
('ZNAME1', 'SCALE'),
('ZVAL1', 2.0),
('ZNAME2', 'SMOOTH'),
('ZVAL2', 1),
]:
assert hdr[key] == val
def test_compression_qlevel_default():
# Check that if not specified, qlevel defaults to 4.
with tempfile.TemporaryDirectory() as tmpdir:
fn = os.path.join(tmpdir, 'test.fits')
H, W = 200, 200
bigimg = np.random.uniform(size=(H, W))
# Default qlevel
with fitsio.FITS(fn, 'rw', clobber=True) as fits:
fits.write(bigimg, compress='GZIP')
size_def = os.stat(fn).st_size
hdr = fitsio.read_header(fn, ext=1)
print(hdr)
for key, val in [
('ZQUANTIZ', 'SUBTRACTIVE_DITHER_1'),
('ZCMPTYPE', 'GZIP_1'),
]:
assert hdr[key] == val
# qlevel=0
with fitsio.FITS(fn, 'rw', clobber=True) as fits:
fits.write(bigimg, compress='GZIP', qlevel=0)
size_0 = os.stat(fn).st_size
# qlevel=4
with fitsio.FITS(fn, 'rw', clobber=True) as fits:
fits.write(bigimg, compress='GZIP', qlevel=4)
size_4 = os.stat(fn).st_size
# qlevel=16
with fitsio.FITS(fn, 'rw', clobber=True) as fits:
fits.write(bigimg, compress='GZIP', qlevel=16)
size_16 = os.stat(fn).st_size
# zero means NO COMPRESSION
assert size_0 > size_4
# heh, lower values mean MORE COMPRESSION
assert size_4 < size_16
assert size_def == size_4
def test_compression_multihdu_diskfile():
# Check multi-HDU case with a normal file
with tempfile.TemporaryDirectory() as tmpdir:
fn = os.path.join(tmpdir, 'test.fits')
img = np.ones((20, 20))
with fitsio.FITS(fn, 'rw', clobber=True) as fits:
# A
fits.write(img, extname='A')
# B
fits.write(img, extname='B', compress='GZIP')
# C
fits.write(
img,
extname='C',
compress='GZIP',
qmethod='SUBTRACTIVE_DITHER_2',
)
# D
fits.write(img, extname='D')
# E
fits.write(img, extname='E', compress='GZIP')
# F
fits.write(img, extname='F', compress=None)
with fitsio.FITS(fn) as fits:
assert len(fits) == 6
hdrA = fits['A'].read_header()
hdrB = fits['B'].read_header()
hdrC = fits['C'].read_header()
hdrD = fits['D'].read_header()
hdrE = fits['E'].read_header()
hdrF = fits['F'].read_header()
# A is uncompressed
assert 'ZCMPTYPE' not in hdrA
# B is gzip
assert hdrB['ZCMPTYPE'] == 'GZIP_1'
assert hdrB['ZQUANTIZ'] == 'SUBTRACTIVE_DITHER_1'
# C is gzip with SD2
assert hdrC['ZCMPTYPE'] == 'GZIP_1'
assert hdrC['ZQUANTIZ'] == 'SUBTRACTIVE_DITHER_2'
# D is not compressed
assert 'ZCMPTYPE' not in hdrD
# E is GZIP again
assert hdrE['ZCMPTYPE'] == 'GZIP_1'
assert hdrE['ZQUANTIZ'] == 'SUBTRACTIVE_DITHER_1'
# F is not compressed
assert 'ZCMPTYPE' not in hdrF
def test_compression_multihdu_memfile():
# Check multi-HDU case with a normal file
with tempfile.TemporaryDirectory() as tmpdir:
fn = os.path.join(tmpdir, 'test.fits')
img = np.ones((20, 20))
with fitsio.FITS("mem://", 'rw', clobber=True) as fits:
# A
fits.write(img, extname='A')
# B
fits.write(img, extname='B', compress='GZIP')
# C
fits.write(
img,
extname='C',
compress='GZIP',
qmethod='SUBTRACTIVE_DITHER_2',
)
# D
fits.write(img, extname='D')
# E
fits.write(img, extname='E', compress='GZIP')
# F
fits.write(img, extname='F', compress=None)
data = fits.read_raw()
with open(fn, 'wb') as f:
f.write(data)
with fitsio.FITS(fn) as fits:
assert len(fits) == 6
hdrA = fits['A'].read_header()
hdrB = fits['B'].read_header()
hdrC = fits['C'].read_header()
hdrD = fits['D'].read_header()
hdrE = fits['E'].read_header()
hdrF = fits['F'].read_header()
# A is uncompressed
assert 'ZCMPTYPE' not in hdrA
# B is gzip
assert hdrB['ZCMPTYPE'] == 'GZIP_1'
assert hdrB['ZQUANTIZ'] == 'SUBTRACTIVE_DITHER_1'
# C is gzip with SD2
assert hdrC['ZCMPTYPE'] == 'GZIP_1'
assert hdrC['ZQUANTIZ'] == 'SUBTRACTIVE_DITHER_2'
# D is not compressed
assert 'ZCMPTYPE' not in hdrD
# E is GZIP again
assert hdrE['ZCMPTYPE'] == 'GZIP_1'
assert hdrE['ZQUANTIZ'] == 'SUBTRACTIVE_DITHER_1'
# F is not compressed
assert 'ZCMPTYPE' not in hdrF
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