PyFITS installs a couple of useful utility programs on your system that are built with PyFITS.
fitscheck is a command line script based on pyfits for verifying and updating the CHECKSUM and DATASUM keywords of .fits files. Fitscheck can also detect and often fix other FITS standards violations. fitscheck facilitates re-writing the non-standard checksums originally generated by pyfits with standard checksums which will interoperate with cfitsio.
fitscheck will refuse to write new checksums if the checksum keywords are missing or their values are bad. Use –force to write new checksums regardless of whether or not they currently exist or pass. Use –ignore-missing to tolerate missing checksum keywords without comment.
Example uses of fitscheck:
Verify and update checksums, tolerating non-standard checksums, updating to standard checksum:
$ fitscheck --checksum either --write *.fits
Write new checksums, even if existing checksums are bad or missing:
$ fitscheck --write --force *.fits
Verify standard checksums and FITS compliance without changing the files:
$ fitscheck --compliance *.fits
Verify original nonstandard checksums only:
$ fitscheck --checksum nonstandard *.fits
Only check and fix compliance problems, ignoring checksums:
$ fitscheck --checksum none --compliance --write *.fits
Verify standard interoperable checksums:
$ fitscheck *.fits
Delete checksum keywords:
$ fitscheck --checksum none --write *.fits
Usage: fitscheck [options] <.fits files...> .e.g. fitscheck example.fits Verifies and optionally re-writes the CHECKSUM and DATASUM keywords for a .fits file. Optionally detects and fixes FITS standard compliance problems. Options: -h, --help show this help message and exit -k [standard | nonstandard | either | none], --checksum=[standard | nonstandard | either | none] Choose FITS checksum mode or none. Defaults standard. -w, --write Write out file checksums and/or FITS compliance fixes. -f, --force Do file update even if original checksum was bad. -c, --compliance Do FITS compliance checking; fix if possible. -i, --ignore-missing Ignore missing checksums. -v, --verbose Generate extra output.
fitsdiff provides a thin command-line wrapper around the FITSDiff interface–it outputs the report from a FITSDiff of two FITS files, and like common diff-like commands returns a 0 status code if no differences were found, and 1 if differences were found:
Usage ===== Compare two FITS image files and report the differences in header keywords and data. fitsdiff [options] filename1 filename2 where filename1 filename2 are the two files to be compared. They may also be wild cards, in such cases, they must be enclosed by double or single quotes, or they may be directory names. If both are directory names, all files in each of the directories will be included; if only one is directory name, then the directory name will be prefixed to the file name(s) specified by the other argument. for example:: fitsdiff "*.fits" "/machine/data1" will compare all FITS files in the current directory to the corresponding files in the directory /machine/data1. Options ======= --help, -h show this help message and exit --quiet, -q Produce no output and just return a status code. --num-diffs=INTEGER, -n INTEGER Max number of data differences (image pixel or table element) to report per extension (default 10). --difference-tolerance=NUMBER, -d NUMBER The relative tolerance for comparison of two numbers, specifically two floating point numbers. This applies to data in both images and tables, and to floating point keyword values in headers (default 0.0). --no-ignore-blanks, -b Don't ignore trailing blanks (whitespace) in string values. Otherwise trailing blanks both in header keywords/values and in table column values) are not treated as significant i.e. without this option 'ABC ' and 'ABC' are considered equivalent. --no-ignore-blank-cards Don't ignore entirey blank cards in headers. Normally fitsdiff does not consider blank cards when comparing headers, but this will ensure that even blank cards match up. --output-file=FILE, -o FILE Output results to this file; otherwise results are printed to stdout. Header Comparison Options ------------------------- --ignore-keywords=KEYWORDS, -k KEYWORDS Comma-separated list of keywords not to be compared. Keywords may contain wildcard patterns. To exclude all keywords, use "*"; make sure to have double or single quotes around the asterisk. --ignore-comments=KEYWORDS, -c KEYWORDS Comma-separated list of keywords whose comments will not be compared. Wildcards may be used as with --ignore-keywords. Table Comparison Options ------------------------ --ignore-fields=COLUMNS, -f COLUMNS Comma-separated list of fields (i.e. columns) not to be compared. All columns may be excluded using "*" as with --ignore-keywords. If the two files are identical within the specified conditions, it will report "No difference is found." If the value(s) of -c and -k takes the form '@filename', list is in the text file 'filename', and each line in that text file contains one keyword. Example ------- fitsdiff -k filename,filtnam1 -n 5 -d 1.e-6 test1.fits test2 This command will compare files test1.fits and test2.fits, report maximum of 5 different pixels values per extension, only report data values larger than 1.e-6 relative to each other, and will neglect the different values of keywords FILENAME and FILTNAM1 (or their very existence). fitsdiff commandline arguments can also be set using the environment variable FITSDIFF_SETTINGS. If the FITSDIFF_SETTINGS environment variable is present, each argument present will override the corresponding argument on the commandline. This environment variable exists to make it easier to change the behavior of fitsdiff on a global level, such as in a set of regression tests.