A small scanf implementation
Python has powerful regular expressions but they can be totally overkill for many simpler situations. Additionally, some common numerical formats require quite complex regex’s to match them robustly. This python implementation of scanf internally translates the simple scanf format into regular expressions, then returns the parsed values.
scanf.scanf(format, s=None, collapseWhitespace=True)
- format: This is the format string comprised of plain text and tokens from the table below.
- s: String to be parsed
- collapseWhitespace: When True, tells scanf to perform a greedy match with whitespace in the input string, allowing for easy parsing of text that has been formatted to be read more easily. This enables better matching in log files where the data has been formatted for easier reading. These cases have variable amounts of whitespace between the columns, depending on the number of characters in the data itself.
scanf supports the following formats:
|%d, %i||int value|
|%7d, %7i||int value with length 7|
|%X, %x||hex value|
|%s||string terminated by whitespace|
Any pattern with a * after the % (e.g., ‘%*f’) will result in scanf matching the pattern but omitting the matched portion from the results. This is helpful when parts of the input string may change but should be ignored.
The underlying regex operation is performed using ‘search’ rather than ‘match’, so scanf will return a match if the pattern string is matched anywhere in the line.
>>> from scanf import scanf >>> scanf("%s - %d errors, %d warnings", "/usr/sbin/sendmail - 0 errors, 4 warnings") ('/usr/sbin/sendmail', 0, 4)
>>> scanf("%o %x %d", "0123 0x123 123") (66, 291, 123)
>>> pattern = 'Power: %f [%], %s, Stemp: %f' >>> text = 'Power: 0.0 [%], Cool, Stemp: 23.73' >>> scanf(pattern, text) (0.0, 'Cool', 23.73)
>>> pattern = 'Power: %f [%], %*s, Stemp: %f' # note the '*' in %*s >>> scanf(pattern, text) (0.0, 23.73)
scanf returns a tuple of parsed values if the input pattern is matched, or None if the format does not match.
For more information see:
Original code from: http://code.activestate.com/recipes/502213-simple-scanf-implementation/
Modified original to make the %f more robust, as well as added %* modifier to skip fields.
- Initial release (internal)
- Changed regex from ‘match’ (only matches at beginning of line) to ‘search’ (matches anywhere in line)
- Bugfix - ignore cast for skipped fields
- Added ‘collapseWhitespace’ flag (defaults to True) to take the search string and replace all whitespace with regex string to match repeated whitespace. This enables better matching in log files where the data has been formatted for easier reading. These cases have variable amounts of whitespace between the columns, depending on the number of characters in the data itself.
- Added ‘extractdata’ function.
1.3.1 - 1.3.3: 2016-06-23
- Initial release to PyPI
- Fixed various issues with metadata for PyPI
- Small modification to scanf.py for Python3 compatibility. Thanks @Gattocrucco!
- Changed README.md to README.rst, removing pypandoc dependency in setup.py
- Removed most of the comments at the beginning of scanf.py, as they were redundant with those in the README.
- Added $^| characters to the list of special characters to escape in ‘scanf_compile’. Thanks @MichaelWedel!
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