other:python:misc_by_jyp
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other:python:misc_by_jyp [2023/03/28 14:10] jypeter [matplotlib related stuff] Added the time axes section |
other:python:misc_by_jyp [2023/04/26 15:50] jypeter Started a Data represenation section |
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| <code>sys.exit('Some optional message about why we are stopping')</code> | <code>sys.exit('Some optional message about why we are stopping')</code> | ||
| + | ===== Data representation ===== | ||
| + | A few notes for a future section or page about about data representation (bits and bytes) on disk and in memory, vs data format | ||
| + | |||
| + | * Binary data representation | ||
| + | * [[https://en.wikipedia.org/wiki/Bit_numbering|Bit numbering]] | ||
| + | * [[https://en.wikipedia.org/wiki/Endianness|Endianness]] | ||
| + | * [[https://en.wikipedia.org/wiki/Integer_(computer_science)|Integers]] | ||
| + | * Using [[https://en.wikipedia.org/wiki/Two%27s_complement|two's complement]] for negative integers | ||
| + | * Range: | ||
| + | * 4-byte integers: −2,147,483,648 to 2,147,483,647 | ||
| + | * 8-byte integers: −9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 | ||
| + | * [[https://en.wikipedia.org/wiki/IEEE_754|Floating point numbers]] (//IEEE 754// standard) | ||
| + | * Range: | ||
| + | * 4-byte float: ~8 significant digits ^10E±38 | ||
| + | * See also [[https://en.wikipedia.org/wiki/Single-precision_floating-point_format|Single-precision floating-point format|Single-precision floating-point format]] | ||
| + | * 8-byte float: ~15 significant digits ^10E±308 | ||
| + | |||
| + | * Array addressing | ||
| + | |||
| + | * disk and ram usage: how to check the usage (available ram and disk), best practice on multi-user systems (how much allowed?) | ||
| + | * ''du'', ''df'', ''cat /proc/meminfo'', ''top'' | ||
| + | |||
| + | * understanding and reverse-engineering //binary// format | ||
| + | * ''od'', ''strings'' | ||
| + | |||
| + | * binary vs text format: ascii, utf, raw | ||
| + | * text related functions in python: ''str'', ''int'', ''float'', ''ord'', ... | ||
| + | * lists conversion with ''map'' and ''join'' | ||
| + | |||
| + | * Misc : ''md5sum'' | ||
| ===== Checking if a file/directory is writable by the current user ===== | ===== Checking if a file/directory is writable by the current user ===== | ||
other/python/misc_by_jyp.txt · Last modified: 2024/04/19 12:02 by jypeter
