other:python:misc_by_jyp
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other:python:misc_by_jyp [2023/04/27 15:52] jypeter [Data representation] Improved |
other:python:misc_by_jyp [2023/04/28 14:11] jypeter [Numerical values] Added low level array addressing |
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| A few notes for a future section or page about about //data representation// (bits and bytes) on disk and in memory, vs //data format// | A few notes for a future section or page about about //data representation// (bits and bytes) on disk and in memory, vs //data format// | ||
| + | |||
| + | |||
| + | ==== Numerical values ==== | ||
| * Binary data representation of some numbers: | * Binary data representation of some numbers: | ||
| Line 113: | Line 116: | ||
| '00000003 00000011' | '00000003 00000011' | ||
| </code> | </code> | ||
| + | |||
| + | * Manipulating binary data with [[https://docs.python.org/3/library/stdtypes.html#binary-sequence-types-bytes-bytearray-memoryview|bytes, bytearray, memoryview]] | ||
| * Array addressing | * Array addressing | ||
| + | * [[https://www.geeksforgeeks.org/calculation-of-address-of-element-of-1-d-2-d-and-3-d-using-row-major-and-column-major-order/|Calculation of address of element of 1-D, 2-D, and 3-D using row-major and column-major order]] | ||
| + | * In other words: //using indices to go from 1-D to n-Dimnensions data// | ||
| + | * The [[https://en.wikipedia.org/wiki/Array_(data_structure)|array]] structure | ||
| * python/C vs Fortran... | * python/C vs Fortran... | ||
| Line 128: | Line 136: | ||
| * Misc : ''md5sum'' | * Misc : ''md5sum'' | ||
| + | |||
| + | ==== Strings ==== | ||
| + | |||
| + | * Encoding, [[https://en.wikipedia.org/wiki/ASCII|ASCII]], [[https://en.wikipedia.org/wiki/Unicode|unicode]], [[https://en.wikipedia.org/wiki/UTF-8|UTF-8]], ... | ||
| + | |||
| + | * Getting the binary representation of a string | ||
| + | * <code>>>> test_string = 'A B 0 1 à µ' | ||
| + | >>> type(test_string) | ||
| + | <class 'str'> | ||
| + | >>> len(test_string) | ||
| + | 11 | ||
| + | >>> test_string_bin = test_string.encode('utf-8') | ||
| + | >>> test_string_bin | ||
| + | b'A B 0 1 \xc3\xa0 \xc2\xb5' | ||
| + | >>> type(test_string_bin) | ||
| + | <class 'bytes'> | ||
| + | >>> len(test_string_bin) | ||
| + | 13 | ||
| + | >>> test_string_bin.hex('-') | ||
| + | '41-20-42-20-30-20-31-20-c3-a0-20-c2-b5' | ||
| + | </code> | ||
| + | |||
| ===== 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
