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--- other:python:misc_by_jyp [2023/03/28 16:10] – [matplotlib related stuff] Added the time axes section jypeter
+++ other:python:misc_by_jyp [2023/04/26 17:50] – Started a Data represenation section jypeter
@@ Line 32: / Line 32: @@
 <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 =====