Json is the new marshall, pickle and cPickle / Python

For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))

Conversion of objects into serial data, such that it can be stored in a file or passed over a network, and restoring it when read back, is a vital topic within any serious object oriented application. It's all very well working with an object on the heap (i.e. in memory while your program runs), but if you dump it out and then restore it, you're going to need to do so in such a way that it can go to a different memory location, as chances are that the addresses it was saved from are going to be in other use when you restore. Thus a serialised format, and json has beceome very much the standard - it's compact, character based rather than binary, quite flexible, and widely supported.

In Python, you may still have reasons to use marshall, pickle and cpickle, or xml, but 9 times out of 10 you'll do better using Json.

This morning I have been working with a 1 Gbyte data flow, and rather than repeat the analysis of my raw data (136 seconds elapsed time) to create the dicts and lists I want to go on and graph, I've chosen to do the extraction once and dump out the Json data to a file. Subsequent runs of my program will check for the file, and read it if present (well under a second!) - see source code here. It's going to save me an awful lot of time during the course this week (and will stop my delegates getting bored) as I'm using Json as my cache. Note the "pretty print" option I have added too - allowing my Json objects to be written raw (which would be the norm), or well formatted (which I've used to show you on our web site - data is [here].
(written 2015-02-22)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles

Y115 - Additional Python Facilities
  [183] The elegance of Python - (2005-01-19)
  [208] Examples - Gadfly, NI Number, and Tcl to C interface - (2005-02-10)
  [239] What and why for the epoch - (2005-03-08)
  [463] Splitting the difference - (2005-10-13)
  [663] Python to MySQL - (2006-03-31)
  [672] Keeping your regular expressions simple - (2006-04-05)
  [753] Python 3000 - the next generation - (2006-06-09)
  [901] Python - listing out the contents of all variables - (2006-10-21)
  [1043] Sending an email from Python - (2007-01-18)
  [1136] Buffering output - why it is done and issues raised in Tcl, Perl, Python and PHP - (2007-04-06)
  [1149] Turning objects into something you can store - Pickling (Python) - (2007-04-15)
  [1305] Regular expressions made easy - building from components - (2007-08-16)
  [1336] Ignore case in Regular Expression - (2007-09-08)
  [1337] A series of tyre damages - (2007-09-08)
  [1876] Python Regular Expressions - (2008-11-08)
  [2407] Testing code in Python - doctest, unittest and others - (2009-09-16)
  [2435] Serialization - storing and reloading objects - (2009-10-04)
  [2462] Python - how it saves on compile time - (2009-10-20)
  [2655] Python - what is going on around me? - (2010-02-28)
  [2721] Regular Expressions in Python - (2010-04-14)
  [2745] Connecting Python to sqlite and MySQL databases - (2010-04-28)
  [2746] Model - View - Controller demo, Sqlite - Python 3 - Qt4 - (2010-04-29)
  [2764] Python decorators - your own, staticmethod and classmethod - (2010-05-14)
  [2765] Running operating system commands from your Python program - (2010-05-14)
  [2786] Factory methods and SqLite in use in a Python teaching example - (2010-05-29)
  [2790] Joining a MySQL table from within a Python program - (2010-06-02)
  [3089] Python regular expressions - repeating, splitting, lookahead and lookbehind - (2010-12-17)
  [3442] A demonstration of how many Python facilities work together - (2011-09-16)
  [3469] Teaching dilemma - old tricks and techniques, or recent enhancements? - (2011-10-08)
  [4085] JSON from Python - first principles, easy example - (2013-05-13)
  [4211] Handling JSON in Python (and a csv, marshall and pickle comparison) - (2013-11-16)
  [4298] Python - an interesting application - (2014-09-18)
  [4451] Running an operating system command from your Python program - the new way with the subprocess module - (2015-03-06)
  [4536] Json load from URL, recursive display, Python 3.4 - (2015-10-14)
  [4593] Command line parameter handling in Python via the argparse module - (2015-12-08)
  [4709] Some gems from Intermediate Python - (2016-10-30)

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Loving programming in Python - and ready to teach YOU how

Previous and next
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Horse's mouth home

Forward to
A first graph with Matplotlib in Python

Some other Articles

Seventh stay away this year - and it's still only February!
Mutable v Immuatble objects in Python, and the implication
Reading command line parameters in Python
A first graph with Matplotlib in Python
Json is the new marshall, pickle and cPickle / Python
Loving programming in Python - and ready to teach YOU how
Adding a PHP build option, rotating an image based on camera data, and a new look at thumbnails in PHP
Accessing a MySQL database from Python with mysql.connector
Images of our rail promotion campaign
Public training courses - upcoming dates

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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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