Training, Open Source Programming Languages

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For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
Handling JSON in Python (and a csv, marshall and pickle comparison)

JSON - JavaScript Object Notation - has become the data encoding standard of choice for many applications far removed from the "Javascript" of its name. It's a compact, readable format which allows collections within a language (that would be lists and dicts in Python, for example) to be encoded into a text string for file storage or network transmission, and easily decoded later / at the other end.

I wrote a demonstration during last week's Python Programming Course to show how JSON data can be read - from a file, or from a web service, and the data loaded into dicts and / or lists with a single call:
  rawinfo = stream.read()
  info = json.loads(rawinfo)


The data can be outpout just as easily:
  rawoutput = json.dumps(info)
  print rawoutput


You do need to import the json module first:
  import json

Source code - [here].

The example also included writing parts of the same data out to a .csv file. You could write this longhand (as I did [here] on a previous course), or you could use a json writer filter:

  import csv
  
  outstream = open("soumya.csv","w")
  author = csv.writer(outstream)
  for visit in info["acc"]:
    print visit["when"],visit["where"],visit["which"]
    author.writerow([visit["when"],visit["where"],visit["which"]])
  outstream.close()


JSON broadly replaces marshalling of data in Python (see old examples [here] and [here]) - not much of a change as (!) the method names are the same. It also replaces pickling - see the older examples [here] and [here].

(written 2013-11-16, updated 2013-11-19)

 
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)
  [4298] Python - an interesting application - (2014-09-18)
  [4439] Json is the new marshall, pickle and cPickle / Python - (2015-02-22)
  [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)

Y201 - Python for DataMunging and System Admin
  [3479] Practical Extraction and Reporting - using Python and Extreme Programming - (2011-10-14)
  [4088] Some tips and techniques for huge data handling in Python - (2013-05-15)
  [4438] Loving programming in Python - and ready to teach YOU how - (2015-02-22)


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If elif elif elif - multiway selection in Python
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Python functions - an introduction to how they work
Some other Articles
Great beauty, but great natural danger
A busy week, and a long flight
Formatting options in Python
Python functions - an introduction to how they work
Handling JSON in Python (and a csv, marshall and pickle comparison)
If elif elif elif - multiway selection in Python
Lists in Tcl - fundamentals in a commented source code example
Tcl + Tk (Wish) - an introduction and revision example
Exception handling in Tcl
Writing the perfect program in Tcl?
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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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