feat(examples): standard library

codes/session_8/libEg1.py

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+# How to Run? Open Terminal> python3 libEg1.py
+# Read the code comments and output on the terminal
+
+# Objective: Know about standard built-in library
+
+# Note: avoid using 'from os import *'.
+# This will keep 'os.open()' from shadowing the built-in 'open()' function
+import os
+
+# Return the currect directory
+print('Current Directory: ', os.getcwd())
+
+# Run command mkdir in the system shell
+# Return '0' means directory got created successfully
+# Return '256' means directory got created failed because its already exists
+print('Create directory "temp": ', os.system('mkdir temp'))
+
+# Change current working directory
+print('Change currect directory to "temp": ', os.chdir('temp'))
+
+print('\n')
+
+# Return a list of all module functions
+print('List of all module functions: ', dir(os))
+
+print('\n')
+
+# System libraries
+import sys
+
+# Arguments are stored in the sys module's argv attributes as a list
+print('Argv list: ', sys.argv) # python3 libEg1.py Hello => ['libEg1.py', 'hello']
+
+print('\n')
+
+# Output
+sys.stdout.write('[STDOUT]: This is ok\n')
+
+# Error output redirection and program termination
+sys.stderr.write('[STDERR]: This is not ok\n')
+
+print('\n')
+
+# Mathematics
+import math
+
+print( math.cos(math.pi / 4) )
+print( math.log(1024, 2) )
+
+print('\n')
+
+# Random
+import random
+
+print('Random choice: ', random.choice(['JavaScript', 'Python', 'Go']) ) # execute multiple times to see the output
+
+# Statistics
+import statistics
+
+data = [2.5, 1.57, 4.32, 5.67, 8.45]
+print('Statistics mean: ', statistics.mean(data) )
+

codes/session_8/libEg2.py

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+# How to Run? Open Terminal> python3 libEg2.py
+# Read the code comments and output on the terminal
+
+# Objective: Know about standard built-in library
+
+# Dates and Times
+from datetime import date
+
+# Get today's date
+now = date.today()
+print("Today's date: ", now)
+
+# Set date
+customDate = date(2000, 12, 2)
+print("Custom date: ", customDate)
+
+print('\n')
+
+# Data compression
+import zlib
+
+print('Data Compression Try 1: \n')
+
+dataStr1 = b'Hello world! my name is Ashwin' # prefix 'b' means bytes-like object
+print('Original: ', len(dataStr1) )
+
+comDataStr1 = zlib.compress(dataStr1)
+print('Compress: ', len(comDataStr1) )
+
+deComDataStr1 = zlib.decompress(comDataStr1)
+print('Decompress: ', len(deComDataStr1) )
+
+print('\n')
+
+print('Data Compression Try 2: \n')
+
+dataStr2 = b'Ashwin Ashwin Ashwin Ashwin' # prefix 'b' means bytes-like object
+print('Original: ', len(dataStr2) )
+
+comDataStr2 = zlib.compress(dataStr2)
+print('Compress: ', len(comDataStr2) )
+
+deComDataStr2 = zlib.decompress(comDataStr2)
+print('Decompress: ', len(deComDataStr2) )
+

codes/session_8/libEg3.py

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+# How to Run? Open Terminal> python3 libEg3.py
+# Read the code comments and output on the terminal
+
+# Objective: Know about standard built-in library
+
+# Doctest
+# The doctest module provides a tool for scanning a module 
+# and validating tests embedded in a programs docstrings.
+# Try changing '20' in below example to see the doctest
+
+def average(values):
+  """Computes the arithmetic mean of a list of numbers
+  >>> print(average([10, 20, 30]))
+  20
+  """
+  return sum(values) / len(values)
+
+import doctest
+doctest.testmod()
+
+# Also, see libEg3.test.py file for unittest module example

codes/session_8/libEg3.test.py

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+# How to Run? Open Terminal> python3 libEg3.test.py
+# Read the code comments and output on the terminal
+
+# Objective: Know about standard built-in library
+
+# The unittest module is not as effortless as the doctest module, 
+# but it allows a more comprehensive set of tests to be maintained in a separate file
+
+import unittest
+from libEg3 import average
+
+class TestStatisticalFunctions(unittest.TestCase):
+
+  def test_average(self):
+
+    self.assertEqual(average([10, 20, 30]), 20)
+
+    with self.assertRaises(ZeroDivisionError):
+      average([])
+
+    with self.assertRaises(TypeError):
+      average(20, 30, 70)
+
+unittest.main()