06_datastructuresExample.py

#!/usr/bin/env python3

"""
Examples using lists, tuples and dictionaries (dict)

https://docs.python.org/3/tutorial/datastructures.html

Jens Dede, 2019, jd@comnets.uni-bremen.de
"""

# Lists
###
print(5*"#", "Lists")
l = [1,2,3]          # List with three values

# Append some items (numbers)
l.append(12)
l.append(13)
l.append(14)
l.append(15)

# Print complete list
print("Complete list", l)

# Print parts of the list
print("First entry:", l[0])
print("Last entry:", l[-1])
print("Only till the 2nd entry:", l[:2])
print("Only the last 2 entries:", l[-2:])

# Change a list item
l[1] = 123

# Lists can be sorted
l.sort()

print("Changed list:", l)

# Iterate over the list
for i in l:
    print("List item", i)

# Tuples
###
# \n creates a new line
print("\n\n",5*"#", "Tuples")

# Create a tuple
t = (1,2,3,4,5)

# Accessing tuple items
print(t, t[0])

# Iterate over a tuple
for i in t:
    print("Tuple item", i)

# Tuples cannot be changed after assigning them!
# Advantage: They are faster than lists


# Dictionaries (dict) (key-value storage)
###
# \n creates a new line
print("\n\n",5*"#", "Dictionaries (dict)")

data = {}   # Empty dict
data["name"] = "My Name"        # Assign value "My Name" using key "name" to dict data
data["address"] = "My Address"

# Access dict item using key
print('data["name"]:', data["name"])

# Print complete dict
print("data:", data)

# Iterate over dict
for key in data:
    print("key:", key)
    print("data:", data[key])

# Init a dictionary with values
myDict = {
        "valueA": "Hallo",
        "valueB": [1,2,3,4]
        }

print(myDict)
print(myDict["valueA"])

# What to try out
#################
# - You can combine the datatypes. Create a list of dictionaries containing the
# first name and the last name. Access the elements and change something.