COMP1531

1.4 - Python - Intro

 

Python

Interpreted V compiled

C program

Python program

Machine Code

Output

Output

Compile

Run

Compile & Run

 

Unlike C, Python is a very broad language with a rich range of libraries.

 

It's simply not possible for us to give you 100 lecture slides to teach you everything you need to know. For many of you, this will be the first course that you have to learn to take the basics from us, and then engage in self-learning to refine your knowledge of the language and it's uses.

Python

CLI (Command line interface)

  • Can be run inline
  • Can be run as cli entry
  • Can be run via a file

Python

Basic code (basics1.py)

name = "Giraffe"
age = 18
height = 2048.11 # mm

num1 = 3 ** 3
num2 = 27 // 3

print(name + ", " + str(age) + ', ' + str(height))
print(name, age, height, sep = ', ')
print(f"{name}, {age}, {height}")
print(type(name))
print(type(age))
print(type(height))
print(f"3 ** 3 == {num1}")
print(f"27 // 3 == {num2}")

Python - Basics

Strings (basics2.py)

  sentence = "My"
  sentence = sentence + " name is"
  sentence += " Pikachu"

  print(sentence)

  print("Hi!!" * 10)

Python strings are immutable

Python - Basics

Control structures, argc/argv (basics3.py)

import sys

argc = len(sys.argv)

empty = True
if argc > 0:
    empty = False

if not empty:
    if argc == 2:
        print("Nearly there")
    elif argc == 3:
        if sys.argv[1] == "H" and sys.argv[2] == "I":
            print("HI to you too")
        else:
             pass
else:
  print("Please enter two letters as command line")

.

Python - Basics

Lists, loops (basics4.py)

names = [ "Hayden", "Rob", "Isaac" ]
names.append("Vivian")

for name in names:
    print(name)

print("===")

names += [ "Eve", "Mia" ]
for i in range(0, len(names)):
    print(names[i])

Python lists are very complicated arrays under the hood. You can read a lot here, here, and here.

Python - Basics

Tuples (basics5.py)

x = 5
y = 6
point = (x, y)
print(point)

a, b = point # destructuring
print(f"{a}, {b}")

names = [ "Giraffe", "Llama", "Penguin" ]
for id, name in enumerate(names):
  print(f"{id} {name}")
  • lists are mutable, tuples are immutable

Python - Basics

Versions

python2

python3

Python

  • Rapidly build applications due to high level nature
  • Very straightforward toolchain to setup and use
  • It's very structured compared to other scripting languages
  • Useful in data science and analytics applications

Why Python?

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