Module 02: Data types and data structures

Preparation

• Read chapter 03 from Dive into Python;
• Read chapter Built-in types from Python's documentation.

Main data types

Data types represent values with common properties. For example int represents all integer numbers. You can perform comparison and mathematical operations on int numbers. str is the type representing text values.

In Python the main data types are int, float, boolean, str, list, dict, tuple and set! Operators for these types are defined in the documentation and will be used in the tasks below. We will explain them as we go along!

DateTime types

Python has special types for working with dates and times. They live in the datetime module.

>>> from datetime import datetime, timedelta
>>> datetime.now()
datetime.datetime(2017, 8, 5, 23, 43, 50, 500589)
>>> datetime.now().isoformat()
'2017-08-05T23:44:02.508418'
>>> datetime.now().year
2017
>>> datetime.now() - timedelta(days=7)
datetime.datetime(2017, 7, 29, 23, 44, 33, 101454)

Tasks & homework

• Implement a function num_add(a, b) which adds two numbers together

• Implement a function num_sub(a, b) which subtracts two numbers

• Implement a function num_mul(a, b) which multiplies two numbers

• Implement a function num_div(a, b) which divides the two numbers

• Implement a function num_floor(a, b) which implements floor division

• Implement a function num_rem(a, b) which implements remainder division

• Define boolean constant IS_TRUE

• Define boolean constant IS_FALSE

• Define the PANCAKE_INGREDIENTS dictionary to include the following keys and values

    flour - 2
    eggs - 4
    milk - 200
    butter - False
    salt - 0.001
  

• Implement a function ingredient_exists(ingr, dict) which returns boolean if the ingredient ingr exists in the dictionary `dict

• Implement a function fatten_pancakes(dict) which returns a dictionary. The return value contains the pancake ingredients where eggs == 6 and butter == True. NOTE: don't change the PANCAKE_INGREDIENTS constant! Use dict.copy() method!

• Implement a function add_sugar(dict) which adds 'sugar' to the list of ingredients and returns a new dictionary

• Implement a function remove_salt(dict) which removes 'salt' from the list of igredients and returns a new dictionary

• Define a list called FIBONACCI_NUMBERS which contains the first 12 Fibonacci numbers:

    1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144
  

• Implement a function add_fibonacci(lst) which extends the list of numbers with the next Fibonacci number

• Implement a function fib_exists(lst, n) which returns boolean. The function checks if the number n exists in the Fibonacci sequence lst

• Implement a function which_fib(lst, n) which returns integer. This is the index of the number n inside the sequence lst counting from 1.

TIP: Use the test.py file to validate your solution is correct.