Eroman: Created page with "= Lecture 2 = Dictionaries, Importing, HTTP Requests, and Classes == Dictionaries == Map keys to values # Make a list >>> a = [1, 2, 3] # get element..."

2017-04-17T10:03:14Z

Created page with "= Lecture 2 = Dictionaries, Importing, HTTP Requests, and Classes == Dictionaries == Map keys to values <source lang="python"># Make a list >>> a = [1, 2, 3] # get element..."

New page

= Lecture 2 =

Dictionaries, Importing, HTTP Requests, and Classes

== Dictionaries ==

Map keys to values

<source lang="python"># Make a list
>>> a = [1, 2, 3]
# get element of a list using the index of an element
>>> a[1]
2
>>> a[0]
1
# get character in a string using the index of a character
>>> hello = "hello"
>>> hello[1]
'e'
# create a dictionary, with name of a programming language as a key
# and the year created as the value
>>> example_dict = {'python': 1991}
>>> example_dict
{'python': 1991}
# get value from a dictionary using the key
>>> example_dict['python']
1991
# accessing a key that does not exist
>>> example_dict['p']
Traceback (most recent call last):
File "<input>", line 1, in <module>
example_dict['p']
KeyError: 'p'
>>> example_dict.get('python')
1991
>>> example_dict.get('pythons')
>>> example_dict.get('pythons', 1990)
1990
# adding a new item (key and value pair) to a dictionary
>>> example_dict['javascript'] = 1995
>>> example_dict
{'javascript': 1995, 'python': 1991}
>>></source>
== Example creation of dictionary ==

Make a dictionary mapping numbers to squares

<source lang="python">def map_numbers_to_squares(numbers):
result = {}
for number in numbers:
result[number] = number ** 2
return result</source>
== TASK 1 ==

Args: multiplier: a number to multiply numbers by numbers: a list of numbers

Returns: dict of numbers, mapping each number to the number multiplied by the multiplier number is the key, the product is the value

<source lang="python">>>> test_function(4, [1,2])
# 1*4 = 4, 2*4 = 8
{1: 3, 2: 8}</source>
Answer:

<source lang="python">def map_products(multiplier, numbers):
result = {}
for number in numbers:
result[number] = number * multiplier
return result
</source>
== Importing ==

<source lang="python">import requests
import requests as r
from requests import get</source>
== Requests library ==

<code>pip3 install requests</code>

<source lang="python">import requests

response = requests.get('http://google.com')

response.text # get the response body as a string

response.json() # if the response is json, convert it into python native types</source>
== TASK 2 ==

Get the bitcoin price in euros, and print it.

== Importable thing ==

== TASK 3 ==

make a function that returns the bitcoin price. From another file, print the price

== Classes ==

This is a basic intro to classes. Classes organize code and provide the basis for the object/type system of python. An object has data and behavior. Classes define new objects. This python course will not require object oriented design, but you should know the basics of a python class.

<source lang="python"># define a class
class Animal:
# this is a magic method.
# __init__ is called when the class is instantiated
# `my_animal = Animal('masha')` makes a new Animal, executes this method, and assigns the new animal to 'my_animal'
def __init__(self, name):
# self refers to newly created instance of the class.
print(id(self))
# this creates an instance attribute 'name'
self.name = name

# define a Dog, which is Animal
# Dog also has the same __init__ method from animal
class Dog(Animal):
def change_name(self, name):
self.name = name

# define a Cat, which is an Animal
class Cat(Animal):
def kak_zavut(self):
return 'minu nimi on {}'.format(self.name)</source>

I719 Fundamentals of Python/lecture2v2 - Revision history

Eroman: Created page with "= Lecture 2 = Dictionaries, Importing, HTTP Requests, and Classes == Dictionaries == Map keys to values # Make a list >>> a = [1, 2, 3] # get element..."