Merge pull request #15 from surister/new_python_answers

Add new python answers
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@ -1642,6 +1642,19 @@ Swarm management which means you can create new swarms in Docker Cloud.
<details>
<summary>What are some characteristics of the Python programming language?</summary><br><b>
```
1. It is a high level general purpose programming language created in 1991 by Guido Van Rosum.
2. The language is interpreted, being the CPython (Written in C) the most used/maintained implementation.
3. It is strongly typed. The typing discipline is duck typing and gradual.
4. Python focuses on readability and makes use of whitespaces/identation instead of brackets { }
5. The python packate manager is called PIP "pip installs packages", having more than 200.000 available packages.
6. Python comes with pip installed and a big standard library that offers the programmer many precooked solutions.
7. In python **Everything** is an object.
There are many other characteristics but these are the main ones that every python programmer should know.
```
</b></details>
<details>
@ -1679,6 +1692,71 @@ PEP8 is a list of coding conventions and style guidelines for Python
<details>
<summary>Explain inheritance and how to use it in Python</summary><br><b>
```
By definition inheritance is the mechanism where an object acts as a base of another object, retaining all its
properties.
So if Class B inherits from Class A, every characteristics from class A will be also available in class B.
Class A would be the 'Base class' and B class would be the 'derived class'.
This comes handy when you have several classes that share the same functionalities.
The basic syntax is:
class Base: pass
class Derived(Base): pass
A more forged example:
class Animal:
def __init__(self):
print("and I'm alive!")
def eat(self, food):
print("ñom ñom ñom", food)
class Human(Animal):
def __init__(self, name):
print('My name is ', name)
super().__init__()
def write_poem(self):
print('Foo bar bar foo foo bar!')
class Dog(Animal):
def __init__(self, name):
print('My name is', name)
super().__init__()
def bark(self):
print('woof woof')
michael = Human('Michael')
michael.eat('Spam')
michael.write_poem()
bruno = Dog('Bruno')
bruno.eat('bone')
bruno.bark()
>>> My name is Michael
>>> and I'm alive!
>>> ñom ñom ñom Spam
>>> Foo bar bar foo foo bar!
>>> My name is Bruno
>>> and I'm alive!
>>> ñom ñom ñom bone
>>> woof woof
Calling super() calls the Base method, thus, calling super().__init__() we called the Animal __init__.
There is a more advanced python feature called MetaClasses that aid the programmer to directly control class creation.
```
</b></details>
<details>
@ -1694,7 +1772,18 @@ PEP8 is a list of coding conventions and style guidelines for Python
```
Shortest way is <code>str[::-1]</code> but not the most efficient.
"Classic" way:
foo = ''
for char in 'pizza':
foo = char + foo
>> 'azzip'
```
</b></details>
<details>
@ -1705,7 +1794,7 @@ Shortest way is <code>str[::-1]</code> but not the most efficient.
<summary>What _ is used for in Python?</summary><br><b>
1. Translation lookup in i18n
2. Hold the result of the last executed expression or statement
2. Hold the result of the last executed expression or statement in the interactive interpreter.
3. As a general purpose "throwaway" variable name. For example: x, y, _ = get_data() (x and y are used but since we don't care about third variable, we "threw it away").
</b></details>
@ -1719,6 +1808,12 @@ Shortest way is <code>str[::-1]</code> but not the most efficient.
<details>
<summary>How to write to a file?</summary><br><b>
```
with open('file.txt', 'w') as file:
file.write("My insightful comment")
```
</b></details>
<details>
@ -1740,8 +1835,22 @@ sorted(x, key=lambda l: l[1])
Extract all type of foods. Final output should be: {'mushrooms', 'goombas', 'turtles'}</summary><br><b>
```
brothers_menu = \
[{'name': 'Mario', 'food': ['mushrooms', 'goombas']}, {'name': 'Luigi', 'food': ['mushrooms', 'turtles']}]
# "Classic" Way
def get_food(brothers_menu) -> set:
temp = []
for brother in brothers_menu:
for food in brother['food']:
temp.append(food)
return set(temp)
set([food for bro in x for food in bro['food']])
```
</b></details>
<details>
@ -1751,9 +1860,18 @@ set([food for bro in x for food in bro['food']])
<details>
<summary>How to reverse a string?</summary><br><b>
Shortest way is: <code>my_string[::-1]</code> but it doesn't mean it's the most efficient one.
Shortest way is: <code>my_string[::-1]</code> but it doesn't mean it's the most efficient one. <br>
Cassic way is:
```
def reverse_string(string):
temp = ""
for char in string:
temp = char + temp
return temp
```
</b></details>
<details>
<summary>Write a function to determine if a given string is a palindrome</summary><br><b>
</b></details>