diff options
Diffstat (limited to 'python.html.markdown')
| -rw-r--r-- | python.html.markdown | 61 |
1 files changed, 31 insertions, 30 deletions
diff --git a/python.html.markdown b/python.html.markdown index 56cb9aac..39e60455 100644 --- a/python.html.markdown +++ b/python.html.markdown @@ -50,17 +50,19 @@ Note: This article applies to Python 3 specifically. Check out [here](http://lea 10.0 / 3 # => 3.3333333333333335 # Modulo operation -7 % 3 # => 1 +7 % 3 # => 1 +# i % j have the same sign as j, unlike C +-7 % 3 # => 2 # Exponentiation (x**y, x to the yth power) 2**3 # => 8 # Enforce precedence with parentheses -1 + 3 * 2 # => 7 +1 + 3 * 2 # => 7 (1 + 3) * 2 # => 8 # Boolean values are primitives (Note: the capitalization) -True # => True +True # => True False # => False # negate with not @@ -126,13 +128,13 @@ b == a # => True, a's and b's objects are equal "This is a string." 'This is also a string.' -# Strings can be added too! But try not to do this. +# Strings can be added too "Hello " + "world!" # => "Hello world!" # String literals (but not variables) can be concatenated without using '+' "Hello " "world!" # => "Hello world!" # A string can be treated like a list of characters -"This is a string"[0] # => 'T' +"Hello world!"[0] # => 'H' # You can find the length of a string len("This is a string") # => 16 @@ -140,10 +142,9 @@ len("This is a string") # => 16 # You can also format using f-strings or formatted string literals (in Python 3.6+) name = "Reiko" f"She said her name is {name}." # => "She said her name is Reiko" -# You can basically put any Python statement inside the braces and it will be output in the string. +# You can basically put any Python expression inside the braces and it will be output in the string. f"{name} is {len(name)} characters long." # => "Reiko is 5 characters long." - # None is an object None # => None @@ -173,7 +174,6 @@ print("Hello, World", end="!") # => Hello, World! # Simple way to get input data from console input_string_var = input("Enter some data: ") # Returns the data as a string -# Note: In earlier versions of Python, input() method was named as raw_input() # There are no declarations, only assignments. # Convention is to use lower_case_with_underscores @@ -186,7 +186,7 @@ some_unknown_var # Raises a NameError # if can be used as an expression # Equivalent of C's '?:' ternary operator -"yahoo!" if 3 > 2 else 2 # => "yahoo!" +"yay!" if 0 > 1 else "nay!" # => "nay!" # Lists store sequences li = [] @@ -482,7 +482,7 @@ except (TypeError, NameError): pass # Multiple exceptions can be handled together, if required. else: # Optional clause to the try/except block. Must follow all except blocks print("All good!") # Runs only if the code in try raises no exceptions -finally: # Execute under all circumstances +finally: # Execute under all circumstances print("We can clean up resources here") # Instead of try/finally to cleanup resources you can use a with statement @@ -506,7 +506,7 @@ print(contents) with open('myfile2.txt', "r+") as file: contents = json.load(file) # reads a json object from a file -print(contents) +print(contents) # print: {"aa": 12, "bb": 21} @@ -735,7 +735,7 @@ class Human: return "*grunt*" # A property is just like a getter. - # It turns the method age() into an read-only attribute of the same name. + # It turns the method age() into a read-only attribute of the same name. # There's no need to write trivial getters and setters in Python, though. @property def age(self): @@ -772,11 +772,10 @@ if __name__ == '__main__': # Call the static method print(Human.grunt()) # => "*grunt*" - - # Cannot call static method with instance of object - # because i.grunt() will automatically put "self" (the object i) as an argument - print(i.grunt()) # => TypeError: grunt() takes 0 positional arguments but 1 was given - + + # Static methods can be called by instances too + print(i.grunt()) # => "*grunt*" + # Update the property for this instance i.age = 42 # Get the property @@ -792,7 +791,7 @@ if __name__ == '__main__': #################################################### # Inheritance allows new child classes to be defined that inherit methods and -# variables from their parent class. +# variables from their parent class. # Using the Human class defined above as the base or parent class, we can # define a child class, Superhero, which inherits the class variables like @@ -920,13 +919,13 @@ class Batman(Superhero, Bat): def __init__(self, *args, **kwargs): # Typically to inherit attributes you have to call super: - # super(Batman, self).__init__(*args, **kwargs) + # super(Batman, self).__init__(*args, **kwargs) # However we are dealing with multiple inheritance here, and super() # only works with the next base class in the MRO list. # So instead we explicitly call __init__ for all ancestors. # The use of *args and **kwargs allows for a clean way to pass arguments, # with each parent "peeling a layer of the onion". - Superhero.__init__(self, 'anonymous', movie=True, + Superhero.__init__(self, 'anonymous', movie=True, superpowers=['Wealthy'], *args, **kwargs) Bat.__init__(self, *args, can_fly=False, **kwargs) # override the value for the name attribute @@ -941,9 +940,9 @@ if __name__ == '__main__': # Get the Method Resolution search Order used by both getattr() and super(). # This attribute is dynamic and can be updated - print(Batman.__mro__) # => (<class '__main__.Batman'>, - # => <class 'superhero.Superhero'>, - # => <class 'human.Human'>, + print(Batman.__mro__) # => (<class '__main__.Batman'>, + # => <class 'superhero.Superhero'>, + # => <class 'human.Human'>, # => <class 'bat.Bat'>, <class 'object'>) # Calls parent method but uses its own class attribute @@ -1030,13 +1029,15 @@ print(say(say_please=True)) # Can you buy me a beer? Please! I am poor :( * [Automate the Boring Stuff with Python](https://automatetheboringstuff.com) * [Ideas for Python Projects](http://pythonpracticeprojects.com) -* [The Official Docs](http://docs.python.org/3/) -* [Hitchhiker's Guide to Python](http://docs.python-guide.org/en/latest/) -* [Python Course](http://www.python-course.eu/index.php) +* [The Official Docs](https://docs.python.org/3/) +* [Hitchhiker's Guide to Python](https://docs.python-guide.org/en/latest/) +* [Python Course](https://www.python-course.eu) * [First Steps With Python](https://realpython.com/learn/python-first-steps/) * [A curated list of awesome Python frameworks, libraries and software](https://github.com/vinta/awesome-python) -* [30 Python Language Features and Tricks You May Not Know About](http://sahandsaba.com/thirty-python-language-features-and-tricks-you-may-not-know.html) +* [30 Python Language Features and Tricks You May Not Know About](https://sahandsaba.com/thirty-python-language-features-and-tricks-you-may-not-know.html) * [Official Style Guide for Python](https://www.python.org/dev/peps/pep-0008/) -* [Python 3 Computer Science Circles](http://cscircles.cemc.uwaterloo.ca/) -* [Dive Into Python 3](http://www.diveintopython3.net/index.html) -* [A Crash Course in Python for Scientists](http://nbviewer.jupyter.org/gist/anonymous/5924718) +* [Python 3 Computer Science Circles](https://cscircles.cemc.uwaterloo.ca/) +* [Dive Into Python 3](https://www.diveintopython3.net/index.html) +* [A Crash Course in Python for Scientists](https://nbviewer.jupyter.org/gist/anonymous/5924718) +* [Python Tutorial for Intermediates](https://pythonbasics.org/) +* [Build a Desktop App with Python](https://pythonpyqt.com/) |