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Diffstat (limited to 'python.html.markdown')
| -rw-r--r-- | python.html.markdown | 80 |
1 files changed, 44 insertions, 36 deletions
diff --git a/python.html.markdown b/python.html.markdown index 8a9ea48f..5c0dc0d8 100644 --- a/python.html.markdown +++ b/python.html.markdown @@ -1,20 +1,25 @@ --- -language: Python +language: python author: Louie Dinh author_url: http://ldinh.ca --- -Python was created by Guido Van Rossum in the early 90's. It is now one of the most popular languages in existence. I fell in love with Python for it's syntactic clarity. It's basically executable pseudocode. +Python was created by Guido Van Rossum in the early 90's. It is now one of the most popular +languages in existence. I fell in love with Python for it's syntactic clarity. It's basically +executable pseudocode. -```Python +Note: This article applies to Python 2.7 specifically, but should be applicable +to Python 2.x. Look for another tour of Python 3 soon! + +```python # Single line comments start with a hash. """ Multiline comments can we written using three "'s """ ----------------------------------------------------- --- 1. Primitive Datatypes and Operators ----------------------------------------------------- +#################################################### +## 1. Primitive Datatypes and Operators +#################################################### # You have numbers 3 #=> 3 @@ -25,7 +30,8 @@ Python was created by Guido Van Rossum in the early 90's. It is now one of the m 10 * 2 #=> 20 35 / 5 #=> 7 -# Division is a bit tricky. It is integer division and floors the results automatically. +# Division is a bit tricky. It is integer division and floors the results +# automatically. 11 / 4 #=> 2 # Enforce precedence with parentheses @@ -58,16 +64,16 @@ not False #=> True None #=> None ----------------------------------------------------- --- 2. Variables and Collections ----------------------------------------------------- +#################################################### +## 2. Variables and Collections +#################################################### # Printing is pretty easy print "I'm Python. Nice to meet you!" # No need to declare variables before assigning to them. -some_var = 5 # Convention is to use lower_case_with_underscores for variables +some_var = 5 # Convention is to use lower_case_with_underscores some_var #=> 5 # Accessing a previously unassigned variable is an exception @@ -97,7 +103,7 @@ del li[2] # li is now [1, 2, 3] li + other_li #=> [1, 2, 3, 4, 5, 6] - Note: li and other_li is left alone # Concatenate lists with extend -li.extend(other_li) # Now li is [1 ,2 ,3 ,4 ,5 ,6] +li.extend(other_li) # Now li is [1, 2, 3, 4, 5, 6] # Check for existence in a list with in 1 in li #=> True @@ -120,10 +126,13 @@ filled_dict = {"one": 1, "two": 2, "three": 3} filled_dict["one"] #=> 1 # Get all keys as a list -filled_dict.keys() #=> ["three", "two", "one"] Note - Dictionary key ordering is not guaranteed. Your results might not match this exactly. +filled_dict.keys() #=> ["three", "two", "one"] +# Note - Dictionary key ordering is not guaranteed. +# Your results might not match this exactly. # Get all values as a list -filled_dict.values() #=> [3, 2, 1] Note - Same as above regarding key ordering. +filled_dict.values() #=> [3, 2, 1] +# Note - Same as above regarding key ordering. # Check for existence of keys in a dictionary with in "one" in filled_dict #=> True @@ -150,9 +159,9 @@ filled_set | other_set #=> set([1, 2, 3, 4, 5, 6]) 10 in filled_set #=> False ----------------------------------------------------- --- 3. Control Flow ----------------------------------------------------- +#################################################### +## 3. Control Flow +#################################################### # Let's just make a variable some_var = 5 @@ -175,7 +184,8 @@ prints: mouse is a mammal """ for animal in ["dog", "cat", "mouse"]: - print "%s is a mammal" % animal # You can use % to interpolate formatted strings + # You can use % to interpolate formatted strings + print "%s is a mammal" % animal """ While loops go until a condition is no longer met. @@ -188,7 +198,7 @@ prints: x = 0 while x < 4: print x - x += 1 # Short hand for x = x + 1 + x += 1 # Shorthand for x = x + 1 # Handle exceptions with a try/except block try: @@ -197,9 +207,9 @@ except IndexError as e: pass # Pass is just a no-op. Usually you would do recovery here. ----------------------------------------------------- --- 4. Functions ----------------------------------------------------- +#################################################### +## 4. Functions +#################################################### # Use def to create new functions def add(x, y): @@ -209,9 +219,9 @@ def add(x, y): # Calling functions with parameters add(5, 6) #=> 11 and prints out "x is 5 and y is 6" # Another way to call functions is with keyword arguments -add(y=6, x=5) # Equivalent to above. Keyword arguments can arrive in any order. +add(y=6, x=5) # Keyword arguments can arrive in any order. -# You can define functions that take a variable number of positional arguments +# You can define functions that take a variable number of arguments def varargs(*args): return args @@ -232,7 +242,6 @@ def create_adder(x): return x + y return adder -# Let's create a new function that always adds 10 to the argument add_10 = create_adder(10): add_10(3) #=> 13 @@ -247,15 +256,11 @@ filter(lambda x: x > 5, [3, 4, 5, 6, 7]) #=> [6, 7] [add_10(i) for i in [1, 2, 3]] #=> [11, 12, 13] [x for x in [3, 4, 5, 6, 7] if x > 5] #=> [6, 7] ----------------------------------------------------- --- 5. Classes ----------------------------------------------------- - -# We can define classes with the class statement -class Human(): # By convention CamelCase is used for classes. - pass +#################################################### +## 5. Classes +#################################################### -# We subclass from object to get a "new-style class". All your code should do this. +# We subclass from object to get a class. class Human(object): # A class attribute. It is shared by all instances of this class @@ -263,18 +268,20 @@ class Human(object): # Basic initializer def __init__(self, name): - self.name = name # We are assigning the argument to the instance's name attribute + # Assign the argument to the instance's name attribute + self.name = name - # A method. All methods take self as the first argument, including the initializer + # A method. All methods take self as the first argument def say(self, msg): return "%s: %s" % (self.name, msg) # A class method is shared among all instances + # They are called with the calling class as the first argument @classmethod def get_species(cls): return cls.species - # Static methods are called without a parameter reference to the class or instance + # Static methods are called without a class or instance reference @staticmethod def grunt(): return "*grunt*" @@ -283,6 +290,7 @@ class Human(object): # Instantiate a class h = Human(name="Harry") print h.say("hi") # prints out "Harry: hi" + i = Human("Ian") print i.say("hello") #prints out "Ian: hello" |