diff options
| -rw-r--r-- | python.html.markdown | 57 |
1 files changed, 44 insertions, 13 deletions
diff --git a/python.html.markdown b/python.html.markdown index 5c0dc0d8..168f1ea1 100644 --- a/python.html.markdown +++ b/python.html.markdown @@ -34,6 +34,10 @@ to Python 2.x. Look for another tour of Python 3 soon! # automatically. 11 / 4 #=> 2 +# To fix division we need to learn about floats. +2.0 # This is a float +5.0 / 2.0 #=> 2.5 ahhh...much better + # Enforce precedence with parentheses (1 + 3) * 2 #=> 8 @@ -90,13 +94,26 @@ li.append(1) #li is now [1] li.append(2) #li is now [1, 2] li.append(4) #li is now [1, 2, 4] li.append(3) #li is now [1, 2, 4, 3] +# Remove from the end with pop +li.pop() #=> 3 and li is now [1, 2, 4] +# Let's put it back +li.append(3) # li is now [1, 2, 4, 3] again. # Access a list like you would any array li[0] #=> 1 +# Look at the last element +li[-1] #=> 4 # Looking out of bounds is an IndexError li[4] # Raises an IndexError -# Remove elements from a list with del +# You can look at ranges with slice syntax. It's an closed/open range for you mathy types. +li[1:3] #=> [2, 4] +# Omit the beginning +li[:3] #=> [1, 2, 4] +# Omit the end +li[2:] #=> [4, 3] + +# Remove arbitrary elements from a list with del del li[2] # li is now [1, 2, 3] # You can add lists @@ -111,11 +128,24 @@ li.extend(other_li) # Now li is [1, 2, 3, 4, 5, 6] # Examine the length with len len(li) #=> 6 -# Tuples are like lists but are immutable +# Tuples are like lists but are immutable. tup = (1, 2, 3) tup[0] #=> 1 tup[0] = 3 # Raises a TypeError +# You can do all those list thingies on tuples too +len(tup) #=> 3 +tup + (4, 5, 6) #=> (1, 2, 3, 4, 5, 6) +tup[:2] #=> (1, 2) +2 in tup #=> True + +# However, you can unpack tuples into variables +a, b, c = (1, 2, 3) # a is now 1, b is now 2 and c is now 3 +# Tuples are created by default if you leave out the parentheses +d, e, f = 4, 5, 6 +# Now look how easy it is to swap to values +e, d = d, e # d is now 5 and e is now 4 + # Dictionaries store mappings empty_dict = {} @@ -150,9 +180,10 @@ filled_set.add(5) # filled_set is now set([1, 2, 3, 4, 5]) # Do set intersection with & other_set = set([3, 4, 5 ,6]) filled_set & other_set #=> set([3, 4, 5]) - # Do set union with | filled_set | other_set #=> set([1, 2, 3, 4, 5, 6]) +# Do set difference with - +set([1,2,3,4]) - set([2,3,5]) #=> set([1, 4]) # Check for existence in a set with in 2 in filled_set #=> True @@ -221,7 +252,7 @@ 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) # Keyword arguments can arrive in any order. -# You can define functions that take a variable number of arguments +# You can define functions that take a variable number of positional arguments def varargs(*args): return args @@ -271,7 +302,7 @@ class Human(object): # Assign the argument to the instance's name attribute self.name = name - # A method. All methods take self as the first argument + # An instance method. All methods take self as the first argument def say(self, msg): return "%s: %s" % (self.name, msg) @@ -281,26 +312,26 @@ class Human(object): def get_species(cls): return cls.species - # Static methods are called without a class or instance reference + # A static method is called without a class or instance reference @staticmethod def grunt(): return "*grunt*" # Instantiate a class -h = Human(name="Harry") -print h.say("hi") # prints out "Harry: hi" +i = Human(name="Ian") +print i.say("hi") # prints out "Ian: hi" -i = Human("Ian") -print i.say("hello") #prints out "Ian: hello" +j = Human("Joel") +print j.say("hello") #prints out "Joel: hello" # Call our class method -h.get_species() #=> "H. sapiens" +i.get_species() #=> "H. sapiens" # Change the shared attribute -h.species = "H. neanderthalensis" -h.get_species() #=> "H. neanderthalensis" +i.species = "H. neanderthalensis" i.get_species() #=> "H. neanderthalensis" +j.get_species() #=> "H. neanderthalensis" # Call the static method Human.grunt() #=> "*grunt*" |