Merge pull request #1504 from dillonjbyrne/patch-1

[python3/en] Cleaned up formatting and clarified output

python3.html.markdown

@@ -33,27 +33,27 @@ Note: This article applies to Python 3 specifically. Check out [here](http://lea
 3  # => 3
 
 # Math is what you would expect
-1 + 1  # => 2
+1 + 1   # => 2
-8 - 1  # => 7
+8 - 1   # => 7
 10 * 2  # => 20
 
 # Except division which returns floats, real numbers, by default
 35 / 5  # => 7.0
 
 # Result of integer division truncated down both for positive and negative.
-5 // 3     # => 1
+5 // 3       # => 1
-5.0 // 3.0 # => 1.0 # works on floats too
+5.0 // 3.0   # => 1.0 # works on floats too
--5 // 3  # => -2
+-5 // 3      # => -2
--5.0 // 3.0 # => -2.0
+-5.0 // 3.0  # => -2.0
 
 # When you use a float, results are floats
-3 * 2.0 # => 6.0
+3 * 2.0  # => 6.0
 
 # Modulo operation
-7 % 3 # => 1
+7 % 3  # => 1
 
 # Exponentiation (x**y, x to the yth power)
-2**4 # => 16
+2**4  # => 16
 
 # Enforce precedence with parentheses
 (1 + 3) * 2  # => 8
@@ -63,20 +63,20 @@ True
 False
 
 # negate with not
-not True  # => False
+not True   # => False
 not False  # => True
 
 # Boolean Operators
 # Note "and" and "or" are case-sensitive
-True and False #=> False
+True and False  # => False
-False or True #=> True
+False or True   # => True
 
 # Note using Bool operators with ints
-0 and 2 #=> 0
+0 and 2     # => 0
--5 or 0 #=> -5
+-5 or 0     # => -5
-0 == False #=> True
+0 == False  # => True
-2 == True #=> False
+2 == True   # => False
-1 == True #=> True
+1 == True   # => True
 
 # Equality is ==
 1 == 1  # => True
@@ -98,13 +98,13 @@ False or True #=> True
 
 # (is vs. ==) is checks if two variable refer to the same object, but == checks
 # if the objects pointed to have the same values.
-a = [1, 2, 3, 4] # Point a at a new list, [1, 2, 3, 4]
+a = [1, 2, 3, 4]  # Point a at a new list, [1, 2, 3, 4]
-b = a # Point b at what a is pointing to
+b = a             # Point b at what a is pointing to
-b is a # => True, a and b refer to the same object
+b is a            # => True, a and b refer to the same object
-b == a # => True, a's and b's objects are equal
+b == a            # => True, a's and b's objects are equal
-b = [1, 2, 3, 4] # Point a at a new list, [1, 2, 3, 4]
+b = [1, 2, 3, 4]  # Point a at a new list, [1, 2, 3, 4]
-b is a # => False, a and b do not refer to the same object
+b is a            # => False, a and b do not refer to the same object
-b == a # => True, a's and b's objects are equal
+b == a            # => True, a's and b's objects are equal
 
 # Strings are created with " or '
 "This is a string."
@@ -113,24 +113,24 @@ b == a # => True, a's and b's objects are equal
 # Strings can be added too! But try not to do this.
 "Hello " + "world!"  # => "Hello world!"
 # Strings can be added without using '+'
-"Hello " "world!"  # => "Hello world!"
+"Hello " "world!"    # => "Hello world!"
 
 # A string can be treated like a list of characters
 "This is a string"[0]  # => 'T'
 
 # .format can be used to format strings, like this:
-"{} can be {}".format("strings", "interpolated")
+"{} can be {}".format("Strings", "interpolated")  # => "Strings can be interpolated"
 
 # You can repeat the formatting arguments to save some typing.
 "{0} be nimble, {0} be quick, {0} jump over the {1}".format("Jack", "candle stick")
-#=> "Jack be nimble, Jack be quick, Jack jump over the candle stick"
+# => "Jack be nimble, Jack be quick, Jack jump over the candle stick"
 
 # You can use keywords if you don't want to count.
-"{name} wants to eat {food}".format(name="Bob", food="lasagna") #=> "Bob wants to eat lasagna"
+"{name} wants to eat {food}".format(name="Bob", food="lasagna")  # => "Bob wants to eat lasagna"
 
 # If your Python 3 code also needs to run on Python 2.5 and below, you can also
 # still use the old style of formatting:
-"%s can be %s the %s way" % ("strings", "interpolated", "old")
+"%s can be %s the %s way" % ("Strings", "interpolated", "old")  # => "Strings can be interpolated the old way"
 
 
 # None is an object
@@ -139,14 +139,14 @@ None  # => None
 # Don't use the equality "==" symbol to compare objects to None
 # Use "is" instead. This checks for equality of object identity.
 "etc" is None  # => False
-None is None  # => True
+None is None   # => True
 
 # None, 0, and empty strings/lists/dicts all evaluate to False.
 # All other values are True
-bool(0)  # => False
+bool(0)   # => False
 bool("")  # => False
-bool([]) #=> False
+bool([])  # => False
-bool({}) #=> False
+bool({})  # => False
 
 
 ####################################################
@@ -154,11 +154,11 @@ bool({}) #=> False
 ####################################################
 
 # Python has a print function
-print("I'm Python. Nice to meet you!")
+print("I'm Python. Nice to meet you!")  # => I'm Python. Nice to meet you!
 
 # By default the print function also prints out a newline at the end.
 # Use the optional argument end to change the end character.
-print("Hello, World", end="!") # => Hello, World!
+print("Hello, World", end="!")  # => Hello, World!
 
 # No need to declare variables before assigning to them.
 # Convention is to use lower_case_with_underscores
@@ -185,7 +185,7 @@ li.pop()        # => 3 and li is now [1, 2, 4]
 li.append(3)    # li is now [1, 2, 4, 3] again.
 
 # Access a list like you would any array
-li[0]  # => 1
+li[0]   # => 1
 # Look at the last element
 li[-1]  # => 3
 
@@ -194,61 +194,61 @@ li[4]  # Raises an IndexError
 
 # You can look at ranges with slice syntax.
 # (It's a closed/open range for you mathy types.)
-li[1:3]  # => [2, 4]
+li[1:3]   # => [2, 4]
 # Omit the beginning
-li[2:]  # => [4, 3]
+li[2:]    # => [4, 3]
 # Omit the end
-li[:3]  # => [1, 2, 4]
+li[:3]    # => [1, 2, 4]
 # Select every second entry
 li[::2]   # =>[1, 4]
 # Return a reversed copy of the list
-li[::-1]   # => [3, 4, 2, 1]
+li[::-1]  # => [3, 4, 2, 1]
 # Use any combination of these to make advanced slices
 # li[start:end:step]
 
 # Make a one layer deep copy using slices
-li2 = li[:] # => li2 = [1, 2, 4, 3] but (li2 is li) will result in false.
+li2 = li[:]  # => li2 = [1, 2, 4, 3] but (li2 is li) will result in false.
 
 # Remove arbitrary elements from a list with "del"
-del li[2]   # li is now [1, 2, 3]
+del li[2]  # li is now [1, 2, 3]
 
 # You can add lists
 # Note: values for li and for other_li are not modified.
-li + other_li   # => [1, 2, 3, 4, 5, 6]
+li + other_li  # => [1, 2, 3, 4, 5, 6]
 
 # 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
+1 in li  # => True
 
 # Examine the length with "len()"
-len(li)   # => 6
+len(li)  # => 6
 
 
 # Tuples are like lists but are immutable.
 tup = (1, 2, 3)
-tup[0]   # => 1
+tup[0]      # => 1
 tup[0] = 3  # Raises a TypeError
 
 # Note that a tuple of length one has to have a comma after the last element but
 # tuples of other lengths, even zero, do not.
-type((1))  # => <class 'int'>
+type((1))   # => <class 'int'>
-type((1,)) # => <class 'tuple'>
+type((1,))  # => <class 'tuple'>
-type(())   # => <class 'tuple'>
+type(())    # => <class 'tuple'>
 
 # You can do most of the list operations on tuples too
-len(tup)   # => 3
+len(tup)         # => 3
-tup + (4, 5, 6)   # => (1, 2, 3, 4, 5, 6)
+tup + (4, 5, 6)  # => (1, 2, 3, 4, 5, 6)
-tup[:2]   # => (1, 2)
+tup[:2]          # => (1, 2)
-2 in tup   # => True
+2 in tup         # => True
 
 # You can unpack tuples (or lists) into variables
-a, b, c = (1, 2, 3)     # a is now 1, b is now 2 and c is now 3
+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 two values
-e, d = d, e     # d is now 5 and e is now 4
+e, d = d, e  # d is now 5 and e is now 4
 
 
 # Dictionaries store mappings
@@ -259,45 +259,45 @@ filled_dict = {"one": 1, "two": 2, "three": 3}
 # Note keys for dictionaries have to be immutable types. This is to ensure that
 # the key can be converted to a constant hash value for quick look-ups.
 # Immutable types include ints, floats, strings, tuples.
-invalid_dict = {[1,2,3]: "123"} # => Raises a TypeError: unhashable type: 'list'
+invalid_dict = {[1,2,3]: "123"}  # => Raises a TypeError: unhashable type: 'list'
-valid_dict = {(1,2,3):[1,2,3]}  # Values can be of any type, however.
+valid_dict = {(1,2,3):[1,2,3]}   # Values can be of any type, however.
 
 # Look up values with []
-filled_dict["one"]   # => 1
+filled_dict["one"]  # => 1
 
 # Get all keys as an iterable with "keys()". We need to wrap the call in list()
 # to turn it into a list. We'll talk about those later.  Note - Dictionary key
 # ordering is not guaranteed. Your results might not match this exactly.
-list(filled_dict.keys())   # => ["three", "two", "one"]
+list(filled_dict.keys())  # => ["three", "two", "one"]
 
 
 # Get all values as an iterable with "values()". Once again we need to wrap it
 # in list() to get it out of the iterable. Note - Same as above regarding key
 # ordering.
-list(filled_dict.values())   # => [3, 2, 1]
+list(filled_dict.values())  # => [3, 2, 1]
 
 
 # Check for existence of keys in a dictionary with "in"
-"one" in filled_dict   # => True
+"one" in filled_dict  # => True
-1 in filled_dict   # => False
+1 in filled_dict      # => False
 
 # Looking up a non-existing key is a KeyError
-filled_dict["four"]   # KeyError
+filled_dict["four"]  # KeyError
 
 # Use "get()" method to avoid the KeyError
-filled_dict.get("one")   # => 1
+filled_dict.get("one")      # => 1
-filled_dict.get("four")   # => None
+filled_dict.get("four")     # => None
 # The get method supports a default argument when the value is missing
 filled_dict.get("one", 4)   # => 1
-filled_dict.get("four", 4)   # => 4
+filled_dict.get("four", 4)  # => 4
 
 # "setdefault()" inserts into a dictionary only if the given key isn't present
 filled_dict.setdefault("five", 5)  # filled_dict["five"] is set to 5
 filled_dict.setdefault("five", 6)  # filled_dict["five"] is still 5
 
 # Adding to a dictionary
-filled_dict.update({"four":4}) #=> {"one": 1, "two": 2, "three": 3, "four": 4}
+filled_dict.update({"four":4})  # => {"one": 1, "two": 2, "three": 3, "four": 4}
-#filled_dict["four"] = 4  #another way to add to dict
+#filled_dict["four"] = 4        #another way to add to dict
 
 # Remove keys from a dictionary with del
 del filled_dict["one"]  # Removes the key "one" from filled dict
@@ -306,31 +306,31 @@ del filled_dict["one"]  # Removes the key "one" from filled dict
 # Sets store ... well sets
 empty_set = set()
 # Initialize a set with a bunch of values. Yeah, it looks a bit like a dict. Sorry.
-some_set = {1, 1, 2, 2, 3, 4}   # some_set is now {1, 2, 3, 4}
+some_set = {1, 1, 2, 2, 3, 4}  # some_set is now {1, 2, 3, 4}
 
 # Similar to keys of a dictionary, elements of a set have to be immutable.
-invalid_set = {[1], 1} # => Raises a TypeError: unhashable type: 'list'
+invalid_set = {[1], 1}  # => Raises a TypeError: unhashable type: 'list'
 valid_set = {(1,), 1}
 
 # Can set new variables to a set
 filled_set = some_set
 
 # Add one more item to the set
-filled_set.add(5)   # filled_set is now {1, 2, 3, 4, 5}
+filled_set.add(5)  # filled_set is now {1, 2, 3, 4, 5}
 
 # Do set intersection with &
 other_set = {3, 4, 5, 6}
-filled_set & other_set   # => {3, 4, 5}
+filled_set & other_set  # => {3, 4, 5}
 
 # Do set union with |
-filled_set | other_set   # => {1, 2, 3, 4, 5, 6}
+filled_set | other_set  # => {1, 2, 3, 4, 5, 6}
 
 # Do set difference with -
-{1, 2, 3, 4} - {2, 3, 5}   # => {1, 4}
+{1, 2, 3, 4} - {2, 3, 5}  # => {1, 4}
 
 # Check for existence in a set with in
 2 in filled_set   # => True
-10 in filled_set   # => False
+10 in filled_set  # => False
 
 
 
@@ -416,12 +416,12 @@ try:
     # Use "raise" to raise an error
     raise IndexError("This is an index error")
 except IndexError as e:
-    pass    # Pass is just a no-op. Usually you would do recovery here.
+    pass                 # Pass is just a no-op. Usually you would do recovery here.
 except (TypeError, NameError):
-    pass    # Multiple exceptions can be handled together, if required.
+    pass                 # Multiple exceptions can be handled together, if required.
-else:   # Optional clause to the try/except block. Must follow all except blocks
+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
@@ -435,11 +435,11 @@ with open("myfile.txt") as f:
 
 filled_dict = {"one": 1, "two": 2, "three": 3}
 our_iterable = filled_dict.keys()
-print(our_iterable) #=> range(1,10). This is an object that implements our Iterable interface
+print(our_iterable)  # => range(1,10). This is an object that implements our Iterable interface
 
 # We can loop over it.
 for i in our_iterable:
-    print(i)    # Prints one, two, three
+    print(i)  # Prints one, two, three
 
 # However we cannot address elements by index.
 our_iterable[1]  # Raises a TypeError
@@ -449,17 +449,17 @@ our_iterator = iter(our_iterable)
 
 # Our iterator is an object that can remember the state as we traverse through it.
 # We get the next object with "next()".
-next(our_iterator)  #=> "one"
+next(our_iterator)  # => "one"
 
 # It maintains state as we iterate.
-next(our_iterator)  #=> "two"
+next(our_iterator)  # => "two"
-next(our_iterator)  #=> "three"
+next(our_iterator)  # => "three"
 
 # After the iterator has returned all of its data, it gives you a StopIterator Exception
-next(our_iterator) # Raises StopIteration
+next(our_iterator)  # Raises StopIteration
 
 # You can grab all the elements of an iterator by calling list() on it.
-list(filled_dict.keys())  #=> Returns ["one", "two", "three"]
+list(filled_dict.keys())  # => Returns ["one", "two", "three"]
 
 
 ####################################################
@@ -469,20 +469,20 @@ list(filled_dict.keys())  #=> Returns ["one", "two", "three"]
 # Use "def" to create new functions
 def add(x, y):
     print("x is {} and y is {}".format(x, y))
-    return x + y    # Return values with a return statement
+    return x + y  # Return values with a return statement
 
 # Calling functions with parameters
-add(5, 6)   # => prints out "x is 5 and y is 6" and returns 11
+add(5, 6)  # => prints out "x is 5 and y is 6" and returns 11
 
 # Another way to call functions is with keyword arguments
-add(y=6, x=5)   # 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
 def varargs(*args):
     return args
 
-varargs(1, 2, 3)   # => (1, 2, 3)
+varargs(1, 2, 3)  # => (1, 2, 3)
 
 # You can define functions that take a variable number of
 # keyword arguments, as well
@@ -490,7 +490,7 @@ def keyword_args(**kwargs):
     return kwargs
 
 # Let's call it to see what happens
-keyword_args(big="foot", loch="ness")   # => {"big": "foot", "loch": "ness"}
+keyword_args(big="foot", loch="ness")  # => {"big": "foot", "loch": "ness"}
 
 
 # You can do both at once, if you like
@@ -507,33 +507,33 @@ all_the_args(1, 2, a=3, b=4) prints:
 # Use * to expand tuples and use ** to expand kwargs.
 args = (1, 2, 3, 4)
 kwargs = {"a": 3, "b": 4}
-all_the_args(*args)   # equivalent to foo(1, 2, 3, 4)
+all_the_args(*args)            # equivalent to foo(1, 2, 3, 4)
-all_the_args(**kwargs)   # equivalent to foo(a=3, b=4)
+all_the_args(**kwargs)         # equivalent to foo(a=3, b=4)
-all_the_args(*args, **kwargs)   # equivalent to foo(1, 2, 3, 4, a=3, b=4)
+all_the_args(*args, **kwargs)  # equivalent to foo(1, 2, 3, 4, a=3, b=4)
 
 # Returning multiple values (with tuple assignments)
 def swap(x, y):
-    return y, x # Return multiple values as a tuple without the parenthesis.
+    return y, x  # Return multiple values as a tuple without the parenthesis.
-                # (Note: parenthesis have been excluded but can be included)
+                 # (Note: parenthesis have been excluded but can be included)
 
 x = 1
 y = 2
-x, y = swap(x, y) # => x = 2, y = 1
+x, y = swap(x, y)     # => x = 2, y = 1
-# (x, y) = swap(x,y) # Again parenthesis have been excluded but can be included.
+# (x, y) = swap(x,y)  # Again parenthesis have been excluded but can be included.
 
 # Function Scope
 x = 5
 
 def setX(num):
     # Local var x not the same as global variable x
-    x = num # => 43
+    x = num    # => 43
-    print (x) # => 43
+    print (x)  # => 43
 
 def setGlobalX(num):
     global x
-    print (x) # => 5
+    print (x)  # => 5
-    x = num # global var x is now set to 6
+    x = num    # global var x is now set to 6
-    print (x) # => 6
+    print (x)  # => 6
 
 setX(43)
 setGlobalX(6)
@@ -549,20 +549,20 @@ add_10 = create_adder(10)
 add_10(3)   # => 13
 
 # There are also anonymous functions
-(lambda x: x > 2)(3)   # => True
+(lambda x: x > 2)(3)                  # => True
-(lambda x, y: x ** 2 + y ** 2)(2, 1) # => 5
+(lambda x, y: x ** 2 + y ** 2)(2, 1)  # => 5
 
 # TODO - Fix for iterables
 # There are built-in higher order functions
-map(add_10, [1, 2, 3])   # => [11, 12, 13]
+map(add_10, [1, 2, 3])          # => [11, 12, 13]
-map(max, [1, 2, 3], [4, 2, 1])   # => [4, 2, 3]
+map(max, [1, 2, 3], [4, 2, 1])  # => [4, 2, 3]
 
-filter(lambda x: x > 5, [3, 4, 5, 6, 7])   # => [6, 7]
+filter(lambda x: x > 5, [3, 4, 5, 6, 7])  # => [6, 7]
 
 # We can use list comprehensions for nice maps and filters
 # List comprehension stores the output as a list which can itself be a nested list
-[add_10(i) for i in [1, 2, 3]]  # => [11, 12, 13]
+[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]
+[x for x in [3, 4, 5, 6, 7] if x > 5]  # => [6, 7]
 
 ####################################################
 ## 5. Classes
@@ -609,15 +609,15 @@ j = Human("Joel")
 print(j.say("hello"))  # prints out "Joel: hello"
 
 # Call our class method
-i.get_species()   # => "H. sapiens"
+i.get_species()  # => "H. sapiens"
 
 # Change the shared attribute
 Human.species = "H. neanderthalensis"
-i.get_species()   # => "H. neanderthalensis"
+i.get_species()  # => "H. neanderthalensis"
-j.get_species()   # => "H. neanderthalensis"
+j.get_species()  # => "H. neanderthalensis"
 
 # Call the static method
-Human.grunt()   # => "*grunt*"
+Human.grunt()    # => "*grunt*"
 
 
 ####################################################
@@ -630,8 +630,8 @@ print(math.sqrt(16))  # => 4
 
 # You can get specific functions from a module
 from math import ceil, floor
-print(ceil(3.7))  # => 4.0
+print(ceil(3.7))   # => 4.0
-print(floor(3.7))   # => 3.0
+print(floor(3.7))  # => 3.0
 
 # You can import all functions from a module.
 # Warning: this is not recommended
@@ -639,7 +639,7 @@ from math import *
 
 # You can shorten module names
 import math as m
-math.sqrt(16) == m.sqrt(16)   # => True
+math.sqrt(16) == m.sqrt(16)  # => True
 
 # Python modules are just ordinary python files. You
 # can write your own, and import them. The name of the
@@ -698,7 +698,7 @@ def say(say_please=False):
     return msg, say_please
 
 
-print(say())  # Can you buy me a beer?
+print(say())                 # Can you buy me a beer?
 print(say(say_please=True))  # Can you buy me a beer? Please! I am poor :(
 ```