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Made the file pep8 compliant (#2601)
Actually nearly compliant, I ran `pep8 code.py --ignore=E402,E501,E712`
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David Haberthür
ven
parent
919e44f843
commit
4737819e5d
@ -5,6 +5,7 @@ contributors:
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- ["Amin Bandali", "http://aminbandali.com"]
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- ["Andre Polykanine", "https://github.com/Oire"]
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- ["evuez", "http://github.com/evuez"]
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- ["habi", "http://github.com/habi"]
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filename: learnpython.py
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---
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@ -34,9 +35,8 @@ Python 3 tutorial.
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as comments
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"""
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####################################################
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## 1. Primitive Datatypes and Operators
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# 1. Primitive Datatypes and Operators
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####################################################
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# You have numbers
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@ -65,29 +65,30 @@ Python 3 tutorial.
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# Note that we can also import division module(Section 6 Modules)
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# to carry out normal division with just one '/'.
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from __future__ import division
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11/4 # => 2.75 ...normal division
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11//4 # => 2 ...floored division
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11 / 4 # => 2.75 ...normal division
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11 // 4 # => 2 ...floored division
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# Modulo operation
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7 % 3 # => 1
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# Exponentiation (x to the yth power)
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2**4 # => 16
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2 ** 4 # => 16
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# Enforce precedence with parentheses
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(1 + 3) * 2 # => 8
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# Boolean Operators
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# Note "and" and "or" are case-sensitive
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True and False #=> False
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False or True #=> True
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True and False # => False
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False or True # => True
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# Note using Bool operators with ints
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0 and 2 #=> 0
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-5 or 0 #=> -5
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0 == False #=> True
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2 == True #=> False
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1 == True #=> True
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0 and 2 # => 0
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-5 or 0 # => -5
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0 == False # => True
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2 == True # => False
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1 == True # => True
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# negate with not
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not True # => False
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@ -129,12 +130,12 @@ not False # => True
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# You can find the length of a string
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len("This is a string") # => 16
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#String formatting with %
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#Even though the % string operator will be deprecated on Python 3.1 and removed
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#later at some time, it may still be good to know how it works.
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# String formatting with %
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# Even though the % string operator will be deprecated on Python 3.1 and removed
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# later at some time, it may still be good to know how it works.
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x = 'apple'
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y = 'lemon'
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z = "The items in the basket are %s and %s" % (x,y)
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z = "The items in the basket are %s and %s" % (x, y)
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# A newer way to format strings is the format method.
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# This method is the preferred way
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@ -170,14 +171,15 @@ bool("") # => False
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####################################################
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## 2. Variables and Collections
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# 2. Variables and Collections
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####################################################
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# Python has a print statement
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print "I'm Python. Nice to meet you!" # => I'm Python. Nice to meet you!
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# Simple way to get input data from console
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input_string_var = raw_input("Enter some data: ") # Returns the data as a string
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input_string_var = raw_input(
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"Enter some data: ") # Returns the data as a string
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input_var = input("Enter some data: ") # Evaluates the data as python code
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# Warning: Caution is recommended for input() method usage
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# Note: In python 3, input() is deprecated and raw_input() is renamed to input()
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@ -194,7 +196,6 @@ some_other_var # Raises a name error
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# Equivalent of C's '?:' ternary operator
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"yahoo!" if 3 > 2 else 2 # => "yahoo!"
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# Lists store sequences
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li = []
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# You can start with a prefilled list
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@ -263,7 +264,6 @@ li.index(7) # Raises a ValueError as 7 is not in the list
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# Examine the length with "len()"
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len(li) # => 6
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# Tuples are like lists but are immutable.
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tup = (1, 2, 3)
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tup[0] # => 1
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@ -283,7 +283,6 @@ g = 4, 5, 6 # => (4, 5, 6)
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# Now look how easy it is to swap two values
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e, d = d, e # d is now 5 and e is now 4
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# Dictionaries store mappings
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empty_dict = {}
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# Here is a prefilled dictionary
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@ -327,7 +326,6 @@ filled_dict["four"] = 4 # now, filled_dict["four"] => 4
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filled_dict.setdefault("five", 5) # filled_dict["five"] is set to 5
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filled_dict.setdefault("five", 6) # filled_dict["five"] is still 5
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# Sets store ... well sets (which are like lists but can contain no duplicates)
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empty_set = set()
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# Initialize a "set()" with a bunch of values
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@ -367,7 +365,7 @@ filled_set | other_set # => {1, 2, 3, 4, 5, 6}
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####################################################
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## 3. Control Flow
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# 3. Control Flow
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####################################################
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# Let's just make a variable
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@ -382,7 +380,6 @@ elif some_var < 10: # This elif clause is optional.
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else: # This is optional too.
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print "some_var is indeed 10."
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"""
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For loops iterate over lists
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prints:
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@ -453,7 +450,7 @@ with open("myfile.txt") as f:
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####################################################
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## 4. Functions
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# 4. Functions
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####################################################
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# Use "def" to create new functions
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@ -461,6 +458,7 @@ def add(x, y):
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print "x is {0} and y is {1}".format(x, y)
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return x + y # Return values with a return statement
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# Calling functions with parameters
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add(5, 6) # => prints out "x is 5 and y is 6" and returns 11
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@ -473,13 +471,16 @@ add(y=6, x=5) # Keyword arguments can arrive in any order.
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def varargs(*args):
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return args
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varargs(1, 2, 3) # => (1, 2, 3)
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# You can define functions that take a variable number of
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# keyword args, as well, which will be interpreted as a dict by using **
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def keyword_args(**kwargs):
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return kwargs
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# Let's call it to see what happens
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keyword_args(big="foot", loch="ness") # => {"big": "foot", "loch": "ness"}
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@ -488,6 +489,8 @@ keyword_args(big="foot", loch="ness") # => {"big": "foot", "loch": "ness"}
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def all_the_args(*args, **kwargs):
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print args
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print kwargs
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"""
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all_the_args(1, 2, a=3, b=4) prints:
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(1, 2)
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@ -502,6 +505,7 @@ all_the_args(*args) # equivalent to foo(1, 2, 3, 4)
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all_the_args(**kwargs) # equivalent to foo(a=3, b=4)
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all_the_args(*args, **kwargs) # equivalent to foo(1, 2, 3, 4, a=3, b=4)
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# you can pass args and kwargs along to other functions that take args/kwargs
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# by expanding them with * and ** respectively
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def pass_all_the_args(*args, **kwargs):
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@ -509,29 +513,36 @@ def pass_all_the_args(*args, **kwargs):
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print varargs(*args)
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print keyword_args(**kwargs)
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# Function Scope
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x = 5
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def set_x(num):
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# Local var x not the same as global variable x
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x = num # => 43
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print x # => 43
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def set_global_x(num):
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global x
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print x # => 5
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x = num # global var x is now set to 6
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print x # => 6
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set_x(43)
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set_global_x(6)
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# Python has first class functions
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def create_adder(x):
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def adder(y):
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return x + y
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return adder
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add_10 = create_adder(10)
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add_10(3) # => 13
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@ -551,16 +562,15 @@ filter(lambda x: x > 5, [3, 4, 5, 6, 7]) # => [6, 7]
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# You can construct set and dict comprehensions as well.
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{x for x in 'abcddeef' if x in 'abc'} # => {'a', 'b', 'c'}
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{x: x**2 for x in range(5)} # => {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}
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{x: x ** 2 for x in range(5)} # => {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}
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####################################################
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## 5. Classes
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# 5. Classes
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####################################################
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# We subclass from object to get a class.
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class Human(object):
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# A class attribute. It is shared by all instances of this class
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species = "H. sapiens"
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@ -575,7 +585,6 @@ class Human(object):
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# Initialize property
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self.age = 0
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# An instance method. All methods take "self" as the first argument
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def say(self, msg):
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return "{0}: {1}".format(self.name, msg)
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@ -637,17 +646,18 @@ i.age # => 42
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del i.age
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i.age # => raises an AttributeError
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####################################################
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## 6. Modules
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# 6. Modules
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####################################################
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# You can import modules
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import math
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print math.sqrt(16) # => 4
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# You can get specific functions from a module
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from math import ceil, floor
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print ceil(3.7) # => 4.0
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print floor(3.7) # => 3.0
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@ -657,9 +667,11 @@ from math import *
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# You can shorten module names
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import math as m
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math.sqrt(16) == m.sqrt(16) # => True
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# you can also test that the functions are equivalent
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from math import sqrt
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math.sqrt == m.sqrt == sqrt # => True
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# Python modules are just ordinary python files. You
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@ -669,8 +681,10 @@ math.sqrt == m.sqrt == sqrt # => True
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# You can find out which functions and attributes
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# defines a module.
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import math
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dir(math)
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# If you have a Python script named math.py in the same
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# folder as your current script, the file math.py will
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# be loaded instead of the built-in Python module.
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@ -679,7 +693,7 @@ dir(math)
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####################################################
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## 7. Advanced
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# 7. Advanced
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####################################################
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# Generators
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@ -693,6 +707,7 @@ def double_numbers(iterable):
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for i in iterable:
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double_arr.append(i + i)
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# Running the following would mean we'll double all values first and return all
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# of them back to be checked by our condition
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for value in double_numbers(range(1000000)): # `test_non_generator`
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@ -700,12 +715,14 @@ for value in double_numbers(range(1000000)): # `test_non_generator`
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if value > 5:
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break
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# We could instead use a generator to "generate" the doubled value as the item
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# is being requested
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def double_numbers_generator(iterable):
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for i in iterable:
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yield i + i
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# Running the same code as before, but with a generator, now allows us to iterate
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# over the values and doubling them one by one as they are being consumed by
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# our logic. Hence as soon as we see a value > 5, we break out of the
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@ -723,22 +740,22 @@ for value in double_numbers_generator(xrange(1000000)): # `test_generator`
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# Just as you can create a list comprehension, you can create generator
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# comprehensions as well.
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values = (-x for x in [1,2,3,4,5])
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values = (-x for x in [1, 2, 3, 4, 5])
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for x in values:
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print(x) # prints -1 -2 -3 -4 -5 to console/terminal
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# You can also cast a generator comprehension directly to a list.
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values = (-x for x in [1,2,3,4,5])
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values = (-x for x in [1, 2, 3, 4, 5])
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gen_to_list = list(values)
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print(gen_to_list) # => [-1, -2, -3, -4, -5]
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# Decorators
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# in this example beg wraps say
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# Beg will call say. If say_please is True then it will change the returned
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# message
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from functools import wraps
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def beg(target_function):
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@wraps(target_function)
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def wrapper(*args, **kwargs):
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@ -749,11 +766,13 @@ def beg(target_function):
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return wrapper
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@beg
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def say(say_please=False):
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msg = "Can you buy me a beer?"
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return msg, say_please
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print say() # Can you buy me a beer?
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print say(say_please=True) # Can you buy me a beer? Please! I am poor :(
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```
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