分刻みで一つの言語を習得するPython編

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Python was created by Guido Van Rossum in the early 90's. It is now one of the most popularlanguages in existence. I fell in love with Python for its syntactic clarity. It's basicallyexecutable pseudocode.
Pythonは90年代初めにGuido Van Rossumによって創設された.現在最も流行しているプログラム言語の一つです.その純粋な文法に一目惚れしました.それはまるで実行可能な偽コードです.
Feedback would be highly appreciated! You can reach me at  @louiedinh  or louiedinh [at] [google's email service]
フィードバックの提出を歓迎します.@louiedinhで私に連絡してもいいし、louiedinhで始まるGoogle Emailアカウントにメールしてもいいです.
Note: This article applies to Python 2.7 specifically, but should be applicableto Python 2.x. Look for another tour of Python 3 soon!
注意:本文はPython 2.7を基準とするが、すべての2.Xバージョン.未来のPython 3を勉強し続けてね!
# Single line comments start with a hash.

#            。

""" Multiline strings can be written

    using three "'s, and are often used

    as comments

         (    )          ,



"""



####################################################

## 1. Primitive Datatypes and Operators

## 1.           

####################################################



# You have numbers

#       

3 #=> 3



# Math is what you would expect

#              

1 + 1 #=> 2

8 - 1 #=> 7

10 * 2 #=> 20

35 / 5 #=> 7



# Division is a bit tricky. It is integer division and floors the results

# automatically.

#        。

#         ,         。

5 / 2 #=> 2



# To fix division we need to learn about floats.

#          ,          。

2.0     # This is a float

2.0     #        

11.0 / 4.0 #=> 2.75 ahhh...much better

11.0 / 4.0 #=> 2.75  ……      



# Enforce precedence with parentheses

#                

(1 + 3) * 2 #=> 8



# Boolean values are primitives

#            

True

False



# negate with not

#    not    

not True #=> False

not False #=> True



# Equality is ==

#       ==

1 == 1 #=> True

2 == 1 #=> False



# Inequality is !=

#         !=

1 != 1 #=> False

2 != 1 #=> True



# More comparisons

#          

1 < 10 #=> True

1 > 10 #=> False

2 <= 2 #=> True

2 >= 2 #=> True



# Comparisons can be chained!

#              !

1 < 2 < 3 #=> True

2 < 3 < 2 #=> False



# Strings are created with " or '

#    "   '       

"This is a string."

'This is also a string.'



# Strings can be added too!

#         !

"Hello " + "world!" #=> "Hello world!"



# A string can be treated like a list of characters

#                 

# (  :     “  ”。)

"This is a string"[0] #=> 'T'



# % can be used to format strings, like this:

# %           ,    :

"%s can be %s" % ("strings", "interpolated")



# A newer way to format strings is the format method.

# This method is the preferred way

#                 :format   。

#           。

"{0} can be {1}".format("strings", "formatted")



# You can use keywords if you don't want to count.

#           ,       (  )。

"{name} wants to eat {food}".format(name="Bob", food="lasagna")



# None is an object

# None      

None #=> None



# Don't use the equality `==` symbol to compare objects to None

# Use `is` instead

#          `==`       None     ,

#     `is`。

"etc" is None #=> False

None is None  #=> True



# The 'is' operator tests for object identity. This isn't

# very useful when dealing with primitive values, but is

# very useful when dealing with objects.

#    `is`               。

# (  :      ,        ,              。)

#                ,

#            。



# None, 0, and empty strings/lists all evaluate to False.

# All other values are True

# None、0               False,

#             True。

0 == False  #=> True

"" == False #=> True





####################################################

## 2. Variables and Collections

## 2.      

####################################################



# 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

                #                    

some_var #=> 5



# Accessing a previously unassigned variable is an exception.

# See Control Flow to learn more about exception handling.

#                  。

#          ,      《   》。

some_other_var  # Raises a name error

                #          



# if can be used as an expression

# if           

"yahoo!" if 3 > 2 else 2 #=> "yahoo!"



# Lists store sequences

#         

li = []

# You can start with a prefilled list

#                

other_li = [4, 5, 6]



# Add stuff to the end of a list with append

#    append              

li.append(1)    #li is now [1]

                #li     [1]

li.append(2)    #li is now [1, 2]

                #li     [1, 2]

li.append(4)    #li is now [1, 2, 4]

                #li     [1, 2, 4]

li.append(3)    #li is now [1, 2, 4, 3]

                #li     [1, 2, 4, 3]

# Remove from the end with pop

#    pop          

li.pop()        #=> 3 and li is now [1, 2, 4]

                #=> 3,   li     [1, 2, 4]

# Let's put it back

#         

li.append(3)    # li is now [1, 2, 4, 3] again.

                # li      [1, 2, 4, 3]  



# Access a list like you would any array

#                 

li[0] #=> 1

# Look at the last element

#         

li[-1] #=> 3



# Looking out of bounds is an IndexError

#              

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]

# Omit the beginning

#     

li[2:] #=> [4, 3]

# Omit the end

#     

li[:3] #=> [1, 2, 4]



# Remove arbitrary elements from a list with del

#    del            

del li[2] # li is now [1, 2, 3]

          # li     [1, 2, 3]



# You can add lists

#        

li + other_li #=> [1, 2, 3, 4, 5, 6] - Note: li and other_li is left alone

              #=> [1, 2, 3, 4, 5, 6] -     li   other_li       



# Concatenate lists with extend

#    extend      

li.extend(other_li) # Now li is [1, 2, 3, 4, 5, 6]

                    #    li   [1, 2, 3, 4, 5, 6]



# Check for existence in a list with in

#   in              

1 in li #=> True



# Examine the length with len

#   len         

len(li) #=> 6





# 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



# 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   1,b   2,c   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

                #    d   5   e   4





# Dictionaries store mappings

#           

empty_dict = {}

# Here is a prefilled dictionary

#            

filled_dict = {"one": 1, "two": 2, "three": 3}



# Look up values with []

#    []      

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.

#    :               。

#                  。



# Get all values as a list

#                

filled_dict.values() #=> [3, 2, 1]

# Note - Same as above regarding key ordering.

#    :          。



# Check for existence of keys in a dictionary with in

#    in                

"one" in filled_dict #=> True

1 in filled_dict #=> False



# Looking up a non-existing key is a KeyError

#                    

filled_dict["four"] # KeyError

                    #     



# Use get method to avoid the KeyError

#       get          

filled_dict.get("one") #=> 1

filled_dict.get("four") #=> None

# The get method supports a default argument when the value is missing

# get              ,         。

filled_dict.get("one", 4) #=> 1

filled_dict.get("four", 4) #=> 4



# Setdefault method is a safe way to add new key-value pair into dictionary

# Setdefault                    

filled_dict.setdefault("five", 5) #filled_dict["five"] is set to 5

                                  #filled_dict["five"]      5

filled_dict.setdefault("five", 6) #filled_dict["five"] is still 5

                                  #filled_dict["five"]     5





# Sets store ... well sets

# set       

empty_set = set()

# Initialize a set with a bunch of values

#              

some_set = set([1,2,2,3,4]) # some_set is now set([1, 2, 3, 4])

                            # some_set     set([1, 2, 3, 4])



# Since Python 2.7, {} can be used to declare a set

#   Python 2.7   ,{}           

filled_set = {1, 2, 2, 3, 4} # => {1, 2, 3, 4}

                             # (  :             ,      2     。)

                             # (  :{}          ,         。)



# Add more items to a set

#              

filled_set.add(5) # filled_set is now {1, 2, 3, 4, 5}

                  # filled_set     {1, 2, 3, 4, 5}



# Do set intersection with &

#    &      

other_set = {3, 4, 5, 6}

filled_set & other_set #=> {3, 4, 5}



# Do set union with |

#    |      

filled_set | other_set #=> {1, 2, 3, 4, 5, 6}



# Do set difference with -

#    -      

{1,2,3,4} - {2,3,5} #=> {1, 4}



# Check for existence in a set with in

#    in              

2 in filled_set #=> True

10 in filled_set #=> False





####################################################

## 3. Control Flow

## 3.    

####################################################



# Let's just make a variable

#          

some_var = 5



# Here is an if statement. Indentation is significant in python!

# prints "some_var is smaller than 10"

#          。    Python         !

#        "some_var is smaller than 10"

# (  :  “some_var   10  ”。)

if some_var > 10:

    print "some_var is totally bigger than 10."

    # (  :  “some_var     10  ”。)

elif some_var < 10:    # This elif clause is optional.

                       #     elif       

    print "some_var is smaller than 10."

    # (  :  “some_var   10  ”。)

else:           # This is optional too.

                #         

    print "some_var is indeed 10."

    # (  :  “some_var    10”。)





"""

For loops iterate over lists

for         

prints:



    dog is a mammal

    cat is a mammal

    mouse is a mammal

"""

for animal in ["dog", "cat", "mouse"]:

    # You can use % to interpolate formatted strings

    #          %        

    print "%s is a mammal" % animal

    # (  :  “%s      ”。)



"""

`range(number)` returns a list of numbers 

from zero to the given number

`range(  )`          ,



prints:



    0

    1

    2

    3

"""

for i in range(4):

    print i



"""

While loops go until a condition is no longer met.

while        ,        。

prints:



    0

    1

    2

    3

"""

x = 0

while x < 4:

    print x

    x += 1  # Shorthand for x = x + 1

            #    x = x + 1      



# Handle exceptions with a try/except block

#    try/except         



# Works on Python 2.6 and up:

#     Python 2.6      :

try:

    # Use raise to raise an error

    #    raise        

    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        。               。





####################################################

## 4. Functions

## 4.   

####################################################



# Use def to create new functions

#    def       

def add(x, y):

    print "x is %s and y is %s" % (x, y)

    # (  :  “x   %s    y   %s”。)

    return x + y    # Return values with a return statement

                    #    return       



# Calling functions with parameters

#          

add(5, 6) #=> prints out "x is 5 and y is 6" and returns 11

          # (  :  “x   5    y   6”,    11)



# 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

# positional arguments

#          ,              。

def varargs(*args):

    return args



varargs(1, 2, 3) #=> (1,2,3)





# You can define functions that take a variable number of

# keyword arguments, as well

#           ,               。

def keyword_args(**kwargs):

    return kwargs



# Let's call it to see what happens

#        ,       :

keyword_args(big="foot", loch="ness") #=> {"big": "foot", "loch": "ness"}



# You can do both at once, if you like

#              ,     :

def all_the_args(*args, **kwargs):

    print args

    print kwargs

"""

all_the_args(1, 2, a=3, b=4) prints:

    (1, 2)

    {"a": 3, "b": 4}

"""



# When calling functions, you can do the opposite of varargs/kwargs!

# 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(1, 2, 3, 4)

all_the_args(**kwargs) # equivalent to foo(a=3, b=4)

                       #     all_the_args(a=3, b=4)

all_the_args(*args, **kwargs) # equivalent to foo(1, 2, 3, 4, a=3, b=4)

                              #     all_the_args(1, 2, 3, 4, a=3, b=4)



# Python has first class functions

#     Python       

def create_adder(x):

    def adder(y):

        return x + y

    return adder



add_10 = create_adder(10)

add_10(3) #=> 13



# There are also anonymous functions

#       

(lambda x: x > 2)(3) #=> True



# There are built-in higher order functions

#            

map(add_10, [1,2,3]) #=> [11, 12, 13]

filter(lambda x: x > 5, [3, 4, 5, 6, 7]) #=> [6, 7]



# We can use list comprehensions for nice maps and filters

#                map   filter

[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

## 5.  

####################################################



# We subclass from object to get a class.

#           ,      。

class Human(object):



    # A class attribute. It is shared by all instances of this class

    #         。             。

    species = "H. sapiens"



    # Basic initializer

    #         (    )

    def __init__(self, name):

        # Assign the argument to the instance's name attribute

        #           name   

        self.name = name



    # An instance method. All methods take self as the first argument

    #          。       self        。

    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



    # A static method is called without a class or instance reference

    #         ,           。

    @staticmethod

    def grunt():

        return "*grunt*"





# Instantiate a class

#       

i = Human(name="Ian")

print i.say("hi")     # prints out "Ian: hi"

                      #     "Ian: hi"



j = Human("Joel")

print j.say("hello")  # prints out "Joel: hello"

                      #     "Joel: hello"



# Call our class method

#         

i.get_species() #=> "H. sapiens"



# Change the shared attribute

#       

Human.species = "H. neanderthalensis"

i.get_species() #=> "H. neanderthalensis"

j.get_species() #=> "H. neanderthalensis"



# Call the static method

#       

Human.grunt() #=> "*grunt*"





####################################################

## 6. Modules

## 6.   

####################################################



# You can import modules

#        

import math

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 floor(3.7) #=> 3.0



# You can import all functions from a module.

# Warning: this is not recommended

#                

#   :         

from math import *



# You can shorten module names

#           

import math as m

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 

# module is the same as the name of the file.

# Python         Python   。

#            ,      。

#            。



# You can find out which functions and attributes

# defines a module.

#                   

import math

dir(math)






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  • 転入先https://github.com/cssmagic/blog/issues/24 
    突っ込む.どんなプログラムでも分を分けてマスターできるようになったら、プログラム猿が毛を乾かす必要があります.の言うなら彼の分间で実现できる私cも実现できるのになぜPYTHONを使わなければならないのですか?