15分でPythonの基本的な文法と一部の特性を理解させます.
24868 ワード
本稿では、Pythonの基本的な構文と一部の特性を迅速に理解するために、オブジェクトに向けて、プログラミングの経験があるパートナーを対象としています.
前言
1.基本タイプと演算子
2.変数と集合
リスト#リスト#
メタグループ
辞書
しゅうごう
Pythonデータセットタイプまとめリスト定義li=[1,2,3,4,[Hello World](リストに任意の基本タイプを含めることができる) タプル定義tup=(1,2,3,4)(リストと似ていますが、タプルは変更できません) 辞書定義方式dic={"one":2,"tow":3,"three":0}(辞書、辞書ですか.key:value方式で存在) 集合定義方式set=set(1,2,3,4)or set={1,2,3,4}(集合内の要素は一意であり、集合サポート&|^+-操作) 3.Python論理演算子
4.関数
5.Pythonのクラス
6.Pythonのモジュール(ライブラリ)
7.Pythonにおける高度な特性(ジェネレータ、装飾器:wraps)
[1]learnxinyminutes、このコードの大部分はこのサイトから取って、ここでこのサイトの作者に感謝します!
作者:Mr_C
リンク:http://www.jianshu.com/p/36ae91c38279
出典:簡書
著作権は作者の所有である.商業転載は著者に連絡して許可を得てください.非商業転載は出典を明記してください.
前言
# Python ‘#’
""" Python
""",
， 。
"""1.基本タイプと演算子
# 3
3 # => 3
#
1 + 1 # => 2
8 - 1 # => 7
10 * 2 # => 20
35 / 5 # => 7
# ，
# ( python2.x 。 ，Python3.x , )
5 / 2 # => 2
10/-3 #python3 -3.3333333333333335 python2 -4
10/3 #python3 3.3333333333333335 python2 3
# ， Python2 ， ，
# ， Python
2.0 #
11.0 / 4.0 # 2.75 ！ ？
# ‘//’ ，python3 .
5 // 3 # => 1
5.0 // 3.0 # => 1.0
-5 // 3 # => -2
-5.0 // 3.0 # => -2.0
from __future__ import division # __future__
# python2 python3
11/4 # => 2.75 ...
11//4 # => 2 ...
#
7 % 3 # => 1
# 2 4
2**4 # => 16
# ， ，
(1 + 3) * 2 # => 8
#
# ：or and
True and False #=> False
False or True #=> True
# ， 0 ，
0 and 2 #=> 0
-5 or 0 #=> -5
0 == False #=> True
2 == True #=> False
1 == True #=> True
# not
not True # => False
not False # => True
# “==”， True ， False
1 == 1 # => True
2 == 1 # => False
# “！=”， True， Flase
1 != 1 # => False
2 != 1 # => True
# /
1 < 10 # => True
1 > 10 # => False
2 <= 2 # => True
2 >= 2 # => True
# Python ，
# False， False
1 < 2 < 3 # => True
2 < 3 < 2 # => False
# " '
"This is a string."
'This is also a string.'
# + ， ？
"Hello " + "world!" # => "Hello world!"
# '+' ，
"Hello " "world!" # => "Hello world!"
# * ， ， ；
importantNote = "
" * 3
print （importantNote）
""" ：
"""
"Hello" * 3 # => "HelloHelloHello"
#
"This is a string"[0] # => 'T'
# % ，
#（ C/C++ %d ，%s ，
# python ， ）
x = 'apple'
y = 'lemon'
z = "The items in the basket are %s and %s" % (x,y)
# .format() ，
"{} is a {}".format("This", "placeholder")
"{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 ,None None，
None # => None
# None ， “==” ， “is”
"etc" is None # => False
None is None # => True
#“is" ，
#
# “is”， ， “is”
# bool
#
# - None
# - 0 (e.g., 0, 0L, 0.0, 0j)
# - 、 (e.g., '', (), [])
# - 、 (e.g., {}, set())
# - ：
# https://docs.python.org/2/reference/datamodel.html#object.__nonzero__
#
# All other values are truthy (using the bool() function on them returns True).
bool(0) # => False
bool("") # => False2.変数と集合
# print()
print ("I'm Python. Nice to meet you!") # => I'm Python. Nice to meet you!
#
input_string_var = raw_input("Enter some data: ") #
input_var = input("Enter some data: ") # python “”or''
# ： python 3 , input() raw_input()
# Python ，python
some_var = 5
some_var # => 5
# if , “ ‘yahool’ 3 2 ， 2“
"yahoo!" if 3 > 2 else 2 # => "yahoo!"リスト#リスト#
# python
li = []
#
other_li = [4, 5, 6]
# append
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]
# pop
li.pop() # => 3 and li is now [1, 2, 4]
# append
li.append(3) # li is now [1, 2, 4, 3] again.
# []
#（ ，index ）
li[0] # => 1
# []
li[0] = 42
li[0] # => 42
# [] ，
li[-1] # => 3
# ， 。
# insert() ，
li[4] # Raises an IndexError
# [:],
# (It's a closed/open range for you mathy types.)
# ， li[1:3], index 1、2 ，
# []
li[1:3] # => [2, 4]
# ， 。
li[2:] # => [4, 3]
li[:3] # => [1, 2, 4]
# [::2] [0] ， 2
li[::2] # =>[1, 4]
# [::-1] ，- ， 1 ， 1
li[::-1] # => [3, 4, 2, 1]
# [] [ ： ： ]
# li[start:end:step]
# "del"
del li[2] # li is now [1, 2, 3]
# “+” , ： + ， （set） + -
li + other_li # => [1, 2, 3, 4, 5, 6]
# "extend()"
li.extend(other_li) # Now li is [1, 2, 3, 4, 5, 6]
# Remove del ， remove ， index
li.remove(2) # li is now [1, 3, 4, 5, 6]
li.remove(2) # remove ，
# ， ， index ，
li.insert(1, 2) # li is now [1, 2, 3, 4, 5, 6] again
# index
li.index(2) # => 1
li.index(7) #
# "in"
1 in li # => True
# "len()"
len(li) # => 6メタグループ
# Tuples( ） ，
tup = (1, 2, 3)
tup[0] # => 1
tup[0] = 3 #
# （ ）
len(tup) # => 3
tup + (4, 5, 6) # => (1, 2, 3, 4, 5, 6)
tup[:2] # => (1, 2)
2 in tup # => True
#
a, b, c = (1, 2, 3) # a 1，b 2，c 3
d, e, f = 4, 5, 6 #
#
g = 4, 5, 6 # => (4, 5, 6)
# Python ：
e, d = d, e # d is now 5 and e is now 4辞書
# Python
empty_dict = {}
#
filled_dict = {"one": 1, "two": 2, "three": 3}
# [] key
filled_dict["one"] # => 1
# "keys()" key
filled_dict.keys() # => ["three", "two", "one"]
# Note - keys .
#
# "values()" ，
#
filled_dict.values() # => [3, 2, 1]
# "in" ，
"one" in filled_dict # => True
1 in filled_dict # => False
# key ，Python
filled_dict["four"] # KeyError
# "get()"
filled_dict.get("one") # => 1
filled_dict.get("four") # => None
# ，get ，
#
filled_dict.get("one", 4) # => 1
filled_dict.get("four", 4) # => 4
# ， []
filled_dict["four"] = 4 # now, filled_dict["four"] => 4
# "setdefault()"
# ： ，setdefault（）
filled_dict.setdefault("five", 5) # filled_dict["five"] is set to 5
filled_dict.setdefault("five", 6) # filled_dict["five"] is still 5しゅうごう
empty_set = set()
# set set()
some_set = set([1, 2, 2, 3, 4]) # some_set is now set([1, 2, 3, 4])
# ！ ！ ！
another_set = set([4, 3, 2, 2, 1]) # another_set is now set([1, 2, 3, 4])
# Python2.7 ，{}
filled_set = {1, 2, 2, 3, 4} # => {1, 2, 3, 4}
# Add
filled_set.add(5) # filled_set is now {1, 2, 3, 4, 5}
# &
other_set = {3, 4, 5, 6}
filled_set & other_set # => {3, 4, 5}
# |
filled_set | other_set # => {1, 2, 3, 4, 5, 6}
# -
{1, 2, 3, 4} - {2, 3, 5} # => {1, 4}
# ^
{1, 2, 3, 4} ^ {2, 3, 5} # => {1, 4, 5}
# >=
{1, 2} >= {1, 2, 3} # => False
# <=
{1, 2} <= {1, 2, 3} # => True
# in
2 in filled_set # => True
10 in filled_set # => FalsePythonデータセットタイプまとめ
#
some_var = 5
# if
if some_var > 10:
print "some_var is totally bigger than 10."
elif some_var < 10: # This elif clause is optional.
print "some_var is smaller than 10."
else: # This is optional too.
print "some_var is indeed 10."
"""
for...in... ：
dog is a mammal
cat is a mammal
mouse is a mammal
"""
for animal in ["dog", "cat", "mouse"]:
# You can use {0} to interpolate formatted strings. (See above.)
print "{0} is a mammal".format(animal)
"""
"range()" ， for
prints:
0
1
2
3
"""
for i in range(4):
print i
"""
"range(lower, upper)" lower upper ,
：range
prints:
4
5
6
7
"""
for i in range(4, 8):
print i
"""
while
prints:
0
1
2
3
"""
x = 0
while x < 4:
print x
x += 1 # Shorthand for x = x + 1
# Python try/except
# Python2.6 ， try...except...:
try:
# raise 。 raise ，raise 。
raise IndexError("This is an index error")
except IndexError as e:
pass # pass ，
except (TypeError, NameError):
pass # python
else: # Python ，
print "All good!"
finally: # finally
print "We can clean up resources here"
# with ， try....except... [with ](http://www.ibm.com/developerworks/cn/opensource/os-cn-pythonwith/)
with open("myfile.txt") as f:
for line in f:
print line4.関数
# def
def add(x, y):
print "x is {0} and y is {1}".format(x, y)
return x + y # return
#
add(5, 6) # => prints out "x is 5 and y is 6" and returns 11
# Python ，
add(y=6, x=5) # Keyword arguments can arrive in any order.
# Python
# *
def varargs(*args):
return args
varargs(1, 2, 3) # => (1, 2, 3)
# ** Key
def keyword_args(**kwargs):
return kwargs
# ** ，Python
keyword_args(big="foot", loch="ness") # => {"big": "foot", "loch": "ness"}
# ， ：
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}
"""
# ， ：
args = (1, 2, 3, 4)
kwargs = {"a": 3, "b": 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(*args, **kwargs) # equivalent to foo(1, 2, 3, 4, a=3, b=4)
# * ** ，
def pass_all_the_args(*args, **kwargs):
all_the_args(*args, **kwargs)
print varargs(*args)
print keyword_args(**kwargs)
# X
x = 5
def set_x(num):
# ， gloabl ，
x = num # => 43
print x # => 43
def set_global_x(num):
global x
print x # => 5
x = num # global ，
print x # => 6
set_x(43)
set_global_x(6)
# /* ， */
def create_adder(x):
def adder(y):
return x + y
return adder
add_10 = create_adder(10)
add_10(3) # => 13
# Lambda
(lambda x: x > 2)(3) # => True
(lambda x, y: x ** 2 + y ** 2)(2, 1) # => 5
# map
map(add_10, [1, 2, 3]) # => [11, 12, 13]
map(max, [1, 2, 3], [4, 2, 1]) # => [4, 2, 3]
filter(lambda x: x > 5, [3, 4, 5, 6, 7]) # => [6, 7]
# ， ：
#add_10(i) for...in... ， 。
[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.Pythonのクラス
# Human ， object
# Python ， class Human(object,orangOutang)
class Human(object):
#
species = "H. sapiens"
__species = "Other.sapiens" # ，
# __init__(), ，python ， ，
# ， ， ：
#__init__ ，
# __del__ ，
#__repr__ ，
#__setitem__
#__getitem__
#__len__
#__cmp__
#__call__
#__add__
#__sub__
#__mul__
#__div__
#__mod__
#__pow__
def __init__(self, name):
# ， ，
#
self.name = name
self.age = 0
# self
#（ ）
def say(self, msg):
return "{0}: {1}".format(self.name, msg)
#
@classmethod
def get_species(cls):
return cls.species
# ，
@staticmethod
def grunt():
return "*grunt*"
# A property is just like a getter.
# It turns the method age() into an read-only attribute
# of the same name.
#property ， getter
@property
def age(self):
return self._age
# This allows the property to be set
@age.setter
def age(self, age):
self._age = age
# This allows the property to be deleted
@age.deleter
def age(self):
del self._age
#
i = Human(name="Ian")
print i.say("hi") # prints out "Ian: hi"
j = Human("Joel")
print j.say("hello") # prints out "Joel: hello"
# "."
i.get_species() # => "H. sapiens"
#
Human.species = "H. neanderthalensis"
i.get_species() # => "H. neanderthalensis"
j.get_species() # => "H. neanderthalensis"
#
Human.grunt() # => "*grunt*"
# age
i.age = 42
# age
i.age # => 42
# age
del i.age
i.age # => raises an AttributeError6.Pythonのモジュール(ライブラリ)
# Python *.py
import math
print math.sqrt(16) # => 4
# /
from math import ceil, floor
print ceil(3.7) # => 4.0
print floor(3.7) # => 3.0
# *
# Warning: this is not recommended
from math import *
#math m
math.sqrt(16) == m.sqrt(16) # => True
# sqrt
from math import sqrt
math.sqrt == m.sqrt == sqrt # => True
#python
import math
dir(math)
# If you have a Python script named math.py in the same
# folder as your current script, the file math.py will
# be loaded instead of the built-in Python module.
# This happens because the local folder has priority
# over Python's built-in libraries.
# Python math.py
# math.py Python
# Python 7.Pythonにおける高度な特性(ジェネレータ、装飾器:wraps)
# Generators ， Python 。
# ， yield 。
# ， ， 。
# return ， yield 。
for i in iterable:
yield i + i
xrange_ = xrange(1, 900000000)
for i in double_numbers(xrange_):
print i
if i >= 30:
break
# wraps，wraps
# Beg will call say. If say_please is True then it will change the returned
# message
from functools import wraps
def beg(target_function):
@wraps(target_function)
def wrapper(*args, **kwargs):
msg, say_please = target_function(*args, **kwargs)
if say_please:
return "{} {}".format(msg, "Please! I am poor :(")
return msg
return wrapper
@beg
def say(say_please=False):
msg = "Can you buy me a beer?"
return msg, say_please
print say() # Can you buy me a beer?
print say(say_please=True) # Can you buy me a beer? Please! I am poor :[1]learnxinyminutes、このコードの大部分はこのサイトから取って、ここでこのサイトの作者に感謝します!
作者:Mr_C
リンク:http://www.jianshu.com/p/36ae91c38279
出典:簡書
著作権は作者の所有である.商業転載は著者に連絡して許可を得てください.非商業転載は出典を明記してください.