From 96f0b3b3903c6f619b4a964a98e1cb0a463c47e6 Mon Sep 17 00:00:00 2001 From: Hinet60613 Date: Mon, 2 Nov 2015 00:03:58 +0800 Subject: Transated Python 2 to zh-tw. Line 01 .. 143 --- zh-tw/python-tw.html.markdown | 731 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 731 insertions(+) create mode 100644 zh-tw/python-tw.html.markdown diff --git a/zh-tw/python-tw.html.markdown b/zh-tw/python-tw.html.markdown new file mode 100644 index 00000000..8381f325 --- /dev/null +++ b/zh-tw/python-tw.html.markdown @@ -0,0 +1,731 @@ +--- +language: python +contributors: + - ["Louie Dinh", "http://ldinh.ca"] + - ["Amin Bandali", "http://aminbandali.com"] + - ["Andre Polykanine", "https://github.com/Oire"] + - ["evuez", "http://github.com/evuez"] +translators: + - ["Michael Yeh", "https://github.com/hinet60613"] +filename: learnpython.py +--- + +Python是在1990年代早期由Guido Van Rossum創建的。它是現在最流行的程式語言之一。我愛上Python是因為他極為清晰的語法，甚至可以說它就是可執行的虛擬碼。 + +非常歡迎各位給我們任何回饋！ 你可以在[@louiedinh](http://twitter.com/louiedinh) 或 louiedinh [at] [google's email service]聯絡到我。 + +註： 本篇文章適用的版本為Python 2.7，但大部分的Python 2.X版本應該都適用。 Python 2.7將會在2020年停止維護，因此建議您可以從Python 3開始學Python。 +Python 3.X可以看這篇[Python 3 教學 (英文)](http://learnxinyminutes.com/docs/python3/). + +讓程式碼同時支援Python 2.7和3.X是可以做到的，只要引入 + [`__future__` imports](https://docs.python.org/2/library/__future__.html) 模組. + `__future__` 模組允許你撰寫可以在Python 2上執行的Python 3程式碼，詳細訊息請參考Python 3 教學。 + +```python + +# 單行註解從井字號開始 + +""" 多行字串可以用三個雙引號 + 包住，不過通常這種寫法會 + 被拿來當作多行註解 +""" + +#################################################### +## 1. 原始型別與運算元 +#################################################### + +# 你可以使用數字 +3 # => 3 + +# 還有四則運算 +1 + 1 # => 2 +8 - 1 # => 7 +10 * 2 # => 20 +35 / 5 # => 7 + +# 除法比較麻煩，除以整數時會自動捨去小數位。 +5 / 2 # => 2 + +# 要做精確的除法，我們需要浮點數 +2.0 # 浮點數 +11.0 / 4.0 # => 2.75 精確多了！ + +# 整數除法的無條件捨去對正數或負數都適用 +5 // 3 # => 1 +5.0 // 3.0 # => 1.0 # 浮點數的整數也適用 +-5 // 3 # => -2 +-5.0 // 3.0 # => -2.0 + +# 我們可以用除法模組(參考第六節:模組)，讓 +# 單一斜線代表普通除法，而非無條件捨去 +from __future__ import division +11/4 # => 2.75 ...普通除法 +11//4 # => 2 ...無條件捨去 + +# 取餘數 +7 % 3 # => 1 + +# 指數 (x的y次方) +2**4 # => 16 + +# 括號即先乘除後加減 +(1 + 3) * 2 # => 8 + +# 布林運算 +# 注意 "and" 和 "or" 的大小寫 +True and False #=> False +False or True #=> True + +# 用整數與布林值做運算 +0 and 2 #=> 0 +-5 or 0 #=> -5 +0 == False #=> True +2 == True #=> False +1 == True #=> True + +# 用not取反向 +not True # => False +not False # => True + +# 等於判斷是用 == +1 == 1 # => True +2 == 1 # => False + +# 不等於判斷是用 != +1 != 1 # => False +2 != 1 # => True + +# 更多比較 +1 < 10 # => True +1 > 10 # => False +2 <= 2 # => True +2 >= 2 # => True + +# 比較是可以串接的 +1 < 2 < 3 # => True +2 < 3 < 2 # => False + +# 字串用單引號 ' 或雙引號 " 建立 +"This is a string." +'This is also a string.' + +# 字串相加會被串接再一起 +"Hello " + "world!" # => "Hello world!" +# 不用加號也可以做字串相加 +"Hello " "world!" # => "Hello world!" + +# ... 也可以做相乘 +"Hello" * 3 # => "HelloHelloHello" + +# 字串可以被視為字元的陣列 +"This is a string"[0] # => 'T' + +# 字串的格式化可以用百分之符號 % +# 儘管在Python 3.1後這個功能被廢棄了，並且在 +# 之後的版本會被移除，但還是可以了解一下 +x = 'apple' +y = 'lemon' +z = "The items in the basket are %s and %s" % (x,y) + +# 新的格式化方式是使用format函式 +# 這個方式也是較為推薦的 +"{} is a {}".format("This", "placeholder") +"{0} can be {1}".format("strings", "formatted") +# 你也可以用關鍵字，如果你不想數你是要用第幾個變數的話 +"{name} wants to eat {food}".format(name="Bob", food="lasagna") + +# 無(None) 是一個物件 +None # => None + +# 不要用等於符號 "==" 對 無(None)做比較 +# 用 "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. + +# Any object can be used in a Boolean context. +# The following values are considered falsey: +# - None +# - zero of any numeric type (e.g., 0, 0L, 0.0, 0j) +# - empty sequences (e.g., '', (), []) +# - empty containers (e.g., {}, set()) +# - instances of user-defined classes meeting certain conditions +# see: 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("") # => False + + +#################################################### +## 2. Variables and Collections +#################################################### + +# Python has a print statement +print "I'm Python. Nice to meet you!" # => I'm Python. Nice to meet you! + +# Simple way to get input data from console +input_string_var = raw_input("Enter some data: ") # Returns the data as a string +input_var = input("Enter some data: ") # Evaluates the data as python code +# Warning: Caution is recommended for input() method usage +# Note: In python 3, input() is deprecated and raw_input() is renamed to input() + +# 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 +# Equivalent of C's '?:' ternary operator +"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 +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 +# Assign new values to indexes that have already been initialized with = +li[0] = 42 +li[0] # => 42 +li[0] = 1 # Note: setting it back to the original value +# 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] +# Select every second entry +li[::2] # =>[1, 4] +# Reverse a copy of the list +li[::-1] # => [3, 4, 2, 1] +# Use any combination of these to make advanced slices +# li[start:end:step] + +# Remove arbitrary elements from a list with "del" +del li[2] # li is now [1, 2, 3] + +# You can add lists +li + other_li # => [1, 2, 3, 4, 5, 6] +# Note: values for li and for other_li are not modified. + +# Concatenate lists with "extend()" +li.extend(other_li) # Now li is [1, 2, 3, 4, 5, 6] + +# Remove first occurrence of a value +li.remove(2) # li is now [1, 3, 4, 5, 6] +li.remove(2) # Raises a ValueError as 2 is not in the list + +# Insert an element at a specific index +li.insert(1, 2) # li is now [1, 2, 3, 4, 5, 6] again + +# Get the index of the first item found +li.index(2) # => 1 +li.index(7) # Raises a ValueError as 7 is not in the list + +# Check for existence in a list with "in" +1 in li # => True + +# Examine the length with "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 +d, e, f = 4, 5, 6 # you can leave out the parentheses +# Tuples are created by default if you leave out the parentheses +g = 4, 5, 6 # => (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 + + +# 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 with "keys()" +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 with "values()" +filled_dict.values() # => [3, 2, 1] +# Note - Same as above regarding key ordering. + +# Check for existence of keys in a dictionary with "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 +filled_dict.get("one") # => 1 +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 +# note that filled_dict.get("four") is still => None +# (get doesn't set the value in the dictionary) + +# set the value of a key with a syntax similar to lists +filled_dict["four"] = 4 # now, filled_dict["four"] => 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 + + +# Sets store ... well sets (which are like lists but can contain no duplicates) +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]) + +# order is not guaranteed, even though it may sometimes look sorted +another_set = set([4, 3, 2, 2, 1]) # another_set is now set([1, 2, 3, 4]) + +# Since Python 2.7, {} can be used to declare a set +filled_set = {1, 2, 2, 3, 4} # => {1, 2, 3, 4} + +# Add more items to a set +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} + +# 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} + +# Do set symmetric difference with ^ +{1, 2, 3, 4} ^ {2, 3, 5} # => {1, 4, 5} + +# Check if set on the left is a superset of set on the right +{1, 2} >= {1, 2, 3} # => False + +# Check if set on the left is a subset of set on the right +{1, 2} <= {1, 2, 3} # => True + +# Check for existence in a set with in +2 in filled_set # => True +10 in filled_set # => False + + +#################################################### +## 3. Control Flow +#################################################### + +# 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" +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 loops iterate over lists +prints: + 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(number)" returns a list of numbers +from zero to the given number +prints: + 0 + 1 + 2 + 3 +""" +for i in range(4): + print i + +""" +"range(lower, upper)" returns a list of numbers +from the lower number to the upper number +prints: + 4 + 5 + 6 + 7 +""" +for i in range(4, 8): + print i + +""" +While loops go until a condition is no longer met. +prints: + 0 + 1 + 2 + 3 +""" +x = 0 +while x < 4: + print x + x += 1 # Shorthand for x = x + 1 + +# Handle exceptions with a try/except block + +# Works on Python 2.6 and up: +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. +except (TypeError, NameError): + pass # Multiple exceptions can be handled together, if required. +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 + print "We can clean up resources here" + +# Instead of try/finally to cleanup resources you can use a with statement +with open("myfile.txt") as f: + for line in f: + print line + +#################################################### +## 4. Functions +#################################################### + +# Use "def" to create new functions +def add(x, y): + print "x is {0} and y is {1}".format(x, y) + 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 + +# 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 args, which will be interpreted as a tuple if you do not use the * +def varargs(*args): + return args + +varargs(1, 2, 3) # => (1, 2, 3) + + +# You can define functions that take a variable number of +# keyword args, as well, which will be interpreted as a dict if you do not use ** +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 args/kwargs! +# Use * to expand positional args and use ** to expand keyword args. +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) + +# you can pass args and kwargs along to other functions that take args/kwargs +# by expanding them with * and ** respectively +def pass_all_the_args(*args, **kwargs): + all_the_args(*args, **kwargs) + print varargs(*args) + print keyword_args(**kwargs) + +# Function Scope +x = 5 + +def set_x(num): + # Local var x not the same as global variable x + x = num # => 43 + print x # => 43 + +def set_global_x(num): + global x + print x # => 5 + x = num # global var x is now set to 6 + print x # => 6 + +set_x(43) +set_global_x(6) + +# Python has first class functions +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 +(lambda x, y: x ** 2 + y ** 2)(2, 1) # => 5 + +# There are built-in higher order functions +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] + +# We can use list comprehensions for nice maps and filters +[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 +#################################################### + +# 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, this is called when this class is instantiated. + # Note that the double leading and trailing underscores denote objects + # or attributes that are used by python but that live in user-controlled + # namespaces. You should not invent such names on your own. + def __init__(self, name): + # Assign the argument to the instance's name attribute + self.name = name + + # Initialize property + self.age = 0 + + + # An instance method. All methods take "self" as the first argument + def say(self, msg): + return "{0}: {1}".format(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*" + + # A property is just like a getter. + # It turns the method age() into an read-only attribute + # of the same name. + @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 + + +# Instantiate a class +i = Human(name="Ian") +print i.say("hi") # prints out "Ian: hi" + +j = Human("Joel") +print j.say("hello") # prints out "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*" + +# Update the property +i.age = 42 + +# Get the property +i.age # => 42 + +# Delete the property +del i.age +i.age # => raises an AttributeError + + +#################################################### +## 6. Modules +#################################################### + +# 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 +# you can also test that the functions are equivalent +from math import sqrt +math.sqrt == m.sqrt == sqrt # => 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. + +# You can find out which functions and attributes +# defines a module. +import math +dir(math) + + +#################################################### +## 7. Advanced +#################################################### + +# Generators help you make lazy code +def double_numbers(iterable): + for i in iterable: + yield i + i + +# A generator creates values on the fly. +# Instead of generating and returning all values at once it creates one in each +# iteration. This means values bigger than 15 wont be processed in +# double_numbers. +# Note xrange is a generator that does the same thing range does. +# Creating a list 1-900000000 would take lot of time and space to be made. +# xrange creates an xrange generator object instead of creating the entire list +# like range does. +# We use a trailing underscore in variable names when we want to use a name that +# would normally collide with a python keyword +xrange_ = xrange(1, 900000000) + +# will double all numbers until a result >=30 found +for i in double_numbers(xrange_): + print i + if i >= 30: + break + + +# Decorators +# in this example beg wraps say +# 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 :( +``` + +## Ready For More? + +### Free Online + +* [Automate the Boring Stuff with Python](https://automatetheboringstuff.com) +* [Learn Python The Hard Way](http://learnpythonthehardway.org/book/) +* [Dive Into Python](http://www.diveintopython.net/) +* [The Official Docs](http://docs.python.org/2/) +* [Hitchhiker's Guide to Python](http://docs.python-guide.org/en/latest/) +* [Python Module of the Week](http://pymotw.com/2/) +* [A Crash Course in Python for Scientists](http://nbviewer.ipython.org/5920182) +* [First Steps With Python](https://realpython.com/learn/python-first-steps/) + +### Dead Tree + +* [Programming Python](http://www.amazon.com/gp/product/0596158106/ref=as_li_qf_sp_asin_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0596158106&linkCode=as2&tag=homebits04-20) +* [Dive Into Python](http://www.amazon.com/gp/product/1441413022/ref=as_li_tf_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=1441413022&linkCode=as2&tag=homebits04-20) +* [Python Essential Reference](http://www.amazon.com/gp/product/0672329786/ref=as_li_tf_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0672329786&linkCode=as2&tag=homebits04-20) -- cgit v1.2.3