From d234d1c8945a7a4fdc812be65de89ca0c6aa52b6 Mon Sep 17 00:00:00 2001 From: Geoff Liu Date: Fri, 31 Oct 2014 17:20:50 -0600 Subject: [PATCH] Finish sections 2 and 3 --- zh-cn/python3-cn.html.markdown | 153 ++++++++++++++++----------------- 1 file changed, 74 insertions(+), 79 deletions(-) diff --git a/zh-cn/python3-cn.html.markdown b/zh-cn/python3-cn.html.markdown index 6ad23600..2c1c03f8 100644 --- a/zh-cn/python3-cn.html.markdown +++ b/zh-cn/python3-cn.html.markdown @@ -9,13 +9,13 @@ translators: filename: learnpython3.py --- -Python was created by Guido Van Rossum in the early 90's. It is now one of the most popular -languages in existence. I fell in love with Python for its syntactic clarity. It's basically -executable pseudocode. +Python是由吉多·范罗苏姆(Guido Van Rossum)在90年代早期设计。它是如今最常用的编程 +语言之一。它的语法简洁且优美，几乎就是可执行的伪代码。 -Feedback would be highly appreciated! You can reach me at [@louiedinh](http://twitter.com/louiedinh) or louiedinh [at] [google's email service] +欢迎大家斧正。英文版原作Louie Dinh [@louiedinh](http://twitter.com/louiedinh) +或着Email louiedinh [at] [谷歌的信箱服务]。中文翻译Geoff Liu。 -Note: This article applies to Python 3 specifically. Check out the other tutorial if you want to learn the old Python 2.7 +注意：这篇教程是特别为Python3写的。如果你想学旧版Python2，我们特别有另一篇教程。 ```python @@ -128,7 +128,7 @@ None # => None "etc" is None # => False None is None # => True -# None，0，空字符串，空列表，空关联数组都算是False +# None，0，空字符串，空列表，空字典都算是False # 所有其他值都是True bool(0) # => False bool("") # => False @@ -176,7 +176,6 @@ li[-1] # => 3 li[4] # 抛出IndexError # 列表有切割语法 -# (It's a closed/open range for you mathy types.) li[1:3] # => [2, 4] # 取尾 li[2:] # => [4, 3] @@ -196,103 +195,101 @@ del li[2] # li is now [1, 2, 3] # 注意：li和other_li的值都不变 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] +# 用extend拼接列表 +li.extend(other_li) # li现在是[1, 2, 3, 4, 5, 6] -# Check for existence in a list with "in" +# 用in测试列表是否包含值 1 in li # => True -# Examine the length with "len()" +# 用len取列表长度 len(li) # => 6 -# Tuples are like lists but are immutable. +# 元组是不可改变的序列 tup = (1, 2, 3) tup[0] # => 1 -tup[0] = 3 # Raises a TypeError +tup[0] = 3 # 抛出TypeError -# 列表允许的操作元组也可以 +# 列表允许的操作元组大都可以 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 -# Tuples are created by default if you leave out the parentheses +# 可以把元组合列表解包，赋值给变量 +a, b, c = (1, 2, 3) # 现在a是1，b是2，c是3 +# 元组周围的括号是可以省略的 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 +# 交换两个变量的值就这么简单 +e, d = d, e # 现在d是5，e是4 -# Dictionaries store mappings +# 用字典表达映射关系 empty_dict = {} -# Here is a prefilled dictionary +# 初始化的字典 filled_dict = {"one": 1, "two": 2, "three": 3} -# Look up values with [] +# 用[]取值 filled_dict["one"] # => 1 -# Get all keys as a list with "keys()". -# We need to wrap the call in list() because we are getting back an iterable. We'll talk about those later. -# Note - Dictionary key ordering is not guaranteed. -# Your results might not match this exactly. + +# 用keys获得所有的键。因为keys返回一个可迭代对象，所以在这里把结果包在list里。我们下面会详细介绍可迭代。 +# 注意：字典键的顺序是不定的，你得到的结果可能和以下不同。 list(filled_dict.keys()) # => ["three", "two", "one"] -# Get all values as a list 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. +# 用values获得所有的值。跟keys一样，要用list包起来，顺序也可能不同。 list(filled_dict.values()) # => [3, 2, 1] -# Check for existence of keys in a dictionary with "in" +# 用in测试一个字典是否包含一个键 "one" in filled_dict # => True 1 in filled_dict # => False -# Looking up a non-existing key is a KeyError +# 访问不存在的键会导致KeyError filled_dict["four"] # KeyError -# Use "get()" method to avoid the KeyError +# 用get来避免KeyError filled_dict.get("one") # => 1 filled_dict.get("four") # => None -# The get method supports a default argument when the value is missing +# 当键不存在的时候get方法可以返回默认值 filled_dict.get("one", 4) # => 1 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 +# setdefault方法只有当键不存在的时候插入新值 +filled_dict.setdefault("five", 5) # filled_dict["five"]设为5 +filled_dict.setdefault("five", 6) # filled_dict["five"]还是5 -# Adding to a dictionary +# 字典赋值 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 # 另一种赋值方法 -# Remove keys from a dictionary with del -del filled_dict["one"] # Removes the key "one" from filled dict +# 用del删除 +del filled_dict["one"] # 从filled_dict中把one删除 -# Sets store ... well sets +# 用set表达集合 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} +# 初始化一个集合，语法跟字典相似。 +some_set = {1, 1, 2, 2, 3, 4} # some_set现在是{1, 2, 3, 4} -#Can set new variables to a set +# 可以把集合赋值于变量 filled_set = some_set -# Add one more item to the set -filled_set.add(5) # filled_set is now {1, 2, 3, 4, 5} +# 为集合添加元素 +filled_set.add(5) # filled_set现在是{1, 2, 3, 4, 5} -# Do set intersection with & +# & 取交集 other_set = {3, 4, 5, 6} filled_set & other_set # => {3, 4, 5} -# Do set union with | +# | 取并集 filled_set | other_set # => {1, 2, 3, 4, 5, 6} -# Do set difference with - +# - 取补集 {1, 2, 3, 4} - {2, 3, 5} # => {1, 4} -# Check for existence in a set with in +# in 测试集合是否包含元素 2 in filled_set # => True 10 in filled_set # => False @@ -315,20 +312,18 @@ else: # else也是可选的 """ -For loops iterate over lists -prints: +用for循环语句遍历列表 +打印: dog is a mammal cat is a mammal mouse is a mammal """ for animal in ["dog", "cat", "mouse"]: - # You can use format() to interpolate formatted strings print("{} is a mammal".format(animal)) """ -"range(number)" returns a list of numbers -from zero to the given number -prints: +"range(number)"返回数字列表从0到给的数字 +打印: 0 1 2 @@ -338,8 +333,8 @@ for i in range(4): print(i) """ -While loops go until a condition is no longer met. -prints: +while循环直到条件不满足 +打印: 0 1 2 @@ -348,49 +343,49 @@ prints: x = 0 while x < 4: print(x) - x += 1 # Shorthand for x = x + 1 + x += 1 # x = x + 1 的简写 -# Handle exceptions with a try/except block +# try/except块处理异常状况 try: - # Use "raise" to raise an error + # 用raise来抛出异常 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是无操作，但是应该在这里处理错误 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 + pass # 可以同时处理不同类的错误 +else: # else语句是可选的，必须在所有的except之后 + print("All good!") # 只有当try运行完没有错误的时候这句才会运行 -# Python offers a fundamental abstraction called the Iterable. -# An iterable is an object that can be treated as a sequence. -# The object returned the range function, is an iterable. + +# Python提供一个叫做可迭代(iterable)的基本抽象。一个可迭代对象是可以被当作序列 +# 的对象。比如说上面range返回的对象就是可迭代的。 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) 是一个实现可迭代接口的对象 -# We can loop over it. +# 可迭代对象可以遍历 for i in our_iterable: - print(i) # Prints one, two, three + print(i) # 打印 one, two, three -# However we cannot address elements by index. -our_iterable[1] # Raises a TypeError +# 但是不可以随机访问 +our_iterable[1] # 抛出TypeError -# An iterable is an object that knows how to create an iterator. +# 可迭代对象知道怎么生成迭代器 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 by calling the __next__ function. +# 迭代器是一个可以记住遍历的位置的对象 +# 用__next__可以取得下一个元素 our_iterator.__next__() #=> "one" -# It maintains state as we call __next__. +# 再一次调取__next__时会记得位置 our_iterator.__next__() #=> "two" our_iterator.__next__() #=> "three" -# After the iterator has returned all of its data, it gives you a StopIterator Exception -our_iterator.__next__() # Raises StopIteration +# 当迭代器所有元素都取出后，会抛出StopIteration +our_iterator.__next__() # 抛出StopIteration -# You can grab all the elements of an iterator by calling list() on it. +# 可以用list一次取出迭代器所有的元素 list(filled_dict.keys()) #=> Returns ["one", "two", "three"]