\u8fed\u4ee3\u5668\u662f\u5b9e\u73b0\u4e86 \u53ef\u8fed\u4ee3\u534f\u8bae\u89c4\u5b9a\uff0c\u53ea\u8981\u4e00\u4e2a\u5bf9\u8c61\u5b9e\u73b0\u4e86 \u63a8\u7406\u53ef\u77e5\uff1a\u8fed\u4ee3\u5668\u4e00\u5b9a\u662f\u53ef\u8fed\u4ee3\u5bf9\u8c61<\/strong><\/p>\n\n\n\n python\u4e2d\u7684\u5bb9\u5668\u7c7b\u578b\u90fd\u662f\u53ef\u8fed\u4ee3\u5bf9\u8c61<\/p>\n<\/blockquote>\n\n\n\n \u91cd\u8981\u7279\u6027\uff1a<\/strong><\/p>\n\n\n\n \u63a8\u5bfc\u5f0f(Comprehension)\u662f\u4e00\u79cd\u7b80\u6d01\u7684\u8bed\u6cd5\uff0c\u7528\u4e8e\u4ece\u4e00\u4e2a\u53ef\u8fed\u4ee3\u5bf9\u8c61\u521b\u5efa\u65b0\u7684\u5217\u8868\u3001\u5b57\u5178\u6216\u96c6\u5408\u3002<\/p>\n\n\n\n Python\u4e2d\u6ca1\u6709\u5143\u7ec4\u63a8\u5bfc\u5f0f\u3002<\/p>\n\n\n\n \u63a8\u5bfc\u5f0f\u901a\u5e38\u6bd4\u7b49\u6548\u7684 \u6ce8\u610f\uff1a\u5f53\u903b\u8f91\u8fc7\u4e8e\u590d\u6742\u65f6\uff0c\u4f7f\u7528\u666e\u901a\u5faa\u73af\u4f1a\u66f4\u6e05\u6670\u6613\u8bfb<\/p>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":" \u8fed\u4ee3\u5668(Iterator) \u8fed\u4ee3\u5668\u662f\u5b9e\u73b0\u4e86__it..<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[52,14],"tags":[54],"class_list":["post-689","post","type-post","status-publish","format-standard","hentry","category-python","category-back","tag-python"],"featured_image_urls":{"full":"","thumbnail":"","medium":"","medium_large":"","large":"","1536x1536":"","2048x2048":""},"author_info":{"info":["\u9648 \u67d0\u4eba"]},"category_info":"Python<\/a> \u540e\u7aef<\/a>","tag_info":"\u540e\u7aef","comment_count":"0","_links":{"self":[{"href":"https:\/\/mitongxue.cn\/index.php\/wp-json\/wp\/v2\/posts\/689","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mitongxue.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mitongxue.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mitongxue.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mitongxue.cn\/index.php\/wp-json\/wp\/v2\/comments?post=689"}],"version-history":[{"count":1,"href":"https:\/\/mitongxue.cn\/index.php\/wp-json\/wp\/v2\/posts\/689\/revisions"}],"predecessor-version":[{"id":690,"href":"https:\/\/mitongxue.cn\/index.php\/wp-json\/wp\/v2\/posts\/689\/revisions\/690"}],"wp:attachment":[{"href":"https:\/\/mitongxue.cn\/index.php\/wp-json\/wp\/v2\/media?parent=689"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mitongxue.cn\/index.php\/wp-json\/wp\/v2\/categories?post=689"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mitongxue.cn\/index.php\/wp-json\/wp\/v2\/tags?post=689"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}__iter__<\/code>\u548c__next__<\/code>\u65b9\u6cd5\u7684\u5bf9\u8c61<\/p>\n\n\n\nclass MyIterator:
\u200b
def __iter__(self):
\"\"\"
\u8981\u6c42\uff1a\u5fc5\u987b\u8fd4\u56de\u8fed\u4ee3\u5668
99.999999%\u7684\u60c5\u51b5\u4e0b\uff0c\u8fd4\u56de\u8fed\u4ee3\u5668\u81ea\u8eab
\"\"\"
return self
\u200b
def __next__(self):
\"\"\"\u8fd4\u56de\u4e0b\u4e00\u4e2a\u503c\"\"\"
pass
obj = MyIterator() # obj \u662f\u4e00\u4e2a\u8fed\u4ee3\u5668<\/code><\/pre>\n\n\n\n\u65e0\u9650\u5e8f\u5217<\/h3>\n\n\n\n
class FibonacciIterator:
\"\"\"\u65e0\u9650\u6590\u6ce2\u90a3\u5951\u6570\u5217\u8fed\u4ee3\u5668\"\"\"
\u200b
def __init__(self):
self.a = 1
self.b = 1
\u200b
def __iter__(self):
return self
\u200b
def __next__(self):
current = self.a
self.a, self.b = self.b, self.a + self.b
return current
\u200b
\u200b
# \u4f7f\u7528\u793a\u4f8b
fib = FibonacciIterator()
\u200b
print(next(fib)) # \u8f93\u51fa: 1 \u7b49\u6548\u4e8e fib.__next__()
print(next(fib)) # \u8f93\u51fa: 1
print(next(fib)) # \u8f93\u51fa: 2
print(next(fib)) # \u8f93\u51fa: 3
print(next(fib)) # \u8f93\u51fa: 5
print(next(fib)) # \u8f93\u51fa: 8
\u200b<\/code><\/pre>\n\n\n\n\u53ef\u8fed\u4ee3\u5bf9\u8c61(Iterable)<\/h2>\n\n\n\n
__iter__()<\/code> \u65b9\u6cd5\uff0c\u4e14\u8fd4\u56de\u4e00\u4e2a\u8fed\u4ee3\u5668\uff0c\u5219\u5b83\u5c31\u662f\u53ef\u8fed\u4ee3\u5bf9\u8c61<\/strong><\/p>\n\n\n\n\n
my_list = [1, 2, 3]
\u200b
# \u8c03\u7528 iter() \u83b7\u53d6\u8fed\u4ee3\u5668
iterator = iter(my_list) # \u7b49\u4ef7\u4e8e my_list.__iter__()
\u200b
print(type(iterator)) # <class 'list_iterator'>
\u200b
# \u4f7f\u7528 next() \u9010\u4e2a\u83b7\u53d6\u503c
print(next(iterator)) # 1
print(next(iterator)) # 2
print(next(iterator)) # 3
\u200b
# print(next(iterator)) # StopIteration! \u6ca1\u6709\u66f4\u591a\u5143\u7d20\u4e86<\/code><\/pre>\n\n\n\n\u5012\u6570\u5bf9\u8c61<\/h3>\n\n\n\n
class Countdown:
\"\"\"\u53ef\u8fed\u4ee3\u5bf9\u8c61\uff1a\u5012\u6570\"\"\"
\u200b
def __init__(self, start):
self.start = start
\u200b
def __iter__(self):
\"\"\"\u8fd4\u56de\u4e00\u4e2a\u65b0\u7684\u8fed\u4ee3\u5668\"\"\"
return CountdownIterator(self.start)
\u200b
\u200b
class CountdownIterator:
\"\"\"\u8fed\u4ee3\u5668\"\"\"
\u200b
def __init__(self, start):
self.current = start
\u200b
def __iter__(self):
return self
\u200b
def __next__(self):
if self.current < 0:
raise StopIteration
num = self.current
self.current -= 1
return num
\u200b
\u200b
cd = Countdown(5)
\u200b
iterator = iter(cd)
print(next(iterator)) # 5
print(next(iterator)) # 4
print(next(iterator)) # 3
print(next(iterator)) # 2
print(next(iterator)) # 1
print(next(iterator)) # 0
# print(next(iterator)) # StopIteration!
\u200b<\/code><\/pre>\n\n\n\n\u6d88\u8d39\u8005<\/h3>\n\n\n\n
1.
for<\/code>\u5faa\u73af<\/h4>\n\n\n\n# for \u5faa\u73af\u4f1a\u81ea\u52a8\u8c03\u7528 iter() \u548c next()
for n in Countdown(3):
print(n) # 3 2 1 0<\/code><\/pre>\n\n\n\n2.
list()<\/code>\u3001tuple()<\/code>\u3001set()<\/code> \u7b49\u6784\u9020\u51fd\u6570<\/strong><\/h4>\n\n\n\nprint(list(Countdown(3))) # [3, 2, 1, 0]
print(tuple(Countdown(3))) # (3, 2, 1, 0)
print(set(Countdown(3))) # {0, 1, 2, 3}<\/code><\/pre>\n\n\n\n3.
*<\/code> \u89e3\u5305\u64cd\u4f5c\u7b26<\/strong><\/h4>\n\n\n\nfirst, *rest = Countdown(3)
print(first) # 3
print(rest) # [2, 1, 0]
\u200b
# \u6216\u7528\u5217\u8868\u89e3\u5305
values = [*Countdown(3)]
print(values) # [3, 2, 1, 0]<\/code><\/pre>\n\n\n\n4.
in<\/code> \u6210\u5458\u5224\u65ad<\/strong><\/h4>\n\n\n\nprint(5 in Countdown(3)) # False
print(2 in Countdown(3)) # True<\/code><\/pre>\n\n\n\n5.
sum()<\/code>\u3001max()<\/code>\u3001min()<\/code> \u7b49\u5185\u7f6e\u51fd\u6570<\/strong><\/h4>\n\n\n\nprint(sum(Countdown(3))) # 6
print(max(Countdown(3))) # 3
print(min(Countdown(3))) # 0<\/code><\/pre>\n\n\n\n6.
zip()<\/code>\u3001map()<\/code>\u3001filter()<\/code> \u7b49\u51fd\u6570<\/strong><\/h4>\n\n\n\n# zip \u5408\u5e76\u591a\u4e2a\u53ef\u8fed\u4ee3\u5bf9\u8c61
names = [\"Alice\", \"Bob\", \"Charlie\"]
ages = [25, 30, 35]
for name, age in zip(names, ages):
print(f\"{name}: {age}\")
# Alice: 25
# Bob: 30
# Charlie: 35
\u200b
# map \u5bf9\u5143\u7d20\u8fdb\u884c\u8f6c\u6362
squares = map(lambda x: x**2, Countdown(3))
print(list(squares)) # [9, 4, 1, 0]
\u200b
# filter \u8fc7\u6ee4\u5143\u7d20
evens = filter(lambda x: x % 2 == 0, Countdown(3))
print(list(evens)) # [2, 0]<\/code><\/pre>\n\n\n\n7.
any()<\/code>\u3001all()<\/code><\/strong><\/h4>\n\n\n\nnumbers = Countdown(3)
print(any(numbers)) # True (\u81f3\u5c11\u4e00\u4e2a\u4e3a\u771f)
print(all(numbers)) # False (\u662f\u5426\u6240\u6709\u90fd\u4e3a\u771f)<\/code><\/pre>\n\n\n\nrange\u51fd\u6570<\/h3>\n\n\n\n
range()<\/code> \u662f Python \u4e2d\u6700\u5e38\u7528\u7684\u53ef\u8fed\u4ee3\u5bf9\u8c61\u4e4b\u4e00\uff0c\u7528\u4e8e\u751f\u6210\u6574\u6570\u5e8f\u5217\uff1a<\/p>\n\n\n\n# range(stop): 0 \u5230 stop-1
for i in range(5):
print(i, end=\" \") # 0 1 2 3 4
\u200b
# range(start, stop): start \u5230 stop-1
for i in range(2, 6):
print(i, end=\" \") # 2 3 4 5
\u200b
# range(start, stop, step): \u6307\u5b9a\u6b65\u957f
for i in range(0, 10, 2):
print(i, end=\" \") # 0 2 4 6 8
\u200b
# \u8d1f\u6570\u6b65\u957f\uff08\u5012\u5e8f\uff09
for i in range(5, 0, -1):
print(i, end=\" \") # 5 4 3 2 1<\/code><\/pre>\n\n\n\n\n
range<\/code> \u4e0d\u4f1a\u4e00\u6b21\u6027\u751f\u6210\u6240\u6709\u6570\u5b57\uff0c\u800c\u662f\u6309\u9700\u751f\u6210<\/li>\n\n\n\nrange<\/code> \u652f\u6301\u968f\u673a\u8bbf\u95ee<\/li>\n<\/ol>\n\n\n\nr = range(0, 100, 2)
\u200b
print(len(r)) # 50
print(r[5]) # 10
print(r[0:5]) # range(0, 10, 2)
print(10 in r) # True
print(11 in r) # False<\/code><\/pre>\n\n\n\n\n
range<\/code> \u662f\u53ef\u8fed\u4ee3\u5bf9\u8c61\uff0c\u4f46\u4e0d\u662f\u8fed\u4ee3\u5668\uff08\u53ef\u4ee5\u91cd\u590d\u4f7f\u7528\uff09<\/li>\n<\/ol>\n\n\n\nr = range(3)
\u200b
for i in r:
print(i, end=\" \") # 0 1 2
print()
\u200b
for i in r:
print(i, end=\" \") # 0 1 2\uff08\u53ef\u4ee5\u518d\u6b21\u904d\u5386\uff09<\/code><\/pre>\n\n\n\n\n
range<\/code> \u5bf9\u8c61\u5728\u5185\u5b58\u4e2d\u53ea\u5b58\u50a8 start<\/code>\u3001stop<\/code>\u3001step<\/code> \u4e09\u4e2a\u503c\uff0c\u65e0\u8bba\u8303\u56f4\u591a\u5927\u90fd\u5360\u7528\u56fa\u5b9a\u5185\u5b58<\/p>\n<\/blockquote>\n\n\n\n\u63a8\u5bfc\u5f0f<\/h3>\n\n\n\n
\u5217\u8868\u63a8\u5bfc\u5f0f<\/h4>\n\n\n\n
# \u57fa\u672c\u8bed\u6cd5\uff1a[\u8868\u8fbe\u5f0f for \u53d8\u91cf in \u53ef\u8fed\u4ee3\u5bf9\u8c61]
squares = [x**2 for x in range(5)]
print(squares) # [0, 1, 4, 9, 16]
\u200b
# \u5e26\u6761\u4ef6\u8fc7\u6ee4\uff1a[\u8868\u8fbe\u5f0f for \u53d8\u91cf in \u53ef\u8fed\u4ee3\u5bf9\u8c61 if \u6761\u4ef6]
evens = [x for x in range(10) if x % 2 == 0]
print(evens) # [0, 2, 4, 6, 8]
\u200b
# \u5e26 if-else \u6761\u4ef6
labels = [\"\u5076\u6570\" if x % 2 == 0 else \"\u5947\u6570\" for x in range(5)]
print(labels) # ['\u5076\u6570', '\u5947\u6570', '\u5076\u6570', '\u5947\u6570', '\u5076\u6570']<\/code><\/pre>\n\n\n\n\u5b57\u5178\u63a8\u5bfc\u5f0f<\/h4>\n\n\n\n
# \u57fa\u672c\u8bed\u6cd5\uff1a{\u952e\u8868\u8fbe\u5f0f: \u503c\u8868\u8fbe\u5f0f for \u53d8\u91cf in \u53ef\u8fed\u4ee3\u5bf9\u8c61}
square_dict = {x: x**2 for x in range(5)}
print(square_dict) # {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}
\u200b
# \u5e26\u6761\u4ef6\u8fc7\u6ee4
odd_squares = {x: x**2 for x in range(10) if x % 2 != 0}
print(odd_squares) # {1: 1, 3: 9, 5: 25, 7: 49, 9: 81}<\/code><\/pre>\n\n\n\n\u96c6\u5408\u63a8\u5bfc\u5f0f<\/h4>\n\n\n\n
# \u57fa\u672c\u8bed\u6cd5\uff1a{\u8868\u8fbe\u5f0f for \u53d8\u91cf in \u53ef\u8fed\u4ee3\u5bf9\u8c61}
square_set = {x**2 for x in range(10)}
print(square_set) # {0, 1, 4, 81, 64, 9, 16, 49, 25, 36}
\u200b
# \u5e26\u6761\u4ef6\u8fc7\u6ee4
evens = {x for x in range(20) if x % 2 == 0}
print(evens) # {0, 2, 4, 6, 8, 10, 12, 14, 16, 18}<\/code><\/pre>\n\n\n\n\u5d4c\u5957\u63a8\u5bfc\u5f0f<\/h4>\n\n\n\n
# \u5d4c\u5957\u5217\u8868\u63a8\u5bfc\u5f0f\uff1a\u5c06\u4e8c\u7ef4\u5217\u8868\u5c55\u5e73
matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
flat = [x for row in matrix for x in row]
print(flat) # [1, 2, 3, 4, 5, 6, 7, 8, 9]
\u200b
# \u7b49\u4ef7\u4e8e\uff1a
# flat = []
# for row in matrix:
# for x in row:
# flat.append(x)
\u200b
# \u5d4c\u5957\u6761\u4ef6
matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
# \u53ea\u4fdd\u7559\u5076\u6570
result = [x for row in matrix for x in row if x % 2 == 0]
print(result) # [2, 4, 6, 8]<\/code><\/pre>\n\n\n\n\u5143\u7ec4\u63a8\u5bfc\u5f0f<\/h4>\n\n\n\n
\u63a8\u5bfc\u5f0f vs \u5faa\u73af<\/h4>\n\n\n\n
for<\/code> \u5faa\u73af\u66f4\u5feb\uff0c\u4e5f\u66f4\u7b80\u6d01\uff1a<\/p>\n\n\n\n# \u63a8\u5bfc\u5f0f\uff08\u63a8\u8350\uff09
squares = [x**2 for x in range(10)]
\u200b
# \u7b49\u6548\u7684\u5faa\u73af\u5199\u6cd5
squares = []
for x in range(10):
squares.append(x**2)<\/code><\/pre>\n\n\n\n\n