标签：运行 self == color level base64编码 async tool 关于
这里记录一些python的一些基础知识，主要内容是高阶函数的使用。或许我的心包有一层硬壳，能破壳而入的东西是极其有限的。所以我才不能对人一往情深。
map()函数接收两个参数，一个是函数，一个是Iterable，map将传入的函数依次作用到序列的每个元素，并把结果作为新的Iterator返回。
def f(x): return x * x print(list(map(f, range(1, 7)))) # [1, 4, 9, 16, 25, 36] print(list(map(lambda x: x * x, range(1, 7)))) # [1, 4, 9, 16, 25, 36]
reduce把一个函数作用在一个序列[x1, x2, x3, ...]上，这个函数必须接收两个参数，reduce把结果继续和序列的下一个元素做累积计算。
from functools import reduce def add(x, y): return x + y print(reduce(add, range(1, 10))) # 45 print(reduce(lambda x, y: x + y, range(1, 10))) # 45
filter()函数用于过滤序列。
def is_odd(n): return n % 2 == 0 print(list(filter(is_odd, range(1, 10)))) # [2, 4, 6, 8] print(list(filter(lambda x: x % 2 == 0, range(1, 10)))) # [2, 4, 6, 8]
sorted()函数用于排序。
def ownSort(n): return str(abs(n))[0] sortList = [-3, 9, -7, 10] print(sorted(sortList)) # [-7, -3, 9, 10] print(sorted(sortList, key=abs)) # [-3, -7, 9, 10] print(sorted(sortList, key=abs, reverse=True)) # [10, 9, -7, -3] print(sorted(sortList, key=ownSort)) # [10, -3, -7, 9]
def scope_test(): def do_local(): spam = "local spam" def do_nonlocal(): nonlocal spam spam = "nonlocal spam" def do_global(): global spam spam = "global spam" spam = "test spam" do_local() print("After local assignment:", spam) do_nonlocal() print("After nonlocal assignment:", spam) do_global() print("After global assignment:", spam) scope_test() print("In global scope:", spam) # After local assignment: test spam # After nonlocal assignment: nonlocal spam # After global assignment: nonlocal spam # In global scope: global spam
Note how the local assignment (which is default) didn’t change scope_test’s binding of spam. The nonlocal assignment changed scope_test’s binding of spam, and the global assignment changed the module-level binding.
import asyncio import random import threading async def Hello(index): print(‘Hello world! index=%s, thread=%s‘ % (index, threading.currentThread())) await asyncio.sleep(random.randint(1, 5)) print(‘Hello again! index=%s, thread=%s‘ % (index, threading.currentThread())) loop = asyncio.get_event_loop() tasks = [Hello(1), Hello(2)] loop.run_until_complete(asyncio.wait(tasks)) loop.close()
运行的结果如下：
Hello world! index=2, thread=<_MainThread(MainThread, started 37900)> Hello world! index=1, thread=<_MainThread(MainThread, started 37900)> Hello again! index=1, thread=<_MainThread(MainThread, started 37900)> Hello again! index=2, thread=<_MainThread(MainThread, started 37900)>
import base64 # base64编码 m = base64.b64encode(b‘my name is huhx.‘) print(m) # b‘bXkgbmFtZSBpcyBodWh4Lg==‘ # # base64解码 bytes = base64.b64decode(m) print(bytes) # b‘my name is huhx.‘
codecs模块的简单使用
print(‘中国‘.encode(‘utf-8‘)) # b‘\xe4\xb8\xad\xe5\x9b\xbd‘ print(‘中国‘.encode(‘gbk‘)) # b‘\xd6\xd0\xb9\xfa‘ import codecs print(codecs.encode(‘中国‘, ‘utf-8‘)) # b‘\xe4\xb8\xad\xe5\x9b\xbd‘ print(codecs.encode(‘中国‘, ‘gbk‘)) # b‘\xd6\xd0\xb9\xfa‘
str对象的encode方法的文档如下：
def encode(self, encoding=‘utf-8‘, errors=‘strict‘): # real signature unknown; restored from __doc__ """ S.encode(encoding=‘utf-8‘, errors=‘strict‘) -> bytes Encode S using the codec registered for encoding. Default encoding is ‘utf-8‘. errors may be given to set a different error handling scheme. Default is ‘strict‘ meaning that encoding errors raise a UnicodeEncodeError. Other possible values are ‘ignore‘, ‘replace‘ and ‘xmlcharrefreplace‘ as well as any other name registered with codecs.register_error that can handle UnicodeEncodeErrors. """ return b""
标签：运行 self == color level base64编码 async tool 关于
原文地址：http://www.cnblogs.com/huhx/p/baseuselearnpython5.html
