python3学习笔记（一）

一. 打印并输出到文件

>>> print("aa","bb"," 11 ","ddddd",sep='-',end='ok/t',file=open("c:/test.txt",'w')) >>> print("-" *40)#打印40个"-"

 

二. 打印字典的值

>>> d = {"a":1,"b":2} >>> print('%(a)s...%(b)s' %d) 1...2 >>> s = ('%(a)s...%(b)s' %d) >>> s '1...2' >>> s = ['%(a)s...%(b)s' %d] >>> s ['1...2'] >>> print("%(__builtins__)s...%(d)s" %vars()) <module 'builtins' (built-in)>...{'a': 1, 'b': 2} >>> vars() {'__builtins__': <module 'builtins' (built-in)>, '__name__': '__main__', '__doc__': None, 'd': {'a': 1, 'b': 2}, '__package__': None} >>> locals() {'__builtins__': <module 'builtins' (built-in)>, '__name__': '__main__', '__doc__': None, 'd': {'a': 1, 'b': 2}, '__package__': None} >>> vars() is locals() #vars()无参数的情况等同locals() True >>> vars() == locals() True >>> a = vars() >>> b = locals() >>> a is b True

 

三. pprint整洁打印

>>> import pprint >>> pprint.pprint(data) ('this is a string', [1, 2, 3, 4], ('more tuples', 1.0, 2.3, 4.5), 'this is yet another string') >>> print(data) ('this is a string', [1, 2, 3, 4], ('more tuples', 1.0, 2.3, 4.5), 'this is yet another string') >>> pp = pprint.PrettyPrinter(indent=4) #缩进4空格 >>> pp.pprint(data) ( 'this is a string', [1, 2, 3, 4], ('more tuples', 1.0, 2.3, 4.5), 'this is yet another string')

 

四. 打印输出重定向

>>> import sys >>> sys.stdout = open('c:/log123.txt','w') >>> print ("aa","bb","1111111112213123") >>> sys.stdout = sys.__stdout__

>>> import sys >>> t = sys.stdout >>> sys.stdout = open("c:/log123.txt",'w') >>> print('1234abcd') >>> sys.stdout = t >>> print("11") 11 >>>

 

五. with方式读取文件直到某行停止

读取文件，直到某一行的文本等于"STOP"停止读取。否则，将一直读取下去。
（注意：停止读取的行文本只能是iter()的第二个参数值，不能包含其他的，空格都不行）

with open("c:/test.txt") as fp: for line in iter(fp.readline,"STOP"): print(line)

 

六. 搜索目录树中包含有某个字符串的文件名的所有文件列表

>>> import glob >>> import fileinput >>> import os >>> import re >>> glob.glob("E:/cdr01") ['E:/cdr01'] >>> glob.glob("E:/cdr01/*")#只返回当前cdr01下面的子目录名和文件名（带路径，但不包含目录树中的所有子目录与文件） ['E:/cdr01//20110113', 'E:/cdr01//20110114', 'E:/cdr01//20110115', 'E:/cdr01//20110116', 'E:/cdr01//20110117', 'E:/cdr01//20110118', 'E:/cdr01//20110119', 'E:/cdr01//20110120', 'E:/cdr01//20110121', 'E:/cdr01//20110122', 'E:/cdr01//20110123', 'E:/cdr01//20110124', 'E:/cdr01//cdr01.rar'] >>> [(a,b,c) for a , b , c in os.walk("E:/cdr01")] #os.walk返回目录树中的所有目录与文件，他将每一目录的子目录与文件都按一个元组来返回。a代表当前搜索目录（或者子目录），b代表当前搜索目录下面所包含的子目录列表，c代表当前搜索目录下面的所有文件名列表。（不带路径（但可以通过与元组第一项进行拼接为目录或者文件路径），并且包含目录树中的所有子目录与文件） [('E:/cdr01', ['20110113', '20110114', '20110115', '20110116', '20110117', '20110118', '20110119', '20110120', '20110121', '20110122', '20110123', '20110124'], ['cdr01.rar']), ('E:/cdr01//20110113', [], ['20110113_6042488744.csv']), ('E:/cdr01//20110114', [], ['20110114_6042488744.csv']), ('E:/cdr01//20110115', [], ['20110115_6042488744.csv']), ('E:/cdr01//20110116', [], ['20110116_6042488744.csv']), ('E:/cdr01//20110117', [], ['20110117_6042488744.csv']), ('E:/cdr01//20110118', [], ['20110118_6042488744.csv']), ('E:/cdr01//20110119', [], ['20110119_6042488744.csv']), ('E:/cdr01//20110120', [], ['20110120_6042488744.csv']), ('E:/cdr01//20110121', [], ['20110121_6042488744.csv']), ('E:/cdr01//20110122', [], ['20110122_6042488744.csv']), ('E:/cdr01//20110123', [], ['20110123_6042488744.csv']), ('E:/cdr01//20110124', [], ['20110124_6042488744.csv'])] >>> list((os.path.join(a,f)) for a , b , c in os.walk("E:/cdr201101") for f in c if re.search('6042488744',os.path.basename(f))) #E:/cdr201101包含很多CSV文件，此方法将搜索目录树中的文件名包含字符串"6042488744"的文件，并将文件名与路径拼接作为绝对路径返回。 ['E:/cdr201101//20110113//20110113_6042488744.csv', 'E:/cdr201101//20110114//20110114_6042488744.csv', 'E:/cdr201101//20110115//20110115_6042488744.csv', 'E:/cdr201101//20110116//20110116_6042488744.csv', 'E:/cdr201101//20110117//20110117_6042488744.csv', 'E:/cdr201101//20110118//20110118_6042488744.csv', 'E:/cdr201101//20110119//20110119_6042488744.csv', 'E:/cdr201101//20110120//20110120_6042488744.csv', 'E:/cdr201101//20110121//20110121_6042488744.csv', 'E:/cdr201101//20110122//20110122_6042488744.csv', 'E:/cdr201101//20110123//20110123_6042488744.csv', 'E:/cdr201101//20110124//20110124_6042488744.csv']

 

七. 字符串转成字节数组，字节数组转成字节串

>>> s = 'abcd123' >>> b = bytearray(s,sys.stdin.encoding) #sys.stdin.encoding相当于locale.getdefaultlocale()[1]获得当前操作系统的编码方式 >>> b bytearray(b'abcd123') >>> b = bytes(s,sys.stdin.encoding) >>> b b'abcd123'

 

八. 字符串与字节的编码与解码

>>> a = b'abc' >>> a.decode() #字节解码为字符串 'abc' >>> b = aa.encode() #字符串编码为字节 >>> b b'abc' >>>

  

九. 处理zip压缩文件

>>> import zipfile >>> f = zipfile.ZipFile("E:/CodeBuilder.zip","r") >>> for name in f.namelist(): data = f.read(name) print(name,len(data),repr(data[:10])) >>> f.close()

>>> import zipfile >>> z = zipfile.ZipFile("E:/test1.zip","w") #创建zip压缩文件包 >>> z.write("E:/testSqliteDB.db.txt") #压缩一个txt文件 >>> z.close() >>> z = zipfile.ZipFile("E:/test1.zip","r") #读取zip压缩文件包 >>> z.extractall()#解压到当前目录，extract可以具体指定解压哪个文件到哪个目录 >>> z.extractall("E:/123/")#解压到指定目录 >>> z.close() >>> import os >>> os.getcwd() #getcwd()可以查看解压的当前目录位置 'C://Python31'

 

十. glob遍历文件夹下面的所有文件并读取内容

>>> import fileinput >>> import glob >>> for line in fileinput.input(glob.glob("E:/TestFolder/*.txt")): print("File name:" + fileinput.filename() + " line length:" + str(len(line))) >>> fileinput.close()

 

十一. shutil拷贝目录树

>>> import shutil >>> shutil.copytree("E:/TestFolder","F:/TestFolder-bak") >>> shutil.copytree("E:/TestFolder","xx") #在TestFolder文件夹里面创建XX目录，并拷贝TestFolder目录到XX目录

 

十二. 获得文件大小的两种方式（二进制读取）

>>> import os >>> os.stat(f).st_size 4753 >>> os.path.getsize(f) 4753

 

十三. mmap 模块提供了操作系统内存映射函数的接口,可以映射字符串与文件内容

可以执行譬如查找、统计、写入等一些操作，但就是基于字节的。

>>> map = mmap.mmap(-1,13) >>> map.write(b"Hello world!") >>> map.readline() b'/x00' >>> map.seek(0) >>> map.readline() b'Hello world!/x00' >>> map.seek(0) >>> map.find(b'w') 6 >>> map.close()

 

十四. dis反编译对象为字节码

>>> import dis >>> def showMsg(xx): print("abc") >>> dis.dis(showMsg) 2 0 LOAD_GLOBAL 0 (print) 3 LOAD_CONST 1 ('abc') 6 CALL_FUNCTION 1 9 POP_TOP 10 LOAD_CONST 0 (None) 13 RETURN_VALUE

十五。profile 与 cProfile分析程序执行性能

profile 模块是标准 Python 分析器，用Python写的。
而cProfile是用C写的，运行起来比profile快，官方推荐用cProfile.

pstats可以处理分析报告。

>>> import profile >>> def testss(n): i = 0 for i in range(n): i = i + 1 return i >>> profile.run("testss(1000000)") 5 function calls in 0.269 CPU seconds Ordered by: standard name ncalls tottime percall cumtime percall filename:lineno(function) 1 0.000 0.000 0.266 0.266 :0(exec) 1 0.002 0.002 0.002 0.002 :0(setprofile) 1 0.266 0.266 0.266 0.266 <pyshell#3>:1(testss) 1 0.000 0.000 0.266 0.266 <string>:1(<module>) 0 0.000 0.000 profile:0(profiler) 1 0.000 0.000 0.269 0.269 profile:0(testss(1000000)) >>> import cProfile >>> cProfile.run("testss(1000000)") #分析速度快些 4 function calls in 0.212 CPU seconds Ordered by: standard name ncalls tottime percall cumtime percall filename:lineno(function) 1 0.212 0.212 0.212 0.212 <pyshell#3>:1(testss) 1 0.000 0.000 0.212 0.212 <string>:1(<module>) 1 0.000 0.000 0.212 0.212 {built-in method exec} 1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler' objects}

 

pstats处理分析报告：

>>> import pstats >>> pr = profile.Profile() >>> pr.run("testss(1000000)") <profile.Profile object at 0x0143C8D0> >>> p = pstats.Stats(pr) >>> pstats = p.sort_stats("time") #按时间排序 >>> pstats.print_stats() #打印在profile.run()中形成的分析报告 5 function calls in 38.856 CPU seconds Ordered by: internal time ncalls tottime percall cumtime percall filename:lineno(function) 1 25.843 25.843 25.843 25.843 :0(setprofile) 1 12.760 12.760 38.856 38.856 profile:0(testss(1000000)) 1 0.253 0.253 0.253 0.253 <pyshell#3>:1(testss) 1 0.000 0.000 0.253 0.253 :0(exec) 1 0.000 0.000 0.253 0.253 <string>:1(<module>) 0 0.000 0.000 profile:0(profiler) <pstats.Stats object at 0x0143C330>