python处理技巧_Python小技巧1
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"-">>> 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())
...{'a': 1, 'b': 2}
>>> vars()
{'__builtins__': , '__name__': '__main__', '__doc__': None, 'd': {'a': 1, 'b': 2}, '__package__': None}
>>> locals()
{'__builtins__': , '__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
>>> 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())
...{'a': 1, 'b': 2}
>>> vars()
{'__builtins__': , '__name__': '__main__', '__doc__': None, 'd': {'a': 1, 'b': 2}, '__package__': None}
>>> locals()
{'__builtins__': , '__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')
>>> 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
>>> 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
>>>
>>> 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)
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']
>>> 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'
>>> 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'
>>>
>>> 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
>>> 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'
>>> 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()
>>> 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>>> 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
>>> 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()
>>> 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
>>> 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 :1(testss) 1 0.000 0.000 0.266 0.266 :1()
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 :1(testss) 1 0.000 0.000 0.212 0.212 :1()
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}
>>> 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 :1(testss) 1 0.000 0.000 0.266 0.266 :1()
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 :1(testss) 1 0.000 0.000 0.212 0.212 :1()
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)")
>>> 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 :1(testss) 1 0.000 0.000 0.253 0.253 :0(exec)
1 0.000 0.000 0.253 0.253 :1()
0 0.000 0.000 profile:0(profiler)
>>> import pstats
>>> pr = profile.Profile()
>>> pr.run("testss(1000000)")
>>> 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 :1(testss) 1 0.000 0.000 0.253 0.253 :0(exec)
1 0.000 0.000 0.253 0.253 :1()
0 0.000 0.000 profile:0(profiler)
python处理技巧_Python小技巧1相关推荐
- python使用技巧_python小技巧
平时开发中,一些使用的技巧,记录一下,持续更新---- 1.当函数默认参数为可变对象时,每次调用函数,是不会重新创建对象的 示例代码1: def ddd(a,b=[]): b.append(a)ret ...
- python查询模块所有类_python 小技巧(import模块、查询类继承关系、安装包)
作者:Vamei 出处:http://www.cnblogs.com/vamei 欢迎转载,也请保留这段声明.谢谢! 在这里列举一些我使用Python时积累的小技巧.这些技巧是我在使用Python过程 ...
- 填坑总结:python内存泄漏排查小技巧
摘要:最近服务遇到了内存泄漏问题,运维同学紧急呼叫解决,于是在解决问题之余也系统记录了下内存泄漏问题的常见解决思路. 本文分享自华为云社区<python内存泄漏排查小技巧>,作者:luti ...
- 菜鸟教程python3 mysql_python基础教程使用Python操作MySQL的小技巧
1.获取插入数据的主键id import pymysql database = pymysql.connect( host="127.0.0.1", port=3306, user ...
- 10个Python进行数据分析的小技巧
Pandas中数据框数据的Profiling过程 Profiling(分析器)是一个帮助我们理解数据的过程,而Pandas Profiling是一个Python包,它可以简单快速地对Pandas 的数 ...
- python 比特输出_Python小碗菜:and/or 与 amp;/| 到底有什么区别
前言 在对Python的学习过程中,经常有人会问:对于逻辑运算,and/or 与 &/| 的区别在哪里?用哪个好?真的是哪个输入简单一点用哪个吗?其实他们是有内在区别的:and和or判断的是 ...
- python变量保存在哪里_python小技巧——将变量保存在本地及读取
在用jupyter notebook写python代码的过程中会产生很多变量,而关闭后或者restart jupyter kernel后所有变量均会消失,想要查看变量就必须将代码重新再运行一遍,而想在 ...
- python win32转pdf 横版_Python 小技巧之 Office 文件转 PDF
文章来源于公众号:Python技术 作者:派森酱 在日常的生活工作中,难免需要用到一些 小Tip 来解决工作中遇到的小难题,今天的文章给大家安利一个方便快捷的小技巧,将 Office(doc/docx ...
- python保存变量到本地_python小技巧——将变量保存在本地及读取
在用jupyter notebook写python代码的过程中会产生很多变量,而关闭后或者restart jupyter kernel后所有变量均会消失,想要查看变量就必须将代码重新再运行一遍,而想在 ...
最新文章
- YOLOv4-5D:一种高效的自动驾驶物体检测器
- canva旋转图片 js_js和canvas实现旋转图片
- 我和AI打了六局王者荣耀,心态崩了
- iOS-生成国际化包-配置App多语言支持
- 【数学与算法】【分段三次Hermite插值】和【分段三次样条插值】
- JS 处理Json 时间带T 时间格式
- mysql自连接查询去重_MySQL命令汇总
- 【mybatis源码系列1】 二级缓存
- Qt连接数据库的方法
- 视频流传输协议RTP/RTCP/RTSP/HTTP的区别
- /bin/bash^M: bad interpreter: No such file or directory
- 树形dp - BNU 39572 Usoperanto
- 1434 区间LCM
- 计算机三级网络技术总结,计算机三级网络技术总结
- 一个简单的conky
- android 注册静态广播接收器VS注册动态广播接收器
- 【软件教程】Spring Tool Suite(STS)
- CIM即时通讯源码初步解析(一款个人推荐的带集群的开源项目)
- python身份证验证程序_python验证身份证信息实例代码
- JavaScript 弹窗