Learning Python(3)

handle string

#大写首字符
>>> 'abc def'.capitalize()
'Abc def'
>>> 'ABC DEF'.lower()
'abc def'
>>> 'abc def'.title()
'Abc Def'
#是否是字母+数字组合
>>> 'abc123'.isalnum()
True
#是否是数字
>>> 'abc'.isdigit()
False
>>> 'abcde'.startswith('ab')
True
>>> 'abcde'.endswith('de')
True
#指定字串第一次出现的索引
>>> 'abcde'.index('bc')
1
>>> 'abcde'.replace('bc','fg')
'afgde'
>>> '1,2,3,4,5,6,7'.split(',',3)
['1', '2', '3', '4,5,6,7']
>>> '1,2,3,4,5,6,7'.rsplit(',',3)
['1,2,3,4', '5', '6', '7']

• string format

name='jilu'
age=27
info='{0} is {1} years old'.format(name,age)
print(info)

• regex

import re
p=re.compile('"(https?://.*?)"',re.IGNORECASE)  #complie()方法里面第一个参数为正则式
with open('HackerNews.htm',encoding='UTF-8') as file_object:
    doc=file_object.read()
for i in p.findall(doc):    #findall()方法接受str完成匹配
    print(i)

• namedtuple

from collections import *
nt=namedtuple('nt','name age loc')
nt1=nt('jilu','27','Beijing')
print(nt1)
#nt(name='jilu', age='27', loc='Beijing')

• Counter

from collections import *
doc='A wiki enables communities of editors and contributors to write documents collaboratively. ' \
    'All that people require to contribute is a computer, Internet access, a web browser and a basic understanding of a simple markup language (e.g., HTML). ' \
    'A single page in a wiki website is referred to as a "wiki page", while the entire collection of pages, which are usually well-interconnected by hyperlinks, is "the wiki". ' \
    'A wiki is essentially a database for creating, browsing, and searching through information. A wiki allows non-linear, evolving, complex and networked text, while also allowing for editor argument, debate and interaction regarding the content and formatting.' \
    'A defining characteristic of wiki technology is the ease with which pages can be created and updated. Generally, there is no review by a moderator or gatekeeper before modifications are accepted and thus lead to changes on the website. ' \
    'Many wikis are open to alteration by the general public without requiring registration of user accounts.'
world_list=doc.split()
print(Counter(world_list))
#Counter({'and': 8, 'a': 8, 'is': 6, 'wiki': 5, 'of': 5, 'to': 5, 'the': 5, 'A': 4...})

• defaultdict

from collections import *
from collections import *
cl = defaultdict(list)
print(cl['key'])
print(cl)
cl['key'].append(1)
cl['key'].append(2)
cl['key'].append(3)
cl['key1'].append(1)
print(cl)
#[]
#defaultdict(<class 'list'>, {'key': []})
#defaultdict(<class 'list'>, {'key': [1, 2, 3], 'key1': [1]})

• string format

name='xianbei'
age=24
print(
    '{0} is {1} years old'.format(name,age)
)
print(
    '{first} is {second} years old'.format(first=name,second=age)
)
print(
    '{0:.3} is a decimal.'.format(1/3.0)    #控制小数点位数，.3是三位小数
)

print(
    '{:<10}{:10}'.format(1,2)
)
#排版控制:{:[对齐方式<^>][宽度]}
#1                  2

• float to int:

>>> import math
>>> for i in [-3.5,-2.8,-0.2,0,0.2,1.5,2.8,3.5]:
...     print(i,int(i),math.trunc(i),math.floor(i),math.ceil(i))
...
-3.5 -3 -3 -4 -3
-2.8 -2 -2 -3 -2
-0.2 0 0 -1 0
0 0 0 0 0
0.2 0 0 0 1
1.5 1 1 1 2
2.8 2 2 2 3
3.5 3 3 3 4

• fabs and sign

>>> import math
>>> math.fabs(-1.1)
1.1
>>> math.copysign(8.6,-2)
-8.6

• sum and factorial

>>> import math
>>> values=[value*0.01 for value in range(10)]
>>> math.fsum(values)
0.45
>>> for i in range(8):
...     print(i,math.factorial(i))
...
0 1
1 1
2 2
3 6
4 24
5 120
6 720
7 5040

• pow, log and exp

>>> math.pow(2,3)
8.0
>>> math.log(8,2)
3.0
>>> math.log(8)         #底为e
2.0794415416798357
>>> math.log(8,math.e)  #how to use e
2.0794415416798357
>>> math.exp(2)
7.38905609893065

• time

>>> import time
>>> time.time()
1517275993.898113
>>> time.ctime()
'Tue Jan 30 09:33:18 2018'
>>> time.gmtime()
time.struct_time(tm_year=2018, tm_mon=1, tm_mday=30, tm_hour=1, tm_min=34, tm_sec=20, tm_wday=1, tm_yday=30, tm_isdst=0)

• random generate

>>> import random
>>> random.seed(5)
>>> for i in range(5):
...     print(random.random())  #random.randint();random.randrange()
...
0.20136665126815378
0.937744482772246
0.7040633890022934
0.8635110837128008
0.3503527767880694

• random operation on list

>>> import random
>>> a=[i for i in range(10)]
>>> for x in range(5):
...     random.shuffle(a)
...     print(a)
...
[9, 8, 0, 4, 7, 5, 2, 1, 3, 6]
[1, 5, 2, 6, 0, 7, 8, 3, 4, 9]
[1, 8, 2, 3, 5, 7, 6, 0, 9, 4]
[5, 0, 1, 9, 8, 7, 4, 6, 3, 2]
[6, 1, 7, 4, 3, 5, 0, 8, 2, 9]
>>> for x in range(5):
...     print(random.choice(a))
...
0
0
6
2
4
>>> for x in range(5):
...     print(random.sample(a,3))
...
[7, 6, 0]
[5, 6, 3]
[8, 7, 6]
[3, 5, 6]
[0, 8, 6]

• gzip

import gzip
with gzip.open('abc.log.gz','w') as gz:
    for x in ['a','b','c']:
        gz.write(bytes(x,'UTF-8'))

• traceback

import traceback
def produce_exception():
    raise Exception('test')
try:
    produce_exception()
except Exception as e:
    print(traceback.format_exc())
#####################################
Traceback (most recent call last):
  File "D:/ITWorkSpace/MyPy/mypy.py", line 6, in <module>
    produce_exception()
  File "D:/ITWorkSpace/MyPy/mypy.py", line 3, in produce_exception
    raise Exception('test')
Exception: test