Python-functional programming, reflection, Random,md5,pickle,json,re,time

Advantages of functional Programming:

scalability, reusability (no Modification of previous code), readability (beginner easy to Understand)

__init__: used as a Python package file, otherwise it's just a folder

__name__: __name__== ' __main__ ' when called internally; __name__== file name when externally invoked

__file__: Current file path

1, The default parameters use

>>> def person (name,action= ' eat ... ', where= ' Beijing '):
... print name,action, ' in ' +where
...
>>> person (' Cxiong ')
Cxiong eat ... in Beijing
>>> person (' xmzhang ', ' sleep ')
Xmzhang Sleep in Beijing
>>> person (' cxiong ', where= ' Shanghai ', action= ' work ')
Cxiong work in Shanghai
>>> person (' cxiong ', ' work ', ' Wuhan ')
Cxiong work in Wuhan

2. variable parameter *arg wrapper as list incoming function

>>> def show (*arg):
... for item in Arg:
.... print item
...
>>> show (' cxiong ', ' Xmzhang ')
Cxiong
Xmzhang
>>>

3. variable parameter **kargs wrapper for dictionary incoming function

>>> def person (**kargs):
... for item in Kargs.items ():
.... print item
...
>>> person (name= ' Cxiong ', age=29)
(' Age ', 29)
(' name ', ' Cxiong ')
>>> person (name= ' Xmzhang ', age=29)
(' Age ', 29)
(' name ', ' Xmzhang ')

When transferring a dictionary, you need to use the **kargs variable;

>>> user_dict={' cxiong ': $, ' Xmzhang ': 29}
>>> person (**user_dict)
(' Cxiong ', 29)
(' Xmzhang ', 29)
>>> person (user_dict)
Traceback (most recent):
File "<stdin>", line 1, in <module>
Typeerror:person () takes exactly 0 arguments (1 given)
>>>

4. Yield Usage

The object is created when the xrange iteration is called, and the object is created lazily;

>>> for I in Xrange (10):
... print I
...
0
1
2
3
4
5
6
7
8
9
>>>

>>> def y ():
... yield 1
...
>>> y1=y ()
>>> Print Y1
<generator Object Y at 0x0293c288>

>>> for item in Y1:
.... print item
...
1
>>> def y ():
... yield 1
... yield 2
... yield 3
... yield 4
... yield 5
...
>>> y2=y ()
>>> Print y2
<generator Object Y at 0x02a31670>
>>> for item in Y2:
.... print item
...
1
2
3
4
5
>>>

>>> def Alexreadlines ():
... seek=0
... while True:
... with open (' c:/cc/abc.html ', ' r ') as F:
... F.seek (seek)
... data=f.readline ()
... if Data:
... Seek=f.tell ()
... yield data
.. else:
.. return
...
>>> for item in Alexreadlines ():
.... print item
...

>>> Print Alexreadlines ()
<generator Object Alexreadlines at 0x02a32cd8>

With open does not need to actively close the file stream

>>> F=open (' c:/cc/abc.html ')
>>> F.read ()
' >>> F.close ()
>>>

>>> with open (' c:/cc/abc.html ') as F:
... f.read ()
...
' >>>

def login (username):

If username== ' Alex ':

Return ' landing success '

Else

Return ' Login failed '

Yield can realize that the function execution process is not completed without waiting for the result of the function execution, that is, not blocking; when the project needs to call the function, call the next () method directly;

5. Lambda function

result= ' GT ' if 1>3 Else ' lt '

Equivalent to

Tmp=none

If 1>3:

tmp= ' GT '

Else

tmp= ' LT '

An anonymous function can only be called once;

Tmp=lambda X,y:x+y

Equivalent

def sum (x, y)

Return X+y

Http://www.cnblogs.com/wupeiqi/articles/4276448.html

6. Built-in Functions

>>> map (lambda x:x+1,[1,2,3]) #all序列
[2, 3, 4]
>>> Filter (lambda x:x==1,[1,23,44]) #True序列
[1]
>>> reduce (LAMBDA x,y:x+y,[1,2,3]) #累加
6
>>>

Enumerate it into an index sequence that can be used to get both the index and the value

>>> l1=[' Money ', ' house ', ' woman ']
>>> for item in enumerate (l1):
.... print item
...
(0, ' \xc7\xae ')
(1, ' \xb7\xbf\xd7\xd3 ')
(2, ' \XC5\XAE\XC8\XCB ')
>>> for item in enumerate (l1):
... print item[0],item[1]
...
0 Money
1 houses
2 women
>>>

Placeholder {},format Replace placeholder

>>> s= ' I am {0},{1} '
>>> s.format (' Cxiong ', 29)
' I am cxiong,29 '

String as an expression operation

>>> a= ' 8+8 '
>>> Eval (a)
16
>>> b= ' 4*2 '
>>> Eval (b)
8

7. Reflection

__import__: importing modules as strings

>>> tmp= ' sys '
>>> model=__import__ (tmp)
>>> Model.path
[' ', ' C:\\python27\\lib\\site-packages\\pip-8.0.3-py2.7.egg ', ' c:\\python27\\lib\\site-packages\\ Paramiko-1.16.0-py2.7.egg ', ' c:\\windows\\system32\\python27.zip ', ' c:\\python27\\dlls ', ' C:\\Python27\\lib ', ' c \ \python27\\lib\\plat-win ', ' c:\\python27\\lib\\lib-tk ', ' c:\\python27 ', ' c:\\python27\\lib\\site-packages ']
>>>

Getattr: executing functions in the form of strings

Mysql,sqlserver

>>> f=getattr (model, ' path ')
>>> F
[' ', ' C:\\python27\\lib\\site-packages\\pip-8.0.3-py2.7.egg ', ' c:\\python27\\lib\\site-packages\\ Paramiko-1.16.0-py2.7.egg ', ' c:\\windows\\system32\\python27.zip ', ' c:\\python27\\dlls ', ' C:\\Python27\\lib ', ' c \ \python27\\lib\\plat-win ', ' c:\\python27\\lib\\lib-tk ', ' c:\\python27 ', ' c:\\python27\\lib\\site-packages ']
>>>

8. Common Module random

>>> Import Random
>>> Random.random ()
0.20107276223352322
>>> Random.random ()
0.08696208484961188
>>> Random.random ()
0.2274291961816528

>>> Random.randint (1,5)
5
>>> Random.randint (1,5)
1
>>> Random.randint (1,5)
1
>>> Random.randint (1,5)
4
>>> Random.randint (1,5)
3
>>>

Scenario: Generate a verification code

code=[]

>>> for I in range (4):
... if I ==random.randint (1,4):
... print random.randint (1,4)
.. else:
... tmp=random.randint (65,90)
.. print CHR (tmp)

9, Common Module HASHLIB:MD5 encryption

>>> Import Hashlib
>>> hash=hashlib.md5 () #md5对象
>>> hash.update (' Admin ')
>>> hash.hexdigest ()
' 21232F297A57A5A743894A0E4A801FC3 '
>>> hash.hexdigest ()

10. Common Modules: Serialized-pickle

Serialization: the binary format formats the Python object as a string;

Deserialization: You can convert an encrypted string to an existing object

Purpose and function: can only be used in python, data storage, all Python objects (classes, functions, dictionaries, lists, etc.) are serialized into files for saving;

Python and Python program to interact with the memory space data, because the hard disk can only hold strings, unable to hold data objects;

>>> Import Pickle
>>> l1=[' cxiong ', 11,22, ' OK ', ' Xmzhang ']
>>> Pickle.dumps (l1)
"(lp0\ns ' Cxiong ' \np1\nai11\nai22\nas ' OK ' \np2\nas ' Xmzhang ' \np3\na."
>>> S1=pickle.dumps (l1)
>>> S1
"(lp0\ns ' Cxiong ' \np1\nai11\nai22\nas ' OK ' \np2\nas ' Xmzhang ' \np3\na."
>>> type (s1)
<type ' str ' >
>>> l1=pickle.loads (s1)
>>> L1
[' cxiong ', one, one, ' OK ', ' Xmzhang ']

In [+]: pickle.dump (l1,open ('/tmp/1.txt ', ' W '))

In [+]: exit
[email protected] ~]$ Cat/tmp/1.txt
(lp0
S ' Cxiong '
P1
AI11
AI22
As ' OK '
P2
As ' Xmzhang '
P3
A.

[email protected] ~]$

In [2]: pickle.load (open ('/tmp/1.txt ', ' r '))
Out[2]: [' cxiong ', one, a, ' OK ', ' Xmzhang ']

11. Common Modules: Serialized-json

Json: data formats supported by all languages; JSON can only serialize regular objects (dictionaries, lists); after JSON serialization, the string format is visible

The difference between JSON and pickle

In [5]: name_dict={' name ': ' Cxiong ', ' age ': 29}

In [6]: json.dumps (name_dict)
Out[6]: ' {' age ': "name": "cxiong"} '

In [7]: pickle.dumps (name_dict)
Out[7]: "(dp0\ns ' age ' \np1\ni29\nss ' name ' \np2\ns ' Cxiong ' \np3\ns."

12. Common Module RE

Character:

\d: Digital

\w: Letters

\ t: Blank

Number:

*：

+

？ ：

{m}:

{m,n}:

Match from scratch; search Global match; match only first

In []: r1=re.match (' \d+ ', ' asdfasd123asdfwe32 ')

In [+]: r2=re.search (' \d+ ', ' asdfasd123asdfwe32 ')

In []: R1

In [+]: R2
Out[21]: <_sre. Sre_match at 0x2e28370>

In []: R1.group ()
---------------------------------------------------------------------------
Attributeerror Traceback (most Recent)
<ipython-input-22-d8a389c401ef> in <module> ()
----> 1 R1.group ()

Attributeerror: ' Nonetype ' object has no attribute ' group '

In [all]: R2.grou
R2.group r2.groupdict r2.groups

In [all]: R2.group ()
Out[23]: ' 123 '

FindAll Match all modes

In []: r3=re.findall (' \d+ ', ' asdfasd123asdfwe32 ')

In [+]: R3
Out[25]: [' 123 ', ' 32 ']

Compile compilation mode

In [1]: import re

In [3]: com=re.compile (' \d+ ')

In [4]: type (com)
Out[4]: _sre. Sre_pattern

In [5]: com.findall (' asdf123aadsf3454aafadsf523 ')
Out[5]: [' 123 ', ' 3454 ', ' 523 ']

Groups () get matching group contents

In [6]: r2=re.search (' (\d+) asdf (\d+) ', ' 1234asdf2345 ')

In [7]: R2.group ()
Out[7]: ' 1234asdf2345 '

In [8]: r2.groups ()
Out[8]: (' 1234 ', ' 2345 ')

Information:

Https://deerchao.net/tutorials/regex/regex-1.htm

13. Common Modules: Time

Three forms of Expression:

Timestamp: seconds after January 1, 1970

Tuples include: year, day, week, etc... time.struct_time

Formatted string 2014-11-1111:11print time.time ()

In [9]: import time

In [ten]: time.time ()
Out[10]: 1494069737.874593

In [all]: time.gmtime ()
Out[11]: time.struct_time (tm_year=2017, tm_mon=5, tm_mday=6, tm_hour=11, tm_min=26, tm_sec=8, tm_wday=5, tm_yday=126, Tm_isdst=0)

In []: time.strftime ('%y-%m-%d%h:%m:%s ')
Out[14]: ' 2017-05-06 04:28:22 '

string format---> tuple format

In [+]: time.strptime (' 2017-05-06 ', '%y-%m-%d ')
Out[16]: time.struct_time (tm_year=2017, tm_mon=5, tm_mday=6, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=5, tm_yday=126, tm_ Isdst=-1)

Tuple format---> timestamp format

In [+]: time.localtime ()
Out[17]: time.struct_time (tm_year=2017, tm_mon=5, tm_mday=6, tm_hour=4, tm_min=30, tm_sec=56, tm_wday=5, tm_yday=126, Tm_isdst=1)

In []: time.mktime (time.localtime ())
Out[18]: 1494070270.0

Python-functional programming, reflection, Random,md5,pickle,json,re,time