Object Oriented Python 简明教程

pickle.dump(mystring, outfile, protocol),

myString = pickle.load(inputfile)

My Cat pussy is White and has 4 legs
Would you like to see her pickled? Here she is!
b'\x80\x03c__main__\nCat\nq\x00)\x81q\x01}q\x02(X\x0e\x00\x00\x00number_of_legsq\x03K\x04X\x05\x00\x00\x00colorq\x04X\x05\x00\x00\x00Whiteq\x05ub.'

[….]
binary_file = open(my_pickled_Pussy.bin', mode='wb')
my_pickled_Pussy = pickle.dump(Pussy, binary_file)
binary_file.close()

MeOw is black
Pussy is white

data1.json
{"menu": {
   "id": "file",
   "value": "File",
   "popup": {
      "menuitem": [
         {"value": "New", "onclick": "CreateNewDoc()"},
         {"value": "Open", "onclick": "OpenDoc()"},
         {"value": "Close", "onclick": "CloseDoc()"}
      ]
   }
}}

json.dump(conf, fh, indent = 4, separators = (‘,’, ‘: ‘))

---
# An employee record
name: Raagvendra Joshi
job: Developer
skill: Oracle
employed: True
foods:
   - Apple
   - Orange
   - Strawberry
   - Mango
languages:
   Oracle: Elite
   power_builder: Elite
   Full Stack Developer: Lame
education:
   4 GCSEs
   3 A-Levels
   MCA in something called com

pdb_example1.py
import pdb
x = 9
y = 7
pdb.set_trace()
total = x + y
pdb.set_trace()

c:\Python\Python361>Python pdb_example1.py
> c:\Python\Python361\pdb_example1.py(8)<module>()
-> total = x + y
(Pdb) x
9
(Pdb) y
7
(Pdb) total
*** NameError: name 'total' is not defined
(Pdb)

(Pdb) c
--Return--
> c:\Python\Python361\pdb_example1.py(8)<module>()->None
-> total = x + y
(Pdb) total
16

import pdb
def squar(x, y):
   out_squared = x^2 + y^2
   return out_squared
if __name__ == "__main__":
   #pdb.set_trace()
   print (squar(4, 5))

c:\Python\Python361>Python pdb_example2.py
> c:\Python\Python361\pdb_example2.py(10)<module>()
-> print (squar(4, 5))
(Pdb)

(Pdb) s
--Call--
>c:\Python\Python361\pdb_example2.py(3)squar()
-> def squar(x, y):

(Pdb) l
1 import pdb
2
3 def squar(x, y):
4 -> out_squared = x^2 + y^2
5
6 return out_squared
7
8 if __name__ == "__main__":
9 pdb.set_trace()
10 print (squar(4, 5))
[EOF]
(Pdb)

(Pdb) x
4
(Pdb) y
5
(Pdb) x^2
6
(Pdb) y^2
7
(Pdb) x**2
16
(Pdb) y**2
25
(Pdb)

import logging

logging.basicConfig(level=logging.INFO)

logging.debug('this message will be ignored') # This will not print
logging.info('This should be logged') # it'll print
logging.warning('And this, too') # It'll print

INFO:root:This should be logged
WARNING:root:And this, too

logging.basicConfig(level = logging.DEBUG)

DEBUG:root:this message will be ignored
INFO:root:This should be logged
WARNING:root:And this, too

#logging.basicConfig(level = logging.DEBUG)

WARNING:root:And this, too

>>> import logging
>>>
>>> logging.DEBUG
10
>>> logging.CRITICAL
50
>>> logging.WARNING
30
>>> logging.INFO
20
>>> logging.ERROR
40
>>>

logging.basicConfig(level = logging.DEBUG, filename = 'logging.log')

logging.basicConfig(level=logging.DEBUG, format = '%(asctime)s %(levelname)s:%(message)s')

2018-03-08 19:30:00,066 DEBUG:this message will be ignored
2018-03-08 19:30:00,176 INFO:This should be logged
2018-03-08 19:30:00,201 WARNING:And this, too

import timeit
print ( 'by index: ', timeit.timeit(stmt = "mydict['c']", setup = "mydict = {'a':5, 'b':10, 'c':15}", number = 1000000))
print ( 'by get: ', timeit.timeit(stmt = 'mydict.get("c")', setup = 'mydict = {"a":5, "b":10, "c":15}', number = 1000000))

by index: 0.1809192126703489
by get: 0.6088525265034692

c:\Python\Python361>Python -m timeit -n 1000000 -s "mydict = {'a': 5, 'b':10, 'c':15}" "mydict['c']"
1000000 loops, best of 3: 0.187 usec per loop

c:\Python\Python361>Python -m timeit -n 1000000 -s "mydict = {'a': 5, 'b':10, 'c':15}" "mydict.get('c')"
1000000 loops, best of 3: 0.659 usec per loop

import timeit

def testme(this_dict, key):
   return this_dict[key]

print (timeit.timeit("testme(mydict, key)", setup = "from __main__ import testme; mydict = {'a':9, 'b':18, 'c':27}; key = 'c'", number = 1000000))

0.7713474590139164