sorted cookbook

When you look at the Python Cookbook, section 9.5, "Defining an adorner that can be modified by the user", has an adorner that takes some time to make a note lest you forget the second time you brush the book.Complete code: https://github.com/blackmatrix7/python-learning/blob/master/python_cookbook/chapter_9/section_5/attach_wrapper.pyThe decorator in the book (called the Accessor function in the book)def attach_wrapper (obj, func=None): if is none

#-*-Coding:utf-8-*-#__author__ = ' Administrator '#一般使用2种方法来解决这个问题isinstance basestring to simply and quickly check the type of a stringdef isstring (obj):Print Isinstance (obj,basestring)It is normal for #如果你第一个想到 (novice) to use Type (obj), but in the case of a veteran, using type (obj) is bad#basestring是str与unicode类型的基类#如果想支持字符串操作, you can use the following methodsdef islinstring (s): #一般 (in most cases) to meet the requirementsTryS+ "Except:return FalseElse:return TruePython

secondary numbers by character device and block device, linked to device/sys/device is a global device architecture, containing all the discovered physical devices registered on various buses, a hierarchical representation model of all the devices in the system, and the most important directory structure for/sys file system management devices./SYS/FS describes all file systems in the system/sys/kernel stores all the adjustable parameters in the kernel/tmp temp file/USR User program storage dire

observe variable values or tap a command such as w to get tracking information.Discuss?Don't make debugging too complicated. Some simple bugs just need to see the program stack information,The actual error is generally the last line of the stack.When you are developing, you can also insert them where you need to debug.print()function to diagnose the information (just delete these print statements when the last release is needed).A common use of the debugger is to observe a variable in a functio

example: You can easily find the total mileage of each driver:does not work properly,However, you can sort the data rows first, and then use limit to select the first row of data:9, generate reports that include summaries and listsUse Pthon to generate summary and list reports:+ View Code? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 import Cookbook import sys import MySQLdb name_map={} conn=Cookbook.conn

Tags: data span Select partial structure ble let count ast1. Copy rows from one table to another 1 into dept_east (Deptno, Dname, loc) 2 Select deptno, dname, loc 3 from Dept 4 where inch ('New York'Boston') 2. Duplicate table structure Changing the Where condition can also copy part of the data 1 mysql>createtableas 2 Select* from film 3- where 1 = 0\g 3. Block insertions to a few columns Create a view that displays only the columns that the user is allowed to access 4. Delete al

1, where clause, and priority is higher than or1 Select * from where Ten or like ' %ark ' and = \gis equivalent to the following query:1 Select * from where Ten or like ' %ark ' and = ) \g2. Connection column value: concat1 Select concat (" " as from Film\g3. Use Case statements1 Selecttitle,2 Case 3 whenLength - Then ' Short' 4 whenLength> - Then 'Long' 5 End 6 asInfo fromFilmwherefilm_id= 1\g4. Randomly select N data1 Select from Order by Rand 5\g5. Find empty values1

dataAfter operating load data, you want to display some diagnostic information for the input data, and when a file is loaded into a table, the information that you see: You can use Show messages to view related diagnostic information.9, skipping data file linesAdding a clause to load data ignore n lines means ignoring the start n rows of the data file, Mysqlimport supports-ignore-lines=n options with the same effect10, specifying the input column orderThe columns and tables in the data file d

First, retrieve data:1. Find rows that meet multiple criteria:SELECT*FromEmpWHEREDEPTNO = 10OR Comm is not NULLOR Sal and DEPTNO = 20;It returns all employees in the department 10 + all employees who receive a commission + 20 of employees with a salary not exceeding $2000.SELECT*FromEmpWHERE(Deptno = 10OR Comm is not NULLOR Sal )and DEPTNO = 20;It only returns to the eligible employees in Department 202. Refer to the alias column in the WHERE clause:SELECT*From(SELECTSal as salary,Comm As Commis

the value of key is the set typec['a'].add (1) c['a'].add (2) c['a'].add (2) c['b'].add (4)Print('the value of key is a dictionary of the list type:', D)Print('the value of key is a dictionary of the set type:'C>>> ================================ RESTART ================================>>>the value of key is a dictionary of list type: Defaultdict (class 'List', {'b': [4],'a': [1, 2, 2]}) The value of key is a dictionary of the set type: Defaultdict (class 'Set', {'b': {4},'a': {1, 2}})>>>One t

Problem: You want to access the element by name to reduce the dependency on the location in the structureSolution: Use the named Tuple collections.namedtuple (). It is a factory method that returns a subclass of the standard tuple type in Python, gives it a type name and the corresponding field name , returns a class that can be instantiated, gives you a defined field name to pass in the value, and so on.The primary purpose of a named tuple is to decouple the code from the location of the elemen

Problem: Want to create a dictionary, which is itself a subset of another dictionarySolution: Use dictionary derivation (dictionary comprehension) to easily solve#example of extracting a subset from a dictionary fromPprintImportpprintprices= { 'ACME': 45.23, 'AAPL': 612.78, 'IBM': 205.55, 'HPQ': 37.20, 'FB': 10.75}#Make A dictionary of pricesP1 = {Key:value forKey, ValueinchPrices.items ()ifValue > 200 }Print("All prices") Pprint (p1)#Make A dictionary of tech stocksTech_names = {'AAPL

If the object is an iterative (any sequence), it can be decomposed, including tuples, lists, strings, files, iterators, and generators, which can be decomposed into separate variables by a simple assignment operation.The only requirement: The total number of variables matches the sequence, otherwise an error will occur;Python 2.7.11 (v2.7.11:6d1b6a68f775, Dec 5, 20:32:19) [MSC v.1500 32bit (Intel)] on Win32type"Copyright","credits" or "license ()" forMore information.>>> p=[4,5]>>>p[4, 5]>>> x,

experimentImportunicodedatan_s1= Unicodedata.normalize ('NFC', s1) n_s2= Unicodedata.normalize ('NFC', S2)Print('n_s1 = = n_s2?', n_s1 = =n_s2)Print('len (n_s1) =', Len (N_S1),'Len (N_S2)', Len (n_s2))Print('*****************************')#(d) Example of normalizing to a decomposed form and stripping accentsT1 = Unicodedata.normalize ('NFD', s1) T2= Unicodedata.normalize ('NFD', S2)Print('T1 = = t2?', t1==T2)Print('len (t1) =', Len (T1),'len (t2) =', Len (T2))Print("'. Join (c forCinchT1if not