advanced features

Advanced FeaturesOne, slice1, taking a list or a tuple element is a very common operation, Python provides the slice (Slice) operator, can greatly simplify this operation. For example a list: L = [ " michael , " sarah , " tracy , " bob , "

SliceL=list (range (100))#L列表循环100次>>>l[:10:2]#前10个数, take one per two>>>L[:1]#: No number before default is 0, 0 to 1>>>L[3]#第3个数>>>l[1:2]#1到2>>>L[:-1]#0到 -1,-1 is counted as a count, at this time 0-99>>>L[::-1]#0到: (: = All), (all): to-1, at which

These objects, which can be directly applied to for the loop, are called iterative objects: Iterable .You can use to isinstance() determine whether an object is an Iterable object:>>> from collections import Iterable>>> isinstance([], Iterable)True>>

Explained on the Python website: class slice ( stop ) classslice(Start,Stop[,Step]) Return a Slice object representing the set of indices specified by range (start, stop, step). The start and step arguments default to None. Slice

One, multi-file editing 1. Use Vim to edit multiple filesThere are two forms of editing multiple files, one being a parameter that is used before entering Vim is multiple files. Another is to enter vim and then edit the other files. Create two new

slices(intercept element, can operate list,tuple,string)L = List (range) # [0,1,2,3,...,]l[0:10] = l[:10] # intercept the first 10 numbers [0,1,2,..., 9 ]# l[-10: # 10 numbers after intercept [90,91,92,...,]l[10:20] # intercept elements

Java annotations are jdk1.5 after the new features, for its application is very broad, we first look at the application of annotations, Baidu Encyclopedia said:As we can see, the role of annotations has three aspects:Write Doc documents: This is a

InheritedAccess control:Public: Access is unrestricted. Protected(Protection): Because of inheritance, the same package can be accessed, different packages of the current subclass of the class can be accessed, different packages are not the subclass

Bloggers in the beginning of the comments when the introduction of the online most are directly introduced to the use or function, no actual application scenarios, length and long lead to learning difficult to understand its intentions, and learn to

3. Advanced Features 3.1 slicesL = List (range (100))L[0:3], starting at index 0, until index 3, but excluding index 3If the first index is 0, you can also omit L[:3]also supports taking the reciprocal element l[-2:] Take the reciprocal 2-bit

The previous article briefly describes the simple crud operation of SEQUOIADB, which will cover the features of a slightly higher point.The cluster environment deployed on my machine has not been deleted after the creation of CS with the name "Foo",

Oracle Partition Table1. Partition table:When the amount of data in the table is increasing, the query data slows down and the performance of the application degrades, so you should consider partitioning the table.After the table is partitioned, the

1.oracle OptimizerThe goal of optimization is divided into 4 categories:Choose (optional)Rule (rules-based)First rows (line one)All rows (all rows)Description: Describe the execution plan for SQLObject owner: Objects SchemaObject Name: Objects

1. Three paradigmsCanonical relationship patterns are called paradigms.First paradigm: In a relational model R, if the values in the value range of each attribute of R are the smallest units of data that cannot be re-divided,The R is called the

Demand:The user needs to submit the encrypted data, after the commit needs to decrypt the restore, the restore has two kinds of results: success and Failure!100 users, before 7 days, to determine whether there is committed data, if there is data

First, the businessA transaction is a unit of work that includes a set of data manipulation commands, such as adding, deleting, altering, and so on, which are run as a whole to the system, either running successfully, or all recoveringUsing

MySQL Management user ManagementCREATE USERUsername identified by 'Password'; New UserCREATE USER@’%' Identified by 'Password';GRANT All Privileges on *.* to[Email protected]'%'; Give the corresponding permission flushPrivileges;After you create

The core of functional programming is to program functions as objects.There are two commonly used methods: Map/reduce,filter, where map and filter are built-in methods, and reduce is not, so import-related modules are required.The map receives two

There are some easy-to-ignore immutable types in Python (str,integer,tuple,none) # error demo in []: def Demo (lst=[]): ....: Lst.append ( " hello return LST ....: in [ 46 []: [ " hello " 47: [ " hello , " ] The Liaoche python

__call__ is a fantastic feature, as long as there is a __call__ method in a type, we can use this type of object as a function.Perhaps the more abstract, for example, will understand.In [107]: F = Absin [108]: F ( -10) out[108]: Ten in[109]: dir (f)