Collections is a python built-in collection module that provides a number of useful collection classes.
Namedtuple
We know that a tuple can represent an immutable collection, for example, a two-dimensional coordinate of a point can be expressed as:
>>> p = (1, 2)
However, it is difficult to see (1, 2) that this tuple is used to represent a coordinate.
Defining a class is a fuss, and namedtuple comes in handy:
>>> from
Counter: Processing a dictionary to calculate the number of occurrences of an element
#! /usr/bin/env python#-*-Coding:utf-8-*-# Author:wanghuafengImport Collections#计数器, Counterobj = collections. Counter ("Asdfghjgioccvbnjrtubvg6782bnsh2bn")Print (obj)#取前4个数, sort by from more to lessret = Obj.most_common (4)Print (ret)#obj: Processed dataFor k,v in Obj.items (): Print (k, v)#elements: Raw valu
This module implements a number of classes, which are very flexible. Can be used to replace Python's built-in dict, list, tuple, set type. And some features are not available for these built-in types.On the network to find some information, focusing on the collections module deque, Defaultdict, Counter class1. Class DequeSimilar to Python's built-in list, but it's a two-way list. Can be manipulated at any endHelp (Collections.deque)Class Deque (__buil
I. Collections introduction in the application development of the collection, several interfaces and several subclasses of the set are the most commonly used, but a set of tool class--collections is provided in the JDK, which can be set up directly by this kind of convenient operation.common methods and constants of collections class
No.
Method
This class is a tool class for Java. util. collection.
Field:Public static final list empty_list;Public static final map empty_map;Public static fianl set empty_set;
Method:Boolean addall (collection C, object...)Add all specified elements to the specified collection. You can specify the elements to be added, or specify them as an array. The same as C. addall (arrays. aslist (elements )).
Int binarysearch (list, object key)The binary search algorithm is used to search for a specified list to obt
The source code is written in C + + Builder.Download: Http://files.cnblogs.com/AnyDelphi/Midas_Source.rarhttp://www.cnblogs.com/AnyDelphi/archive/2009/08/13/1545175.html#2264357The previous version of the Midas.dll Delphi 2007 compiled program if the Midas.dll with Delphi 2010 will be wrong.This edition will not be.Http://www.cnblogs.com/AnyDelphi/archive/2009/06/15/1503362.htmlDelphi 2010 in the public Mid
Clojure provides several powerful data structures (collections)I. Types of collections1. VectorEquivalent to an array such as: [2 3 5], ["Ad" "Adas" "Adadsads"]2. ListEquivalent to a linked list, such as: ' (2 3 5), ' ("Ad" "Adas" "Adadsads")Compared to vectors, [] becomes (), and because () the symbol is used for function calls, in order to differentiate, it needs to be preceded by a single quotation mark '3. MapSyntax format such as: {: a 1:b 1}Map
Note that it is not a collection (Interface), but a collection (s cannot be dropped ).The definition of the collections class can be described in one sentence. "This class only provides some static methods (there are actually three constants). These methods can be used to operate on the collection object or return the collection object. "Briefly introduces the methods provided by OSS.The collections class p
A Simple Analysis of the source code of the sort () method in Collections, collectionssort
The sort method code of Collections:
public static Definition of this method: This method is divided into three steps:
(1) Replace list with an object Array
(2) pass this object array to the sort method of the Arrays class (that is to say, the sort of collections act
endindex)Returns a new string that is a substring of this string.
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Char[] ToCharArray ()This string converts to a new character array.
40
String toLowerCase ()Converts all characters in this string to lowercase by using the default locale's rules.
41
String toLowerCase (Locale Locale)Converts all characters in this string to lowercase using the rule given by the locale.
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String toString ()This object (this is already a string.) ) itself is returned.
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String toUpperCase ()Converts all char
Tags: when ... tar explicit IMU one database following BSPMongoDB stores BSON documents, i.e. data records, in collections; The collections in databases. DatabasesIn MongoDB, databases hold collections of documents. To select a database to use, in the MONGO Shell, issue the use statement, as in the following Example Use MyDBCreate a DatabaseIf A database does n
1. Disable RttiThe disabled method is simple, which is to be in the project (DPR file. Delphi2010 The following definition is added before the uses statement of the project file is the Dproj file, but the DPR file is still the default writing code for the project file:{Reduce EXE size by disabling as much of RTTI as possible (Delphi 2009/2010)}{$IF compilerversion >= 21.0}{$WEAKLINKRTTI on}{$RTTI EXPLICIT METHODS ([]) PROPERTIES ([]) fields ([])}{$IFE
Delphi MSComm Real-time serial communicationMSComm controls are rich in properties that are closely related to serial communication, providing a variety of operations on the serial port, which makes serial communication very easy. The MSComm has many control properties, and the commonly used properties are as follows:1). Commport: Sets or returns the serial port number, which defaults to 1.2). Setting: Set or return serial communication parameters in
Fastscript calls the Delphi process:1. Create an event-handling method first: Tfscallmethodevent2.Then call the Tfsscript.addmethod method, the first parameter is the syntax of the Delphi method, and the second parameter is a handle to the tfscallmethodevent link. As in Delphi there is a process for delphifunc, ...Procedure Tform1.delphifunc (s:string; i:integer)
Delphi Attribute Property (suitable for beginners Delphi)
propery in Delphi
Preface:
For Delphi Beginners, have object-oriented knowledge and Java or VC programming experience to read. a common attribute
We can often see this code in the Delphi class: Propert Property att
Python standard library notes (4)-collections module, pythoncollections
This module provides several very useful Python container types1. Container
Name
Function Description
OrderedDict
Dict that maintains the key Insertion Sequence
Namedtuple
Generate a tuple subclass that can access element content by name
Counter
Counter, mainly used to count
Deque
Similar to a list container, you can
collections are created separately, and the document is inserted. Delete > Db.blogs.remove () // Delete all documents in the collection.
> Db.blogs.remove ({"title": "Hello!"}) // deletes the document for the specified condition, and the current statement deletes "title" as "Hello!" The document. Two, set A collection is a set of documents that corresponds to a data table in a relational database. Dynamic mode The collection is in dynamic
Learn the collections of Python every day.The Collections module provides several additional data types based on the built-in data types (dict, list, set, tuple): Chainmap, Counter, deque, Defaultdict, Namedtuple and Ordereddict and so on.ChainmapChainmap is a new feature of Python3, which is used to make multiple maps a new unit (the original map structure still exists, similar to the map being present in
Python learning-collections series, pythoncollections
I. counter (counter) Counter is a supplement to the dictionary type and is used to track the number of occurrences. ps: it has all the functions of the dictionary + its own functions.Example:>>> From collections import Counter>>> C = Counter ('adsassdsdads ')>>> Print (c)Counter ({'A': 4, 'D': 4, 's': 5 })Basic operation method: >>> C = Counter ('abcdeab
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