"; if (type! = Null type! = Undefined) {rackType = type;} var addRack = function (element) {if (element amp; pos) {element. setPosition (pos. clone (); element. rackType = rackType; element. setClient ('R _ id', ID); // adds an id to the created cabinet, you can find the corresponding cabinet if (rackType = 'emptyack') {element based on this id. setClient ('bycustom', true);} if (! EmpRack) {element. loaded = true; window. setTimeout (function () {showChart (element) ;}, 500) ;}}; var = '. /em
system. Maintain any action on the data in Namenode, such as creating or deleting files, moving files or directories.4.3 data replication
Because HDFs is designed to reliably and securely store large amounts of data on a set of commodity hardware. Because this hardware is prone to failure, HDFS needs to process data in a way that makes it easy to retrieve data in the event of a hardware failure in one or more systems. HDFS uses data replication as a strategy for providing fault-tolerant functio
HDFS employs a strategy called rack-aware (rack-aware) to improve data reliability, availability, and utilization of network bandwidth. Large HDFs instances typically run on a cluster of computers spanning multiple racks, and communication between two machines on different racks needs to go through the switch. In most cases, the bandwidth between two machines in the same
: Calculates the word frequency vector of a given size from a document, using the hash method, which requires each "document" to be represented by an iterative sequence of objects.
#IDF计算逆文档频率 from
pyspark.mllib.feature import HASHINGTF,IDF
rdd=sc.wholetextfiles ("Data"). Map (Lambda (name , text): Text.split ())
TF=HASHINGTF ()
tfvectors=tf.transform (RDD). Cache ()
#计算
specified or changed later when the file is created. All files in HDFS are written at one time, and there must be only one writer at any time.
Namenode manages data block replication. It periodically receives heartbeat signals and block status reports (Blockreport) from each Datanode in the cluster ). The received heartbeat signal means that the Datanode node is working properly. The block Status Report contains a list of all data blocks on the Datanode.
Copy storage: the first step
The stora
everything is automated, all you need to do is to wait and press the button as prompted.Vi. Introduction of the projectThe project file for Eclipse has just been generated and is now imported. Menu File-import, press "Next", select Project file import finished, project management perspective will appear study node, on the project node, press the right mouse button, open the pop-up menu, select Maven2 menu item, pop-up submenu->enable, click on the Open, In the group ID, enter: study.Opens the s
The full name of the BM25 algorithm is Okapi BM25, which is an extension of the binary independent model and can be used to sort the relevance of the search.The default correlation algorithm for Sphinx is the BM25. You can also choose to use the BM25 algorithm after Lucene4.0 (the default is TF-IDF). If you are using SOLR, just modify the Schema.xml and add the following line to
Class="SOLR." Bm25similarity "/>
BM25 is also based on the w
frequency index" (Inverse Document Frequency, abbreviated as IDF), the mathematical formula is log (D/DW) (W is subscript), D is the total number of pages. Assuming that the number of Chinese pages d=10 billion, stop the word ' "in all pages appear, its occurrence of the number of DW=10 billion, then its idf=log (1 billion/1 billion) =log (1) = 0. "Atomic energy" appears in 2 million pages, that is, dw=200
over it.
The following describes a fixed query and document set, which consists of a query Q and three documents:
Q: "gold silver truck"
D1: "shipment of gold damaged in a fire"
D2: "delivery of silver arrived in a silver truck"
D3: "shipment of gold arrived in a truck"
In this document set, there are three documents, so d = 3. If a term appears only in one of the three documents, the IDF of the term is lg (D/DFI) = lg (3/1) = 0.477. Similarly, if a
article, then, count the Document Frequency (IDF: Inverse Document Frequency) of this word, the number of occurrences in all articles, and divide the total number of articles by this number, that is, the total number of articles divided by the number of articles that appear in the word. From the above definition, we can see that the more important a word is, the more frequent the word appears. The more the word appears only in this article, the less
, finally, evolvesLucene's Practical Scoring Function(The latter is connected directly with Lucene classes and methods ).
Lucene combines Boolean model (BM) of Information Retrieval with Vector Space Model (VSM) of Information Retrieval-documents "approved" by BM are scored by VSM.
In VSM, events and queries are represented as weighted vectors in a multi-dimen1_space, where each distinct index term is a dimension, and weights are Tf-idf values.
VSM
[Elasticsearch] control relevance (2)-The PSF (Practical Scoring Function) in Lucene is upgraded during Query
Practical Scoring Function in Lucene
For Multiterm Queries, Lucene uses the Boolean Model, TF/IDF, and Vector Space Model to combine them, used to collect matching documents and calculate their scores.
Query multiple entries like the following:
GET /my_index/doc/_search{ query: { match: { text: quick fox } }}
Internally, It is r
http://blog.csdn.net/chencheng126/article/details/50070021Refer to this blogger's blog post.principle1. The requirement of text similarity calculation begins with the search engine. The search engine needs to calculate the similarity between the "user query" and the many "pages" crawled down so that the most similar rows are returned to the user in the first place. 2, the main use of the algorithm is Tf-idftf:term frequencyWord frequencyIdf:inverse Document FrequencyReverse Document FrequencyThe
. Test set connected to the WiFi record, remove Bssid, and the feature range connected to the WiFi record, find the same BSSID record count of the top N stores.
TF-IDF Select the first 3 samples.
TF−IDF=TF (Word frequency) ∗idf (inverse document rate) TF-IDF = TF (Word frequency) *
. Before the official launch, the cluster architecture needs to be deployed, and the storage cluster for server power outages, rack power outages and other data high-availability testing, the need for Ceph disaster preparation artifact " fault domain ." There are 24 servers available to build a Ceph storage cluster.Depending on the requirements of the storage management platform and the size of the cluster, you need to implement:Plan the physical envi
Enterprises can perform better rack-level control and audit without the need to comprehensively rebuild data center cabinets or racks. Selecting the attached good test plan can provide the Organization with the actual operations required to ensure that the deployment is successful in preparation for a more complete deployment.
The Data Center Administrator keeps an eye on the security operations of the data center every day. Therefore, in any ca
. In the computer market, there are a variety of network management applications to help network administrators to monitor network connectivity, however, it is noteworthy that most of these applications are working on the network layer, not the physical connection layer, it can only tell the network administrator which logical link is broken, which device can not be connected, However, you cannot tell the administrator the location of the physical error and the cause of the problem, whether the
short text, I will at least give it a 10000-dimensional vector, and this 10000-dimensional vector only used in 3 positions. But with the frequency will appear unfair phenomenon, for example, "we" the word, it appears the frequency is relatively high, that its vector is relatively large, so, word frequency almost do not have to do features, commonly used features such as TF/IDF, mutual information, data gain, χ2 statistics and other methods . Just men
The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion;
products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the
content of the page makes you feel confusing, please write us an email, we will handle the problem
within 5 days after receiving your email.
If you find any instances of plagiarism from the community, please send an email to:
info-contact@alibabacloud.com
and provide relevant evidence. A staff member will contact you within 5 working days.