ranking

Learning to Rank之Ranking SVM 简介

由 陌路散爱 提交于 2020-02-10 14:23:34
排序一直是信息检索的核心问题之一，Learning to Rank(简称LTR)用机器学习的思想来解决排序问题(关于Learning to Rank的简介请见我的博文 Learning to Rank简介 )。LTR有三种主要的方法：PointWise，PairWise，ListWise。Ranking SVM算法是PointWise方法的一种，由R. Herbrich等人在2000提出, T. Joachims介绍了一种基于用户Clickthrough数据使用Ranking SVM来进行排序的方法(SIGKDD, 2002)。 1. Ranking SVM的主要思想 Ranking SVM是一种Pointwise的排序算法, 给定查询q, 文档d 1 >d 2 >d 3 (亦即文档d 1 比文档d 2 相关, 文档d 2 比文档d 3 相关, x 1 , x 2 , x 3 分别是d 1 , d 2 , d 3 的特征)。为了使用机器学习的方法进行排序，我们将排序转化为一个分类问题。我们定义新的训练样本, 令x 1 -x 2 , x 1 -x 3 , x 2 -x 3 为正样本,令x 2 -x 1 , x 3 -x 1 , x 3 -x 2 为负样本, 然后训练一个二分类器(支持向量机)来对这些新的训练样本进行分类，如下图所示: 左图中每个椭圆代表一个查询,

PercentRank algorithm in VBA

由 可紊 提交于 2020-02-07 07:11:28
问题 I have found an answer to the question "How to assign a rank number to an array when ties exist" in Php and (looked lilke) C++. I also found a couple of answers about Excel's PercentRank in language I do not know. Can someone help me to do this in VBA? I need to calculate the PercentRank from 12 values in Access fopr a report and I cannot use Excel. Here's an example of what I am after: Per Val %Rank 01 80 0.82 02 74 0.45 03 88 1.00 04 60 0.00 05 86 0.91 06 68 0.18 07 64 0.09 08 78 0.64 09 76

Get current rank using mysql

由 点点圈 提交于 2020-01-25 01:58:08
问题 i've got this query to get the rank of rows, order by some field SET @rank=0; SELECT @rank:=@rank+1 AS rank, id, ammopacks FROM users GROUP BY id ORDER BY ammopacks DESC; How about getting the rank of "x" id, without ranking all them before? I don't want to know all users rank, just only one id. Is it possible? Thanks in advance 回答1: You can do this with a subquery: select count(*) as rank from users u where u.ammopacks >= (select ammopacks from users u2 where u2.id = x) This doesn't do

ranking entries in mysql table

由 自古美人都是妖i 提交于 2020-01-22 09:57:05
问题 I have a MySQL table with many rows. The table has a popularity column. If I sort by popularity, I can get the rank of each item. Is it possible to retrieve the rank of a particular item without sorting the entire table? I don't think so. Is that correct? An alternative would be to create a new column for storing rank, sort the entire table, and then loop through all the rows and update the rank. That is extremely inefficient. Is there perhaps a way to do this in a single query? 回答1: There is

Duplicates removal using Group By, Rank, Row_Number

由 丶灬走出姿态 提交于 2020-01-16 09:49:28
问题 I have two tables. One is CustomerOrders and the other is OrderCustomerRef - lookup table. Both tables have one-to-many relationship - one customer may be associated with multiple orders. CustomerOrders table has duplicate Customers (same LName, FName, Email). But they have different Cust_IDs. I need to merge all duplicate contacts in the base Customer table (one-to-one). (this table is not shown here). Step 1: Need to find out which Cust_ID should be merged into which corresponding duplicate

一文理解Ranking Loss/Contrastive Loss/Margin Loss/Triplet Loss/Hinge Loss

由 旧街凉风 提交于 2020-01-16 00:42:48
一文理解Ranking Loss/Contrastive Loss/Margin Loss/Triplet Loss/Hinge Loss 翻译自FesianXu， 2020/1/13, 原文链接 https://gombru.github.io/2019/04/03/ranking_loss/ 前言 ranking loss在很多不同的领域，任务和神经网络结构（比如siamese net或者Triplet net）中被广泛地应用。其广泛应用但缺乏对其命名标准化导致了其拥有很多其他别名，比如对比损失Contrastive loss，边缘损失Margin loss，铰链损失hinge loss和我们常见的三元组损失Triplet loss等。 本文翻译自https://gombru.github.io/2019/04/03/ranking_loss/，如有谬误，请提出指正，谢谢。 ranking loss函数：度量学习 不像其他损失函数，比如交叉熵损失和均方差损失函数，这些损失的设计目的就是学习如何去直接地预测标签，或者回归出一个值，又或者是在给定输入的情况下预测出一组值，这是在传统的分类任务和回归任务中常用的。ranking loss的目的是去预测输入样本之间的相对距离。这个任务经常也被称之为 度量学习 (metric learning)。 在训练集上使用ranking

how to rank array's index in PHP

由 三世轮回 提交于 2020-01-15 05:46:21
问题 I need rank in my system. I have an array $arr = array(120,26,38,96,22); . I need to rank the index inside without changing their position. The output I need is something like: 120 is rank 1, 26 is rank 4, 38 is rank 3, 96 is rank 2, 22 is rank 5 I've tried this, but all ranked as rank 1: <?php $arr = array(120,26,38,96,22); $rank = 0; $score=false; $rows = 0; foreach($arr as $sort){ $rows++; if($score != $arr){ $score = $arr; $rank = $rows; }echo $sort.' is rank '.$rank.'</br>'; } ?> And

SQL - select distinct records in one field with highest records from another field

由 人走茶凉 提交于 2020-01-13 03:57:11
问题 In a scenario where I have a table like so: int id (PK) int staff_id int skill_id bit mainskill I want to select only ONE record for each staff member (represented by staff_id) listing their main skill as represented by a (1) in mainskill. If no main skill is present, I want to return any of the skill records for that staff member. For example: id staff_id skill_id mainskill 1 1 24 1 2 1 55 0 3 1 7 0 4 4 24 0 5 4 18 0 6 6 3 0 7 6 18 1 The query should return: id staff_id skill_id mainskill 1

Using a mysql-variable in java (for a ranking-query)

由 回眸只為那壹抹淺笑 提交于 2020-01-06 08:29:27
问题 I'd like to create a ranking in a MySQL-Table for Users, sorted by their score. I already found a nice Query for that, but this Query is only working with phpmyadmin, not in java... I got the following MySQL-Query which works well in phpmyadmin to create a Ranking: SET @r=0; UPDATE `hg_stats` SET `stats_rank`= @r:= (@r+1) ORDER BY `stats_score` DESC; In Java: try { preparedStatement = connection.prepareStatement("SET @r=0; UPDATE `hg_stats` SET `stats_rank`= @r:= (@r+1) ORDER BY `stats_score`

Solr remove ranking or modify ranking feature

由 佐手、 提交于 2020-01-06 05:36:09
问题 I want to optimise my Solr engine. I don't want ranked results. I just want all docs which match my query is there any way I can remove it . So that retrieving data improves ? 回答1: There is no need to remove relevancy ranking to achieve what you want. By setting the rows parameter to the same number as the numfound you will retrieve all documents matching your query. http://url-to-some-server/solr/select?q=somequery&rows=200 if you want the documents sorted in another way than by relevance,
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