A recommendation engine tries to predict how much a user will enjoy certain goods (movies, books, songs, etc) and makes recommendations. They are often used by online vendors to suggest new purchases.

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7 views

Obtain Precision and Recall from Click through data

I am trying to build a graph of precision and recall using click data. I have two data sources. First data source has all the user clicked item_ids based on a given query_id. Second data source has ...
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1answer
23 views

Matrix Factorization in Recommender Systems: Multiple solutions?

I have implemented a recommender system for predicting user ratings based on the matrix factorization approach. $$ r_{ui}=μ+b_u+b_i+q_i^T p_u $$ Where q and p are found by mimization of the squared ...
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14 views

How to set preferences for ALS implicit feedback in Collaborative Filtering?

I am trying to use Spark MLib ALS with implicit feedback for collaborative filtering. Input data has only two fields userId and ...
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16 views

Diversity metric for recommender

I have some specific question regarded to diversity metric for recommender. Do I need real the test set to evaluate the diversity metric? I want to understand it basically. For recall and precision ...
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1answer
16 views

Sparse Collaborative Filtering

Does anyone know of any Python code examples for sparse collaborative filtering. Everything I can find revolves around using prebuilt packages (e.g. Mahout, GraphLab), but I'm learning to learn the ...
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33 views

Statistical quality criteria for classifiers and recommenders

I want to know several points regarding the evaluation of data sets. I would like to know which metrics are the best for the evaluation of: a) recommenders and classifiers b) online and offline ...
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1answer
60 views

Low Rank Matrix Factorization Collaborative Filtering - given a sparse set of feature data

I'm playing with a "minor" variation on an otherwise typical low rank matrix factorization collaborative filtering algorithm. I'm mostly following Andrew Ng's description in Coursera's online ML ...
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1answer
14 views

Recommendation Engine With Physical Distance Cutoff

I am looking to develop a recommendation engine for local stores to users. There are approximately 1 million stores in the database and around 1 million users. The 1Mx1M matrix for a user-based ...
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1answer
56 views

Recommenderlab - Getting the user_id out the RealRatingMatrix containing UBCF recommendations

I'm trying to use recommenderlab (with RSTUDIO) to get recommendations.When I'm using UBCF I can't extract the user id out of the realRatingMatrix containing the predictions, although I can do it with ...
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1answer
30 views

Inference on survey results

I have user responses to different types of surveys (e.g. "car survey", "lifestyle survey",...). Most of the users have answered just a very small number of surveys. I would like to predict the ...
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2answers
81 views

Generating recommendations using matrix multiplications

The Mahout In Action (Chapter 6) book contains a recommendation method based on matrix multiplication that uses co-occurrence data (C) in combination with user preferences (U) to generate user ...
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1answer
36 views

How to verify implementation of SVD in Javascript

I have implemented the SVD algortihm for my Node.js project for collaborative filtering of a sparse dataset based on this paper by GroupLens. For calculating the SVD, I am using the package node-svd ...
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36 views

Who will follow who based on tags?

Suppose users in a system like a social network are described by a number of tags. The number of tags can be assumed to be less than 10. Example John: funny musician geek professor Peter: skinny ...
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84 views

How to categorize classifiers and matrix factorization methods?

I have a classification problem which is solved by a variety of methods. Among the methods are unsupervised methods, traditional classifiers and a supervised matrix factorization methods. The problem ...
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33 views

Examples for Attacks on Recommender Systems [closed]

It is known, that recommender systems based on CF can be attacked by injecting fake profiles. Are there any documented, real-world instances of attacks, that are known to the public, i.e. what the ...
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27 views

Positive and negative examples in Rocchio-based recommender

I am exploring the usage of Rocchio-based recommenders in e-commerce and news portals and trying to wrap my head about the concept of a negative rating. Often in e-commerce or news portals there is no ...
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92 views

Incremental SVD Recommendation System

I have the following Octave/Matlab code to compute an SVD-like matrix-decomposition: ...
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13 views

Practical problem computing de k-nearest neighbors in CF?

I’m trying to apply de knn to a very dynamic system where users (like/dislike) items very frequently and new items became available all the time. My question is how often should the algorithm ...
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29 views

What does it mean when Recommender Systems are making recommendations based on “static” data as opposed to “dynamic” recommender systems?

Much of new trends in recommender systems are based on giving recommendations taking into account changing user/services/items preferences or requirements. They mention, traditional recommenders make ...
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25 views

Can collaborative filtering be cast as a classical regression problem?

Having the Netflix challenge in mind: collaborative filtering is typically presented as a matrix dimension reduction. My question is how does the problem relate to classical regression (supervised ...
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3answers
62 views

The role of the bias terms in matrix factorization formulas?

I'm reading about matrix factorization for recommender systems. A basic matrix factorization model would be something like: $(p_i \times q_j ) + b_i + b_j$. That formula would compute the rating for ...
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28 views

The name data sparsity in different applications

I am recently surveying the techniques or algorithms which handle the data sparsity problems in various fields. And I find quite similar name "data sparsity" or "sparse data" is used including the ...
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1answer
26 views

Pairwise compatibility metric

I work at a company that sells clothes, and I've had good results with using cosine similarity to determine which products are "similar" to each other simply based on who owns them. I wanted to take ...
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53 views

Profile variable in collaborative filtering

I'm trying to create a recommendation system based on purchases. I did some tests and I found that for some groups of customers, the recommender works very well, but not for others. How can I ...
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33 views

Propensity in linear models and bilinear regression models

I'm reading this paper about matrix factorization. In the paper they want to combine the features of the nodes in the model (page 6). First they illustrate the simple idea of combining the features of ...
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1answer
53 views

Intuition behind matrix factorization formulations?

I'm reading this paper about matrix factorization. In the paper they propose to use this factorization for the adjacency (or similarity) matrix $G$ using the following formulation: $G = U \Lambda U^T$ ...
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1answer
62 views

Updating SVD in Recommender Systems for change in ratings

I have read that there are projection based methods to accomodate for new user's ratings or for the ratings for a new item in SVD. However, I want to know how to update my feature space for change in ...
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65 views

Difference between Factorization machines and Matrix Factorization?

I came across the term Factorization Machines in recommender systems. I know what Matrix Factorization is for recommender systems but never heard of Factorization Machines. So what's the difference?
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2answers
24 views

Assumption behind few latent features in recommender systems?

I know in recommender systems you have a rating matrix and then you factorize this matrix into two matrices and then learn those matrices with gradient descent. In those matrices we specify the number ...
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2answers
66 views

Meaning of latent features?

I'm trying to understand matrix factorization models for recommender systems and I always read 'latent features', but what does that mean? I know what a feature means for a training dataset but I'm ...
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1answer
52 views

Matrix Factorization Recommendation Systems with Only “Like Ratings”

I'm trying to build a recommendation system, but I only have data on what my user's have "liked" i.e. all non-missing data has the same numeric value. Is it possible for me to using matrix ...
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92 views

Spectral clustering using RBF Kernel function in R

I have extracted user-features and item features in my recommender system using a modified SVD approach built on ALSE (loosely based on Yehuda Koren's paper). I now want to cluster items not directly ...
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23 views

Adding new item to recommender's options? [duplicate]

My shop has 20-items with a recommender system on top which analyses history of purchases and recommends items to buy each time customer returns. Now I want to add an additional item to choose from, ...
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1answer
101 views

What does the parameter $\alpha$ do in the Jaccard method for binaryRatingsMatrix in R recommenderlab?

What is the role of the parameter 'alpha' in the recommenderlab R package's use of Jaccard method in the recommender model for ...
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2answers
133 views

Matrix Factorization algorithms for Recommender Systems

I need to learn about Matrix Factorization for recommender systems, so I downloaded this paper https://datajobs.com/data-science-repo/Recommender-Systems-[Netflix].pdf but I found it too shallow. It ...
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57 views

Stratified Cross-Validation with Collaborative Filtering

My dataset consists of binary preferences ($0$ or $1$) given by users on items like this: User-ID | Item-ID | Preference If a user has not given a preference to an item, then it is not in ...
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45 views

Calculate Weights in pearson Correlation

I have user, movie data for recommendation purpose, where some of the users have rated relatively very fewer movies in compare to other users.I learned that while using Pearson Correlation to ...
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95 views

SVD application for a Boolean sparse Matrix

Basically, I am trying to have a recommender system based on SVD for a Boolean utility matrix. ie If at all some entries are present in the utility matrix, they will be 1 (I made it pseudo-implicit ...
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1answer
243 views

Evaluating matrix factorization algorithms for Netflix

I've been trying to implement Simon Funk's movie recommendation algorithm explained here. I understand how the user and item factors are computed. However the evaluation method is not clearly ...
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84 views

graphical methods / deep architectures for collaborative filtering

Having read "Restricted Boltzmann Machines for Collaborative Filtering" (Salakhutdinov et. al. 2007), I'm wondering if there has been any follow-up work on applying graphical and/or deep architectures ...
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38 views

Evaluating methods for news recommendation from an online experiment

I have data from an experiment that evaluated 3 methods for recommendation of news articles based on their content. The experiment showed an article that the user read and 6 recommendations presented ...
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31 views

Collaborative filtering for real values prediction

I have a data with users performances (scale between 0 to 1) on different tests and would like to test the accuracy of prediction when the data is sparse by removing randomly some records. In other ...
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161 views

What's wrong with my Kernel algorithm (Kernel SVD)?

I have a user-item matrix $A$ as data input, which is a sparse matrix containing a large number of missing values (as zeros). Each row is a user, and each column is an item. Generally, I am conducting ...
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85 views

Item-based collaborative filtering – Can you add demographic information to initial user×item matrix?

I am building an item-based collaborative filter recommendation system. I have a matrix of users and items, which in this case, are products that were either bought or not (i.e., binary: ...
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55 views

How to optimize a SVD recommender regarding number of factors?

I am using R to do recommendation based on pureSVD. It is basically to choose the number of factors and then SVD the user-item matrix and then restore the matrix and provide top-N recommendations for ...
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32 views

Recommending Items based on Multiple Similarity Metrics

I'm building a recommendation systems that suggests items to a user based on items chosen by similar users. It's similar to collaborative filtering, although I am using multiple dimensions to describe ...
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43 views

Recommendation System with Graph Database

Hi I'm looking into creating a recommendation system based on a graph database for an ecommerce website. Basically something like amazon, "if my customer's have bought these products recommend some ...
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34 views

how to compare a user-based collaborative filtering with item-based

Apart from prediction accuracy, what are good evaluation metrics for comparing user-based and item-based collaborative filtering
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27 views

Collaborative Filtering, matrix decomposition, and incorporate various kinds of data

Just about every matrix factorization (e.g., SVD++) has some matrix that includes a n users and m (e.g.,) ratings. Here is my question, how do you include information like demographic information, ...
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44 views

clustering in Item-based collaborative filtering

I read about item-based collaborative filtering in the paper from Sawar et al. I want to apply clustering on items to find the most similar items and then apply the prediction. Is this a good ...