1,721,121 research outputs found
RecTime: Real-Time recommender system for online broadcasting
No full textRecommender systems for online broadcasting become important as the number of channels has been increasing. In online broadcasting, to provide accurate recommendation, recommender systems should take time factors as well as users' condition into account, but the conventional systems don't. This paper proposes a real-time recommender system for online broadcasting called RecTime which considers time factors and preferences simultaneously. Specifically, RecTime employs a 4-d tensor factorization, which considers two more dimensions regarding the time factors, while typical collaboriative filtering methods only consider two dimensions, users and items. By factorizing the 4-d tensor, the system naturally identifies the recommendation time and the items at the same time. In our experiments on real-world data, RecTime properly models users' watching patterns and significantly outperforms previous methods in terms of the accuracy on the recommendation time as well as the items. (C) 2017 Elsevier Inc. All rights reserved.1141sciescopu
OCAM: Out-of-core coordinate descent algorithm for matrix completion
No full textRecently, there are increasing reports that most datasets can be actually stored in disks of a single off-the-shelf workstation, and utilizing out-of-core methods is much cheaper and even faster than using a distributed system. For these reasons, out-of-core methods have been actively developed for machine learning and graph processing. The goal of this paper is to develop an efficient out-of-core matrix completion method based on coordinate descent approach. Coordinate descent-based matrix completion (CD-MC) has two strong benefits over other approaches: 1) it does not involve heavy computation such as matrix inversion and 2) it does not have step-size hyper-parameters, which reduces the effort for hyper-parameter tuning. Existing solutions for CD-MC have been developed and analyzed for in-memory setting and they do not take disk-I/O into account. Thus, we propose OCAM, a novel out-of-core coordinate descent algorithm for matrix completion. Our evaluation results and cost analyses provide sound evidences supporting the following benefits of OCAM: (1) Scalability - OCAM is a truly scalable out-of-core method and thus decomposes a matrix larger than the size of memory, (2) Efficiency - OCAM is super fast. OCAM is up to 10x faster than the state-of-the-art out-of-core method, and up to 4.1x faster than a competing distributed method when using eight machines. The source code of OCAM will be available for reproducibility. (C) 2019 Published by Elsevier Inc.11Nsciescopu
Harmonized representation learning on dynamic EHR graphs
No full textWith the rise of deep learning, several recent studies on deep learning-based methods for electronic health records (EHR) successfully address real-world clinical challenges by utilizing effective representations of medical entities. However, existing EHR representation learning methods that focus on only diagnosis codes have limited clinical value, because such structured codes cannot concretely describe patients' medical conditions, and furthermore, some of the codes assigned to patients contain errors and inconsistency; this is one of the well-known caveats in the EHR. To overcome this limitation, in this paper, we fuse more detailed and accurate information in the form of natural language provided by unstructured clinical data sources (i.e., clinical notes). We propose HORDE, a unified graph representation learning framework to embed heterogeneous medical entities into a harmonized space for further downstream analyses as well as robustness to inconsistency in structured codes. Our extensive experiments demonstrate that HORDE significantly improves the performances of conventional clinical tasks such as subsequent code prediction and patient severity classification compared to existing methods, and also show the promising results of a novel EHR analysis about the consistency of each diagnosis code assignment.11Nscopu
An encoder-decoder switch network for purchase prediction
No full textUsers in e-commerce tend to click on items of their interest. Eventually, the more frequently an item is clicked by a user, the more likely the item will be purchased by the user after all. However, what if a user clicked on every item only once before purchases? This is a frequently observed user behavior in reality, but predicting which of the clicked items will be purchased is a challenging task. This paper addresses a practical yet widely overlooked task of predicting purchase items within a non-duplicate click session, i.e., a session in which every item is clicked only once. We propose an encoder-decoder neural architecture to simultaneously model users' click and purchase behaviors. The encoder captures a user's intent contained in the user's click session, and the decoder, which is equipped with pointer network via a switch gate, extracts relevant clicked items for future purchase candidates. To the best of our knowledge, our work is the first to address the task of purchase prediction given non-duplicate click sessions. Experiments demonstrate that our proposed method outperforms the state-of-the-art purchase prediction methods by up to 18% in terms of recall. (C) 2019 Elsevier B.V. All rights reserved.1
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