Camille Charbonnier

  1. Sparsity with sign-coherent groups of variables via the cooperative-Lasso.

    Authors: Camille Charbonnier, Julien Chiquet, Yves Grandvalet
    Subjects: Methodology
    Abstract

    We consider the problems of estimation and selection of parameters endowed
    with a known group structure, when the groups are assumed to be sign-coherent,
    that is, gathering either non-negative, non-positive or null parameters. To
    tackle this problem we propose a new penalty that we call the cooperative-Lasso
    penalty. We derive the optimality conditions defining the cooperative-Lasso
    estimate for generalized linear models and propose an efficient active set
    algorithm suited to high-dimensional problems.

  2. Weighted-Lasso for Structured Network Inference from Time Course Data.

    Authors: Camille Charbonnier, Julien Chiquet, Christophe Ambroise
    Subjects: Applications
    Abstract

    We present a weighted-Lasso method to infer the parameters of a first-order
    vector auto-regressive model that describes time course expression data
    generated by directed gene-to-gene regulation networks. These networks are
    assumed to own a priori internal structures of connectivity which drive the
    inference method. Solution to the optimization problem is efficiently computed
    using an active-set algorithm. We illustrate the performance both on synthetic
    data and on the yeast regulation network by analyzing Spellman et al's dataset.

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