view sparse_instance.py @ 460:fda72e944104

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author Joseph Turian <turian@iro.umontreal.ca>
date Tue, 07 Oct 2008 23:07:23 -0400
parents 217c8789284b
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"""
Sparse instances.
Each instance is represented as dict with key dimension.
Dimensions not present in the dict have value 0.
"""

from numpy import zeros

def to_vector(instances, dimensions):
    """
    Convert sparse instances to vectors.
    @type instances: list of sparse instances
    @param dimensions: The number of dimensions in each instance.
    @rtype: numpy matrix (instances x dimensions)
    @todo: Allow this function to convert SINGLE instances (not lists).
    """
    v = zeros((len(instances), dimensions))
    l = len(instances)
    for i in range(l):
        for idx in instances[i].keys():
            v[i][idx] = instances[i][idx]
    return v