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annotate sparse_instance.py @ 472:69c800af1370

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changed weight initialization for logistic regression
author James Bergstra <bergstrj@iro.umontreal.ca>
date Thu, 23 Oct 2008 13:26:42 -0400
parents 217c8789284b
children
rev   line source
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Joseph Turian <turian@gmail.com>
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1 """
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2 Sparse instances.
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3 Each instance is represented as dict with key dimension.
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4 Dimensions not present in the dict have value 0.
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Joseph Turian <turian@gmail.com>
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5 """
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6
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7 from numpy import zeros
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8
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9 def to_vector(instances, dimensions):
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10 """
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11 Convert sparse instances to vectors.
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12 @type instances: list of sparse instances
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13 @param dimensions: The number of dimensions in each instance.
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14 @rtype: numpy matrix (instances x dimensions)
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15 @todo: Allow this function to convert SINGLE instances (not lists).
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16 """
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17 v = zeros((len(instances), dimensions))
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18 l = len(instances)
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19 for i in range(l):
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20 for idx in instances[i].keys():
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21 v[i][idx] = instances[i][idx]
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22 return v