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If there are
only two classes, we typically use a single real
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valued output
that has target values of 1 for the “positive”
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class and 0 (or
sometimes -1) for the other class
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For
probabilistic class labels the target value can then
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be
the probability of the positive class and the output of
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the
model can also represent the probability the model
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gives
to the positive class.
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If there are N
classes we often use a vector of N target
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values
containing a single 1 for the correct class and zeros
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elsewhere.
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For
probabilistic labels we can then use a vector of
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class
probabilities as the target vector.
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