Table Of Contents
Table Of Contents

NegativeLogLikelihood

class mxnet.metric.NegativeLogLikelihood(eps=1e-12, name='nll-loss', output_names=None, label_names=None)[source]

Computes the negative log-likelihood loss.

The negative log-likelihoodd loss over a batch of sample size \(N\) is given by

\[-\sum_{n=1}^{N}\sum_{k=1}^{K}t_{nk}\log (y_{nk}),\]

where \(K\) is the number of classes, \(y_{nk}\) is the prediceted probability for \(k\)-th class for \(n\)-th sample. \(t_{nk}=1\) if and only if sample \(n\) belongs to class \(k\).

Parameters:
  • eps (float) – Negative log-likelihood loss is undefined for predicted value is 0, so predicted values are added with the small constant.
  • name (str) – Name of this metric instance for display.
  • output_names (list of str, or None) – Name of predictions that should be used when updating with update_dict. By default include all predictions.
  • label_names (list of str, or None) – Name of labels that should be used when updating with update_dict. By default include all labels.

Examples

>>> predicts = [mx.nd.array([[0.3, 0.7], [0, 1.], [0.4, 0.6]])]
>>> labels   = [mx.nd.array([0, 1, 1])]
>>> nll_loss = mx.metric.NegativeLogLikelihood()
>>> nll_loss.update(labels, predicts)
>>> print nll_loss.get()
('nll-loss', 0.57159948348999023)
__init__(eps=1e-12, name='nll-loss', output_names=None, label_names=None)[source]

Initialize self. See help(type(self)) for accurate signature.

Methods

__init__([eps, name, output_names, label_names]) Initialize self.
get() Gets the current evaluation result.
get_config() Save configurations of metric.
get_name_value() Returns zipped name and value pairs.
reset() Resets the internal evaluation result to initial state.
update(labels, preds) Updates the internal evaluation result.
update_dict(label, pred) Update the internal evaluation with named label and pred