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mindspore.nn.ConfusionMatrixMetric

class mindspore.nn.ConfusionMatrixMetric(skip_channel=True, metric_name='sensitivity', calculation_method=False, decrease='mean')

The performance matrix of measurement classification model is the model whose output is binary or multi class. The correlation measure of confusion matrix was calculated from the full-scale tensor, and the average values of batch, class channel and iteration were collected. This function supports the calculation of all measures described below: the metric name in parameter metric_name.

If you want to use confusion matrix to calculate, such as ‘PPV’, ‘TPR’, ‘TNR’, use this class. If you only want to calculate confusion matrix, please use ‘mindspore.metrics.ConfusionMatrix’.

Parameters

• skip_channel (bool) – Whether to skip the measurement calculation on the first channel of the predicted output. Default: True.

• metric_name (str) – The names of indicators are in the following range. Of course, you can also set the industry common aliases for these indicators. Choose from: [“sensitivity”, “specificity”, “precision”, “negative predictive value”, “miss rate”, “fall out”, “false discovery rate”, “false omission rate”, “prevalence threshold”, “threat score”, “accuracy”, “balanced accuracy”, “f1 score”, “matthews correlation coefficient”, “fowlkes mallows index”, “informedness”, “markedness”].

• calculation_method (bool) – If true, the measurement for each sample will be calculated first. If not, the confusion matrix of all samples will be accumulated first. As for classification task, ‘calculation_method’ should be False. Default: False.

• decrease (str) – Define the mode to reduce the calculation result of one batch of data. Decrease is used only if calculation_method is True. Default: “mean”. Choose from: [“none”, “mean”, “sum”, “mean_batch”, “sum_batch”, “mean_channel”, “sum_channel”].

Supported Platforms:

Ascend GPU CPU

Examples

>>> metric = ConfusionMatrixMetric(skip_channel=True, metric_name="tpr",
...                                calculation_method=False, decrease="mean")
>>> metric.clear()
>>> x = Tensor(np.array([[[0], [1]], [[1], [0]]]))
>>> y = Tensor(np.array([[[0], [1]], [[0], [1]]]))
>>> metric.update(x, y)
>>> x = Tensor(np.array([[[0], [1]], [[1], [0]]]))
>>> y = Tensor(np.array([[[0], [1]], [[1], [0]]]))
>>> avg_output = metric.eval()
>>> print(avg_output)
[0.5]

clear()

Clears the internal evaluation result.

eval()

Computes confusion matrix metric.

Returns

ndarray, the computed result.

update(*inputs)

Update state with predictions and targets.

inputs:

Input y_pred and y. y_pred and y are a Tensor, a list or an array.

• y_pred (ndarray) - Input data to compute. It must be one-hot format and first dim is batch. The shape of y_pred is $(N,C,...)$ or $(N,...)$. As for classification tasks, y_pred should has the shape [BN] where N is larger than 1. As for segmentation tasks, the shape should be [BNHW] or [BNHWD].

• y (ndarray) - Compute the true value of the measure. It must be one-hot format and first dim is batch. The shape of y is $(N,C,...)$.

Raises

ValueError – If the number of the inputs is not 2.