# tf.keras.metrics.MeanSquaredError

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|---|---|
| [![](https://www.tensorflow.org/images/tf_logo_32px.png) TensorFlow 1 version](https://www.tensorflow.org/versions/r1.15/api_docs/python/tf/keras/metrics/MeanSquaredError) | [![](https://www.tensorflow.org/images/GitHub-Mark-32px.png) View source on GitHub](https://github.com/tensorflow/tensorflow/blob/v2.0.0/tensorflow/python/keras/metrics.py#L1977-L2001) |

Computes the mean squared error between `y_true` and `y_pred`.

#### View aliases


**Main aliases**

[`tf.metrics.MeanSquaredError`](https://www.tensorflow.org/api_docs/python/tf/keras/metrics/MeanSquaredError)
**Compat aliases for migration**

See
[Migration guide](https://www.tensorflow.org/guide/migrate) for
more details.

[`tf.compat.v1.keras.metrics.MeanSquaredError`](https://www.tensorflow.org/api_docs/python/tf/keras/metrics/MeanSquaredError)

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    tf.keras.metrics.MeanSquaredError(
        name='mean_squared_error', dtype=None
    )

For example, if `y_true` is \[0., 0., 1., 1.\], and `y_pred` is \[1., 1., 1., 0.\]
the mean squared error is 3/4 (0.75).

#### Usage:

    m = tf.keras.metrics.MeanSquaredError()
    m.update_state([0., 0., 1., 1.], [1., 1., 1., 0.])
    print('Final result: ', m.result().numpy())  # Final result: 0.75

Usage with tf.keras API:

    model = tf.keras.Model(inputs, outputs)
    model.compile('sgd', metrics=[tf.keras.metrics.MeanSquaredError()])

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| ## Args ||
|---|---|
| `fn` | The metric function to wrap, with signature `fn(y_true, y_pred, **kwargs)`. |
| `name` | (Optional) string name of the metric instance. |
| `dtype` | (Optional) data type of the metric result. |
| `**kwargs` | The keyword arguments that are passed on to `fn`. |

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## Methods

### `reset_states`

[View source](https://github.com/tensorflow/tensorflow/blob/v2.0.0/tensorflow/python/keras/metrics.py#L203-L209)

    reset_states()

Resets all of the metric state variables.

This function is called between epochs/steps,
when a metric is evaluated during training.

### `result`

[View source](https://github.com/tensorflow/tensorflow/blob/v2.0.0/tensorflow/python/keras/metrics.py#L361-L371)

    result()

Computes and returns the metric value tensor.

Result computation is an idempotent operation that simply calculates the
metric value using the state variables.

### `update_state`

[View source](https://github.com/tensorflow/tensorflow/blob/v2.0.0/tensorflow/python/keras/metrics.py#L558-L583)

    update_state(
        y_true, y_pred, sample_weight=None
    )

Accumulates metric statistics.

`y_true` and `y_pred` should have the same shape.

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| Args ||
|---|---|
| `y_true` | The ground truth values. |
| `y_pred` | The predicted values. |
| `sample_weight` | Optional weighting of each example. Defaults to 1. Can be a `Tensor` whose rank is either 0, or the same rank as `y_true`, and must be broadcastable to `y_true`. |

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| Returns ||
|---|---|
| Update op. ||

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