# Regularizers¶

Regularizers are applied to weights and embeddings without the need for labels or tuples.

Here is an example of a weight regularizer being passed to a loss function.

```
from pytorch_metric_learning import losses, regularizers
R = regularizers.RegularFaceRegularizer()
loss = losses.ArcFaceLoss(margin=30, num_classes=100, embedding_size=128, weight_regularizer=R)
```

## BaseRegularizer¶

```
regularizers.BaseWeightRegularizer(collect_stats = False,
reducer = None,
distance = None)
```

An object that extends this class can be passed as the `embedding_regularizer`

into any loss function. It can also be passed as the `weight_regularizer`

into any class that extends WeightRegularizerMixin.

**Parameters**

**collect_stats**: If True, will collect various statistics that may be useful to analyze during experiments. If False, these computations will be skipped. Want to make`True`

the default? Set the global COLLECT_STATS flag.**reducer**: A reducer object. If None, then the default reducer will be used.**distance**: A distance object. If None, then the default distance will be used.

**Default distance**:

**Default reducer**:

## CenterInvariantRegularizer¶

Deep Face Recognition with Center Invariant Loss

This encourages unnormalized embeddings or weights to all have the same Lp norm.

```
regularizers.CenterInvariantRegularizer(**kwargs)
```

**Default distance**:

`LpDistance(normalize_embeddings=False, p=2, power=1)`

- The distance must be
`LpDistance(normalize_embeddings=False, power=1)`

. However,`p`

can be changed.

- The distance must be

**Default reducer**:

## LpRegularizer¶

This encourages embeddings/weights to have a small Lp norm.

```
regularizers.LpRegularizer(p=2, power=1, **kwargs)
```

**Parameters**

**p**: The type of norm. For example,`p=1`

is the Manhattan distance, and`p=2`

is Euclidean distance.

**Default distance**:

- This regularizer does not use a distance object, so setting this parameter will have no effect.

**Default reducer**:

## RegularFaceRegularizer¶

RegularFace: Deep Face Recognition via Exclusive Regularization

This should be applied as a weight regularizer. It penalizes class vectors that are very close together.

```
regularizers.RegularFaceRegularizer(**kwargs)
```

**Default distance**:

`CosineSimilarity()`

- Only inverted distances are compatible. For example,
`DotProductSimilarity()`

also works.

- Only inverted distances are compatible. For example,

**Default reducer**:

## SparseCentersRegularizer¶

SoftTriple Loss: Deep Metric Learning Without Triplet Sampling

This should be applied as a weight regularizer. It encourages multiple class centers to "merge", i.e. group together.

```
regularizers.SparseCentersRegularizer(num_classes, centers_per_class, **kwargs)
```

**Parameters**

**num_classes**: The number of classes in your training dataset.**centers_per_class**: The number of rows in the weight matrix that correspond to 1 class.

**Default distance**:

`CosineSimilarity()`

- This is the only compatible distance.

**Default reducer**:

## ZeroMeanRegularizer¶

Signal-to-Noise Ratio: A Robust Distance Metric for Deep Metric Learning

```
regularizers.ZeroMeanRegularizer(**kwargs)
```

**Equation**

In this equation, `N`

is the batch size, `M`

is the size of each embedding.

**Default distance**:

- This regularizer does not use a distance object, so setting this parameter will have no effect.

**Default reducer**: