Allow additional parameters in compute_mat

[celsofranssa]

Hello,

The following code snippet shows a custom distance function that scales the simple dot distance with the rewards associated with each embedding.

import torch
from pytorch_metric_learning.distances import BaseDistance


class CustomDistance(BaseDistance):

    def __init__(self, params):
        super().__init__(params, is_inverted=True)
        assert self.is_inverted
        # dict of ref_emb rewards
        self.rewards = params.rewards

    def compute_mat(self, embeddings_ids, embeddings, ref_emb_ids, ref_emb):
        mat =  20 * torch.einsum("ab,cb->ac", embeddings, ref_emb)
        for col, ref_emb_idx in ref_emb_ids.items():
            mat[:, col] *= self.rewards[ref_emb_idx]

However, the loss function call of mat = self.distance(embeddings, ref_emb) not allows calling the overridden method compute_mat(self, embeddings_ids, embeddings, ref_emb_ids, ref_emb) (containing the embeddings and ref_emb ids) required to get the embedding reward and scale the corresponding distance value.

Is there a workaround?

Thank you.

[celsofranssa]

Hello @KevinMusgrave
Do you have any suggestions here?

[KevinMusgrave]

Would overriding the forward method work?

pytorch-metric-learning/src/pytorch_metric_learning/distances/base_distance.py

Line 26 in adfb78c

def forward(self, query_emb, ref_emb=None):

I guess it depends where embeddings_ids and ref_emb_ids is coming from.

[KevinMusgrave]

Or do you mean you need to change the mat = self.distance(embeddings, ref_emb) in the loss function?

[celsofranssa]

Or do you mean you need to change the mat = self.distance(embeddings, ref_emb) in the loss function?

Would overriding the forward method work?

Exactly @KevinMusgrave,

I am already using the very nice NTXentLoss. Recently, I discovered that scaling the simple dot distance with the rewards associated with each embedding is beneficial for my research task. At this point, I need to access the embedding identifier because each embedding has its associated reward.

[KevinMusgrave]

I see, so you also need to modify NTXentLoss to take in those ids?

[celsofranssa]

I see, so you also need to modify NTXentLoss to take in those ids?

If there is no other overriding approach, yes.

[KevinMusgrave]

Yeah I don't think there's another approach. The only other way would be to set some attribute of your custom distance object before computing the loss.

dist_fn = CustomDistance()
loss_fn = NTXentLoss(distance=dist_fn)

...
dist_fn.curr_ref_ids = ref_ids
loss = loss_fn(...)

# inside dist_fn refer to self.curr_ref_ids

[celsofranssa]

Yeah I don't think there's another approach. The only other way would be to set some attribute of your custom distance object before computing the loss.

dist_fn = CustomDistance()
loss_fn = NTXentLoss(distance=dist_fn)

...
dist_fn.curr_ref_ids = ref_ids
loss = loss_fn(...)

# inside dist_fn refer to self.curr_ref_ids

I see. For a feature release, it would be great if the mat = self.distance(embeddings, ref_emb) function accepts additional parameters to leverage some custom distance implementations.

[celsofranssa]

Hello,

Is there any progress here?

[KevinMusgrave]

Sorry, no progress yet