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Add option to ignore zero vectors in get_cossim_loss

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Matthw Honnibal 2019-10-06 19:20:54 +02:00
parent cbc2cee2c8
commit 615ebe584f
1 changed files with 11 additions and 3 deletions
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14
spacy/_ml.py
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@ -953,16 +953,24 @@ class CharacterEmbed(Model):
return output, backprop_character_embed
def get_cossim_loss(yh, y):
def get_cossim_loss(yh, y, ignore_zeros=False):
xp = get_array_module(yh)
# Find the zero vectors
if ignore_zeros:
zero_indices = xp.abs(y).sum(axis=1) == 0
# Add a small constant to avoid 0 vectors
yh = yh + 1e-8
y = y + 1e-8
# https://math.stackexchange.com/questions/1923613/partial-derivative-of-cosine-similarity
xp = get_array_module(yh)
norm_yh = xp.linalg.norm(yh, axis=1, keepdims=True)
norm_y = xp.linalg.norm(y, axis=1, keepdims=True)
mul_norms = norm_yh * norm_y
cosine = (yh * y).sum(axis=1, keepdims=True) / mul_norms
d_yh = (y / mul_norms) - (cosine * (yh / norm_yh ** 2))
loss = xp.abs(cosine - 1).sum()
losses = xp.abs(cosine - 1)
if ignore_zeros:
# If the target was a zero vector, don't count it in the loss.
d_yh[zero_indices] = 0
losses[zero_indices] = 0
loss = losses.sum()
return loss, -d_yh