Sentence Transformers (S-BERT) model basic understanding with python
Summary
TLDRUn résumé captivant fournissant un bref aperçu précis du script, engageant les utilisateurs et attisant leur intérêt.
Takeaways
- 🤖 Le Sentence Transformer est un cadre Python pour obtenir des embeddings de pointe pour des phrases, textes et images.
- 🔢 Les embeddings transforment des données textuelles ou visuelles en nombres que les modèles d'apprentissage automatique peuvent comprendre.
- 🛠 Il existe plusieurs méthodes pour encoder des données textuelles en nombres, comme TF-IDF, Count Vectorizer et Word2Vec.
- 📊 Un Sentence Transformer utilise des réseaux siamois pour générer des embeddings à partir de paires de phrases.
- 🤔 Les embeddings sont généralement de taille 100x768, représentant la longueur maximale de la séquence par la dimension de l'embedding.
- 🏊♂️ Le pooling moyen est utilisé pour réduire la dimensionnalité des embeddings et obtenir un output agrégé.
- 🛠 Pour entraîner un Sentence Transformer, il faut optimiser les poids du modèle en fonction de la similarité des phrases d'entrée.
- 📚 Utiliser un Sentence Transformer pré-entraîné permet de convertir facilement des textes en embeddings pour diverses tâches NLP.
- 🔧 Pour entraîner son propre Sentence Transformer, il est nécessaire de disposer d'un ensemble de données de paires de phrases similaires.
- 🔄 Les embeddings générés par un modèle personnalisé peuvent différer de ceux d'un modèle pré-entraîné, offrant une adaptabilité aux tâches spécifiques.
Q & A
Qu'est-ce qu'un Sentence Transformer ?
-Un Sentence Transformer est un framework Python conçu pour fournir des embeddings de pointe pour les phrases, le texte et les images, permettant de convertir ces données en nombres que les modèles de machine learning peuvent comprendre.
Pourquoi avons-nous besoin de transformer les phrases en embeddings ?
-Nous avons besoin de transformer les phrases en embeddings car les modèles de machine learning ne peuvent pas traiter directement les données textuelles ou les images. Les embeddings convertissent ces données en nombres, rendant possible leur traitement par ces modèles.
Quels sont les différents types d'embeddings disponibles ?
-Il existe plusieurs types d'embeddings, notamment TF-IDF, Count Vectorizer, Word2Vec, et des vectorisateurs de phrases. Ces méthodes permettent de coder les données textuelles en formats numériques.
Comment fonctionne l'entraînement d'un Sentence Transformer ?
-L'entraînement d'un Sentence Transformer utilise un réseau siamois avec deux modèles BERT, en passant des paires de phrases à ces modèles pour générer des embeddings. Ces embeddings sont ensuite soumis à un processus de pooling et optimisés pour rapprocher les scores des phrases similaires.
Quelle est la taille typique des embeddings générés par un Sentence Transformer ?
-La taille typique des embeddings générés par un Sentence Transformer est de 768 dimensions, bien que cela puisse varier en fonction de la configuration spécifique du modèle.
Comment peut-on utiliser un Sentence Transformer pré-entraîné ?
-Pour utiliser un Sentence Transformer pré-entraîné, il suffit d'installer le framework, télécharger un modèle pré-entraîné et passer des phrases au modèle pour obtenir leurs embeddings, qui peuvent ensuite être utilisés pour diverses tâches de NLP.
Quels sont les avantages de l'utilisation de Sentence Transformers pour les embeddings ?
-Les avantages incluent la capacité de gérer des données textuelles complexes, fournir des représentations riches et nuancées des données d'entrée, et améliorer les performances des modèles de machine learning sur diverses tâches de NLP.
Peut-on entraîner son propre Sentence Transformer ?
-Oui, il est possible d'entraîner son propre Sentence Transformer à partir de zéro en utilisant des paires de phrases similaires comme données d'entraînement, ce qui sera couvert plus en détail dans une discussion future.
Quel est le processus pour obtenir les embeddings à partir d'un modèle Sentence Transformer ?
-Le processus implique de passer des phrases au modèle Sentence Transformer à l'aide de la méthode 'encode', qui retourne les embeddings correspondants pour chaque phrase.
Comment les embeddings de Sentence Transformer sont-ils utilisés dans des tâches downstream ?
-Les embeddings de Sentence Transformer peuvent être utilisés dans des tâches downstream telles que l'analyse de sentiments, la classification, la régression, et bien d'autres, en fournissant une représentation numérique riche pour l'entrée textuelle.
Outlines
📘 Introduction aux Sentence Transformers
Ce segment introduit les Sentence Transformers, expliquant leur utilité en tant que cadre Python pour générer des embeddings de pointe pour des phrases, textes et images. L'explication commence par définir ce que sont les embeddings, nécessaires pour convertir des données textuelles ou visuelles en numériques afin de les rendre compréhensibles pour les modèles d'apprentissage automatique. Plusieurs types d'embeddings sont brièvement mentionnés, tels que TF-IDF, Count Vectorizer, Word2Vec, et Sentence Vectorizer, pour illustrer différentes méthodes de conversion du texte en nombres. L'accent est mis sur la profondeur de l'explication plutôt que sur la largeur des applications possibles des Sentence Transformers.
🔍 Formation d'un Sentence Transformer
Dans cette partie, le processus de formation d'un Sentence Transformer est décrit en détail. Il est expliqué que contrairement aux méthodes traditionnelles, la formation implique l'utilisation d'un réseau basé sur Siamese avec des paires de phrases fournies à deux modèles BERT distincts pour générer des embeddings. La taille standard des embeddings est discutée, avec un focus sur le processus de pooling pour condenser les embeddings en une sortie moyenne utilisée pour comparer la similarité des phrases. Cette section met en lumière le mécanisme derrière la formation des modèles en utilisant des exemples concrets pour faciliter la compréhension.
🚀 Utilisation et Formation Personnalisée des Sentence Transformers
Ce dernier segment aborde la manière d'utiliser les Sentence Transformers pré-entraînés pour convertir les phrases en embeddings, et comment ces embeddings peuvent être utilisés dans diverses tâches de traitement de langage naturel telles que l'analyse de sentiments et la classification. L'installation du package nécessaire et l'exemple d'encodage de phrases sont présentés pour illustrer le processus. Ensuite, la discussion se tourne vers la formation personnalisée de Sentence Transformers à l'aide de jeux de données de paires de phrases similaires, soulignant la flexibilité et l'adaptabilité des modèles pour des besoins spécifiques. La vidéo se termine sur une invitation aux spectateurs à suggérer des sujets pour de futures discussions, soulignant l'engagement envers l'éducation et le partage de connaissances.
Mindmap
Keywords
💡embeddings
💡modèle pré-entraîné
💡phrase
💡réseau siamois
💡similitude
💡classification
💡régression
💡pooling
💡dimension
💡entraînement
Highlights
Sentence transformer is a Python framework for state-of-the-art sentence, text and image embeddings.
Embeddings convert textual data, images or sentences into numbers that machine learning models can understand.
Sentence transformer uses a siamese network architecture with two BERT models.
Sentences are passed to the BERT models to generate embeddings.
If sentences are similar, a close score is given. If dissimilar, a 0 score is given.
The model is optimized to understand similarity and dissimilarity between sentences.
Pooling takes the average of the embeddings to create a pooled output vector.
To use sentence transformers, install with pip and load a pre-trained model.
Pass sentences to the model to encode them into embeddings.
Use embeddings for downstream NLP tasks like classification and sentiment analysis.
Can create custom sentence transformer model trained on similar sentence pairs.
Custom model creates different embeddings compared to pre-trained models.
Want to cover training custom model in next video.
Let me know in comments if you want other NLP topics covered.
See you in next video!
Transcripts
today uh we will be talking about
sentence transformer
so
what is the sentence transformer how it
works
why we need to have a sentence
transformer
all the things we will try to see in
today's discussion
so stay
focused because
this is the first time
that
i'm going to cover this and i will go a
bit in detail i don't want to cover the
breath
but i want to focus more on the depth
part
so we will see
how it works as well as how to train a
sentence transformer for your own use
how can we use pre-trained sentence
transformer all the things we will try
to cover in this
video
so
let's start with the with the first
thing first
what is a sentence transformer
so by definition if you will see a
sentence transformer is a python
framework we know what is the framework
right we will try to
we will try to go in detail
in whatever we are saying okay it's a
python framework
for state of the art sentence text and
image embeddings
to
embed our
sentences text or images we use this
framework
but
then the next question comes what is the
embedding
because a term came here as embeddings
what is the embedding so you might be
aware that
to train any machine learning model we
can't directly feed
the textual data or images
or
or
your sentences to it
you have to convert these textual data
images or sentences
into some type of numbers that a model
can understand
any machine learning model
will work only on numbers
so once you convert that textual data to
numbers then you can feed it to the
model
so that's why we need to come up with
there are multiple techniques how you
can encode your data
from
text to
[Music]
embeddings text to different formats
text to numbers you can see
so embedding
is coming from there so basically you
want to translate your textual
information into some type of numbers
you can consider it this way
now the next question is
what are the different types of
embeddings that we have
we are actually having multiple types of
embeddings if you will try to think and
type
in a textual domain
in nlp
so one is the
kind of i don't want to go much in
detail but uh
to understand it
uh
based on like this is the example that
we are having
sentence was he goes to school
okay this sentence we can't directly
feed to the model then we have to
convert this sentence into some
embeddings
there are embeddings like tf idf
vectorization count vectorizer
or word to whack
or sentence vectorizer like we are
we are coming to that
so there are multiple ways we can encode
it
so but the easiest way
could be
like we want to represent it in some
kind of vector format
now
so we we got it clearly right so
sentence transformer is nothing but it's
a kind of
python framework that will give us
the state of the art sentence text or
image embeddings okay
now the next question that comes to our
mind
is basically
how to train a sentence transformer
so training the sentence transformer is
different
from our traditional uh
way of dealing the things
so let's go to the paper where they
mention that how to train a sentence
transformer let me quickly go to the
paper
so here
as you can see
we will be passing
pair of sentences to the model
so it's a siamese based network
we will be having two but models
we will pass sentence a and sentence b
to these models
what once we will pass these
these sentences to these models they
will generate embeddings
okay
if our maximum
length
in this case is
let's take for example 100
then the embedding size
will be 100 cross 768 if we consider the
768 embeddings okay
but usually gives us the 768 embeddings
so we will be getting 100 cross 768
embeddings out of it
here also we will be getting 100 cross
768 but the next question that you can
ask is basically
if
the sentence size
is of two tokens or three tokens
so what will be the embedding size in
that case so again it will be 100 cross
768 because you have mentioned
that your maximum sequence length is 768
right so whenever you will not be having
any tokens it will consider them as zero
whenever you will be having some tokens
we will be having embeddings related to
that
clear
now once we have 100 crores 768
embeddings here 100 quotes
768 embeddings here we will apply
pooling on top of that
pooling is nothing but it's just
will take the average of that embeddings
for example let's let's come back here
and try to understand it in more detail
for example we are having a sentence
he
goes
to
school
okay
whatever birth model will do it will
give us
embeddings related to this he
okay so let's take an example rather
than
giving 768 embeddings for simplicity i'm
taking
embedding as
five
uh dimension embeddings or three
dimension embedding for
simplicity so it will be something like
one two one one two three
four goes also he goes to school it will
try to give it will first organize and
then give us the embedding so let's say
some two three and four
similarly for two
it will give him bearings as
to five and
six
for school also
embeddings like
six seven and eight
so
the final size of these embeddings will
be if we are considering maximum
sequence length as 4
then it will be of size 4
uh
4
cross 5
right
right
in the pooling layer
what we do in the pooling
we have different type of pooling like
mint pooling max pooling or average
pooling we generally take
average pooling in case of sentence
transformer
so we take this dimension
take the average of it so 2 plus 1 3
plus 2
5 plus 6
so it will be 6 by
6
by 4
6 by 4
11 by four sorry
eleven by four and then
seventeen by four
then your
twenty one by 4
this will be your pooled output we used
to call it pooled output so what will be
the dimension of this one this pooled
output
the dimension will be
1 by
3
sorry here also we will be having
4 cross 3
so you are just taking all the
dimensions
zero dimension one dimension two
dimension and taking the average of it
and this will be our pooled output
okay let's back to the paper go back to
the paper that we were discussing
then we will be having this pooled
output as u vector and v vector
then what we do we try to optimize it
based on
the kind of loss function that we are
choosing but
but consider it this way that if both
the sentences are pretty much similar
then we will give a closer score
okay in that case
what will happen that
this score will be one
if both the sentences are dissimilar we
will give it as a zero
and we will try to optimize the weights
of these bird models
based on that
okay
so it will try to understand that these
two sentences are similar and these two
sentences are dissimilar that's what we
are going to train this model on
okay
i hope that is clear
now that part is clear how can we train
the sentence transformer
now let's go to the next part
that is basically how to use a sentence
transformer what we need to do
to use a sentence transformer
so to use a sentence transformer we
first
we need to understand where we can use
it
second
uh how can we basically
train our own sentence transformer
okay to use a sentence transformer
we let me go to the
notebook here
you have to
install it
so you can simply do pip install
nsu sentence transformer and it will
install it for you
now
from the sentence transformers library
you can
take a pre-trained model that model like
i just discussed was also
been trained
on similar sentences pairs
okay and they have put it here in
sentence transformer
you can check it from hugging page also
okay
once the model is downloaded
then
we will be passing some sentences to
these models
sentence a sentence b sentence c and
what this model will give us it will
give us the embeddings related to these
particular sentences
okay
so if we'll just model dot we'll do
model dot in code and pass all the
sentences then we will get the
embeddings
and those embeddings we can see sentence
by sentence okay
so for example
this was our first sentence this
framework generate embeddings for each
input sentence
and the embedding that we are getting is
this one what will be the size of
embedding the size of embedding will be
768
correct
yeah then we can go to the next sentence
this is my next sentence
and this is the embedding that it will
be generating
okay so whenever you try to
convert a particular text
a paragraph
or any kind of
textual information
then you can use these kind of
pre-trained models to convert it into
embeddings and feed it to your model to
further
downstream tasks like sentiment analysis
like
classification
regression anything you want to do
okay
so i hope that is clear how can we use a
pre-trained model
now
the next thing is basically how can we
the next thing is basically how can
we train our own sentence transformer
so for that we used to
have some similar
sentences pairs data set available
and we can directly train
a model sentence transformer model from
scratch we will try to cover that part
in the next
discussion
also uh we will try to cover that um
taking some simple data
how can we train our
sentence transformer model
and
how the embeddings will be different
from the pre-trained models once
okay
so i hope you like the video if you like
it just
mention in the comment if there is any
topic that you want me to cover in
[Music]
text or nlp then definitely let me know
thanks thanks for your time
see you in the next video bye
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