GPT vs BERT: Which is Higher?. Evaluating two large-language fashions… | by Pranay Dave | Jun, 2023

Evaluating two large-language fashions: Method and instance

Picture created by DALLE and PPT by writer (

The rise in reputation of generative AI has additionally led to a rise within the variety of giant language fashions. On this story, I’ll make a comparability between two of them: GPT and BERT. GPT (Generative Pre-trained Transformer) is developed by OpenAI and is predicated on decoder-only structure. Alternatively, BERT (Bidirectional Encoder Representations from Transformers) is developed by Google and is an encoder-only pre-trained mannequin

Each are technically completely different, however, they’ve an analogous goal — to carry out pure language processing duties. Many articles examine the 2 from a technical perspective. Nevertheless, on this story, I’d examine them based mostly on the standard of their goal, which is pure language processing.

Tips on how to examine two utterly completely different technical architectures? GPT is decoder-only structure and BERT is encoder-only structure. So a technical comparability of a decoder-only vs encoder-only structure is like evaluating Ferrari vs Lamborgini — each are nice however with utterly completely different expertise beneath the chassis.

Nevertheless, we are able to make a comparability based mostly on the standard of a standard pure language activity that each can do — which is the era of embeddings. The embeddings are vector representations of a textual content. The embeddings kind the premise of any pure language processing activity. So if we are able to examine the standard of embeddings, then it may possibly assist us decide the standard of pure language duties, as embeddings are foundational for pure language processing by transformer structure.

Proven beneath is the comparability strategy which I’ll take.

Comparability strategy (picture by writer)

I made a toss of a coin, and GPT gained the toss! So allow us to begin with GPT first. I’ll take textual content from Amazon’s nice meals opinions dataset. Evaluations are a great way to check each fashions, as opinions are expressed in pure language and are very spontaneous. They embody the sensation of consumers, and may comprise all forms of languages — good, dangerous, the ugly! As well as, they will have many misspelled phrases, emojis in addition to generally used slang.

Right here is an instance of the evaluate textual content.

Instance of a buyer evaluate (picture by writer)

As a way to get the embeddings of the textual content utilizing GPT, we have to make an API name to OpenAI. The result’s embedding or vector of dimension of 1540 for every textual content. Here’s a pattern knowledge which incorporates the embeddings.

Embeddings obtained from mannequin (picture by writer)

The subsequent step is clustering and visualization. One can use KMeans to cluster the embedding vector and use TSNE to cut back the 1540 dimensions to 2 dimensions. Proven beneath are the outcomes after clustering and dimensionality discount.

GPT embedding clustering (picture by writer)

One can observe that the clusters are very nicely fashioned. Hovering over a number of the clusters will help perceive the that means of the clusters. For instance, the crimson cluster is expounded to pet food. Additional evaluation additionally exhibits that GPT embeddings have appropriately recognized that the phrase ‘Canine’ and ‘Dawg’ are related and positioned them in the identical cluster.

General, GPT embeddings give good outcomes as indicated by the standard of clustering.

Can BERT carry out higher? Allow us to discover out. There are a number of variations of the BERT mannequin corresponding to bert-base-case, bert-base-uncased, and many others.. Primarily they’ve completely different embedding vector sizes. Right here is the end result based mostly on Bert base which has an embedding dimension of 768.

BERT embedding (768) clustering (picture by writer)

The inexperienced cluster corresponds to pet food. Nevertheless one can observe that the clusters are extensively unfold and never very compact in comparison with GPT. The principle cause is that the embedding vector size of 768 is inferior in comparison with the embedding vector size of 1540 of GPT.

Luckily, BERT additionally provides the next embedding dimension of 1024. Listed below are the outcomes.

BERT embedding (1024) clustering (picture by writer)

Right here the orange cluster corresponds to pet food. The cluster is comparatively compact, which is a greater end result in comparison with the embedding of 768. Nevertheless, there are some factors that are far-off from the middle. These factors are incorrectly categorized. For instance, there’s a evaluate for espresso, however it’s got incorrectly categorized as pet food as a result of it’s got a phrase Canine in it.

Clearly, GPT does a greater job and supplies higher-quality embeddings in comparison with BERT. Nevertheless, I’d not like to present all credit score to GPT as there are different points to the comparability. Here’s a abstract desk

GPT wins over BERT for the embedding high quality offered by the upper embedding dimension. Nevertheless, GPT required a paid API, whereas BERT is free. As well as, the BERT mannequin is open-source, and never black-box so you can also make additional evaluation to grasp it higher. The GPT fashions from OpenAI are black-box.

In conclusion, I’d suggest utilizing BERT for medium advanced textual content corresponding to internet pages or books which have curated textual content. GPT can be utilized for very advanced textual content corresponding to buyer opinions that are utterly in pure language and never curated.

Here’s a Python code snippet that implements the method described within the story. For illustration, I’ve given GPT instance. The BERT one is analogous.

##Import packages
import openai
import pandas as pd
import re
import contextlib
import io
import tiktoken
from openai.embeddings_utils import get_embedding
from sklearn.cluster import KMeans
from sklearn.manifold import TSNE

##Learn knowledge
file_name = 'path_to_file'
df = pd.read_csv(file_name)

##Set parameters
embedding_model = "text-embedding-ada-002"
embedding_encoding = "cl100k_base" # this the encoding for text-embedding-ada-002
max_tokens = 8000 # the utmost for text-embedding-ada-002 is 8191
top_n = 1000
encoding = tiktoken.get_encoding(embedding_encoding)
col_embedding = 'embedding'
n_iter = 1000

##Will get the embedding from OpenAI
def get_embedding(textual content, mannequin):
openai.api_key = "YOUR_OPENAPI_KEY"
textual content = textual content.substitute("n", " ")
return openai.Embedding.create(enter = [text], mannequin=mannequin)['data'][0]['embedding']

col_txt = 'Overview'
df["n_tokens"] = df[col_txt].apply(lambda x: len(encoding.encode(x)))
df = df[df.n_tokens <= max_tokens].tail(top_n)
df = df[df.n_tokens > 0].reset_index(drop=True) ##Take away if there no tokens, for instance clean strains
df[col_embedding] = df[col_txt].apply(lambda x: get_embedding(x, mannequin='text-embedding-ada-002'))
matrix = np.array(df[col_embedding].to_list())

##Make clustering
kmeans_model = KMeans(n_clusters=n_clusters,random_state=0)
kmeans = kmeans_model.match(matrix)
kmeans_clusters = kmeans.predict(matrix)

tsne_model = TSNE(n_components=n_tsne, verbose=0, random_state=42, n_iter=n_iter,init='random')
tsne_out = tsne_model.fit_transform(matrix)

The dataset is accessible right here with license CC0 Public area. Both commercial and non-commercial use of it is permitted.

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