Mar 10, 2022

Clustering

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This article has been archived and may contain outdated information. It reflects approaches, models, or technologies that were current at the time of writing but may no longer represent best practices or the latest developments.

We use a simple k-means algorithm to demonstrate how clustering can be done. Clustering can help discover valuable, hidden groupings within the data. The dataset is created in the Get_embeddings_from_dataset Notebook.

# imports
import numpy as np
import pandas as pd
from ast import literal_eval

# load data
datafile_path = "./data/fine_food_reviews_with_embeddings_1k.csv"

df = pd.read_csv(datafile_path)
df["embedding"] = df.embedding.apply(literal_eval).apply(np.array)  # convert string to numpy array
matrix = np.vstack(df.embedding.values)
matrix.shape

(1000, 1536)

We show the simplest use of K-means. You can pick the number of clusters that fits your use case best.

from sklearn.cluster import KMeans

n_clusters = 4

kmeans = KMeans(n_clusters=n_clusters, init="k-means++", random_state=42)
kmeans.fit(matrix)
labels = kmeans.labels_
df["Cluster"] = labels

df.groupby("Cluster").Score.mean().sort_values()

/opt/homebrew/lib/python3.11/site-packages/sklearn/cluster/_kmeans.py:870: FutureWarning: The default value of `n_init` will change from 10 to 'auto' in 1.4. Set the value of `n_init` explicitly to suppress the warning
  warnings.warn(

Cluster
0    4.105691
1    4.191176
2    4.215613
3    4.306590
Name: Score, dtype: float64
from sklearn.manifold import TSNE
import matplotlib
import matplotlib.pyplot as plt

tsne = TSNE(n_components=2, perplexity=15, random_state=42, init="random", learning_rate=200)
vis_dims2 = tsne.fit_transform(matrix)

x = [x for x, y in vis_dims2]
y = [y for x, y in vis_dims2]

for category, color in enumerate(["purple", "green", "red", "blue"]):
    xs = np.array(x)[df.Cluster == category]
    ys = np.array(y)[df.Cluster == category]
    plt.scatter(xs, ys, color=color, alpha=0.3)

    avg_x = xs.mean()
    avg_y = ys.mean()

    plt.scatter(avg_x, avg_y, marker="x", color=color, s=100)
plt.title("Clusters identified visualized in language 2d using t-SNE")

Text(0.5, 1.0, 'Clusters identified visualized in language 2d using t-SNE')
image generated by notebook

Visualization of clusters in a 2d projection. In this run, the green cluster (#1) seems quite different from the others. Let's see a few samples from each cluster.

from openai import OpenAI
import os

client = OpenAI(api_key=os.environ.get("OPENAI_API_KEY", "<your OpenAI API key if not set as env var>"))

# Reading a review which belong to each group.
rev_per_cluster = 5

for i in range(n_clusters):
    print(f"Cluster {i} Theme:", end=" ")

    reviews = "\n".join(
        df[df.Cluster == i]
        .combined.str.replace("Title: ", "")
        .str.replace("\n\nContent: ", ":  ")
        .sample(rev_per_cluster, random_state=42)
        .values
    )

    messages = [
        {"role": "user", "content": f'What do the following customer reviews have in common?\n\nCustomer reviews:\n"""\n{reviews}\n"""\n\nTheme:'}
    ]

    response = client.chat.completions.create(
        model="gpt-4",
        messages=messages,
        temperature=0,
        max_tokens=64,
        top_p=1,
        frequency_penalty=0,
        presence_penalty=0)
    print(response.choices[0].message.content.replace("\n", ""))

    sample_cluster_rows = df[df.Cluster == i].sample(rev_per_cluster, random_state=42)
    for j in range(rev_per_cluster):
        print(sample_cluster_rows.Score.values[j], end=", ")
        print(sample_cluster_rows.Summary.values[j], end=":   ")
        print(sample_cluster_rows.Text.str[:70].values[j])

    print("-" * 100)

Cluster 0 Theme: The theme of these customer reviews is food products purchased on Amazon.
5, Loved these gluten free healthy bars, saved $$ ordering on Amazon:   These Kind Bars are so good and healthy & gluten free.  My daughter ca
1, Should advertise coconut as an ingredient more prominently:   First, these should be called Mac - Coconut bars, as Coconut is the #2
5, very good!!:   just like the runts<br />great flavor, def worth getting<br />I even o
5, Excellent product:   After scouring every store in town for orange peels and not finding an
5, delicious:   Gummi Frogs have been my favourite candy that I have ever tried. of co
----------------------------------------------------------------------------------------------------
Cluster 1 Theme: Pet food reviews
2, Messy and apparently undelicious:   My cat is not a huge fan. Sure, she'll lap up the gravy, but leaves th
4, The cats like it:   My 7 cats like this food but it is a little yucky for the human. Piece
5, cant get enough of it!!!:   Our lil shih tzu puppy cannot get enough of it. Everytime she sees the
1, Food Caused Illness:   I switched my cats over from the Blue Buffalo Wildnerness Food to this
5, My furbabies LOVE these!:   Shake the container and they come running. Even my boy cat, who isn't 
----------------------------------------------------------------------------------------------------
Cluster 2 Theme: All the reviews are about different types of coffee.
5, Fog Chaser Coffee:   This coffee has a full body and a rich taste. The price is far below t
5, Excellent taste:   This is to me a great coffee, once you try it you will enjoy it, this 
4, Good, but not Wolfgang Puck good:   Honestly, I have to admit that I expected a little better. That's not 
5, Just My Kind of Coffee:   Coffee Masters Hazelnut coffee used to be carried in a local coffee/pa
5, Rodeo Drive is Crazy Good Coffee!:   Rodeo Drive is my absolute favorite and I'm ready to order more!  That
----------------------------------------------------------------------------------------------------
Cluster 3 Theme: The theme of these customer reviews is food and drink products.
5, Wonderful alternative to soda pop:   This is a wonderful alternative to soda pop.  It's carbonated for thos
5, So convenient, for so little!:   I needed two vanilla beans for the Love Goddess cake that my husbands 
2, bot very cheesy:   Got this about a month ago.first of all it smells horrible...it tastes
5, Delicious!:   I am not a huge beer lover.  I do enjoy an occasional Blue Moon (all o
3, Just ok:   I bought this brand because it was all they had at Ranch 99 near us. I
----------------------------------------------------------------------------------------------------

It's important to note that clusters will not necessarily match what you intend to use them for. A larger amount of clusters will focus on more specific patterns, whereas a small number of clusters will usually focus on largest discrepencies in the data.