Clustering

, ,
Mar 10, 2022
Open in Github

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.