Schemi di clustering uniformi

Ora che hai preso familiarità con l’impatto dei semi (seeds), vediamo il bias del k-means clustering verso la formazione di cluster uniformi.

Per il prossimo esercizio useremo un insieme di dati a forma di topo. Un insieme di dati a forma di topo è un gruppo di punti che ricorda la testa di un topo: presenta tre cluster di punti disposti in cerchi, uno per il muso e due per le orecchie.

Ecco come si presenta tipicamente un insieme di dati a forma di topo (Fonte).

I dati sono memorizzati in un DataFrame di pandas, mouse. x_scaled e y_scaled sono i nomi delle colonne delle coordinate X e Y standardizzate dei punti dati.

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Analisi di cluster in Python

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Istruzioni dell'esercizio

Importa le funzioni kmeans e vq da SciPy.
Genera i centri dei cluster usando la funzione kmeans() con tre cluster.
Crea le etichette di cluster con vq() utilizzando i centri generati sopra.

Esercizio pratico interattivo

Prova a risolvere questo esercizio completando il codice di esempio.

# Import the kmeans and vq functions
____

# Generate cluster centers
cluster_centers, distortion = ____

# Assign cluster labels
mouse['cluster_labels'], distortion_list = ____

# Plot clusters
sns.scatterplot(x='x_scaled', y='y_scaled', 
                hue='cluster_labels', data = mouse)
plt.show()

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Questo esercizio fa parte del corso

Analisi di cluster in Python

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Before you are ready to classify news articles, you need to be introduced to the basics of clustering. This chapter familiarizes you with a class of machine learning algorithms called unsupervised learning and then introduces you to clustering, one of the popular unsupervised learning algorithms. You will know about two popular clustering techniques - hierarchical clustering and k-means clustering. The chapter concludes with basic pre-processing steps before you start clustering data.

Exercise 1: Unsupervised learning: basics Exercise 2: Unsupervised learning in real world Exercise 3: Pokémon sightings Exercise 4: Basics of cluster analysis Exercise 5: Pokémon sightings: hierarchical clustering Exercise 6: Pokémon sightings: k-means clustering Exercise 7: Data preparation for cluster analysis Exercise 8: Normalize basic list data Exercise 9: Visualize normalized data Exercise 10: Normalization of small numbers Exercise 11: FIFA 18: Normalize data

This chapter focuses on a popular clustering algorithm - hierarchical clustering - and its implementation in SciPy. In addition to the procedure to perform hierarchical clustering, it attempts to help you answer an important question - how many clusters are present in your data? The chapter concludes with a discussion on the limitations of hierarchical clustering and discusses considerations while using hierarchical clustering.

Exercise 1: Basics of hierarchical clustering Exercise 2: Hierarchical clustering: ward method Exercise 3: Hierarchical clustering: single method Exercise 4: Hierarchical clustering: complete method Exercise 5: Visualize clusters Exercise 6: Visualize clusters with matplotlib Exercise 7: Visualize clusters with seaborn Exercise 8: How many clusters?Exercise 9: Create a dendrogram Exercise 10: How many clusters in comic con data?Exercise 11: Limitations of hierarchical clustering Exercise 12: Timing run of hierarchical clustering Exercise 13: FIFA 18: exploring defenders

This chapter introduces a different clustering algorithm - k-means clustering - and its implementation in SciPy. K-means clustering overcomes the biggest drawback of hierarchical clustering that was discussed in the last chapter. As dendrograms are specific to hierarchical clustering, this chapter discusses one method to find the number of clusters before running k-means clustering. The chapter concludes with a discussion on the limitations of k-means clustering and discusses considerations while using this algorithm.

Exercise 1: Basi del clustering k-means Exercise 2: K-means clustering: primo esercizio Exercise 3: Tempo di esecuzione del clustering k-means Exercise 4: Quanti cluster?Exercise 5: Metodo del gomito su cluster distinti Exercise 6: Metodo del gomito su dati uniformi Exercise 7: Limiti del clustering k-means Exercise 8: Impatto dei semi sui cluster distinti Exercise 9: Schemi di clustering uniformi

Esercizio in corso

Exercise 10: FIFA 18: difensori, ritorno

Now that you are familiar with two of the most popular clustering techniques, this chapter helps you apply this knowledge to real-world problems. The chapter first discusses the process of finding dominant colors in an image, before moving on to the problem discussed in the introduction - clustering of news articles. The chapter concludes with a discussion on clustering with multiple variables, which makes it difficult to visualize all the data.

Exercise 1: Dominant colors in images Exercise 2: Extract RGB values from image Exercise 3: How many dominant colors?Exercise 4: Display dominant colors Exercise 5: Document clustering Exercise 6: TF-IDF of movie plots Exercise 7: Top terms in movie clusters Exercise 8: Clustering with multiple features Exercise 9: Clustering with many features Exercise 10: Basic checks on clusters Exercise 11: FIFA 18: what makes a complete player?Exercise 12: Farewell!