Komponen utama pertama

Komponen utama pertama dari data adalah arah di mana data memiliki variasi terbesar. Pada latihan ini, tugas Anda adalah menggunakan PCA untuk menemukan komponen utama pertama dari pengukuran panjang dan lebar sampel biji, lalu merepresentasikannya sebagai sebuah panah pada plot sebar.

Array grains berisi panjang dan lebar sampel biji. PyPlot (plt) dan PCA sudah diimpor untuk Anda.

Latihan ini adalah bagian dari kursus

Unsupervised Learning in Python

Petunjuk latihan

Buat plot sebar untuk pengukuran biji. Ini telah dilakukan untuk Anda.
Buat sebuah instans PCA bernama model.
Sesuaikan model ke data grains.
Ekstrak koordinat rata-rata data menggunakan atribut .mean_ dari model.
Ambil komponen utama pertama dari model menggunakan atribut .components_[0,:].
Plot komponen utama pertama sebagai sebuah panah pada plot sebar menggunakan fungsi plt.arrow(). Anda harus menentukan dua argumen pertama — mean[0] dan mean[1].

Latihan interaktif praktis

Cobalah latihan ini dengan menyelesaikan kode contoh berikut.

# Make a scatter plot of the untransformed points
plt.scatter(grains[:,0], grains[:,1])

# Create a PCA instance: model
model = ____

# Fit model to points
____

# Get the mean of the grain samples: mean
mean = ____

# Get the first principal component: first_pc
first_pc = ____

# Plot first_pc as an arrow, starting at mean
plt.arrow(____, ____, first_pc[0], first_pc[1], color='red', width=0.01)

# Keep axes on same scale
plt.axis('equal')
plt.show()

Edit dan Jalankan Kode

Latihan ini adalah bagian dari kursus

Unsupervised Learning in Python

SkillTag.level.intermediateSkillTag.label

4.8+

Mulai Kursus Gratis

Learn how to discover the underlying groups (or "clusters") in a dataset. By the end of this chapter, you'll be clustering companies using their stock market prices, and distinguishing different species by clustering their measurements.

Exercise 1: Unsupervised Learning Exercise 2: How many clusters?Exercise 3: Clustering 2D points Exercise 4: Inspect your clustering Exercise 5: Evaluating a clustering Exercise 6: How many clusters of grain?Exercise 7: Evaluating the grain clustering Exercise 8: Transforming features for better clusterings Exercise 9: Scaling fish data for clustering Exercise 10: Clustering the fish data Exercise 11: Clustering stocks using KMeans Exercise 12: Which stocks move together?

In this chapter, you'll learn about two unsupervised learning techniques for data visualization, hierarchical clustering and t-SNE. Hierarchical clustering merges the data samples into ever-coarser clusters, yielding a tree visualization of the resulting cluster hierarchy. t-SNE maps the data samples into 2d space so that the proximity of the samples to one another can be visualized.

Exercise 1: Visualizing hierarchies Exercise 2: How many merges?Exercise 3: Hierarchical clustering of the grain data Exercise 4: Hierarchies of stocks Exercise 5: Cluster labels in hierarchical clustering Exercise 6: Which clusters are closest?Exercise 7: Different linkage, different hierarchical clustering!Exercise 8: Intermediate clusterings Exercise 9: Extracting the cluster labels Exercise 10: t-SNE for 2-dimensional maps Exercise 11: t-SNE visualization of grain dataset Exercise 12: A t-SNE map of the stock market

Dimension reduction summarizes a dataset using its common occuring patterns. In this chapter, you'll learn about the most fundamental of dimension reduction techniques, "Principal Component Analysis" ("PCA"). PCA is often used before supervised learning to improve model performance and generalization. It can also be useful for unsupervised learning. For example, you'll employ a variant of PCA will allow you to cluster Wikipedia articles by their content!

Exercise 1: Memvisualisasikan transformasi PCA Exercise 2: Data berkorelasi di alam Exercise 3: Menghilangkan korelasi pengukuran biji dengan PCA Exercise 4: Komponen utama Exercise 5: Dimensi intrinsik Exercise 6: Komponen utama pertama

Latihan Saat Ini

Exercise 7: Varians dari fitur PCA Exercise 8: Dimensi intrinsik dari data ikan Exercise 9: Reduksi dimensi dengan PCA Exercise 10: Reduksi dimensi pada pengukuran ikan Exercise 11: Array frekuensi kata tf-idf Exercise 12: Pengelompokan Wikipedia bagian I Exercise 13: Mengelompokkan Wikipedia bagian II

In this chapter, you'll learn about a dimension reduction technique called "Non-negative matrix factorization" ("NMF") that expresses samples as combinations of interpretable parts. For example, it expresses documents as combinations of topics, and images in terms of commonly occurring visual patterns. You'll also learn to use NMF to build recommender systems that can find you similar articles to read, or musical artists that match your listening history!

Exercise 1: Non-negative matrix factorization (NMF)Exercise 2: Non-negative data Exercise 3: NMF applied to Wikipedia articles Exercise 4: NMF features of the Wikipedia articles Exercise 5: NMF reconstructs samples Exercise 6: NMF learns interpretable parts Exercise 7: NMF learns topics of documents Exercise 8: Explore the LED digits dataset Exercise 9: NMF learns the parts of images Exercise 10: PCA doesn't learn parts Exercise 11: Building recommender systems using NMF Exercise 12: Which articles are similar to 'Cristiano Ronaldo'?Exercise 13: Recommend musical artists part I Exercise 14: Recommend musical artists part II Exercise 15: Final thoughts