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Dimensionality Reduction and Feature Extraction

PCA, factor analysis, feature selection, feature extraction, and more

Feature transformation techniques reduce the dimensionality in the data by transforming data into new features. Feature selection techniques are preferable when transformation of variables is not possible, e.g., when there are categorical variables in the data. For a feature selection technique that is specifically suitable for least-squares fitting, see Stepwise Regression.

Functions

fscnca Feature selection using neighborhood component analysis for classification
fsrnca Feature selection using neighborhood component analysis for regression
sequentialfs Sequential feature selection
relieff Importance of attributes (predictors) using ReliefF algorithm
rica Feature extraction by using reconstruction ICA
sparsefilt Feature extraction by using sparse filtering
transform Transform predictors into extracted features
tsne t-Distributed Stochastic Neighbor Embedding
barttest Bartlett's test
canoncorr Canonical correlation
pca Principal component analysis of raw data
pcacov Principal component analysis on covariance matrix
pcares Residuals from principal component analysis
ppca Probabilistic principal component analysis
factoran Factor analysis
rotatefactors Rotate factor loadings
nnmf Nonnegative matrix factorization
cmdscale Classical multidimensional scaling
mahal Mahalanobis distance
mdscale Nonclassical multidimensional scaling
pdist Pairwise distance between pairs of objects
squareform Format distance matrix
procrustes Procrustes analysis

Classes

FeatureSelectionNCAClassification Feature selection for classification using neighborhood component analysis (NCA)
FeatureSelectionNCARegression Feature selection for regression using neighborhood component analysis (NCA)

Using Objects

ReconstructionICA Feature extraction by reconstruction ICA
SparseFiltering Feature extraction by sparse filtering

Topics

Feature Selection

Robust Feature Selection Using NCA for Regression

Perform feature selection that is robust to outliers using a custom robust loss function in NCA.

Neighborhood Component Analysis (NCA) Feature Selection

Neighborhood component analysis (NCA) is a non-parametric and embedded method for selecting features with the goal of maximizing prediction accuracy of regression and classification algorithms.

Feature Extraction

Feature Extraction Workflow

This example shows a complete workflow for feature extraction from image data.

Extract Mixed Signals

This example shows how to use rica to disentangle mixed audio signals.

Feature Extraction

Feature extraction is a set of methods to extract high-level features from data.

t-SNE Multidimensional Visualization

Visualize High-Dimensional Data Using t-SNE

This example shows how t-SNE creates a useful low-dimensional embedding of high-dimensional data.

tsne Settings

This example shows the effects of various tsne settings.

t-SNE

t-SNE is a method for visualizing high-dimensional data by nonlinear reduction to two or three dimensions, while preserving some features of the original data.

t-SNE Output Function

Output function description and example for t-SNE.

PCA and Canonical Correlation

Analyze Quality of Life in U.S. Cities Using PCA

Perform a weighted principal components analysis and interpret the results.

Partial Least Squares Regression and Principal Components Regression

This example shows how to apply Partial Least Squares Regression (PLSR) and Principal Components Regression (PCR), and discusses the effectiveness of the two methods.

Principal Component Analysis (PCA)

Principal Component Analysis reduces the dimensionality of data by replacing several correlated variables with a new set of variables that are linear combinations of the original variables.

Factor Analysis

Analyze Stock Prices Using Factor Analysis

Use factor analysis to investigate whether companies within the same sector experience similar week-to-week changes in stock prices.

Factor Analysis

Factor analysis is a way to fit a model to multivariate data to estimate interdependence of measured variables on a smaller number of unobserved (latent) factors.

Nonnegative Matrix Factorization

Perform Nonnegative Matrix Factorization

Perform nonnegative matrix factorization using the multiplicative and alternating least-squares algorithms.

Nonnegative Matrix Factorization

Nonnegative matrix factorization (NMF) is a dimension-reduction technique based on a low-rank approximation of the feature space.

Multidimensional Scaling

Classical Multidimensional Scaling

Use cmdscale to perform classical (metric) multidimensional scaling, also known as principal coordinates analysis.

Multidimensional Scaling

Multidimensional scaling allows you to visualize how near points are to each other for many kinds of distance or dissimilarity metrics and can produce a representation of data in a small number of dimensions.

Nonclassical and Nonmetric Multidimensional Scaling

Perform nonclassical multidimensional scaling using mdscale.

Procrustes Analysis

Compare Handwritten Shapes Using Procrustes Analysis

Use Procrustes analysis to compare two handwritten numerals.

Procrustes Analysis

Procrustes analysis minimizes the differences in location between compared landmark data using the best shape-preserving Euclidian transformations

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