General
Feature extraction involves simplifying the amount of resources required to describe a large set of data accurately. When performing analysis of complex data one of the major problems stems from the number of variables involved. Analysis with a large number of variables generally requires a large amount of memory and computation power or a classification algorithm which overfits the training sample and generalizes poorly to new samples. Feature extraction is a general term for methods of constructing combinations of the variables to get around these problems while still describing the data with sufficient accuracy.
Best results are achieved when an expert constructs a set of application-dependent features. Nevertheless, if no such expert knowledge is available general dimensionality reduction techniques may help. These include:
- Principal component analysis
- Semidefinite embedding
- Multifactor dimensionality reduction
- Multilinear subspace learning
- Nonlinear dimensionality reduction
- Isomap
- Kernel PCA
- Multilinear PCA
- Latent semantic analysis
- Partial least squares
- Independent component analysis
- Autoencoder
Read more about this topic: Feature Extraction
Famous quotes containing the word general:
“[The Republican Party] consists of those who, believing in the doctrine that mankind are capable of governing themselves and hating hereditary power as an insult to the reason and an outrage to the rights of men, are naturally offended at every public measure that does not appeal to the understanding and to the general interest of the community.”
—James Madison (1751–1836)
“We do not need to minimize the poverty of the ghetto or the suffering inflicted by whites on blacks in order to see that the increasingly dangerous and unpredictable conditions of middle- class life have given rise to similar strategies for survival. Indeed the attraction of black culture for disaffected whites suggests that black culture now speaks to a general condition.”
—Christopher Lasch (b. 1932)
“Anti-Nebraska, Know-Nothings, and general disgust with the powers that be, have carried this county [Hamilton County, Ohio] by between seven and eight thousand majority! How people do hate Catholics, and what a happiness it was to show it in what seemed a lawful and patriotic manner.”
—Rutherford Birchard Hayes (1822–1893)