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:
“We all have known
Good critics, who have stamped out poets hopes;
Good statesmen, who pulled ruin on the state;
Good patriots, who, for a theory, risked a cause;
Good kings, who disembowelled for a tax;
Good Popes, who brought all good to jeopardy;
Good Christians, who sat still in easy-chairs;
And damned the general world for standing up.
Now, may the good God pardon all good men!”
—Elizabeth Barrett Browning (18061861)
“The first general store opened on the Cold Saturday of the winter of 1833 ... Mrs. Mary Miller, daughter of the stores promoter, recorded in a letter: Chickens and birds fell dead from their roosts, cows ran bellowing through the streets; but she failed to state what effect the freeze had on the gala occasion of the store opening.”
—Administration in the State of Sout, U.S. public relief program (1935-1943)
“A point has been reached where the peoples of the Americas must take cognizance of growing ill-will, of marked trends toward aggression, of increasing armaments, of shortening tempersa situation which has in it many of the elements that lead to the tragedy of general war.... Peace is threatened by those who seek selfish power.”
—Franklin D. Roosevelt (18821945)