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MNIST Class

MNIST Dataset of handwritten digits.
Inheritance Hierarchy
SystemObject
  Accord.DataSets.BaseWebDataSet
    Accord.DataSets.BaseSparseDataSet
      Accord.DataSetsMNIST

Namespace:  Accord.DataSets
Assembly:  Accord.DataSets (in Accord.DataSets.dll) Version: 3.8.0
Syntax
public class MNIST : SparseDataSet
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The MNIST type exposes the following members.

Constructors
  NameDescription
Public methodMNIST
Downloads and prepares the MNIST dataset.
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Properties
  NameDescription
Public propertyPath
Gets the path to the directory where the datasets will be stored.
(Inherited from WebDataSet.)
Public propertyTesting
Gets the testing set of the MNIST dataset.
Public propertyTraining
Gets the training set of the MNIST dataset.
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Methods
  NameDescription
Protected methodDownload
Downloads the dataset from a specified URL, saving it to disk, and returning it as a set of sparse vectors>. If the dataset already exists in the disk, it will not be redownloaded again.
(Inherited from SparseDataSet.)
Public methodEquals
Determines whether the specified object is equal to the current object.
(Inherited from Object.)
Protected methodFinalize
Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.
(Inherited from Object.)
Public methodGetHashCode
Serves as the default hash function.
(Inherited from Object.)
Public methodGetType
Gets the Type of the current instance.
(Inherited from Object.)
Protected methodMemberwiseClone
Creates a shallow copy of the current Object.
(Inherited from Object.)
Public methodToString
Returns a string that represents the current object.
(Inherited from Object.)
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Extension Methods
  NameDescription
Public Extension MethodHasMethod
Checks whether an object implements a method with the given name.
(Defined by ExtensionMethods.)
Public Extension MethodIsEqual
Compares two objects for equality, performing an elementwise comparison if the elements are vectors or matrices.
(Defined by Matrix.)
Public Extension MethodTo(Type)Overloaded.
Converts an object into another type, irrespective of whether the conversion can be done at compile time or not. This can be used to convert generic types to numeric types during runtime.
(Defined by ExtensionMethods.)
Public Extension MethodToTOverloaded.
Converts an object into another type, irrespective of whether the conversion can be done at compile time or not. This can be used to convert generic types to numeric types during runtime.
(Defined by ExtensionMethods.)
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Remarks

The MNIST database (Mixed National Institute of Standards and Technology database) is a large database of handwritten digits that is commonly used for training various image processing systems. The database is also widely used for training and testing in the field of machine learning. It was created by "re-mixing" the samples from NIST's original datasets. The creators felt that since NIST's training dataset was taken from American Census Bureau employees, while the testing dataset was taken from American high school students, it was not well-suited for machine learning experiments. Furthermore, the black and white images from NIST were normalized to fit into a 20x20 pixel bounding box and anti-aliased, which introduced grayscale levels.

The MNIST database contains 60,000 training images and 10,000 testing images. Half of the training set and half of the test set were taken from NIST's training dataset, while the other half of the training set and the other half of the test set were taken from NIST's testing dataset. There have been a number of scientific papers on attempts to achieve the lowest error rate; one paper, using a hierarchical system of convolutional neural networks, manages to get an error rate on the MNIST database of 0.23 percent. The original creators of the database keep a list of some of the methods tested on it. In their original paper, they use a support vector machine to get an error rate of 0.8 percent.

References:

See Also