ArffTools

.NET library for reading and writing Weka attribute-relation file format (ARFF) files

Features

• Read and write ARFF files
• Supports relational attributes
• Supports sparse instances
• Supports instance weights
• Proper quoting and escaping of special characters

Usage

Reading ARFF files:

using (ArffReader arffReader = new ArffReader("glass.arff"))
{
    ArffHeader header = arffReader.ReadHeader();    
    object[] instance;    
    while ((instance = arffReader.ReadInstance()) != null)
    {
        // process instance
    }    
}

Reading all instances at a time:

object[][] instances = arffReader.ReadAllInstances();

Writing ARFF files:

using (ArffWriter arffWriter = new ArffWriter("iris.arff"))
{
    arffWriter.WriteRelationName("iris");
    arffWriter.WriteAttribute(new ArffAttribute("sepallength", ArffAttributeType.Numeric));
    arffWriter.WriteAttribute(new ArffAttribute("sepalwidth", ArffAttributeType.Numeric));
    arffWriter.WriteAttribute(new ArffAttribute("petallength", ArffAttributeType.Numeric));
    arffWriter.WriteAttribute(new ArffAttribute("petalwidth", ArffAttributeType.Numeric));
    arffWriter.WriteAttribute(new ArffAttribute("class", ArffAttributeType.Nominal("Iris-setosa", "Iris-versicolor", "Iris-virginica")));
    arffWriter.WriteInstance(new object[] { 5.1, 3.5, 1.4, 0.2, 0 });
}

Instances are represented as object[] whose elements correspond to the attribute values. ARFF attribute types are mapped to .NET types as follows:

ARFF attribute type	.NET type
numeric, integer, real	double
nominal	int
string	string
date	DateTime
relational	object[][]

Missing values are represented as null. Sparse instances are represented as normal instances in memory.