private void WriteAttribute(ArffAttribute attribute, int indent)
{
string type = attribute.Type.ToString();
if (indent != 0)
{
streamWriter.Write(new string(' ', indent));
}
streamWriter.WriteLine("@attribute {0} {1}", QuoteAndEscape(attribute.Name), type);
if (attribute.Type is ArffRelationalAttribute relationalAttribute)
{
foreach (ArffAttribute childAttribute in relationalAttribute.ChildAttributes)
{
WriteAttribute(childAttribute, indent + 2);
}
if (indent != 0)
{
streamWriter.Write(new string(' ', indent));
}
streamWriter.WriteLine("@end {0}", QuoteAndEscape(attribute.Name));
}
}
/// <summary>
/// Determines whether this object is equal to another object (an <see cref="ArffAttribute"/> with the same name and type).
/// </summary>
/// <param name="obj">The object to compare with the current object.</param>
/// <returns><c>true</c> if the specified object is equal to the current object; otherwise, <c>false</c>.</returns>
public override bool Equals(object obj)
{
ArffAttribute other = obj as ArffAttribute;
if (other == null)
{
return(false);
}
return(other.Name == Name && other.Type.Equals(Type));
}
/// <summary>
/// Reads relation name and attribute declarations as an <see cref="ArffHeader"/> instance.
/// </summary>
/// <returns><see cref="ArffHeader"/> instance with read data.</returns>
/// <exception cref="ObjectDisposedException"/>
/// <exception cref="InvalidOperationException"/>
/// <exception cref="InvalidDataException"/>
public ArffHeader ReadHeader()
{
if (disposed)
{
throw new ObjectDisposedException(GetType().FullName);
}
if (arffHeader != null)
{
throw new InvalidOperationException("The header has already been read by a previous call of ReadHeader.");
}
List <ArffAttribute> attributes = new List <ArffAttribute>();
ReadToken(expectedToken: "@relation", ignoreCase: true, skipEndOfLine: true, endOfLine: false, quoting: false);
string relationName = ReadToken(endOfLine: false);
ReadToken(endOfLine: true);
while (true)
{
string token = ReadToken(skipEndOfLine: true, endOfLine: false, quoting: false);
if (string.Equals(token, "@attribute", StringComparison.OrdinalIgnoreCase))
{
ArffAttribute attribute = ReadAttribute();
attributes.Add(attribute);
}
else if (string.Equals(token, "@data", StringComparison.OrdinalIgnoreCase))
{
ReadToken(endOfLine: true);
break;
}
else
{
throw new InvalidDataException($"Unexpected token \"{token}\". Expected \"@attribute\" or \"@data\".");
}
}
if (attributes.Count == 0)
{
throw new InvalidDataException("Expected at least one \"@attribute\".");
}
arffHeader = new ArffHeader(relationName, attributes);
return(arffHeader);
}
/// <summary>
/// Writes an attribute declaration (@attribute <...>) for the specified <see cref="ArffAttribute"/>.
/// Must be called after the relation name has been written and before any data instances are written.
/// </summary>
/// <param name="attribute">An <see cref="ArffAttribute"/> object representing the attribute.</param>
/// <exception cref="ObjectDisposedException"/>
/// <exception cref="ArgumentNullException"/>
/// <exception cref="ArgumentException"/>
/// <exception cref="InvalidOperationException"/>
/// <exception cref="IOException"/>
public void WriteAttribute(ArffAttribute attribute)
{
if (disposed)
{
throw new ObjectDisposedException(GetType().FullName);
}
if (step != 1 && step != 2)
{
throw new InvalidOperationException("All attributes must be written after the relation name and before any instances.");
}
if (attribute == null)
{
throw new ArgumentNullException(nameof(attribute));
}
WriteAttribute(attribute, 0);
writtenAttributes.Add(attribute);
step = 2;
}
private void WriteValue(object value, ArffAttribute attribute, TextWriter textWriter)
{
if (value == null)
{
textWriter.Write("?");
}
else if (value is double doubleValue)
{
textWriter.Write(doubleValue.ToString(CultureInfo.InvariantCulture));
}
else if (value is string stringValue)
{
textWriter.Write(QuoteAndEscape(stringValue));
}
else if (value is int || value is Enum)
{
// the cast fails if value is an enum with an underlying type other than int
// but checking the type via Enum.GetUnderlyingType(value.GetType()) == typeof(int)
// to throw a more helpful exception is probably not worth it
int nominalValue = (int)value;
ReadOnlyCollection <string> values = (attribute.Type as ArffNominalAttribute)?.Values;
if (values == null || nominalValue < 0 || nominalValue >= values.Count)
{
throw new ArgumentException("Instance is incompatible with types of written attributes.", "instance");
}
textWriter.Write(QuoteAndEscape(values[nominalValue]));
}
else if (value is DateTime dateTimeValue)
{
string dateFormat = (attribute.Type as ArffDateAttribute)?.DateFormat;
if (dateFormat == null)
{
throw new ArgumentException("Instance is incompatible with types of written attributes.", "instance");
}
textWriter.Write(QuoteAndEscape(dateTimeValue.ToString(dateFormat, CultureInfo.InvariantCulture)));
}
else if (value is object[][] relationalValue)
{
ReadOnlyCollection <ArffAttribute> relationalAttributes = (attribute.Type as ArffRelationalAttribute)?.ChildAttributes;
if (relationalAttributes == null)
{
throw new ArgumentException("Instance is incompatible with types of written attributes.", "instance");
}
using (StringWriter stringWriter = new StringWriter())
{
for (int j = 0; j < relationalValue.Length; j++)
{
if (relationalValue[j].Length != relationalAttributes.Count)
{
throw new ArgumentException("Instance is incompatible with types of written attributes.", "instance");
}
// sparse format does not seem to be supported in relational values
// instance weights seem to be supported in the format but they cannot be represented with an object[] alone, so we don't support them for now
WriteInstanceData(relationalValue[j], false, relationalAttributes, stringWriter);
if (j != relationalValue.Length - 1)
{
stringWriter.WriteLine();
}
}
textWriter.Write(QuoteAndEscape(stringWriter.GetStringBuilder().ToString()));
}
}
else
{
throw new ArgumentException("Unsupported data type in instance.", "instance");
}
}
private ArffAttribute ReadAttribute()
{
string attributeName = ReadToken(endOfLine: false);
string typeString = ReadToken(endOfLine: false, quoting: false);
ArffAttributeType attributeType;
if (string.Equals(typeString, "numeric", StringComparison.OrdinalIgnoreCase) ||
string.Equals(typeString, "integer", StringComparison.OrdinalIgnoreCase) ||
string.Equals(typeString, "real", StringComparison.OrdinalIgnoreCase))
{
attributeType = ArffAttributeType.Numeric;
ReadToken(endOfLine: true);
}
else if (string.Equals(typeString, "string", StringComparison.OrdinalIgnoreCase))
{
attributeType = ArffAttributeType.String;
ReadToken(endOfLine: true);
}
else if (string.Equals(typeString, "date", StringComparison.OrdinalIgnoreCase))
{
string dateFormat = ReadToken();
if (dateFormat == null)
{
attributeType = ArffAttributeType.Date();
}
else
{
attributeType = ArffAttributeType.Date(dateFormat);
ReadToken(endOfLine: true);
}
}
else if (typeString == "{")
{
List <string> nominalValues = new List <string>();
while (true)
{
string value = ReadToken(out bool quoted, endOfLine: false);
if (!quoted && value == "}")
{
break;
}
else if (!quoted && value == ",")
{
continue;
}
else
{
nominalValues.Add(value);
}
}
attributeType = ArffAttributeType.Nominal(nominalValues);
ReadToken(endOfLine: true);
}
else if (string.Equals(typeString, "relational", StringComparison.OrdinalIgnoreCase))
{
ReadToken(endOfLine: true);
List <ArffAttribute> childAttributes = new List <ArffAttribute>();
while (true)
{
string token = ReadToken(skipEndOfLine: true, endOfLine: false, quoting: false);
if (string.Equals(token, "@attribute", StringComparison.OrdinalIgnoreCase))
{
ArffAttribute attribute = ReadAttribute();
childAttributes.Add(attribute);
}
else if (string.Equals(token, "@end", StringComparison.OrdinalIgnoreCase))
{
ReadToken(expectedToken: attributeName, endOfLine: false);
ReadToken(endOfLine: true);
break;
}
else
{
throw new InvalidDataException($"Unexpected token \"{token}\". Expected \"@attribute\" or \"@end\".");
}
}
attributeType = ArffAttributeType.Relational(childAttributes);
}
else
{
throw new InvalidDataException($"Unexpected token \"{typeString}\". Expected attribute type.");
}
return(new ArffAttribute(attributeName, attributeType));
}