/// <summary>
/// Converts the specified expression to a CharacterVector.
/// </summary>
/// <param name="expression">The expression.</param>
/// <returns>The LogicalVector. Returns <c>null</c> if the specified expression is not vector.</returns>
public static CharacterVector AsCharacter(this SymbolicExpression expression)
{
if (!expression.IsVector())
{
return(null);
}
IntPtr coerced = IntPtr.Zero;
if (expression.IsFactor())
{
coerced = expression.GetFunction <Rf_asCharacterFactor>()(expression.DangerousGetHandle());
}
else
{
coerced = expression.GetFunction <Rf_coerceVector>()(expression.DangerousGetHandle(), SymbolicExpressionType.CharacterVector);
}
return(new CharacterVector(expression.Engine, coerced));
}
