private OutputProperties InitOutputProperties(IQueryable <T> data)
{
var arg = Expression.Parameter(typeof(T), "x");
var selectArgs = Expression.Parameter(typeof(IGrouping <,>).MakeGenericType(outputFeature.DataType, typeof(T)), "x");
var selectCtor = Expression.New(typeof(GroupInfo));
//int Count<TSource>(this IEnumerable<TSource> source);
var countMethod = typeof(Enumerable).GetMethods().First(x => x.Name == "Count").MakeGenericMethod(typeof(T));
var selectMemberInit = Expression.MemberInit(selectCtor,
Expression.Bind(typeof(GroupInfo).GetProperty("Output"), Expression.Convert(Expression.Property(selectArgs, "Key"), typeof(object))),
Expression.Bind(typeof(GroupInfo).GetProperty("Count"), Expression.Call(countMethod, selectArgs))
);
var selectLambdaExpression = Expression.Lambda(selectMemberInit, selectArgs);
var groupedData = IQueryableHelper.GroupBy(data, outputFeature.Selector, typeof(T), outputFeature.DataType);
var groups = (IQueryableHelper.Select(groupedData, selectLambdaExpression, typeof(IGrouping <,>).MakeGenericType(outputFeature.DataType, typeof(T)),
typeof(GroupInfo)) as IQueryable <GroupInfo>).ToArray();
return(new DecisionTreeOutputProperties()
{
DataCount = groups.Sum(x => x.Count),
OutputDistribution = groups.ToDictionary(x => x.Output, x => x.Count),
});
}
private GroupInfo[] GroupFeatureWithOutput(Feature feature, IQueryable <T> data)
{
var arg = Expression.Parameter(typeof(T), "x");
var groupByType = typeof(GroupBy <,>).MakeGenericType(feature.DataType, outputFeature.DataType);
var ctor = Expression.New(groupByType);
var inputExp = new ReplaceExpressionVisitor((feature.Selector as LambdaExpression).Parameters[0], arg)
.Visit((feature.Selector as LambdaExpression).Body);
var outputExp = new ReplaceExpressionVisitor((outputFeature.Selector as LambdaExpression).Parameters[0], arg)
.Visit((outputFeature.Selector as LambdaExpression).Body);
var bindExpInput = Expression.Bind(groupByType.GetProperty("Input"), inputExp);//TODO: FIX THIS
var bindExpOutput = Expression.Bind(groupByType.GetProperty("Output"), outputExp);
var groupByExpression = Expression.MemberInit(ctor, new MemberBinding[] { bindExpInput, bindExpOutput });
var lambdaExpression = Expression.Lambda(groupByExpression, arg);
var groups = IQueryableHelper.GroupBy(data, lambdaExpression, typeof(T), groupByType);
var selectArgs = Expression.Parameter(typeof(IGrouping <,>).MakeGenericType(groupByType, typeof(T)), "x");
var selectCtor = Expression.New(typeof(GroupInfo));
//int Count<TSource>(this IEnumerable<TSource> source);
var countMethod = typeof(Enumerable).GetMethods().First(x => x.Name == "Count").MakeGenericMethod(typeof(T));
var selectMemberInit = Expression.MemberInit(selectCtor,
Expression.Bind(typeof(GroupInfo).GetProperty("Input"), Expression.Convert(Expression.Property(Expression.Property(selectArgs, "Key"), "Input"), typeof(object))),
Expression.Bind(typeof(GroupInfo).GetProperty("Output"), Expression.Convert(Expression.Property(Expression.Property(selectArgs, "Key"), "Output"), typeof(object))),
Expression.Bind(typeof(GroupInfo).GetProperty("Count"), Expression.Call(countMethod, selectArgs))
);
var selectLambdaExpression = Expression.Lambda(selectMemberInit, selectArgs);
var selectedGroups = IQueryableHelper.Select(groups, selectLambdaExpression, typeof(IGrouping <,>)
.MakeGenericType(groupByType, typeof(T)), typeof(GroupInfo)) as IQueryable <GroupInfo>;
return(selectedGroups.ToArray());
//var groups = this.GetType().GetMethod("GenericGroup")
// .MakeGenericMethod(feature.DataType, OutputFeature.DataType)
// .Invoke(this, new object[] { data, groupByExpression, arg }) as GroupInfo[];
}