/// <summary>
/// Filter items by feature.
/// </summary>
/// <param name="items">Input items to filter.</param>
/// <param name="featureToAsk">Selected feature which is was asked.</param>
/// <param name="value">Value which user put. If type of feature is numeric, then this value will be median.</param>
/// <param name="index">Valid only in numerics type. If user select under median, the index is 0 otherwise 1.</param>
/// <returns>Filtered items.</returns>
public async Task <IEnumerable <PimItem> > FilterItemsByFeature(
IEnumerable <PimFeature> allFeatures,
IEnumerable <PimItem> items,
FeatureToAsk featureToAsk,
string value,
int index = -1)
{
var pimItemResult = new List <PimItem>();
switch (featureToAsk.Type)
{
case FeatureType.Alphanumeric:
foreach (var item in items)
{
var features = await _featuresService.GetFeaturesByNoAsync(item.No, allFeatures);
var filteredItem = features.Where(i => i.Number == featureToAsk.Number).ToList();
if (filteredItem.Count() == 0)
{
pimItemResult.Add(item);
}
else
{
if (filteredItem[0].Value == value)
{
pimItemResult.Add(item);
}
}
}
return(pimItemResult);
case FeatureType.Numeric:
// Special case for Unit Price
if (featureToAsk.Number == Constants.UnitPriceType)
{
if (index == 0)
{
return(items.Where(i => Convert.ToDouble(i.Unit_Price) <= Convert.ToDouble(value)).ToList());
}
else if (index == 1)
{
return(items.Where(i => Convert.ToDouble(i.Unit_Price) > Convert.ToDouble(value)).ToList());
}
}
foreach (var item in items)
{
var features = await _featuresService.GetFeaturesByNoAsync(item.No, allFeatures);
var filteredItem = features.Where(i => i.Number == featureToAsk.Number).ToList();
if (filteredItem.Count() == 0)
{
pimItemResult.Add(item);
}
else
{
if (index == 0)
{
if (double.Parse(filteredItem[0].Value, CultureInfo.InvariantCulture) <= double.Parse(value, CultureInfo.InvariantCulture))
{
pimItemResult.Add(item);
}
}
if (index == 1)
{
if (double.Parse(filteredItem[0].Value, CultureInfo.InvariantCulture) > double.Parse(value, CultureInfo.InvariantCulture))
{
pimItemResult.Add(item);
}
}
}
}
return(pimItemResult);
default:
return(items);
}
}
/// <summary>
/// Method choose from inputs items features to ask. It's sorts features by order and computed information gain.
/// </summary>
/// <param name="items">List of items.</param>
/// <returns>Ordered features to ask.</returns>
public async Task <List <FeatureToAsk> > GetAllFeaturesToAsk(IEnumerable <PimItem> items)
{
var features = await _featuresService.GetAllFeaturesByItemAsync();
var itemsNos = items.ToList().Select(i => i.No).ToList();
var featuresByInputItems = features.Where(f => itemsNos.Contains(f.Key)).ToList();
var featureToAsks = new List <FeatureToAsk>();
foreach (var feature in featuresByInputItems)
{
List <string> added = new List <string>();
foreach (var ftr in feature.Value)
{
// Check if already in feature to ask
var index = featureToAsks.FindIndex(f => f.Number == ftr.Number);
if (!(index >= 0))
{
// Add to feature to ask
var featureToAsk = new FeatureToAsk(ftr.Number, ftr.Description, ftr.Order, ftr.Unit_Shorthand_Description);
featureToAsk.ValuesList = new HashSet <string>();
// Added new feature value
if (ftr.Value != string.Empty)
{
added.Add(ftr.Description);
featureToAsk.ValuesList.Add(ftr.Value);
}
featureToAsks.Add(featureToAsk);
}
else
{
// Check if same item doesnt content same attribut
if (!added.Contains(ftr.Description))
{
if (ftr.Value != string.Empty)
{
added.Add(ftr.Description);
featureToAsks[index].ValuesList.Add(ftr.Value);
}
}
}
}
}
// Added to features to ask the unit price which is by default not in features
var unitPriceFeature = new FeatureToAsk(Constants.UnitPriceType, Messages.UnitPrice, 1, string.Empty);
unitPriceFeature.ValuesList = new HashSet <string>();
foreach (var item in items)
{
unitPriceFeature.ValuesList.Add(item.Unit_Price.ToString("F", CultureInfo.CreateSpecificCulture("en-US")));
}
featureToAsks.Add(unitPriceFeature);
// Features without value or with one value are meaningless - they don't help
var filteredFeatureToAsk = featureToAsks.Where(i => i.ValuesList.Count > 1).ToList();
// Set type of feature - numeric, text, etc
filteredFeatureToAsk.ForEach(i => i.SetAndCheckType());
// For every feature compute information gain
filteredFeatureToAsk.ForEach(i => i.ComputeInformationGain(items.ToList()));
// Order features by Order and information gain
var orderedFeaturesToAsk = filteredFeatureToAsk
.OrderByDescending(i => i.Order)
.ThenByDescending(i => i.InformationGain)
.ToList();
return(orderedFeaturesToAsk);
}
