public int SimilarityMapInitial()
{
DateTime lastUpdateTime;
if (db.NewsSimilarityMaps.Any())
{
lastUpdateTime = db.NewsSimilarityMaps.Max(o => o.UpdateTime);
}
else
{
lastUpdateTime = new DateTime(2000, 1, 1);
}
var newAddedNewsIDs = (from o in db.NewsContainer
where o.Time > lastUpdateTime
select o.Id).ToList();
int currentUpdateCount = 0;
foreach (var item in newAddedNewsIDs)
{
NewsSimilarityMap newMap = new NewsSimilarityMap
{
OwingNewsId = item,
UpdateTime = new DateTime(2000, 1, 1)
};
db.NewsSimilarityMaps.Add(newMap);
currentUpdateCount++;
if (currentUpdateCount % 1000 == 0)
{
Console.WriteLine("{0}条新闻相似度映射已被添加！", currentUpdateCount);
}
}
return(db.SaveChanges());
}
/// <summary>
/// 统计每条新闻的相似新闻
/// </summary>
public int CollectSimilarity(bool isFirstCollected = false)
{
IEnumerable <NewsCategory> typeDB = db.NewsCategorys;
foreach (var type in typeDB)
{
IEnumerable <News> typeNewsContainer = db.NewsContainer.Where(o => o.Category == type.Name).ToList();
if (typeNewsContainer == null)
{
throw new Exception("找不到指定类别的新闻");
}
foreach (var item in typeNewsContainer)
{
//LinkedList<NewsSimilarityMap> itemMapContainer = new LinkedList<NewsSimilarityMap>();
Dictionary <int, int> updateMapNews = new Dictionary <int, int>();
var tmpList = new List <News>(); tmpList.Add(item);
IEnumerable <News> exceptedNewsContainer = null;
if (isFirstCollected)
{
exceptedNewsContainer = typeNewsContainer.Except(tmpList);
}
else
{
exceptedNewsContainer = typeNewsContainer.Where(o => o.Time > item.Time).Except(tmpList);
}
foreach (var readyItem in exceptedNewsContainer)
{
//两新闻间相似度计算策略
var newMap = new NewsSimilarityMap();
newMap.OwingNewsId = item.Id;
int similarity = 0;
//如果新闻来源相同，则相似度加2
if (IsSimilaritySource(item.Source, readyItem.Source))
{
similarity = 2;
}
else
{
similarity = 0;
}
similarity += GetKeyWordSimilarity(item.Keywords, readyItem.Keywords);
if (similarity != 0)
{
updateMapNews.Add(readyItem.Id, similarity);
}
}
NewsSimilarityMap map = db.NewsSimilarityMaps.FirstOrDefault(o => o.OwingNewsId == item.Id);
if (map == null)
{
throw new Exception(string.Format("不存在ID为{0}的新闻相似度映射", item.Id));
}
var oldMapNews = Serialization.ConvertStrToDic(map.StrRelatedNewsIds, map.StrSimilarities);
var currentMapNews = updateMapNews.Union(oldMapNews).OrderByDescending(o => o.Value).Take(similarityNum);
//out修饰符无法对属性使用
string tmpRelatedNewIds, tmpSimilarities;
Serialization.ConvertEnumToStr(currentMapNews, out tmpRelatedNewIds, out tmpSimilarities);
map.StrRelatedNewsIds = tmpRelatedNewIds;
map.StrSimilarities = tmpSimilarities;
//保存修改
map.UpdateTime = DateTime.Now;
db.Entry(map).State = EntityState.Modified;
}
}
return(db.SaveChanges());
}