Vanou’s Blog

///<summary>
///Extention Method For IEnumerable Objects that returns random items from the source
///</summary>
///<typeparam name=”T”>Type of objects in array</typeparam>
///<param name=”source”>IEnumerable source(items in source must be of type T)</param>
///<param name=”howMany”>Number of items toreturn</param>
///<returns>Randomly returns a List T of specified number of items inthe IEnumerable source</returns>
public static List<T>TakeRandom<T>(this IEnumerable<T> source,int howMany)
{
    //if the source object is null the function return a new List<T>
    if(source ==null)
        return new List<T>();

    var array = source.ToArray();
    Random random =new Random();
    for(vari = 0; i <Math.Min(howMany,array.Length); i++)
    {
        var currentItem = random.Next(i, array.Length);
        var temp = array[i];
        array[i] = array[currentItem];
        array[currentItem] = temp;
    }
    return array.Take<T>(howMany).ToList();
}
///<summary>
///Extension method for IEnumerable objects that return an item randomly chosen from the source
///</summary>
///<typeparam name=”T”>Type of object contained in the source</typeparam>
///<param name=”source”>IEnumerable source that contains many T objects</param>
///<returns>Returns an item of type T</returns>
public staticT TakeRandom<T>(this IEnumerable<T> source)
{
    //if the IEnumerable source object is null the function returns the default(T)
    if (source ==null)
        return default(T);
    List<T> list = TakeRandom(source, 1);
    T objectToReturn =default(T);
    if (list !=null)
        if (list.Count > 0)
            objectToReturn = list[0];
    return objectToReturn;
}
///<summary>
///Extension Method for IEnumerable object that returns if the collection is Empty
///</summary>
///<typeparam name=”T”></typeparam>
///<param name=”source”>IEnumerable object</param>
///<returns>Returns true if there is no items in the collection</returns>
public static bool IsEmpty<T>(this IEnumerable<T> source)
{
    if (source ==null)
        return true;
    else
        return source.Count() == 0 ?true:false;
}
///<summary>
///Extension method for objects that implement the IList interface
///This method update an item from the list with a new one
/////TODO: maybe add the predicate in the function itself to find if oldItem has a match in the list
///</summary>
///<typeparam name=”T”>T of objects in the List</typeparam>
///<param name=”source”>Source List (must implement IList)</param>
///<param name=”oldItem”>Old Item T to find and update</param>
///<param name=”newIitem”>New Item T</param>
public static void Update<T>(this IList<T> source,T oldItem, T newIitem)
{
    if (source !=null)
    {
        for (inti = 0; i <= source.Count() – 1; i++)
        {
            if (source[i].ToString() == oldItem.ToString())
            {
                source[i] = newIitem;
                //once the item is found, exit the function
                break;
            }
        }
    }
}