How to delete a Dictionary row that is a Double by using an Int?

Question

Hi,

I have a Dictionary object that is formed using a double as its key values. It looks like this:

Dictionary<double, ClassName> VariableName = new Dictionary<double, ClassName>();

For my project I have to have the key as the double as I require values like 1.1,1.2,2.1,2.2,etc in my system.

Everything in my system works great except when I want to delete all the keys in a group eg all the 1 values would be 1.1,1.2, etc.

I can delete rows if I know the full value of the key eg 1.1 but in my system I will only know the whole number.

I tried to do the following but get an error:

DictionaryVariable.Remove(j => Convert.ToInt16(j.Key) == rowToEdit).OrderByDescending(j => j.Key);

Is there anyway to remove all rows per int value by converting the key?

Thanks, Rich

Answer 1

First, consider using Decimal instead of Double. Double is floating-point and it is not appropriate for exact comparisons (which is essential for key-value lookups). You would still be able to handle numbers such as 1.1 or 2.2.

Second, what you need is:

dictionary.Remove(rowToEdit); // where rowToEdit is the
                              // key of the key-value par you want
                              // to remove

EDIT: To remove values where rowToEdit is an integer and you want remove everthing where rowToEdit <= k < (rowToEdit + 1)

var removedKeys = x.Keys
    .Where(k => k >= 0 ? Math.Floor(k) : Math.Ceiling(k) == rowToEdit).ToArray();
foreach (var key in removedKeys) dictionary.Remove(key);

Answer 2

Try this:

var filter = dictionary.Where(x => x.Key - rowToEdit < 1).ToArray();
foreach (var pair in filter)
{
    dictionary.Remove(pair.Key);
}

Answer 3

You can use LINQ:

var itemsToDelete = from key in dictionary.Keys where ((int)key).Equals(intValueToDelete) select key;
foreach (var keyToDelete in itemsToDelete)
{
    dictionary.Remove(value);
}