Question

i need to read data from some excel sheets. The data in the excel sheets is already formatted in such a way that i am able to get the desired data by using this method.

This is what i am doing:

using (var conn = new OleDbConnection(strBld.ToString()))
{
    conn.Open();

    IEnumerable<IDictionary<string, object>> excelDataRaw = 
        conn.Query("select * from [Curves$A:IT]").
        Cast<IDictionary<string, object>>();

    int i = 0;
    string previousKey = null;
    var curve = new List<IEnumerable<object>>();
    var excelData = new Dictionary<string, IDictionary<object, object>>();
    //var excelData = new Dictionary<string, IDictionary<string, decimal>>();

    foreach (var key in excelDataRaw.Select(dictionary => dictionary.Keys).
        ElementAt(i))
    {
        string key1 = key;
        // gets the data from one column within the excel file
        curve.Add(excelDataRaw.Select(col => col[key1]).
            Where(row => row != null).ToList());

        if (i % 2 == 0)
        {
            // store the column header
            previousKey = key;
        }

        if (i % 2 == 1)
        {
            // merge the data from the first column (keys)
            // with the data from the second column (values)
            IEnumerable<object> keys = curve[i - 1];
            IEnumerable<object> values = curve[i];
            // cast works but than you can't zip the lists together
            //IEnumerable<string> keys = curve[i - 1].Cast<string>();
            //IEnumerable<decimal> values = curve[i].Cast<decimal>();

            // zip them together on their index
            var dic = keys.Zip(values, (k, v) => new { k, v }).
                ToDictionary(x => x.k, x => x.v);

            if (previousKey != null)
            {
                if (!excelData.ContainsKey(previousKey))
                {
                    excelData.Add(previousKey, dic);
                }
            }
        }

        ++i;
    }
}

I extract all data from the excel file (excelDataRaw). i then select all data that belongs together into a list (curve) and combine two lists that belong to each other into a dictionary (dic). The final result is a dictionary (excelData) that contains the column head from the excel file as a key (previousKey) and the data relevant to this column head as a dictionary (dic).

I would like to cast the dictionary (excelData) from

Dictionary<string, IDictionary<object, object>> 

into

Dictionary<string, IDictionary<string, decimal>> 

but i can’t cast object into string or decimal and i can’t zip the lists together to get the dictionary (dic) after casting each list to the desired type. Has anyone an idea how to achieve the desired result(type)?

Answer 1

Well i found a solution, I must have overlooked the obvious yesterday. A good night of sleep helps sometimes :).

IEnumerable<object> keys = curve[i - 1];
IEnumerable<object> values =
    curve[i].Where(content => decimal.TryParse(content.ToString(), out num));
    Dictionary<string, decimal> dic =
        keys.Zip(values, (k, v) => new { k, v }).ToDictionary(
            x => (string)x.k, x => decimal.Parse(x.v.ToString()));
if (previousKey != null)
{
    if (!excelData.ContainsKey(previousKey))
    {
        excelData.Add(previousKey, dic);
    }
}