Convert columns to rows using LINQ
In this article we will do the same thing, but using C#’s arrays and datatables, using the power of LINQ or Lambda expressions
C# array collection or List<T> rows to columns to DataTable
Here is the C# object
var data = new[] {
new { Product = "Product 1", Year = 2009, Sales = 1212 },
new { Product = "Product 2", Year = 2009, Sales = 522 },
new { Product = "Product 1", Year = 2010, Sales = 1337 },
new { Product = "Product 2", Year = 2011, Sales = 711 },
new { Product = "Product 2", Year = 2012, Sales = 2245 },
new { Product = "Product 3", Year = 2012, Sales = 1000 }
};
var pivotTable1 = data.ToPivotTable(item => item.Year, item => item.Product, items => items.Any() ? items.Sum(x => x.Sales) : 0);
jsonStr = JsonConvert.SerializeObject(pivotTable);
//Row to column
Below is the extension method we defined
public static DataTable ToPivotTable<T, TColumn, TRow, TData>(
this IEnumerable<T> source,
Func<T, TColumn> columnSelector,
Expression<Func<T, TRow>> rowSelector,
Func<IEnumerable<T>, TData> dataSelector)
{
DataTable table = new DataTable();
var rowName = ((MemberExpression)rowSelector.Body).Member.Name;
table.Columns.Add(new DataColumn(rowName));
var columns = source.Select(columnSelector).Distinct();
foreach (var column in columns)
table.Columns.Add(new DataColumn(column.ToString()));
var rows = source.GroupBy(rowSelector.Compile())
.Select(rowGroup => new
{
Key = rowGroup.Key,
Values = columns.GroupJoin(
rowGroup,
c => c,
r => columnSelector(r),
(c, columnGroup) => dataSelector(columnGroup))
});
foreach (var row in rows)
{
var dataRow = table.NewRow();
var items = row.Values.Cast<object>().ToList();
items.Insert(0, row.Key);
dataRow.ItemArray = items.ToArray();
table.Rows.Add(dataRow);
}
return table;
}
You can create a static class for the extension method and put it there.
To convert year values into columns and get a pivot table:
C# Convert List<T> collection rows to anonymous object collection
After converting the columns to rows, you may want to get a List<dynamic> or dynamic[] instead of getting a DataTable. It's very convenient in ASP. NET Web API returns a JSON response.
To do this, I updated the extension method to get the dynamic object. Use the following extension method:
?
public static List<dynamic> ToPivotArray<T, TColumn, TRow, TData>(
this IEnumerable<T> source,
Func<T, TColumn> columnSelector,
Expression<Func<T, TRow>> rowSelector,
Func<IEnumerable<T>, TData> dataSelector)
{
var arr = new List<object>();
var cols = new List<string>();
String rowName = ((MemberExpression)rowSelector.Body).Member.Name;
var columns = source.Select(columnSelector).Distinct();
cols =(new []{ rowName}).Concat(columns.Select(x=>x.ToString())).ToList();
var rows = source.GroupBy(rowSelector.Compile())
.Select(rowGroup => new
{
Key = rowGroup.Key,
Values = columns.GroupJoin(
rowGroup,
c => c,
r => columnSelector(r),
(c, columnGroup) => dataSelector(columnGroup))
}).ToArray();
foreach (var row in rows)
{
var items = row.Values.Cast<object>().ToList();
items.Insert(0, row.Key);
var obj = GetAnonymousObject(cols, items);
arr.Add(obj);
}
return arr.List();
}
private static dynamic GetAnonymousObject(IEnumerable<string> columns, IEnumerable<object> values)
{
IDictionary<string, object> eo = new ExpandoObject() as IDictionary<string, object>;
int i;
for (i = 0; i < columns.Count(); i++)
{
eo.Add(columns.ElementAt<string>(i), values.ElementAt<object>(i));
}
return to him;
}
ExpandoObject is used to create dynamic objects
Now, to convert rows to columns and get dynamic array
C# Convert Datatable rows to Datatable
Let's have a data table with the same data
DataTable myDataTable = new DataTable();
myDataTable.Columns.AddRange(new DataColumn[3] { new DataColumn("Product"),
new DataColumn("Year", typeof(int)), new DataColumn("Sales", typeof(int)) });
myDataTable.Rows.Add("Product 1", 2009, 1212);
myDataTable.Rows.Add("Product 2", 2009, 522);
myDataTable.Rows.Add("Product 1", 2010, 1337);
myDataTable.Rows.Add("Product 2", 2011, 711);
myDataTable.Rows.Add("Product 2", 2012, 2245);
myDataTable.Rows.Add("Product 3", 2012, 1000);
You can use the same extension method to get a row-to-column DataTable as shown below.
DataTable to List<dynamic>:
If you need to convert a DataTable to a List of dynamic objects, then use the following extension method:
public static List<dynamic> ToDynamicList(this DataTable dt)
{
var list = new List<dynamic>();
foreach (DataRow row in dt.Rows)
{
dynamic dyn = new ExpandoObject();
list.Add(dyn);
foreach (DataColumn column in dt.Columns)
{
var dic = (IDictionary<string, object>)dyn;
dic[column.ColumnName] = row[column];
}
}
return list;
}