Programmatically add column definitions to a DataGrid in Wpf and MVVM? -

i want create pivot table in user interface.

note please note number of columns not static.

and er diagram

here main view model

public class mainviewmodel : viewmodelbase {      public observablecollection<colorviewmodel> colors { get; set; } } 

colorviewmodel class

public class colorviewmodel : viewmodelbase {     public public observablecollection<sizeqtyinformationviewmodel> sizeqtyinformationlist { get; set; } } 

sizeqtyinformationviewmodel class

public sizeqtyinformationviewmodel : viewmodelbase {     public size { get; set; }      public quantity { get; set; } } 

so now, wanna bind these datagrid , desired result.

i have idea don't know how implement this.

the idea is:

if can define column definitions programmatically, able bind columns well.

is there way implement above idea? or there way solve problem?