Calculate Columns Row Total in SharePoint Designer 2010 (Data Form/XSLT Web Part)

Question

I am using Data Form Web Part in SharePoint Designer 2010 (or XSLT Web Part would also work):

I have a table like below:

ColumnA         ColumnB         Status

Project1        Task1.1         Completed

Project1        Task1.2         Pending

Project1        Task1.3         Completed

Project2        Task2.1         Completed

Project3        Task3.1         Completed

Project3        Task3.2         Completed

Project3        Task3.3         Completed

Project3        Task3.4         Pending

Project3        Task3.5         Pending

What I want to achieve is:

Project1        66.67 ((Completed Task / Total Task) * 100)

Project2        100

Project3        60

Answer 1

I don't think this can be done with the SPD 2010 Visual Designer, but could probably be done by hand coding some custom xslt. In my opinion however , your best bet would be to get the data to the browser using csom or rest or spservices and render it there using javascript (maybe jsrender templates). I think you need either custom XSLT or custom javascript to do this.