Best way to render two dimensional table in grails -

i need table displayed , headings, have 2 lists:

list1 = [a, b, c, d, e, f, g] 

and list2 list of maps

list2 = [ [from: a, to: a, val:20],           [from: a, to: b, val:10],           [from: a, to: c, val:30],           [from: b, to: a, val:10],           [from: b, to: b, val:40] ] 

the result should be

from  b  c  d e f g       20 10 30 - - - -  b      10 40 -  - - - -   c      -  -  -  - - - -  d      -  -  -  - - - -    e      -  -  -  - - - -  f      -  -  -  - - - -  g      -  -  -  - - - - 

how can that?

<table>     <tr>         <th>from</th>         <th>to</th>         <g:each in="${list1}" var="item">             <th>${item}</th>         </g:each>     </tr>     <g:each in="${list1}" var="fromitem">         <tr>             <td>${fromitem}</td>             <td></td>             <g:each in="${list1}" var="toitem">                 <td>                       ${list2.find{it.from==fromitem && it.to==toitem}?.val?:"-"}                 </td>              </g:each>          </tr>      </g:each> </table>