Linq multi level grouping -

i trying implement multi level grouping in linq

in sql that.

select varid, variable, ut ,         (case when resultat >= 0 sum(resultat) else 0) positive,        (case when resultat < 0 sum(resultat) else 0) negatif        (select varid, variable, ut , valeur, sum( resultat ) indicrow               group varid, variable, ut , valeur) group varid, variable, ut  

i have created in linq can't find way group on result of group by

var chartline = indicrow in indic_dt.asenumerable()                             //where seltradeid.contains(indicrow.field<int>("tradenum"))                             group indicrow new                             {                                 gpvariable = indicrow.field<string>("variable"),                                 gput = indicrow.field<string>("ut"),                                 gpvarid = indicrow.field<int>("varid"),                                 gpvalue = indicrow.field<double>("valeur")                             } rdval                             select new                             {                                 varid = rdval.key.gpvarid,                                 variable = rdval.key.gpvariable,                                 ut = rdval.key.gput,                                 valeur = rdval.key.gpvalue,                                 resultat = rdval.sum(indicrow => indicrow.field<double>("resultat_euronet"))                             }; 

the final goal obtain 5 columns datatable (varid, variable, ut, positive, negative)

the general pattern fro two-level grouping is

from t in mains group t t.groupproperty1 maingroup select new { maingroup.key,              maincount = maingroup.count(),               subgroups = mg in maingroup                          group mg mg.groupproperty2 subgroup                          select new { subgroup.key,                                       subcount = subgroup.count()                                     }            } 

so main grouping varid, variable, ut , sub grouping valeur, because sub group contains items of 1 main group.