Accessing local variable in angularjs controller

It's possible this could be a timing issue. Perhaps the for-loop is executing before the $http.get() returns a result. Have you tried executing the for-loop after $scope.rep is initialized like so?

(function loadData(){
    $http.get('result.json').
        then(function(data) {
                    angular.forEach(data['data'],function(value, key){
                        $scope.rep[key] = value;
                        $scope.rep[key].marketValue    = parseFloat(value.marketValue);
                        $scope.rep[key].cash           = parseFloat(value.cash);
                    });
                } ,
                 function(data) {
                    console.log("My error: " + data);
                }
            );
        })
        .then(function() {
          for (var i = 0; i < $scope.rep.length; i++) {
            $scope.totals.marketValue += $scope.rep[i].marketValue;
            $scope.totals.cash += $scope.rep[i].cash;
          }
        })(); // IIFE

$http.get() returns a promise, and only once that promise gets resolved does it run all the code in the .then() blocks. (Either the first success callback one if the promise was resolved, or the second error callback if the promise is rejected.)

By the time your code reaches the for loop, you've received a promise object from the $http.get(), but you haven't yet run the code inside the .then() block, where you're setting values inside $scope.rep. The for loop doesn't execute because $scope.rep.length is 0, so no iterations.

To fix this, you could put your for loop inside your .then() block like this:

(function loadData() {
    $http.get('result.json')
        .then(function (data) {
            angular.forEach(data['data'], function (value, key) {
                $scope.rep[key] = value;
                $scope.rep[key].marketValue = parseFloat(value.marketValue);
                $scope.rep[key].cash = parseFloat(value.cash);
            });

            for (var i = 0; i < $scope.rep.length; i++) {
                $scope.tot.marketValue += $scope.rep[i].marketValue;
                $scope.tot.cash += $scope.rep[i].cash;
            }
        }, function (data) {
            console.log("My error: " + data);
        });
})();

I believe that should do it.