Jqgrid : toolbar search options – range select from a drop down-Collection of common programming errors

I need help to do range select on jqgrid data using the filter toolbar drop down – I checked the sopt options it only has –

['equal','not equal', 'less', 'less or equal','greater','greater or equal', 'begins with','does not begin with','is in','is not in','ends with','does not end with','contains','does not contain']

and I am not able to find any clue on how to do range with this on the toolbar. I have a drop down that has values like "All", "1-4", "5-9" on my filter toolbar and when I select say '1-4' I want the grid to populate all rows that fall in that range. I looked at a bunch of examples for filter from stackoverflow and trirand itself but they all seem to be for the search box. I am grateful for any help to achieve this, Thanks.

I was able to achieve this filter by range based on sample multi-word sample- http://www.ok-soft-gmbh.com/jqGrid/MultiwordSearchingToolbar.htm. Most of the code is from above mentioned sample with minor changes. Modified baseed on feedback from Oleg to make it as le and ge.

    modifySearchingFilter = function (separator) {
            var i, rules, rule, parts, group, str;
            var filters = $.parseJSON(this.p.postData.filters); 
            if(separator != '-')
              return;
            if (filters && typeof filters.rules !== 'undefined' && filters.rules.length > 0) {
                rules = filters.rules;
                for (i = 0; i < rules.length; i++) {
                    rule = rules[i];
                    if (rule.op === 'range') {
                        // Range should only have 2 parts lowerbound and upperbound
                        parts = rule.data.split(separator);
                        if (parts.length == 2) {
                            if (typeof filters.groups === 'undefined') {
                                    filters.groups = [];
                            }
                            group = {
                                groupOp: 'AND',
                                groups: [],
                                rules: []
                            };
                            filters.groups.push(group);
                            // Breaking to 2 rules one le and other ge
                            group.rules.push({
                                        data: (parts[0]),
                                        op: "ge",
                                        field: rule.field
                                    });                             
                            group.rules.push({
                                        data: (parts[1]),
                                        op: "le",
                                        field: rule.field
                                    });                                                                     
                            rules.splice(i, 1);     
                            i--; // to skip i++                             
                        }
                    }
                }
                this.p.postData.filters = JSON.stringify(filters);
            }
        },


 //using range op so that it is not confused with other ops
 setRangeSearchSelect = function(columnName) {
        grid.jqGrid('setColProp', columnName,
        {
           stype: 'select',
           searchoptions: {                                 value:buildRangeSearchSelect(),
                 sopt:['range'],                            
        }
     });
    };

 grid.jqGrid('filterToolbar',  
    {
     stringResult:true, 
     searchOnEnter:true,      
     defaultSearch:"cn", 
     beforeSearch: function () {  
       modifySearchingFilter.call(this, '-');    
     }});