Automatically Rebasing Variables Using a Condition

This example QScript includes a function for rebasing variables.

Method

function rebaseQuestion(question_name, condition) {
         var x = project.dataFiles[0].getQuestionByName(question_name);
         var q_variables = x.variables;
         var qt = x.questionType;
         var is_text = qt == "Text" || qt == "Text - Multi"
         var rebased_vars = [];
         var last = q_variables[q_variables.length-1]; 
         // For each variable, create the appropriate rebased variable.
         for (var j=0;j<q_variables.length;j++) {
             var expression = "if (" + condition + ") "+ q_variables[j].name.toString() + "; else NaN";
             var rebased_var = project.dataFiles[0].newJavaScriptVariable(expression, is_text, q_variables[j].name.toString() + "rebased",q_variables[j].label.toString() , last);
             rebased_vars.push(rebased_var);
             last = rebased_var;
          }
         var new_question = project.dataFiles[0].setQuestion(x.name + " - rebased", qt, rebased_vars);
         if (!is_text) 
             copyValueAttributesForQuestion(x, new_question );
            project.dataFiles[0].moveAfter(x.variables,project.dataFiles[0].variables[project.dataFiles[0].variables.length-1]);
            x.isHidden=true;
            log("The question: \"" + x.name + "\" has been rebased using the condition " + condition + ".");
}

//Copies the value attributes from one variable to another
function copyValueAttributesForVariable(from_variable, to_variable){
         var n = from_variable.uniqueValues
         var values = from_variable.uniqueValues;
         var qt = to_variable.question.questionType;
         var qt_old = from_variable.question.questionType;
         if (qt != qt_old)
           alert("Question types are different.");
         for (var i=0; i<values.length; i++){
             var v = values[i];
         if (qt != "Text" && qt != "Text - Multi"){
               to_variable.valueAttributes.setLabel(v,from_variable.valueAttributes.getLabel(v));
               to_variable.valueAttributes.setIsMissingData(v,from_variable.valueAttributes.getIsMissingData(v));
            if (qt == "Pick Any" || qt == "Pick Any - Compact" || qt == "Pick Any - Grid")
               to_variable.valueAttributes.setCountThisValue(v,from_variable.valueAttributes.getCountThisValue(v));
            else
               to_variable.valueAttributes.setValue(v,from_variable.valueAttributes.getValue(v));
            }
         }
}

//This function copies attributes, variable by variable, from one question to another
function copyValueAttributesForQuestion(from_question, to_question){
         var x = from_question.variables;
         var y = to_question.variables;
         if (y.length != x.length)
         alert('Questions contain different numbers of variables.');
         for (var j=0;j<x.length;j++) 
           copyValueAttributesForVariable(x[j], y[j])
}

Note, the rebaseQuestion function calls two other functions which need to also be included: copyValueAttributesForVariable and copyValueAttributesForQuestion.

Example

The below example filters a series of variable sets based on rules relating to Q2 and Q3:

rebaseQuestion("Q5. Brand associations","Q3 <= 4 && Q2 == 1")
rebaseQuestion("Q10. Why drinks more than one cola","Q3 <= 4 && Q2 == 1")
rebaseQuestion("Q11. Main difference between cola drinkers","Q3 <= 4 && Q2 == 1")
rebaseQuestion("Q6. Brand attitude (numeric -100 to 100)","Q3 <= 4 && Q2 == 1")
rebaseQuestion("Q1. Fragments coded","Q3 <= 4")
rebaseQuestion("Q2. Gender","Q3 <= 4 && Q2 == 1")
rebaseQuestion("Q3. Age","Q3 <= 4")
rebaseQuestion("Q4. Frequency of drinking","Q3 <= 4")

Note, the function code under the Method section needs to additionally appear within your script when running this.