I am trying to manipulate a text (.tex) document (a multiple-choice exam) in Stata, which I realize is a bit strange. I have copied the text to the data editor so that each line is an observation for the variable v1. I have found Stata quite handy for text manipulation, but I am stuck on one issue: I need to duplicate specific blocks of four observations (the MCQ choices) and insert them directly below the original, so that I can manipulate the correct answer. To do this, I thought to start by inserting four blank rows after each question, and then doing a replace. However, I haven't found a way to do this, including through the ingap command.

It is possible to identify each MCQ using strmatch because each question-line begins with "\mc", and likewise the block of choices ends with the same value "\end{MC}". Here is a snippet of the data:

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str145 v1
"%Label1: "                                                                                                                                      
"\mc The production possibility curve (PPC) represents the \_\_\_\_\_\_\_\_ combinations of goods that can be produced with available resources."
"\begin{MC}"                                                                                                                                     
"\item minimum attainable"                                                                                                                       
"\item maximum attainable"                                                                                                              
"\item only"                                                                                                                                     
"\item equitable"                                                                                                                                
"\end{MC}"                                                                                                                                       
"%Label2: "                                                                                                                                      
"\mc A point on the production possibility curve (PPC) is \_\_\_\_ if it is outside of the curve."                                     
"\begin{MC}"                                                                                                                                     
"\item attainable and efficient"                                                                                                                 
"\item attainable and inefficient"                                                                                                               
"\item unattainable"                                                                                                                             
"\item \textbf{None of the above}"                                                                                                               
"\end{MC}"                                                                                                                                       
end
I would like to manipulate the data so that it would now be:

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str145 v1
"%Label1: "                                                                                                                                      
"\mc The production possibility curve (PPC) represents the \_\_\_\_\_\_\_\_ combinations of goods that can be produced with available resources."
"\begin{MC}"                                                                                                                                     
"\item minimum attainable"                                                                                                                       
"\item \textbf{maximum attainable}"                                                                                                              
"\item only"                                                                                                                                     
"\item equitable"                                                                                                                                
"\end{MC}"    
"\begin{MC}"                                                                                                                                     
"\item minimum attainable"                                                                                                                       
"\item \textbf{maximum attainable}"                                                                                                              
"\item only"                                                                                                                                     
"\item equitable"                                                                                                                                
"\end{MC}"                                                                                                                                              
"%Label2: "                                                                                                                                      
"\mc A point on the production possibility curve (PPC) is \_\_\_\_\_\_\_\_\_ if it is outside of the curve."                                     
"\begin{MC}"                                                                                                                                     
"\item attainable and efficient"                                                                                                                 
"\item attainable and inefficient"                                                                                                               
"\item unattainable"                                                                                                                             
"\item \textbf{None of the above}"                                                                                                               
"\end{MC}"                                
"\begin{MC}"                                                                                                                                     
"\item attainable and efficient"                                                                                                                 
"\item attainable and inefficient"                                                                                                               
"\item unattainable"                                                                                                                             
"\item \textbf{None of the above}"                                                                                                               
"\end{MC}"                                                                                                                                         
end