addding a counting colum to a numpy array in python : I have a 2d numpy array ans i.e  
    
    ans=[8,5,9,2,4]


  
i want to convert it into a 2d array like  
   

    ans=
    {[1,8],  
    [2,5],       
    [3,9],  
    [4,2],  
    [5,4]}  
the first column is in sequence 
        
    [1,2,3......500,501..]
how to do this in python

 