def calc_default_colors(p_index):
    """List of default colors, lines, and markers to use if user does not 
    specify them in the input yaml file.
    
    Parameters
    ----------
    p_index : integer
        Number of pairs in analysis class
    
    Returns
    -------
    list
        List of dictionaries containing default colors, lines, and 
        markers to use for plotting for the number of pairs in analysis class
        
    """
    x = [dict(color='b', linestyle='--',marker='x'),
         dict(color='g', linestyle='-.',marker='o'),
         dict(color='r', linestyle=':',marker='v'),
         dict(color='c', linestyle='--',marker='^'),
         dict(color='m', linestyle='-.',marker='s')]
    #Repeat these 5 instances over and over if more than 5 lines.
    return x[p_index % 5]