def assign_x_coord(row):
    """
    Assigns an x-coordinate to Statcast's strike zone numbers. Zones 11, 12, 13,
    and 14 are ignored for plotting simplicity.
    """
    # left third of strik zone
    if row.zone in [1,4,7]:
        return 1

    # middle third of strike zone
    if row.zone in [2,5,8]:
        return 2

    # right third of strike zone
    if row.zone in [3,6,9]:
        return 3