def get_max_length(matrix, tactics):
    """Given a matrix and a tactics list, returns the maximum column size"""

    max_len = 0
    for tactic in tactics:
        if matrix.get(tactic['x_mitre_shortname']):
            if len(matrix[tactic['x_mitre_shortname']]) > max_len:
                max_len = len(matrix[tactic['x_mitre_shortname']])
    return max_len