Generate json by prediction.

def generate_predict_json(position1_result, position2_result, ids, passage_tokens):
    '''
    Generate json by prediction.
    '''
    predict_len = len(position1_result)
    logger.debug('total prediction num is %s', str(predict_len))

    answers = {}
    for i in range(predict_len):
        sample_id = ids[i]
        passage, tokens = passage_tokens[i]
        kbest = find_best_answer_span(
            position1_result[i], position2_result[i], len(tokens), 23)
        _, start, end = kbest[0]
        answer = passage[tokens[start]['char_begin']:tokens[end]['char_end']]
        answers[sample_id] = answer
    logger.debug('generate predict done.')
    return answers