使用斯坦福大学，我想在完成pos标记后获得句子中的所有形容词和名词，并将它们存储在单独的字符串中

from nltk.tag import StanfordPOSTagger
from nltk.tokenize import word_tokenize

# 设置Stanford NLP的路径和模型文件路径
stanford_pos_dir = 'stanford-postagger'
stanford_pos_model = stanford_pos_dir + '/models/english-bidirectional-distsim.tagger'
stanford_pos_jar = stanford_pos_dir + '/stanford-postagger.jar'

# 初始化Stanford POS标注器
pos_tagger = StanfordPOSTagger(stanford_pos_model, stanford_pos_jar)

# 输入句子
sentence = "I want to extract all the adjectives and nouns from this sentence."

# 分词
tokens = word_tokenize(sentence)

# 进行POS标记
pos_tags = pos_tagger.tag(tokens)

# 提取形容词和名词
adjectives = []
nouns = []
for word, pos in pos_tags:
    if pos.startswith('JJ'):  # 形容词的词性标记以'JJ'开头
        adjectives.append(word)
    elif pos.startswith('NN'):  # 名词的词性标记以'NN'开头
        nouns.append(word)

# 将形容词和名词存储在单独的字符串中
adjectives_str = ' '.join(adjectives)
nouns_str = ' '.join(nouns)

# 打印结果
print("Adjectives:", adjectives_str)
print("Nouns:", nouns_str)