Elasticsearch edge_ngram token_chars 空格

Question

有人可以告诉我 Elasticsearch edge_ngram token_chars whitespace 是如何工作的吗？ Token_chars 应该定义将包含在令牌中的符号。那么如果我使用 token_chars: ['letter', 'digit', 'whitespace'] 在短语“2 red foxes”的上下文中意味着什么？据我了解，它将以这种方式生成令牌 ['2', '2', '2 r', '2 re', '2 red']。我是对的吗，令牌没有按空格拆分，但空格将包含在令牌中？ 谢谢

Answer 1

总的来说，你是对的，但这也取决于 min_gram 和 max_gram 参数值。

往下看

示例 1.

min_gram = 2 和 max_gram = 10

映射

PUT /so54090009
{
  "settings": {
    "analysis": {
      "analyzer": {
        "my_analyzer": {
          "tokenizer": "my_tokenizer"
        }
      },
      "tokenizer": {
        "my_tokenizer": {
          "type": "edge_ngram",
          "min_gram": 2,
          "max_gram": 10,
          "token_chars": [
            "letter",
            "digit",
            "whitespace"
          ]
        }
      }
    }
  }
}

分析

POST /so54090009/_analyze
{
  "analyzer": "my_analyzer",
  "text": "2 red foxes"
}

回应

{
  "tokens": [
    {
      "token": "2 ",
      "start_offset": 0,
      "end_offset": 2,
      "type": "word",
      "position": 0
    },
    {
      "token": "2 r",
      "start_offset": 0,
      "end_offset": 3,
      "type": "word",
      "position": 1
    },
    {
      "token": "2 re",
      "start_offset": 0,
      "end_offset": 4,
      "type": "word",
      "position": 2
    },
    {
      "token": "2 red",
      "start_offset": 0,
      "end_offset": 5,
      "type": "word",
      "position": 3
    },
    {
      "token": "2 red ",
      "start_offset": 0,
      "end_offset": 6,
      "type": "word",
      "position": 4
    },
    {
      "token": "2 red f",
      "start_offset": 0,
      "end_offset": 7,
      "type": "word",
      "position": 5
    },
    {
      "token": "2 red fo",
      "start_offset": 0,
      "end_offset": 8,
      "type": "word",
      "position": 6
    },
    {
      "token": "2 red fox",
      "start_offset": 0,
      "end_offset": 9,
      "type": "word",
      "position": 7
    },
    {
      "token": "2 red foxe",
      "start_offset": 0,
      "end_offset": 10,
      "type": "word",
      "position": 8
    }
  ]
}

示例 2.

min_gram = 1 和 max_gram = 5

映射

PUT /so54090009
{
  "settings": {
    "analysis": {
      "analyzer": {
        "my_analyzer": {
          "tokenizer": "my_tokenizer"
        }
      },
      "tokenizer": {
        "my_tokenizer": {
          "type": "edge_ngram",
          "min_gram": 1,
          "max_gram": 5,
          "token_chars": [
            "letter",
            "digit",
            "whitespace"
          ]
        }
      }
    }
  }
}

分析

POST /so54090009/_analyze
{
  "analyzer": "my_analyzer",
  "text": "2 red foxes"
}

回应

{
  "tokens": [
    {
      "token": "2",
      "start_offset": 0,
      "end_offset": 1,
      "type": "word",
      "position": 0
    },
    {
      "token": "2 ",
      "start_offset": 0,
      "end_offset": 2,
      "type": "word",
      "position": 1
    },
    {
      "token": "2 r",
      "start_offset": 0,
      "end_offset": 3,
      "type": "word",
      "position": 2
    },
    {
      "token": "2 re",
      "start_offset": 0,
      "end_offset": 4,
      "type": "word",
      "position": 3
    },
    {
      "token": "2 red",
      "start_offset": 0,
      "end_offset": 5,
      "type": "word",
      "position": 4
    }
  ]
}