本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# \$1abs
<a name="abs"></a>

Amazon DocumentDB 中的`$abs`運算子會傳回數字的絕對值。它可用於彙總管道，對數值欄位執行數學操作。

**參數**
+ `number`：將傳回絕對值的數值表達式。

## 範例 (MongoDB Shell)
<a name="abs-examples"></a>

此範例示範 `$abs`運算子的使用情況，以尋找數值欄位的絕對值。

**建立範例文件**

```
db.numbers.insertMany([
  { "_id": 1, "value": -5 },
  { "_id": 2, "value": 10 },
  { "_id": 3, "value": -3.14 },
  { "_id": 4, "value": 0 }
]);
```

**查詢範例**

```
db.numbers.aggregate([
  { $project: {
    "_id": 1,
    "absolute_value": { $abs: "$value" }
  }}
]);
```

**輸出**

```
[
  { "_id": 1, "absolute_value": 5 },
  { "_id": 2, "absolute_value": 10 },
  { "_id": 3, "absolute_value": 3.14 },
  { "_id": 4, "absolute_value": 0 }
]
```

## 程式碼範例
<a name="abs-code"></a>

若要檢視使用 `$abs`命令的程式碼範例，請選擇您要使用的語言標籤：

------
#### [ Node.js ]

```
const { MongoClient } = require('mongodb');

async function main() {
  const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');
  const db = client.db('test');
  const collection = db.collection('numbers');

  const result = await collection.aggregate([
    { $project: {
      "_id": 1,
      "absolute_value": { $abs: "$value" }
    }}
  ]).toArray();

  console.log(result);
  await client.close();
}

main();
```

------
#### [ Python ]

```
from pymongo import MongoClient

def main():
    client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
    db = client['test']
    collection = db['numbers']

    result = list(collection.aggregate([
        { '$project': {
            "_id": 1,
            "absolute_value": { "$abs": "$value" }
        }}
    ]))

    print(result)
    client.close()

if __name__ == "__main__":
    main()
```

------