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> 计算输入值的移动平均。

# groupArrayMovingAvg

<div id="groupArrayMovingAvg">
  ## groupArrayMovingAvg
</div>

引入版本：v20.1.0

计算输入值的移动平均。

<Note>
  该函数采用向零舍入。
  它会截去对结果数据类型无意义的小数位。
</Note>

**语法**

```sql theme={null}
groupArrayMovingAvg(numbers_for_summing)
groupArrayMovingAvg(window_size)(numbers_for_summing)
```

**参数**

* `window_size` — 计算窗口的大小。若未指定，函数会将窗口大小设为该列中的行数。[`UInt64`](/zh/reference/data-types/int-uint)

**参数列表**

* `numbers_for_summing` — 结果为数值数据类型值的表达式。[`(U)Int*`](/zh/reference/data-types/int-uint) 或 [`Float*`](/zh/reference/data-types/float) 或 [`Decimal`](/zh/reference/data-types/decimal)

**返回值**

返回一个与输入数据大小相同的数组。对于非 Decimal 输入，数组包含 Float64 值。对于 Decimal 输入，数组包含标度与输入相同的 Decimal 值。[`Array`](/zh/reference/data-types/array)

**示例**

**用法示例**

```sql title=Query theme={null}
CREATE TABLE t
(
    `int` UInt8,
    `float` Float32,
    `dec` Decimal32(2)
)
ENGINE = Memory;

INSERT INTO t VALUES (1, 1.1, 1.10), (2, 2.2, 2.20), (4, 4.4, 4.40), (7, 7.77, 7.77);

SELECT
    groupArrayMovingAvg(int) AS I,
    groupArrayMovingAvg(float) AS F,
    groupArrayMovingAvg(dec) AS D
FROM t;
```

```response title=Response theme={null}
┌─I────────────────────┬─F─────────────────────────────────────────────────────────────────────────────┬─D─────────────────────┐
│ [0.25,0.75,1.75,3.5] │ [0.2750000059604645,0.8250000178813934,1.9250000417232513,3.8675000369548798] │ [0.27,0.82,1.92,3.86] │
└──────────────────────┴───────────────────────────────────────────────────────────────────────────────┴───────────────────────┘
```

**指定窗口大小**

```sql title=Query theme={null}
SELECT
    groupArrayMovingAvg(2)(int) AS I,
    groupArrayMovingAvg(2)(float) AS F,
    groupArrayMovingAvg(2)(dec) AS D
FROM t;
```

```response title=Response theme={null}
┌─I───────────────┬─F───────────────────────────────────────────────────────────────────────────┬─D─────────────────────┐
│ [0.5,1.5,3,5.5] │ [0.550000011920929,1.6500000357627869,3.3000000715255737,6.085000038146973] │ [0.55,1.65,3.30,6.08] │
└─────────────────┴─────────────────────────────────────────────────────────────────────────────┴───────────────────────┘
```