> For the complete documentation index, see [llms.txt](https://eastlakeside.gitbook.io/interpy-zh/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://eastlakeside.gitbook.io/interpy-zh/map_n_filter/reduce.md).

# Reduce

当需要对一个列表进行一些计算并返回结果时，`Reduce` 是个非常有用的函数。举个例子，当你需要计算一个整数列表的乘积时。

通常在 python 中你可能会使用基本的 for 循环来完成这个任务。

现在我们来试试 reduce：

```python
from functools import reduce
product = reduce( (lambda x, y: x * y), [1, 2, 3, 4] )

# Output: 24
```


---

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