# Python 匿名表达式

Python 高阶函数编程，使用 lambda 表达式获取key，将list转成dict

```python

def list_to_dict(list, key_func):
    d = {}
    for item in list:
        k = key_func(item)
        v = item
        list = d.get(k)
        if list is None:
            d[k] = [v]
        else:
            d[k].append(v)

    return d


if __name__ == '__main__':
    list = [
        {"name": "alice", "age": 100},
        {"name": "middle", "age": 100},
        {"name": "bob", "age": 200}
    ]
    # TODO(You): 请在此调用 list_to_dict 方法，将 list 转成dict
    print(ret)
```

请选出下列**实现错误**的选项。

## template

```python

def list_to_dict(list, key_func):
    d = {}
    for item in list:
        k = key_func(item)
        v = item
        list = d.get(k)
        if list is None:
            d[k] = [v]
        else:
            d[k].append(v)

    return d


if __name__ == '__main__':
    list = [
        {"name": "alice", "age": 100},
        {"name": "middle", "age": 100},
        {"name": "bob", "age": 200}
    ]
    ret = list_to_dict(list, lambda item: item['age'])
    print(ret)
```

## 答案

```python
ret = list_to_dict(list, lambda item: 
    item['age']
)
```

## 选项

### A

```python
ret = list_to_dict(list, lambda item: item['age'])
```

### B

```python
def get_key(item):
    return item['age']

ret = list_to_dict(list, get_key)
```

### C

```python
get_key = lambda item: item['age']
ret = list_to_dict(list, get_key)
```