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| 1 | +#### map(__func, __iter) |
| 2 | +map会将一个函数映射到一个输入列表的所有元素上. |
| 3 | +```python |
| 4 | +list_x = [1, 2, 3, 4, 5, 6, 7, 8] |
| 5 | +list_x_multi_two = map(lambda x: 2 * x, list_x) |
| 6 | +# <map object at 0x000001E696035DA0> |
| 7 | +print(list_x_multi_two) |
| 8 | +# [2, 4, 6, 8, 10, 12, 14, 16] |
| 9 | +print(list(list_x_multi_two)) |
| 10 | +``` |
| 11 | + |
| 12 | +#### filter(__func, __iter) |
| 13 | +过滤列表中的元素 |
| 14 | +```python |
| 15 | +list_x = [1, 2, 3, 4, 5, 6, 7, 8] |
| 16 | +list_x_more_than_5 = filter(lambda x: x > 5, list_x) |
| 17 | +# <filter object at 0x000001E69601D630> |
| 18 | +print(list_x_more_than_5) |
| 19 | +# [6, 7, 8] |
| 20 | +print(list(list_x_more_than_5)) |
| 21 | +``` |
| 22 | + |
| 23 | +#### 列表推导式部分情况可以替代map，filter函数 |
| 24 | +```python |
| 25 | +# [2, 4, 6, 8, 10, 12, 14, 16] |
| 26 | +print([x*2 for x in list_x]) |
| 27 | + |
| 28 | +# [6, 7, 8] |
| 29 | +print([x for x in list_x if x > 5]) |
| 30 | +``` |
| 31 | + |
| 32 | +#### reduce(func, sequence) |
| 33 | +对参数序列中元素进行累计计算。用传给 reduce 中的函数 function（有两个参数）先对集合中的第 1、2 个元素进行操作，得到的结果再与第三个数据用 function 函数运算，最后得到一个结果。 |
| 34 | +```python |
| 35 | +from functools import reduce |
| 36 | + |
| 37 | +sum_ = reduce((lambda x, y:x+y), list_x) |
| 38 | +print(sum_) # 36 |
| 39 | +``` |
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