如何在列表，字典，集合中根据条件筛选数据？

思路：
列表解析：[for x in data if x >= 0]
filter函数：filter(lambda x:x>=0 ,data)
字典解析：{k,v for k,v in d.items() if v > 90}
集合：{x for x in s if x % 3 == 0}

代码：

In [7]: from random import randint

In [8]: l = [ randint(-10,10) for _ in range(10) ]

In [9]: l
Out[9]: [-9, -7, 4, -9, 3, 10, 3, 10, -2, 4]

In [10]: [x for x in l if x >= 0]
Out[10]: [4, 3, 10, 3, 10, 4]

In [11]: g = filter(lambda x: x>=0,l)

In [12]: g
Out[12]: <filter at 0x7fa6af0967b8>

In [13]: next(g)
Out[13]: 4

In [14]: next(g)
Out[14]: 3

In [15]: next(g)
Out[15]: 10

In [16]: next(g)
Out[16]: 3

In [17]: next(g)
Out[17]: 10

In [18]: 

In [18]: next(g)
Out[18]: 4

In [19]: next(g)
---------------------------------------------------------------------------
StopIteration                             Traceback (most recent call last)
<ipython-input-19-e734f8aca5ac> in <module>
----> 1 next(g)

StopIteration: 

In [20]: list(g)
Out[20]: []

In [21]: g = filter(lambda x: x>=0,l)

In [22]: list(g)
Out[22]: [4, 3, 10, 3, 10, 4]

In [23]: {'Student%d' % i: randint(50,100) for i in range(1,21)}
Out[23]: 
{'Student1': 70,
 'Student2': 67,
 'Student3': 90,
 'Student4': 81,
 'Student5': 86,
 'Student6': 50,
 'Student7': 67,
 'Student8': 86,
 'Student9': 73,
 'Student10': 95,
 'Student11': 96,
 'Student12': 67,
 'Student13': 68,
 'Student14': 58,
 'Student15': 92,
 'Student16': 67,
 'Student17': 81,
 'Student18': 54,
 'Student19': 100,
 'Student20': 68}

In [24]: d = {'Student%d' % i: randint(50,100) for i in range(1,21)}

In [25]: d
Out[25]: 
{'Student1': 69,
 'Student2': 71,
 'Student3': 75,
 'Student4': 76,
 'Student5': 74,
 'Student6': 79,
 'Student7': 99,
 'Student8': 95,
 'Student9': 98,
 'Student10': 54,
 'Student11': 60,
 'Student12': 67,
 'Student13': 59,
 'Student14': 97,
 'Student15': 79,
 'Student16': 51,
 'Student17': 92,
 'Student18': 84,
 'Student19': 78,
 'Student20': 64}

In [26]: {k:v for k,v in d.items() if v >= 90}
Out[26]: 
{'Student7': 99,
 'Student8': 95,
 'Student9': 98,
 'Student14': 97,
 'Student17': 92}

In [27]: d.items()
Out[27]: dict_items([('Student1', 69), ('Student2', 71), ('Student3', 75), ('Student4', 76), ('Student5', 74), ('Student6', 79), ('Student7', 99), ('Student8', 95), ('Student9', 98), ('Student10', 54), ('Student11', 60), ('Student12', 67), ('Student13', 59), ('Student14', 97), ('Student15', 79), ('Student16', 51), ('Student17', 92), ('Student18', 84), ('Student19', 78), ('Student20', 64)])

In [28]: g = filter(lambda item:item[1] >= 90,d.items())

In [29]: g
Out[29]: <filter at 0x7fa6aeec4630>

In [30]: list(g)
Out[30]: 
[('Student7', 99),
 ('Student8', 95),
 ('Student9', 98),
 ('Student14', 97),
 ('Student17', 92)]

In [31]: g = filter(lambda item:item[1] >= 90,d.items())

In [32]: dict(g)
Out[32]: 
{'Student7': 99,
 'Student8': 95,
 'Student9': 98,
 'Student14': 97,
 'Student17': 92}

In [33]: {randint(0,20) for _ in range(20)}
Out[33]: {5, 6, 7, 8, 10, 11, 12, 13, 14, 17, 18, 19, 20}

In [34]: s = {randint(0,20) for _ in range(20)}

In [35]: s
Out[35]: {1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16}

In [36]: { x for x in s if x % 3 == 0 }
Out[36]: {6, 9, 12}

In [37]: