构造字典

有一个列表values=[1,3,5,7,9,12,56,98,23,77,67,87,99,4,3,43,54,23],请构造一个字典，当值小于50时key为small，当值大于等于50时key为big。

方法一：

dic = {}   #定义一个空的字典values=[1,3,5,7,9,12,56,98,23,77,67,87,99,4,3,43,54,23]for i in values:       #对字典进行遍历    if i < 50 :        if ‘small‘ in dic.keys():       #判断small这个key是否在字典中            dic[‘small‘].append(i)              else:            dic[‘small‘]=[i]                else:        if ‘big‘ in dic.keys():            dic[‘big‘].append(i)        else:            dic[‘big‘]=[i]print("The new dictionary is %s" % dic)

The new dictionary is {‘small‘: [1, 3, 5, 7, 9, 12, 23, 4, 3, 43, 23], ‘big‘: [56, 98, 77, 67, 87, 99, 54]}

方法二：

import collectionsdic = collections.defaultdict(list)   #定义一个字典，默认是列表values=[1,3,5,7,9,12,56,98,23,77,67,87,99,4,3,43,54,23]for i in values:    if i < 50:        dic[‘small‘].append(i)    else:        dic[‘big‘].append(i)print("The new dictionary is %s" % dic)

The new dictionary is defaultdict(<class ‘list‘>, {‘small‘: [1, 3, 5, 7, 9, 12, 23, 4, 3, 43, 23], ‘big‘: [56, 98, 77, 67, 87, 99, 54]})

以上两种方法仅供参考，有需要的朋友可以看一下，共同探讨共同进步。

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