Python将列表第j行的元素与其他行匹配

Question

我有一个列表列表，我想在其中比较特定列的所有元素以查找匹配项。更具体地说，我有下表：

Item_No.      features
   A        ['X','Y','Z']
   B          ['X','Y']
   C            ['Y']
   D            ['S']

我想看看物品A是否与其他物品有任何共同特征。在这种情况下，我想获得这样的东西：

Item_No.    features      Common
   A      ['X','Y','Z']    B,C
   B        ['X','Y']       A,C
   C          ['Y']         A,B
   D          ['S']         0

我将如何在 python 上进行此操作？

Answer 1

def common(x,y):
    """Do list x and y have an element in common?"""
    for e in x:
        if e in y:
            return True
    return False

#listnames and their content
data = [('A',['X','Y','Z']),
        ('B',['X','Y']),
        ('C',['Y']),
        ('D',['S'])]

# touples of listnames and an array of listnames it 
data_common = [] overlaps with
# try common on each pair of lists saving their names.
for N,A in d:
    data_common.append((N,[n for n,a in data if(n is not N and common(A,a))]))
print(data_common)

输出：[('A', ['B', 'C']), ('B', ['A', 'C']), ('C', ['A', 'B']), ('D', [])]

这个挺贵的，大概O(m^2*n^2)，m=max(len(data[,1])), n=len(data) 并且当然可以进行优化，因为每个列表都经过实际检查 互相两次。