Question

我编写的代码是从我的计算机创建文件的键值对并将它们存储在列表a中。这是代码：

groups = defaultdict(list)
with open(r'/home/path....file.txt') as f:
    lines=f.readlines()
    lines=''.join(lines)
    lines=lines.split()
    a=[]
    for i in lines:
        match=re.match(r"([a,b,g,f,m,n,s,x,y,z]+)([-+]?[0-9]*\.?[0-9]+)",i,re.I)
        if match:
            a.append(match.groups())
print a

现在我想查找特定键是否在该列表中。例如，我的代码生成了这个输出：

[('X', '-6.511'),('Y', '-40.862'), 
('X', '-89.926'),('N', '7304'),
('X', '-6.272'), ('Y', '-40.868'), 
('X', '-89.979'),('N', '7305'),
('Y', '-42.101'),('Z', '238.517'),
('N', '7306'),   ('Y','-43.334'), 
('Z', '243.363'),('N', '7307')]

现在，在输出中，密钥为'X'，'Y'，'Z'，'N'但我正在寻找的密钥为A，{{ 1}}，B，G，F，M，N，S，X，{{1} }。因此，对于那些不在输出中的键，输出应显示类似Y，Z的内容。

Answer 1

for node in ['A', 'B', 'G', 'F', 'M', 'N', 'S', 'X', 'Y', 'Z']:
    if node not in groups.keys():
        print "%s not in list"%(node)

在遍历列表时使用变量和打印函数

我认为这就是你想要的。

Answer 2

您可以将您的元组列表作为dict读取并检查密钥是否存在：

d=[('X', '-6.511'),('Y', '-40.862'), 
('X', '-89.926'),('N', '7304'),
('X', '-6.272'), ('Y', '-40.868'), 
('X', '-89.979'),('N', '7305'),
('Y', '-42.101'),('Z', '238.517'),
('N', '7306'),   ('Y','-43.334'), 
('Z', '243.363'),('N', '7307')]

k=['A', 'B', 'G', 'F', 'M', 'N', 'S', 'X', 'Y', 'Z']
dt=dict(d)
for i in k:
    if i in dt:
        print i," has found"
    else:
        print i," has not found"

输出：

A  has not found
B  has not found
G  has not found
F  has not found
M  has not found
N  has found
S  has not found
X  has found
Y  has found
Z  has found

Answer 3

mylist = [('X', '-6.511'),('Y', '-40.862'), 
('X', '-89.926'),('N', '7304'),
('X', '-6.272'), ('Y', '-40.868'), 
('X', '-89.979'),('N', '7305'),
('Y', '-42.101'),('Z', '238.517'),
('N', '7306'),   ('Y','-43.334'), 
('Z', '243.363'),('N', '7307')]

missing = [ x for x in 'ABGFMNSXYZ' if x not in set(v[0] for v in mylist) ]
for m in missing:
    print "{} not in list".format(m)

给出：

A not in list
B not in list
G not in list
F not in list
M not in list
S not in list

如何在python中从键值对中搜索键

3 个答案: