Python 迭代字典值
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Iterating over dict values
提问by Mike.G
If i would like to iterate over dictionary values that are stored in a tuple.
如果我想遍历存储在元组中的字典值。
i need to return the object that hold the "CI" value, i assume that i will need some kind of a for loop :
我需要返回保存“CI”值的对象，我假设我需要某种 for 循环：
z = {'x':(123,SE,2,1),'z':(124,CI,1,1)}
for i, k in db.z:
for k in db.z[i]:
if k == 'CI':
return db.z[k]
i am probably missing something here, a point of reference would be good.
我可能在这里遗漏了一些东西，一个参考点会很好。
if there is a faster way doing so it would all so help greatly
如果有更快的方法这样做，这一切都会有很大帮助
采纳答案by GLHF
z = {'x':(123,"SE",2,1),'q':(124,"CI",1,1)}
for i in z.keys(): #reaching the keys of dict
for x in z[i]: #reaching every element in tuples
if x=="CI": #if match found..
print ("{} holding {}.".format(i,x)) #printing it..
This might solve your problem.
这可能会解决您的问题。
Output:
输出：
>>>
q holding CI.
>>>
Edit for your comment:
编辑您的评论：
def func(*args):
mylist=[]
z = {'x':(123,"SE",2,1),'q':(124,"CI",1,1)}
for x,y in z.items():
for t in args:
if t in y:
mylist.append(x)
return mylist
print (func(1,"CI"))
Output:
输出：
>>>
['q', 'q', 'x']
>>>
Hope this is what you want, otherwise first method is already printing all keys, example output:
希望这是您想要的，否则第一种方法已经打印所有键，示例输出：
if x==1 or x=="CI":
>>>
x holding 1.
q holding CI.
q holding 1.
q holding 1.
>>>
回答by Urban48
z = {'x':(123,"SE",2,1),'q':(124,"CI",1,1)}
for key, val in z.items():
if 'CI' in val:
return z[key]
回答by Hackaholic
try this:
尝试这个：
>>> z = {'x':(123,'SE',2,1),'z':(124,'CI',1,1)}
>>> list(filter(lambda x:'CI' in z.get(x),z))
['z']
回答by zehnpaard
Ways to iterate over a dictionary
迭代字典的方法
First things first, there are a few ways you can loop over a dictionary.
首先，有几种方法可以遍历字典。
Looping directly over the dictionary:
直接在字典上循环：
>>> z = {'x':(123,'SE',2,1),'z':(124,'CI',1,1)}
>>> for key in z:
... print key,
...
'x' 'z'
Notice that the loop variables that get returned when you just loop over a dictionary are the keys, not the values associated with those keys.
请注意，当您遍历字典时返回的循环变量是键，而不是与这些键关联的值。
Looping over the values of a dictionary:
循环字典的值：
>>> z = {'x':(123,'SE',2,1),'z':(124,'CI',1,1)}
>>> for value in z.values(): # Alternatively itervalues() for memory-efficiency (but ugly)
... print value,
...
(123,'SE',2,1) (124,'CI',1,1)
Looping over both the keys and the values:
遍历键和值：
>>> z = {'x':(123,'SE',2,1),'z':(124,'CI',1,1)}
>>> for key, value in z.items(): # Again, iteritems() for memory-efficiency
... print key, value,
...
'x' (123,'SE',2,1) 'z' (124,'CI',1,1)
The latter two are somewhat more efficient than looping over keys and running z[key] to obtain the value. It's also arguably more readable.
后两者比循环键并运行 z[key] 来获取值更有效。它也可以说更具可读性。
Building on these...
建立在这些...
List Comprehensions
列表推导式
List comprehensionsare great. For the simple case of searching for just 'CI':
列表理解很棒。对于仅搜索“CI”的简单情况：
>>> z = {'x':(123,'SE',2,1),'z':(124,'CI',1,1)}
>>> [key for key, value in z.items() if 'CI' in value]
['z']
For finding dict keys that hold several search items:
查找包含多个搜索项的字典键：
>>> z = {'x':(123,'SE',2,1),'z':(124,'CI',1,1)}
>>> search_items = ('CI', 1) # Only keys that hold both CI and 1 will match
>>> [key for key, value in z.items() if all(item in value for item in search_items)]
['z']
For finding dict keys that hold any of multiple search items:
要查找包含多个搜索项中的任何一个的 dict 键：
>>> z = {'x':(123,'SE',2,1),'z':(124,'CI',1,1)}
>>> search_items = ('CI', 'SE', 'JP') # Keys that hold any of the three items will match
>>> [key for key, value in z.items() if any(item in value for item in search_items)]
['x', 'z']
If the latter two look a bit too complex as one-liners, you can re-write the last bit as a separate function.
如果后两者看起来有点过于复杂，那么您可以将最后一位重写为单独的函数。
>>> z = {'x':(123,'SE',2,1),'z':(124,'CI',1,1)}
>>> search_items = ('CI', 'SE', 'JP') # Keys that hold any of the three items will match
>>> def match_any(dict_value, search_items):
... return any(item in dict_value for item in search_items)
...
>>> [key for key, value in z.items() if match_any(value, search_items)]
['x', 'z']
Once you get used to the [x for x in iterable if condition(x)] syntax, the format should be very easy to read and follow.
一旦你习惯了 [x for x in iterable if condition(x)] 语法，格式应该很容易阅读和遵循。
回答by franksands
There's no need to retrieve the key if you're only interested in the values:
如果您只对值感兴趣，则无需检索密钥：
In Python 2.x:
在 Python 2.x 中：
z = {'x':(123,"SE",2,1),'q':(124,"CI",1,1)}
for value in z.itervalues():
if 'CI' in value:
return value
In Python 3.x:
在 Python 3.x 中：
z = {'x':(123,"SE",2,1),'q':(124,"CI",1,1)}
for value in z.values():
if 'CI' in value:
return value
