在python中使用字典中的部分子值检索主键

Question

I have a dictionary which has subkeys and sub values. I want to print a list of the main keys that contain a certain value in the subkey. I hope the example makes it clear:

cssStyleDict= {'.c13':{'color':'#000',
               'font-family':'"Arial"',
               'font-weight':'700',
               'vertical-align':'baseline'},
               '.c6':{'font-weight':'700'}, 
               '.c7':{'color':'#000',
               'font-size':'11pt',
               'font-weight':'700',
               'text-decoration':'none'},
               '.c2':{'background-color':'#ff0'}}

I want to print a list of all keys that contain {'font-weight':'700'} . I have tried this:

def getKeysByValue(dictOfElements, valueToFind):
    listOfKeys = list()
    listOfItems = dictOfElements.items()
    for item  in listOfItems:
        if item[1] == valueToFind:
            listOfKeys.append(item[0])
    return  listOfKeys

listOfKeys = getKeysByValue(cssStyleDict, {'font-weight':'700'} )
for key in listOfKeys:
    print(key)

But of course this only gives me an exact match. I've also tried using a regex expression, but to no avail. The output should be a list containing .c13 .c6 .c7

Thanks in advance if anyone can help.

Answer 1

You can try this way:

>>> [ i for i in cssStyleDict if cssStyleDict[i].get('font-weight') == '700' ]
['.c13', '.c6', '.c7']

Answer 2

To use the code that you've posted as a base for your answer, you only need to change the condition of the if-statement. Currently, you are checking for a perfect match because you have used “==“

However, Python comes with a great operator that does exactly what you need: “in”.

Thus, your new condition should be:

        If valueToFind in item[1]:

Hope this makes sense!

Answer 3

Clean and Clear Approach using dictonary built-ins.

cssStyleDict= {'.c13':{'color':'#000',
               'font-family':'"Arial"',
               'font-weight':'700',
               'vertical-align':'baseline'},
               '.c6':{'font-weight':'700'}, 
               '.c7':{'color':'#000',
               'font-size':'11pt',
               'font-weight':'700',
               'text-decoration':'none'},
               '.c2':{'background-color':'#ff0'}}

for key, val in cssStyleDict.items():
  if(cssStyleDict[key].__contains__('font-weight')):
    if(cssStyleDict[key]['font-weight'] == '700'):
      print(key)

Answer 4

I would do it by first checking each dict for that key, then comparing the value to the expected one.

def getKeysByValue(dictOfElements, valueToFind):
    listOfKeys = list()
    listOfItems = dictOfElements.items()
    for k,v in listOfItems:
        try:
            if v[valueToFind[0]] == valueToFind[1]:
                listOfKeys.append(k)
        except KeyError:
            pass
    return  listOfKeys

listOfKeys = getKeysByValue(cssStyleDict, ('font-weight', '700') )
for key in listOfKeys:
    print(key)