遍历在列表中具有列表的字典

Question

I'm trying to figure out a way to match a value in a nested list in a dictionary. Let's say I have this structure;

dict2 = {'key1': [ 2, ['value1', 3], ['value2', 4] ], 'key2' : [1, ['value1', 2], ['value2', 5] ], 'key3' : [7, ['value1', 6], ['value2', 2], ['value3', 3] ] }

Now let's say for key1, I want iterate through the first value of the lists only to look for a data match. So if my data is "value2" and i want to look for it in key1, then I want it to skip the '2' and check the first object in the two lists which are; value1, value2 for a match and that's it.

Tried doing this but it gave a keyerror: 1;

if 'value1' in dict2[1][1:]:
    print 'true'
else:
    print 'false'

Is this possible to do? Is there another way to do match search? Thanks.

Answer 1

The code in your question is using a numeric index instead of the string 'key1'. Here's a modified version that should work:

if 'value1' in {array[0] for array in dict2.get('key1', [])[1:]}:
    print 'true'
else:
    print 'false'

That looks at all of the elements after the first in the array associated with 'key1' in your dictionary, if it exists.

Answer 2

If you're confident that the given nested dictionary always has this format, then we can do something like:

def find_value(nested_dict, value):
    for key, nested_list in nested_dict.items():  # If Python 2, use .iteritems() instead.
        for inner_list in nested_list[1:]:
            if value == inner_list[0]:
                return True
    return False

dict2 = {'key1': [ 2, ['value1', 3], ['value2', 4] ], 'key2' : [1, ['value1', 2], ['value2', 5] ], 'key3' : [7, ['value1', 6], ['value2', 2], ['value3', 3] ] }

print(find_value(dict2, 'value2'))  # True
print(find_value(dict2, 'value5'))  # False

Answer 3

Try this instead:

if 'value1' in d['key1'][1]:
     print('Value 1 found')

if 'value2' in d['key1'][2]:
     print('Value 1 found')

Answer 4

If you are looking only inside the lists you may do something like this:

for key, value in my_dict.items():
    for item in value:
        if isintance(item, list):
            if desired_value in item:
                return item # Here it is!

Answer 5

Try this:

for x,v in dict2.items():
   if x == "key1":
     for i, e in enumerate(v):
        try:
            if e[0] == 'value2':
               print "True"
            else: print "False"
        except:pass