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Reduce nested dictionary to "top-key-root-element" dictionary

I would like to derive a dictionary from a nested dictionary with the top keys as keys and the root elements as values. This post is similar to this one, but I would like to end up with a dictionary not with a list of lists.
Example: How to get from this
d = {'foo':{'a':{'b':['1','2']}},
'bar':{'a':{'b':{'c':'3'}}}}
to this?
{'foo': ['1', '2'], 'bar': '3'}

d = {'foo':{'a':{'b':['1','2']}},
'bar':{'c':{'d':'3'}}}
def get_last_value(d):
if isinstance(d, dict):
for k, v in d.items():
return get_last_value(v)
return d
result = {k:get_last_value(v) for k, v in d.items()}
print(result)
result:
{'foo': ['1', '2'], 'bar': '3'}

d = {'foo':{'a':{'b':['1','2']}},
'bar':{'c':{'d':'3'}}}
for key, value, in d.items():
print(key, value.values())

Update dictionary key(s) by drop starts with value from key in Python

I have a dictionary dict:
dict = {'drop_key1': '10001', 'drop_key2':'10002'}
The key(s) in dict startswith drop_, i would like to update dict by dropping drop_ value from key(s):
dict = {'key1': '10001', 'key2':'10002'}
What is the best approach to do it?

something like
d1 = {'drop_key1': '10001', 'drop_key2':'10002'}
d2 = {k[5:]:v for k,v in d1.items()}
print(d2)
output
{'key1': '10001', 'key2': '10002'}

One approach is, for each key value in the dictionary, you can replace the part of the string with the new string value. For instance:
d = {k.replace('drop_', ''): v for k, v in d.items() if k.strip().startswith('drop_')}
or you can define a function, and get the index of the searched string ("drop_"). If the search string index is 0, then remove it. For instance:
def change_key(key, search):
start_idx = key.find(search)
if start_idx == 0:
key = key.replace(search, "")
return key
d = {change_key(k, search="drop_"): v for k, v in d.items()}
Result:
{'key1': '10001', 'key2': '10002'}
Note that if you use a method, then you can guarantee to remove the search string if it is at the beginning of the string. For instance:
d = {' drop_key1': '10001', 'drop_key2': '10002'}
d = {change_key(k, search="drop_"): v for k, v in d.items()}
Result:
{' drop_key1': '10001', 'key2': '10002'}

How to add index to a list inside a dictionary

I have a dictionary here:
dict = {'A':['1','1','1','1','1'], 'B':['2','2'], 'C':['3','3','3','3']}
What is the necessary process to get the following result?
dict = {'A':['1_01','1_02','1_03','1_04','1_05'], 'B':['2_01','2_02'], 'C':['3_01','3_02','3_03','3_04']}
I have been learning python for quite a while now but dictionary is kind of new to me.

As others mentioned, refrain from using built-in keywords as variable names, such as dict. I kept it for simplicity on your part.
This is probably the most pythonic way of doing it (one line of code):
dict = {key:[x+"_0"+str(cnt+1) for cnt,x in enumerate(value)] for key,value in dict.items()}
You could also iterate through each dictionary item, and then each list item and manually change the list names as shown below:
for key,value in dict.items():
for cnt,x in enumerate(value):
dict[key][cnt] = x+"_0"+str(cnt+1)
Also, as some others have mentioned, if you want numbers greater than 10 to save as 1_10 rather than 1_010 you can you an if/else statement inside of the list comprehension...
dict = {key:[x+"_0"+str(cnt+1) if cnt+1 < 10 else x+"_"+str(cnt+1) for cnt,x in enumerate(value)] for key,value in dict.items()}

First iterate on keys.
Then loop on keys you are getting on key like for 'A' value is ['1','1','1','1','1'] then we can change the element at ['1','1','1','1','1']
enumerate() helps you iterate on index,value then index starts with zero as per your expected output add 1 to index. As you want the trailing 0 before each count we did '%02d'% (index+1)
Like this:
dict = {'A':['1','1','1','1','1'], 'B':['2','2'], 'C':['3','3','3','3']}
for i in dict.keys(): #iterate on keys
for index,val in enumerate(dict[i]): #took value as we have key in i
element='%02d'% (index+1) #add trailing 0 we converted 1 to int 01
dict[i][index]=val+"_"+ str(element) #assign new value with converting integer to string
print(dict)
Output:
{'A': ['1_01', '1_02', '1_03', '1_04', '1_05'], 'C': ['3_01', '3_02', '3_03', '3_04'], 'B': ['2_01', '2_02']}

Use enumerate to iterate over list keeping track of index:
d = {'A':['1','1','1','1','1'], 'B':['2','2'], 'C':['3','3','3','3']}
newd = {}
for k, v in d.items():
newd[k] = [f'{x}_0{i}' for i, x in enumerate(v, 1)]
print(newd)
Also a dictionary-comprehension:
d = {k: [f'{x}_0{i}' for i, x in enumerate(v, 1)] for k, v in d.items()}
Note: Don't name your dictionary as dict because it shadows the built-in.

d= {'A':['1','1','1','1','1'], 'B':['2','2'], 'C':['3','3','3','3']}
{x:[j + '_'+ '{:02}'.format(i+1) for i,j in enumerate(y)] for x,y in d.items()}

adict = {'A':['1','1','1','1','1'], 'B':['2','2'], 'C':['3','3','3','3'], 'D': '23454'}
newdict = {}
for i,v in adict.items():
if isinstance(v, list):
count = 0
for e in v:
count += 1
e += '_0' + str(count)
newdict[i] = newdict.get(i, [e]) + [e]
else:
newdict[i] = newdict.get(i, v)
print (newdict)
#{'A': ['1_01', '1_01', '1_02', '1_03', '1_04', '1_05'], 'B': ['2_01', '2_01', '2_02'], 'C': ['3_01', '3_01', '3_02', '3_03', '3_04'], 'D': '23454'}
This solution will check for whether your value in the dictionary is a list before assigning an index to it

You can use a dictcomp:
from itertools import starmap
d = {
'A': ['1', '1', '1', '1', '1'],
'B': ['2', '2'],
'C': ['3', '3', '3', '3']
}
f = lambda x, y: '%s_%02d' % (y, x)
print({k: list(starmap(f, enumerate(v, 1))) for k, v in d.items()})
# {'A': ['1_01', '1_02', '1_03', '1_04', '1_05'], 'B': ['2_01', '2_02'], 'C': ['3_01', '3_02', '3_03', '3_04']}

Python Join 2 dictionaries into 3rd, 2D dictionary where key from dictionary 2 is list value in dictionary 1

I couldn't find this particular python dictionary question anywhere.
I have two dictionaries:
dict1 = {'key1':['val1','val2','val3']}
dict2 = {'val1':['a','b','c']}
I want a 3rd, 2D dictionary with:
dict3 = {'key1': {'val1':['a','b','c']} }
So, joining 2 dictionaries where the key of the second dictionary is a list value of the first dictionary.
I was trying some nested looping along the lines of:
for key1, val1 in dict1.items():
for key2, in val2 in dict2.items():
# do something here
I am not sure if that is the best way to do this.

This is best done by iterating over dict1 and looking for matching values in dict2:
result = {}
for key, value_list in dict1.items():
result[key] = subdict = {}
for value in value_list:
try:
subdict[value] = dict2[value]
except KeyError:
pass
Result:
{'key1': {'val1': ['a', 'b', 'c']}}

You can use a dictionary comprehension and then check if the final result contains only one dictionary. If the latter is true, then a dictionary of dictionaries will be the final result; else, a listing of dictionaries will be stored for the key:
dict1 = {'key1':['val1','val2','val3']}
dict2 = {'val1':['a','b','c']}
new_dict = {a:[{i:dict2[i]} for i in b if i in dict2] for a, b in dict1.items()}
last_result = {a:b if len(b) > 1 else b[0] for a, b in new_dict.items()}
Output:
{'key1': {'val1': ['a', 'b', 'c']}}

dict1 = {
'key1':['val1','val2','val3']
}
dict2 = {
'val1':['a','b','c']
}
dict3 = {
key : { val_key : dict2[val_key]
for val_key in val_list if (val_key in dict2.keys())
} for key, val_list in dict1.items()
}

You can try this solution .
dict1 = {'key1':['val1','val2','val3']}
dict2 = {'val1':['a','b','c']}
join_dict={}
for i,j in dict1.items():
for sub_l,sub_value in dict2.items():
if sub_l in j:
join_dict[i]={sub_l:sub_value}
print(join_dict)
output:
{'key1': {'val1': ['a', 'b', 'c']}}

How to get a list which is a value of a dictionary by a value from the list?

I have the following dictionary :
d = {'1' : [1, 2, 3, 4], '2' : [10, 20, 30, 40]}
How do I get the corresponding key I'm searching by a value from one of the lists?
Let's say I want key '1' if I'm looking for value 3 or key '2' if I'm looking for value 10.

You can reverse the dictionary into this structure to do that kind of lookup:
reverse_d = {
1: '1',
2: '1',
3: '1',
4: '1',
10: '2',
…
}
which can be built by looping over each value of each key:
reverse_d = {}
for key, values in d.items():
for value in values:
reverse_d[value] = key
or more concisely as a dict comprehension:
reverse_d = {value: key for key, values in d.items() for value in values}
Lookups are straightforward now!
k = reverse_d[30]
# k = '2'
This only offers better performance than searching through the whole original dictionary if you do multiple lookups, though.

You can use a generator expression with a filtering condition, like this
>>> def get_key(d, search_value):
... return next(key for key, values in d.items() if search_value in values)
...
>>> get_key(d, 10)
'2'
>>> get_key(d, 2)
'1'
If none of the keys contain the value being searched for, None will be returned.
>>> get_key(d, 22)
None

This is my first time to answer question. How about this method?
def get_key(d,search_value):
res = []
for v in d.items():
if search_value in v[1]:
res.append(v[0])
return res
>>> D = {'a':[2,2,3,4,5],'b':[5,6,7,8,9]}
>>> getkey.get_key(D,2)
['a']
>>> getkey.get_key(D,9)
['b']
>>> getkey.get_key(D,5)
['a', 'b']