Python dictionary replace values

Question

I have a dictionary with 20 000 plus entries with at the moment simply the unique word and the number of times the word was used in the source text (Dante's Divine Comedy in Italian).

I would like to work through all entries replacing the value with an actual definition as I find them. Is there a simple way to iterate through the keywords that have as a value a number in order to replace (as I research the meaning)?

The dictionary starts:

{'corse': 378, 'cielo,': 209, 'mute;': 16, 'torre,': 11, 'corsa': 53, 'assessin': 21, 'corso': 417, 'Tolomea': 21}  # etc. 

Sort of an application that will suggest a keyword to research and define.

Answer 1

You cannot select on specific values (or types of values). You'd either make a reverse index (map numbers back to (lists of) keys) or you have to loop through all values every time.

If you are processing numbers in arbitrary order anyway, you may as well loop through all items:

for key, value in inputdict.items():     # do something with value     inputdict[key] = newvalue 

otherwise I'd go with the reverse index:

from collections import defaultdict  reverse = defaultdict(list) for key, value in inputdict.items():     reverse[value].append(key) 

Now you can look up keys by value:

for key in reverse[value]:     inputdict[key] = newvalue 

Answer 2

via dict.update() function

In case you need a declarative solution, you can use dict.update() to change values in a dict.

Either like this:

my_dict.update({'key1': 'value1', 'key2': 'value2'}) 

or like this:

my_dict.update(key1='value1', key2='value2') 

via dictionary unpacking

Since Python 3.5 you can also use dictionary unpacking for this:

my_dict = { **my_dict, 'key1': 'value1', 'key2': 'value2'} 

Note: This creates a new dictionary.

via merge operator or update operator

Since Python 3.9 you can also use the merge operator on dictionaries:

my_dict = my_dict | {'key1': 'value1', 'key2': 'value2'} 

Note: This creates a new dictionary.

Or you can use the update operator:

my_dict |= {'key1': 'value1', 'key2': 'value2'}