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Let's suppose that I have a dictionary like that:

input_dict = {'3': 2, '5': 4, '36': 7,'62':6}

and I want to have that as an output:

input_dict = {'3': 9, '5': 4, '6':6}

Basically, I want to do the following things:

  1. Keep only the first character of the keys
  2. If after that some keys are the same then add their values

What is the most efficient way to do this?

You can use a defaultdict and slice the key strings keeping only the first character:

from collections import defaultdict

d = defaultdict(int)
for k,v in input_dict.items():
    d[k[0]] += v

# defaultdict(int, {'3': 9, '5': 4, '6': 6})

PC Pest Control: Protect Your Computers from Malicious Internet , value name lickspeed DoubleClickspeed lo -- |esensitivity value data espeed 5. You use the Registry Editor to edit existing keys and values, create new keys and press Ctrl+F.) To find successive keys with the same value, press the F3 key. Adding and Deleting Kegs and Values When you edit the Registry to rid it of  Dictionary is quite a useful data structure in programming that is usually used to hash a particular key with value, so that they can be retrieved efficiently. Let’s discuss various ways of swapping the keys and values in Python Dictionary. Method#1 (Does not work when there are multiple same values):

Use this:

new_dict = {}
for key, val in input_dict.items():
    if key[0] not in new_dict:
        new_dict[key[0]] = val
        new_dict[key[0]] += val


{'3': 9, '5': 4, '6': 6}

Comp-Computer Science_TB-11-R, On the other hand the key does the same thing. You can add, remove and modify the values in dictionaries. To declare a dictionary the syntax is: directory​-name = {key : value, key, value, , keyN : valueN} The keys of this dictionary may  I think the best way to do this is to have lists of lists (dictionaries of lists if you want keys) as the dictionary values, to store multiple entries under the same key, here's the lists of lists:

You could use the get method from a dictionary:

input_dict = {'3': 2, '5': 4, '36': 7, '62': 6}

result = {}
for k, v in input_dict.items():
    key = k[0]
    result[key] = v + result.get(key, 0)



{'3': 9, '5': 4, '6': 6}

Knoppix Hacks: Tips and Tools for Hacking, Repairing, and Enjoying , #91 Edit the Windows Registry cd <key> - change key ls | dir [<key>] - show subkeys type <value> - show key value st [<hexaddr>] - show struct info nk <​keyname> - add key dk that you use are ls and cd, much in the same way as on the command line. However, instead of directories, you list the contents of registry keys. You cannot modify the key. Instead, delete the key and add a new value for key + 1 – P.K Dec 21 '09 at 2:29

Python, Python | Sum list of dictionaries with same key the task is to return a single dictionary with sum values with the same key. sum the values with same keys Counter({'a': 140, 'c': 100, 'b': 88}). Method #3: Naive Method. filter_none. edit Since keys are what dictionaries use to lookup values, you can't really change them. The closest thing you can do is to save the value associated with the old key, delete it, then add a new entry with the replacement key and the saved value. Several of the other answers illustrate different ways this can be accomplished.

20. Dictionaries, They map keys, which can be any immutable type, to values, which can be any One way to create a dictionary is to start with the empty dictionary and add key:​value pairs. The key:value pairs of the dictionary are separated by commas. why we use dictionaries at all when the same concept of mapping a key to a value  Object.keys, values, entries. For plain objects, the following methods are available: Object.keys(obj) – returns an array of keys. Object.values(obj) – returns an array of values. Object.entries(obj) – returns an array of [key, value] pairs. Please note the distinctions (compared to map for example):

Dictionary Data Structures in Python 3, Dictionaries map keys to values, making key-value pairs that can then store data. values in the sammy dictionary can similarly be called using the same format: In our example, that would use the variable name and be sammy.keys() . Just as you can add key-value pairs and change values within the dictionary data​  \$\begingroup\$ thank you very much for your answer :) although i must admit i am thoroughly puzzled so i tried running your code and what i understand is the first time it runs through the dictionary all the Parameters that already have a numeric value get added to evaluated_keys and somehow to locals. but then during the second run through it magically computes the remaining Parameters