Python Dictionary contains List as Value – How to update?

Question

I have a dictionary which has value as a list.

dictionary = { 
               'C1' : [10,20,30] 
               'C2' : [20,30,40]
             }

Let’s say I want to increment all the values in list of C1 by 10, how do I do it?

dictionary.get('C1') gives me the list but how do i update it?

Asked By: Deepak

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Source

Answer 1

Probably something like this:

original_list = dictionary.get('C1')
new_list = []
for item in original_list:
  new_list.append(item+10)
dictionary['C1'] = new_list

Answered By: girasquid

Answer 2

dictionary["C1"]=map(lambda x:x+10,dictionary["C1"])

Should do it…

Answered By: Utku Zihnioglu

Answer 3

>>> dictionary = {'C1' : [10,20,30],'C2' : [20,30,40]}
>>> dictionary['C1'] = [x+1 for x in dictionary['C1']]
>>> dictionary
{'C2': [20, 30, 40], 'C1': [11, 21, 31]}

Answered By: Paolo Bergantino

Answer 4

An accessed dictionary value (a list in this case) is the original value, separate from the dictionary which is used to access it. You would increment the values in the list the same way whether it’s in a dictionary or not:

l = dictionary.get('C1')
for i in range(len(l)):
    l[i] += 10

Answered By: Gabe

Answer 5

why not just skip .get altogether and do something like this?:

for x in range(len(dictionary["C1"]))
    dictionary["C1"][x] += 10

Answered By: user5261053

Answer 6

for i,j in dictionary .items():
    if i=='C1':
        c=[]
        for k in j:
            j=k+10
            c.append(j)
            dictionary .update({i:c})

Answered By: Loki

Python Dictionary contains List as Value – How to update?

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