CODEWITHSUNDEEP
pythonlistdictionary
Mike Issa
Mike Issa

Reputation: 295

Convert elements in a list using a dictionary key

I have a list of values that match with certain keys from a dictionary I created earlier.

myDict = {1:'A',2:'B',3:'C'}
myList = ['A','A','A','B','B','A','C','C']

How can I create/convert myList into something like:

myNewList = [1,1,1,2,2,1,3,3]

Could someone point me in the right direction?

Not sure if it matters, I created the dictionary using json in another script, and I am now loading the created dictionary in my current script.

Upvotes: 3

Views: 111

Answers (3)

Jose Enrique Marquez
Jose Enrique Marquez

Reputation: 105

myDict = {1:'A',2:'B',3:'C'}

myList = ['A','A','A','B','B','A','C','C']

value = [key for i in myList for key, value in myDict.iteritems() if i == value]

print value

I recommend you read a bit about the compression list http://docs.python.org.ar/tutorial/3/datastructures.html

Upvotes: 1

user61026
user61026

Reputation: 46

This works too:

myNewList = []
for val in myList:
    for key, value in myDict.iteritems():
        if val == value:
        myNewList.append(key)

Upvotes: 0

CookieOfFortune
CookieOfFortune

Reputation: 13984

One easy way is to just invert myDict and then use that to map the new list:

myNewDict = {v: k for k, v in myDict.iteritems()}
myNewList = [myNewDict[x] for x in myList]

Also take a look at this for Python naming conventions: What is the naming convention in Python for variable and function names?

Upvotes: 8

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