How to compare two lists and get the indices of new values

user_10169418 0
Viewed 66

I am trying to find the index of a new name in the list. I've found the new renters name, but for some reason the index function is not working.

new = ["Maria", "Eric", "Bram", 'Bernardo', 'Bob']
old = ['Karel', 'Maria', 'Eric', 'Bram', 'Bernardo']

newrenter = list(set(new) - set(old))

print(newrenter)

newindex = new.index(newrenter)

print(newindex)

Which outputs:

['Bob']

Then the following error:

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Input In [9], in <cell line: 8>()
      4 newrenter = list(set(new) - set(old))
      6 print(newrenter)
----> 8 newindex = new.index(newrenter)
     10 print(newindex)

ValueError: ['Bob'] is not in list

It is probably an easy conversion of the type but I cant find how?

list python
2 Answers

newrenter is ['Bob'] and as you can see 'bob' is in your list not ['bob']. your code expects a list in another list. but 'new' only contains string elements.

I can not see your expectation of using .index(). but I imagine this will helps you:

newindex = new.index(newrenter[0])

And if you need all of remaining items indexes, try this:

new = ["Maria", 'Martin', "Eric", "Bram", 'Bernardo', 'Bob']  # I add Martin for better clue
old = ['Karel', 'Maria', 'Eric', 'Bram', 'Bernardo']

newrenter = list(set(new) - set(old))

for v in newrenter:
    print("value:", v, end=" - ")
    print("index in new:", new.index(v))

This code will return:

value: Bob - index in new: 5
value: Martin - index in new: 1
user_37447470

You were close with the attempt, this will work:

    new = ["Maria", "Eric", "Bram", 'Bernardo', 'Bob']
    old = ['Karel', 'Maria', 'Eric', 'Bram', 'Bernardo']
    
    l = list(set(new) - set(old))
    
    for x in l:
        print(new.index(x))

this is the result:

4
user_159439510
Related