Replace elements in lists based on indexes python

March 26, 2022

Community of stackoverflow:

I have a list "rest" which is the following:

rest=[5, 7, 11, 4]

I have another list which is b:

b=[21, 22, 33, 31, 23, 15, 19, 13, 6]

And I have a "last" list:

last=[33, 19, 40, 21, 31, 22, 6, 15, 13, 23]

I have to replace the first 4 elements in b with the elements in rest. How can I replace the elements in last according to the matches with b to get the rest elements?

for example:

     5   7   11   4   #elements from rest
b= [21, 22, 33, 31, 23, 15, 19, 13, 6]

to get last list as the following:

last=[11, 19, 40, 5, 4, 7, 6, 15, 13, 23]  #elements that matched with b were replaced by rest

How can I do this?

>Solution :

Try this:

rest=[5, 7, 11, 4]
b=[21, 22, 33, 31, 23, 15, 19, 13, 6]
last=[33, 19, 40, 21, 31, 22, 6, 15, 13, 23]

for i, l in enumerate(last):
    if l in b:
        if b.index(l) < len(rest):
            last[i] = rest[b.index(l)]
            
print(last)