[Tutor] Replace nth item with single value in each nested list

[Mats Wichmann]

On 5/14/20 3:16 AM, EK Esawi via Tutor wrote:
> Hi All--
> 
> i have a nested list like this a=[[1,2],[4,5],[7,8]]. i want to replace the second element in each nested list with a specific value
> i want something like this [[1,11],[4,11],]7,11]. I tried several things but nothing worked.
> I am hoping for a list comprehension solution

It depends on how well-formed your data is. If it *always* looks like
the above (the items in 'a' are always lists, and always have at least
two elements), then:

for sub in a:
    sub[1] = 11

If not consistent, then you have to take a bit more care to deal with
errors.

It also depends on what you want.  A list comprehension could be
written, but will give you a new list. Since lists are mutable you have
the change in place option - if you want it.