"group" items in list

Question

I have [string, int,int],[string, int,int]... kind of list that I want to group with a different list

[string1, int1,int1] + [string2, int2,int2] = ["string+string2", int1+int1+int2+int2]

the History goes like I have already made import function that gets me compounds:

ex[Ch3, 15.3107,15.284] kinda like this...

I have a function that gives me: dictionary{0:"CH3"} and another that gives me: List ["CH3",30.594700000000003]

def group_selectec_compounds(numCompound,values)

values can be list of list that have everything I also have dic made that is something like this {0:["CH4"],...} numCoumpound should be various variables (I think) or tuple of keys? So I can do the math for the user.

In the end I want something like: ["CH3+CH4",61.573] it can also be: ["CH3+CH4+H2SO4",138.773]

Answer 1

I would solve this using '+'.join , sum and comprehensions:

>>> data = [['string1', 2, 3], ['string2', 4, 5], ['string3', 6, 7]]
>>> ['+'.join(s for s, _, _ in data), sum(x + y for _, x, y in data)]
['string1+string2+string3', 27]

Answer 2

First, create a dictionary that stores the location of the type:

helper = {}
for elem in lst1:
  elemType = str(type(elem))
  if elemType not in helper:
    helper[elemType] = lst1.index[elem]

Now you have a dictionary that indexes your original list by type, you just have to run the second list and append accordingly:

for elem in lst2:
  elemType = str(type(elem))
  if elemType not in helper:
    #in case list 2 contains a type that list 1 doesn't have
    lst1.append(elem)
    helper[elemType] = lst1.index[elem]
  else:
    lst1[helper[elemType]] += elem

Hope this makes sense! I have not vetted this for correctness but the idea is there.

Edit: This also does not solve the issue of list 1 having more than 1 string or more than 1 int, etc., but to solve that should be trivial depending on how you wish to resolve that issue.

2nd Edit: This answer is generic, so it doesn't matter how you order the strings and ints in the list, in fact, lst1 can be [string, int, double] and lst2 can be [int, double, string] and this would still work, so it is robust in case the order of your list changes