Using index from a list to get another value/element in another list

Question

I have project wherein I have to get the index of certain element in a list, then use that index to get another value in another list.

For example,

j_set = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
on_going = [1]
e_list = [[], [1], [1], [2], [3], [3], [5], [4, 7], [6], [8, 9], [10]]

So far, the code looks like this:

if isinstance(on_going, int):
    on_going = [on_going]
idx = [y for y, x in enumerate(e_list) if x in on_going] # code to get index in e_list
print(idx)

for i in idx:
    q_active = j_set.append(i)
    print(q_active)

The objective is to get the corresponding index of value/element in on_going from e_list. Then, use that index to get corresponding activity from j_set and store in q_active.

Expected output:
q_active = [2, 3]

The problem is, with the code above, I am getting an output for storing values in q_active as:

[1, 2] #idx output
None
None

Any help would be appreciated! Thanks!

@HarshaBiyani edited my post already. Input is actually the value in on_going. So for, on_qoing = 1, it will try to look for its 'match' in e_list and get the index of that match. Using that index, get its corresponding value in j_set then store in q_active. — AJ Gayeta
– AJ Gayeta, Commented Jun 9, 2020 at 5:50

A.J. Uppal · Accepted Answer · 2020-06-09 05:50:07Z

1

Perhaps use a list_comprehension:

print([j_set[item] for i in on_going for item in range(len(e_list)) if i in e_list[item]])
#[2, 3]

answered Jun 9, 2020 at 5:50

A.J. Uppal

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Harsha Biyani · Accepted Answer · 2020-06-09 05:49:39Z

1

You can use enumerate to get index and data from list:

e_list = [[], [1], [1], [2], [3], [3], [5], [4, 7], [6], [8, 9], [10]]
for data_index, data_val in enumerate(e_list):
  print(data_index, data_val)
  # write business logic here

answered Jun 9, 2020 at 5:49

Harsha Biyani

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