How to fill array in Python by rest values?

Question

I have a full list: f = [A,B,C,D,E].

And short list: s = [A,B,D]

I want to get result list as short list + all rest values from full list that there are not in short list.

Result should be:

nlist = [A,B,D,C,E]

I tried two loops:

let nlist = s
for f in full:
  for s in short:
     if s not in f:
         nlist.append(f)

But I think it is wrong way

If your nlist is everything from s plus everything from l that is not in s, isn't then your nlist inevitably going to contain the same items as your original l? (Not necessarily in the same order though, admittedly) — Schnitte, May 25 '22 at 17:41
To be clear: for this input example, what should the result be? — Karl Knechtel, May 25 '22 at 17:48

score 2 · Accepted Answer · answered May 25 '22 at 17:38

2

Use list comprehension:

lst = short_lst + [x for x in long_lst if x not in short_lst]

answered May 25 '22 at 17:38

Timur Shtatland

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After that operation I got array but elements in short array is in another sequence, I have to safe them – Mandalina May 25 '22 at 17:59

score 0 · Answer 2 · answered May 25 '22 at 18:13

If the lists f and s do not contain dublicates (like in your example), it is also possible do the following,

f = ["A", "B", "C", "D", "E"]
s = ["A", "B", "D"]

s.extend(set(f) ^ set(s))
print(s) # output: ['A', 'B', 'D', 'E', 'C']

where the ^ operator is the symmetric difference operator. If you want to know the difference between the difference and symmetric difference, I recommend checking out this question. However, Timur's answer is probably the approach you were looking for.

Drakax · Answer 3 · 2022-05-25T19:26:16.713

0

Method to concatenate the unique values from multiple lists of different size and sort them:

x = ['I','G','F','A']
y = ['H','E','B','J','B']
z = ['D','C','A']

nlist = sorted(set(x+y+z))
nlist

#output
['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J']

edited May 25 '22 at 19:26

answered May 25 '22 at 18:14

Drakax

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score 0 · Answer 4 · answered May 25 '22 at 18:33

For huge full_list size try:

full_list = ['A','B','C','D','E']
short_list = ['A','B','D']

for i,s in enumerate(short_list):
    if s in full_list:
        full_list[full_list.index(s)] = full_list[i]
        full_list[i]=s
print(full_list)

Result

[A,B,D,C,E]

Note

This method is slightly faster than others as you sort the full_list inplace.
But it's less readable compared to other answers.

How to fill array in Python by rest values?

4 Answers4