CODEWITHSUNDEEP
pythonlistelement
Aidan Daly
Aidan Daly

Reputation: 11

Merging elements of a specific value with its neighbouring element in a list

I'm trying to combine certain elements in a list if they are of a specific value with its righter-neighbouring element. (The specific value in this case being a minus sign).
Say I have the following list: 

x = ['0', '0', '8', '-', '6', '4', '0', '5', '1', '2', '1', '2', '-', '5']

What can I do to the list so that It'll look like this?:

x = ['0', '0', '8', '-6', '4', '0', '5', '1', '2', '1', '2', '-5']

I basically need every instance of the element '-' to be paired with the next element (of which the index is +1 of the index of the minus sign). Sorry if this is quite vague, I'm still quite new to python and as such my terminology may be lacking.

Upvotes: 0

Views: 33

Answers (2)

Osman Mamun
Osman Mamun

Reputation: 2882

neg = False
out = []
for i in x:
    if i == '-':
        neg = True
    else:
        if neg:
            out += ['-' + i]
            neg = False
        else:
            out += [i]


In [18]: out
Out[18]: ['0', '0', '8', '-6', '4', '0', '5', '1', '2', '1', '2', '-5']

In the code above, there is flag neg which indicates previous item was a minus sign or not (True means it was a minus sign). Then we populate the out list with the element from x with the rule that if you have - then set the flag to True but do nothing. Then if the element is not - and neg is True then append negative of the element and set the flag to False, but if the flag is False just append the element.

Upvotes: 1

Heyran.rs
Heyran.rs

Reputation: 513

Try this:

x = ['0', '0', '8', '-', '6', '4', '0', '5', '1', '2', '1', '2', '-', '5']

for i in range(len(x)):
    if x[i] == '-':
        x[i+1] = x[i] + x[i+1]

y = [i for i in x if i != '-']
print(y)

It merges elements, then remove all of minus sign'-' from list.

Upvotes: 0

Related Questions