How to remove duplicates only if consecutive in a

Question

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Removing elements that have consecutive duplicates (5 answers)

Closed 6 months ago.

For a string such as '12233322155552', by removing the duplicates, I can get '1235'.

But what I want to keep is '1232152', only removing the consecutive duplicates.

Answer 1

Hint: the itertools module is super-useful. One function in particular, itertools.groupby, might come in really handy here:

itertools.groupby(iterable[, key])

Make an iterator that returns consecutive keys and groups from the iterable. The key is a function computing a key value for each element. If not specified or is None, key defaults to an identity function and returns the element unchanged. Generally, the iterable needs to already be sorted on the same key function.

So since strings are iterable, what you could do is:

use groupby to collect neighbouring elements
extract the keys from the iterator returned by groupby
join the keys together

which can all be done in one clean line..

Answer 2

+1 for groupby. Off the cuff, something like:

from itertools import groupby
def remove_dupes(arg):
    # create generator of distinct characters, ignore grouper objects
    unique = (i[0] for i in groupby(arg))
    return ''.join(unique)

Cooks for me in Python 2.7.2

Answer 3

First of all, you can't remove anything from a string in Python (google "Python immutable string" if this is not clear).

M first approach would be:

foo = '12233322155552'
bar = ''
for chr in foo:
    if bar == '' or chr != bar[len(bar)-1]:
        bar += chr

or, using the itertools hint from above:

''.join([ k[0] for k in groupby(a) ])