Group Repeated Sequential Items in List


Looking for some pointers on where to start with this as I’m at a bit of a loss.

I have a variable number of lists with a variable number of items in each. In these lists some elements repeat sequentially that I would like to ‘Group’. For instance, the list B, A, B, C, C, C, A, C, A, A would become B, A, B, 3C, A, C, 2A.

Ideally, I’d like to do it with nodes as my Python journey has stalled yet again but even a starting point would be great!

Any help gratefully received.



See if that helps. Better show some images.

No, unfortunately not… this might explain it better, I essentially need to count the number of consecutive items in a list… when the item value changes the count restarts. Does that make sense?

Once I have the number of consecutive items would then need to drop the duplicates from the original list…

@Keith_Wilkinson1 I know it’s Python but see if this works for you.

from itertools import groupby
grouped = [(len(list(groups)),keyValue) for keyValue,groups in groupby(IN[0])]
OUT = [str(count)+str(key) if count>1 else str(key) for count,key in grouped]

And if you need only the count then try this:

from itertools import groupby
OUT = [len(list(groups)) for keyValue,groups in groupby(IN[0])]
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Python can help you directly get that as well!

from itertools import groupby
OUT = [keyValue for keyValue,groups in groupby(IN[0])]

Or you can do something using the OOTB nodes like this.

I took this post as a base but I’m sure there would be better node solutions out there.
SplitList.dyn (32.5 KB)


list value.dyn (10.0 KB)

I thing its easy,

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Ah, this is genius and does exactly what i need I need to go and unpick it a little but some new stuff in here for me to learn.

I’ll take a look at the Python script as well but this works for me right now, many thanks for taking the time to help, much appreciated.

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Thanks for taking the time to look at this but unfortunately what you have doesn’t quite work for me as it’s just totaling the different unique values - I need to preserve the original list format and just group values where they duplicate. @AmolShah solution hits the mark though so all good from my end.