# Separate lists with "true" and "false" values from lists with only "true" values

Hi there.

Maybe someone could help me with this. I have a data tree with several lists in it, for example one with only “true” values and one with several “true” and “false” values.
How can I separate these lists with only “true”-values from those with “true” and “false” in it?

(I have tried the split tree component but couldn’t come up with a working split mask input.)

Thanks in advance. Your idea is correct, you do need Split Tree. The problem is figuring out which paths in the original tree represent lists with all identical values. I came up with a rather geeky solution, which is to compute the Mass Addition of all boolean lists and their inverse. Lists which contain only false values have a total sum of zero (false=0, true=1). Lists which contain only true values have a total sum of zero if the values are inverted. Thus, by multiplying the two sums, we can figure out whether at least one of them is zero. This pattern then ultimately be used to get the correct paths out of the list. split sets.gh (12.3 KB)

Another way to approach this is to create sets out of the lists. Lists which only contain identical values will result in sets with only one element.

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Works fine…thanks a lot for the quick and profound answer.