Search a list of values in a list

[cameyo]

What is the best method to search for a list of values in a list?
Example:
(set 'pat '(1 4 6))
(set 'lst '(2 2 2 1 4 6 2 2 2 1 4 6 2 2 1))

(ref-lst pat lst) ==> 3 ;the first index
and/or
(ref-all-lst pat lst) ==> (3 9) ;all indexes

[ralph.ronnquist]

Code: Select all

(find pat lst (fn (needles item) (member item needles)))

find-all doesn't work for that though

with ref/ref-all:

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(ref pat lst (fn (needles item) (member item needles))))
(ref-all pat lst (fn (needles item) (member item needles)))

It might need "flat" on the ref-all but ref/ref-all also traverses the lst recursively if it's deeper.

EDIT: correction

[cameyo]

Thanks Ralph.
But I would like to find the starting index of the sequence 1 4 6, not the single number indices.

[ralph.ronnquist]

Ah, I misunderstood. That's slightly more convoluted. I suppose one approach could be something like the following:

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(filter (fn (i) (= pat (i (length pat) lst))) (flat (ref-all (pat 0) lst)))

[cameyo]

This solves my question.
Thanks again Ralph.
Have a nice day.