In reference to the above question, I apologize but I've posed the question incorrectly. Let me try again.

I have two lists consisting of dates and measurements. I would like to deduplicate the first list by eliminating elements that (partially) match elements in the second.

Here is the first list:

lis1 = {{Today, "a", 2, "b", 2}, {Today, "c", 3, "d", 3}, {Today, "e", 5, "f", 6}, {Today, "g", 7, "h", 8}};

The second list is structured similarly, with the exception that the Date may be any of the 3 days prior to today, say:

lis2 = {{DatePlus[Today,-2],"a","xx","b","xx"},{DatePlus[Today,-1],"e","xx","f","xx"}, {DatePlus[Today,-3],"p","xx","q","xx"}}

I'd like to strike the members of lis1 where the second (a, e) and fourth (b, f) sub-elements of the list members are identical to the second and fourth sub-elements of some member of lis2, resulting in:

res = {{Today, "c", 3, "d", 3},{Today, "g", 7, "h", 8}}

Hope this is clearer!


1 Answer 1

pattern = Alternatives @@ 
   ({Alternatives @@ DateRange[#, DatePlus[#, {3, "Day"}]], #2, _, #4, _} & @@@ lis2);

DeleteCases[lis1, pattern]

enter image description here

MatrixForm /@ {lis1, lis2, DeleteCases[lis1, pattern]}

enter image description here

  • $\begingroup$ many thanks @kglr $\endgroup$
    – Suite401
    Sep 23, 2021 at 20:41
  • $\begingroup$ @Suite401, my pleasure. Thank you for the accept. $\endgroup$
    – kglr
    Sep 23, 2021 at 20:43

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