I have a long list (Table) consisting of "True"s and "False"s. I would like to identify the position in the list of the last entry that takes the value "False". Is there a way to do this?

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    $\begingroup$ Last[Position[list,False,1]][[1]]? $\endgroup$ Jul 23, 2019 at 0:38
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    $\begingroup$ Ironically, there is a command FirstPosition but no LastPosition. $\endgroup$ Jul 23, 2019 at 0:39
  • $\begingroup$ I am sure i saw a question very similar to this but can't find it. $\endgroup$
    – kglr
    Jul 23, 2019 at 0:49

1 Answer 1


You can use FirstPosition on Reversed input list:

Length[list] + 1 - FirstPosition[False] @ Reverse[list]

Alternatively, use PositionIndex:

Last @ PositionIndex[list][False]

or Position:

Last @ Position[False][list]

or SequenceCases:

SequenceCases[list, a:{___, False} :> Length[a]]

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