Dear list



I have a matrix composed of islandID as rows and speciesID as columns.

IslandID: Island A, B, C….O (15 islands in total)

SpeciesID: D0001, D0002, D0003….D0100 (100 species in total)



The cell of the matrix describes presence (1) or absence (0) of the species
in an island.



Now I would like to search how many species are found in (1, presence) for
Island A, Island D, and Island L respectively.



Please kindly advise the R code for the search purpose.

Thank you.

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