29.1 BlistList

BlistList( list, sub )

BlistList returns a new boolean list that describes the list sub as a sublist of the list list, which must have no holes. That is BlistList returns a boolean list blist of the same length as list such that blist[i] is true if list[i] is in sub and false otherwise.

list need not be a proper set (see Sets), even though in this case BlistList is most efficient. In particular list may contain duplicates. sub need not be a proper sublist of list, i.e., sub may contain elements that are not in list. Those elements of course have no influence on the result of BlistList.

    gap> BlistList( [1..10], [2,3,5,7] );
    [ false, true, true, false, true, false, true, false, false, false ]
    gap> BlistList( [1,2,3,4,5,2,8,6,4,10], [4,8,9,16] );
    [ false, false, false, true, false, false, true, false, true, false ]

ListBlist (see ListBlist) is the inverse function to BlistList.

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