# Find row elements of a table in another table

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EldaEbrithil 30 Oct 2020
댓글: EldaEbrithil 30 Oct 2020
Hi all
A and B are two tables; I want to know if a set of values of the first row of A is contained in B; i need also the index of that row. Is it possible?
Thank you for the help
Regards

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### 채택된 답변

help ismember % 'row' option
ISMEMBER True for set member. LIA = ISMEMBER(A,B) for arrays A and B returns an array of the same size as A containing true where the elements of A are in B and false otherwise. LIA = ISMEMBER(A,B,'rows') for matrices A and B with the same number of columns, returns a vector containing true where the rows of A are also rows of B and false otherwise. [LIA,LOCB] = ISMEMBER(A,B) also returns an array LOCB containing the lowest absolute index in B for each element in A which is a member of B and 0 if there is no such index. [LIA,LOCB] = ISMEMBER(A,B,'rows') also returns a vector LOCB containing the lowest absolute index in B for each row in A which is a member of B and 0 if there is no such index. The behavior of ISMEMBER has changed. This includes: - occurrence of indices in LOCB switched from highest to lowest - tighter restrictions on combinations of classes If this change in behavior has adversely affected your code, you may preserve the previous behavior with: [LIA,LOCB] = ISMEMBER(A,B,'legacy') [LIA,LOCB] = ISMEMBER(A,B,'rows','legacy') Examples: a = [9 9 8 8 7 7 7 6 6 6 5 5 4 4 2 1 1 1] b = [1 1 1 3 3 3 3 3 4 4 4 4 4 9 9 9] [lia1,locb1] = ismember(a,b) % returns lia1 = [1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 1 1 1] locb1 = [14 14 0 0 0 0 0 0 0 0 0 0 9 9 0 1 1 1] [lia,locb] = ismember([1 NaN 2 3],[3 4 NaN 1]) % NaNs compare as not equal, so this returns lia = [1 0 0 1], locb = [4 0 0 1] Class support for inputs A and B, where A and B must be of the same class unless stated otherwise: - logical, char, all numeric classes (may combine with double arrays) - cell arrays of strings (may combine with char arrays) -- 'rows' option is not supported for cell arrays - objects with methods SORT (SORTROWS for the 'rows' option), EQ and NE -- including heterogeneous arrays derived from the same root class See also ISMEMBERTOL, INTERSECT, UNION, UNIQUE, UNIQUETOL, SETDIFF, SETXOR, SORT, SORTROWS. Documentation for ismember doc ismember Other functions named ismember categorical/ismember duration/ismember sym/ismember cell/ismember gpuArray/ismember tabular/ismember dataset/ismember mtree/ismember tall/ismember datetime/ismember

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EldaEbrithil 30 Oct 2020
is it a problem to have a column of zeros in B?
A = A{:, :};
B = B{:, :};
EldaEbrithil 30 Oct 2020
ok thanks

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R2019a

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