setdiff

Arguments

a, b

vectors, matrices or hypermatrices of real or complex numbers, encoded integers, booleans, or strings. Sparse-encoded inputs are accepted. Both a and b must have the same data type (and integer type), but may mix dense and sparse encoding.

If the option orien="r" is used, a and b must have the same number of columns. If the orien="c" is used, they must have the same number of rows.

orien

oriented processing:

• "r": rows of a are searched among b ones.
• "c": columns of a are searched among b ones.
• no orien: elements of a are searched among b ones.

v

Array with a's data type and encoding:

• sorted vector of a's components that are not in b.
• orien="r": matrix of rows of a that are not in b, sorted in lexicographic order.
• orien="c": matrix of columns of a that are not in b, sorted in lexicographic order.

ka

vector of linear indices of selected a's components, rows, or columns, such that

• v = a(ka), or
• v = a(ka,:) (orien="r"), or
• v = a(:,ka) (orien="c")

Description

setdiff(a, b,..) computes and returns the elements or rows or columns of a that are NOT in b.

All duplicates (elements or rows or columns) are removed from a and from b before processing.

If a is an hypermatrix and the "r" option is used, a is replaced with the matrix of all its rows over all its higher dimensions, before processing. Same thing if b is an hypermatrix. If the "c" option is used, a or/and "b" are replaced with the respective matrices of all their columns.

The format of results is presented in the following table, according to the shape of a and the orien option. In all cases, if all entities of a are in b, [] is returned for v as for ka:

v and ka become empty if a is empty (whatever is b), or if all a elements are in b.

For booleans, setdiff(…) is useful mainly with the "r" or "c" options.

Examples

Example #1:

a = grand(1, 10,"uin", 0, 9)
b = grand(2, 4, "uin", 0, 9)
[d, k] = setdiff(a, b);
d, k

--> a = grand(1, 10,"uin", 0, 9)
 a  =
   2.   2.   4.   5.   4.   1.   9.   5.   8.   3.

--> b = grand(2, 4, "uin", 0, 9)
 b  =
   5.   0.   9.   9.
   5.   6.   0.   4.

--> [d, k] = setdiff(a, b);
--> d, k
 d  =
   1.   2.   3.   8.

 k  =
   6.   1.   10.   9.

Example #2: column-wise processing

a = grand(2, 7,"uin", 0, 3)
b = grand(2, 10, "uin", 0, 3)
[d, k] = setdiff(a, b, "c");
d, k

--> a = grand(2, 7,"uin", 0, 3)
 a  =
   0.   1.   0.   2.   3.   0.   2.
   2.   2.   2.   1.   0.   1.   2.

--> b = grand(2, 10, "uin", 0, 3)
 b  =
   1.   1.   3.   1.   1.   1.   3.   0.   2.   0.
   3.   3.   2.   2.   0.   0.   1.   0.   1.   0.

--> [d, k] = setdiff(a, b, "c");
--> d, k
 d  =
   0.   0.   2.   3.
   1.   2.   2.   0.

 k  =
   6.   1.   7.   5.

Example #3: with some text

v1 = tokens("ab  ca  ba  bb  ca  cb  ba  aa  cc  bc  ac  aa")'
v2 = tokens("cc  ac  ca  bb  ac  bc  ab")'
[r, k] = setdiff(v1, v2);
r, k

--> v1 = tokens("ab  ca  ba  bb  ca  cb  ba  aa  cc  bc  ac  aa")'
 v1  =
!ab  ca  ac  bb  ca  cb  ba  aa  cc  bc  ac  aa  !

--> v2 = tokens("cc  ac  ca  bb  ac  bc  ab")'
 v2  =
!cc  ac  ca  bb  ac  bc  ab  !

--> [r, k] = setdiff(v1, v2);
--> r, k
 r  =
!aa  ba  cb  !

 k  =
   8.   3.   6.

See also

• unique — extracts (and sorts) distinct elements, rows or columns of a matrix
• union — Set of all elements, rows, or columns of two arrays, without duplicates
• members — count (and locate) in an array each element or row or column of another array
• vectorfind — locates occurences of a (wildcarded) vector in a matrix or hypermatrix

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