ismember 判断A中的元素在B中有没有出现
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.
对于数组A合B，返回一个和A同样尺寸的数组，若A某位置的元素在B中出现，则LIA相应位置为true,否则为false
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.
对于具有同样列数的A和B，返回一个向量，行数和A相同，如果A的该行在B中出现，则LIA该行的值为1，如果A的该行在B中没有出现过，返回0
[LIA,LOCB] = ismember(A,B) also returns an array LOCB containing
the highest absolute index in B for each element in A which is a member of
B and 0 if there is no such
index.
LOCB和数组A的大小一样，里面包含A中元素在B中出现的位置，最大绝对值位置，即如果B中有两个元素和A中某元素相同，那么就返回索引值最大的那个位置
[LIA,LOCB]
= ismember(A,B,‘rows‘) also returns a vector LOCB containing the highest
absolute index in B for each row in A which is a member of B and 0 if there is
no such index.
同上
In a future release, the behavior of ismember will
change including:
- occurrence of indices in LOCB will switch from highest to
lowest
- tighter restrictions on combinations of classes
In order
to see what impact those changes will have on your code, use:
[LIA,LOCB] = ismember(A,B,‘R2012a‘)
[LIA,LOCB] =
ismember(A,B,‘rows‘,‘R2012a‘)
If the changes in behavior adversely
affect your code, you may preserve
the current 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 = [16 16 0 0 0 0 0 0 0 0 0 0
13 13 0 3 3 3]
[lia2,locb2] = ismember(a,b,‘R2012a‘)
%
returns
lia2 = [1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 1 1 1]
locb2 =
[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
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