finding all instances in a vector

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Hi all,

is there an easy way to find all instances of, say, numbers in vector x in a target vector, y?

For example, if I have a vector x which is: [ 1 4 10 ] how do i find all 1's 4's and 10's in y: [ 1 2 3 4 5 6 7 8 9 10 ]

sorry if this is a basic question.. i could write a for-loop of course, but i imagine there must be a more elegant way to do this. Thanks in advance!

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Liz 2011-7-21

sorry, i have to add one other thing.. it actually has to find all instances, even duplicates.. so it would be more like

x = [1 4 10] and y = [1 2 3 4 4 4 5 4 6 4 7 8 9 10]

the cyclist 2011-7-21

No problem that this is a basic question! You asked it clearly and specifically, with an example of what you wanted. Good question.

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Answer 1

the cyclist 2011-7-21

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You want the ismember() function.

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Liz 2011-7-21

oh! i get it now, you were right..

if i have

x = [1 4 10] and y = [1 2 3 4 4 4 5 4 6 4 7 8 9 10]

i can say: out = ismember(y,x) and i get:

out =

Columns 1 through 14

1 0 0 1 0 0 0 0 0 1 1 0 0 1

Columns 15 through 20

0 0 0 0 0 1

thank you!

the cyclist 2011-7-21

Note that if you call ismember() with two outputs, then the first output indicates that the element was found, and the second output is an index to WHICH element of "x" it was.

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