Pulling subset from a 2D matrix

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Simon 2013-9-5

Hi,

I am struggling how to extract part of a 2D matrix based on logical criteria:

example:

a=[1 1 1 ; 2 2 2 ; 3 3 3]
b=a<3  % let say I want to have the subset where a<3
mySubset=a.*b

how can I obtain the subset using logic and not having a line of zeros where a=3?

Thanks

Azzi Abdelmalek 2013-9-5

编辑：Azzi Abdelmalek 2013-9-5

a=[1 1 1 ; 2 2 2 ; 3 3 3]
b==a<3
mySubset=a.*b

Simon 2013-9-5

Thanks! I was not aware of the function all()

Roger Stafford 2013-9-5

The 'all' method only works if all elements of a row in 'a' are less than 3. In general I think what you really want is

mySubset = a(b);

The result will be a one-dimensional array but in the general case that is unavoidable.

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