How to find elements of a vector falling between minimum and maximum of an other vector without loop.

Dear Community,

is there other way, than a loop to find elements in a vector b falling between the minimum and the maximum of vector a?

Let's say:

a=(1:1:10);
b=[5.5 11];
for i=1:length(b)
  if b(:,i)>min(a) && b(:,i)<max(a)
    c(:,i)=1;
  else
    c(:,i)=0;
  end
end

Thanks for your suggestions! lg

Answer 1

[Sulaymon Eshkabilov]

Logical indexing is the best option, e.g.:

a=(1:1:10);
b=[5.5 11; 13, 3; 10.5 10];
IDX = find(b>min(a) & b<max(a));
C(IDX)=1;

[Stephen23]

This answer actually shows linear indexing (the output from the superfluous FIND), not logical indexing.

Remove the superfluous FIND to use simpler and more efficient logical indexing.

Also note that because C is not preallocated, it could have fewer elements than a.

[Levente Gellért]

Dear All, many thanks for the nice comments! lg

Answer 2

[Yazan]

c = zeros(size(b));
c(b>min(a(:)) & b<max(a(:))) = 1;

[Stephen23]

Simpler:

c = b>min(a(:)) & b<max(a(:))

[Levente Gellért]

Dear All, many thanks for the nice comments! lg

Answer 3

[dpb]

>> iswithin(b,min(a),max(a))
ans =
  1×2 logical array
   1   0
>> 

is a common-enough idiom I have a utility function for the purpose--

>> function flg=iswithin(x,lo,hi)
% returns T for values within range of input
% SYNTAX:
%  [log] = iswithin(x,lo,hi)
%      returns T for x between lo and hi values, inclusive

  flg= (x>=lo) & (x<=hi);
end

It isn't any different than writing the logical expression in line except as a function it has the advantage of moving the test to a lower level that is often very helpful in writing concise, legible expressions at the user level.

[Levente Gellért]

Dear All, many thanks for the nice comments! lg

Answer 4

[Matt J]

a=(1:1:10);
b=[5.5 11];

[~,~,c]=histcounts([0,5.5,10,11],[min(a),max(a)+eps(max(a))])

c = 1×4

0 1 1 0

[Levente Gellért]

Dear All, many thanks for the nice comments! lg