Find closest value in large array

Hey guys,

I have a dataset that is around 4000 rows long and I want to write my script so the user can enter a pressure, and then the script will find the closest values in said data set. How do I go about this?

%------------------------------------------------------------------------%
% Request pressure limits                                                %
%------------------------------------------------------------------------%

UL = input('Enter upper pressure limit (in hPa): ','s');
LL = input('Enter lower pressure limit (in hPa): ','s');

This is all I have so far, any help would be appreciated!

Answer 1

[James]

I have seen a solution to this before, I think the answer was to subtract the value you are looking for, then use the min function on the absolute value of the result. i.e.

a = [1 2 3 4 5]

i want to find the closet value to 3.2.

[m,i] = min(abs(a-3.2));

m is how close the value (3.2) was to the closest value in the array and i is the index at which it was found. in this example, m is 0.2 and i is 3.

hope that helps, james

Answer 2

[Anusha B]

One way to do this is as follows:

For example: Suppose there is a vector with 100 elements and you want to find an element closest to the value that you specify:

x=rand(100,1); %Generating a vector with 100 random elements.

x0=0.321; %Value specified 

y=find((x-x0)<0.5); %Finding indices of all elements whose difference with the value specified is 0.5. (Here my error tolerance is 0.5)

z=x(y); %Creating a vector with the values that satisfy the above condition

closestval=min(z-x0); %Finding the value from this vector that is closest to the value specified.

Hope this helps.