count elements falling within certain thresholds in array in matlab?

Question

I have a huge vector. I have to count values falling within certain ranges. the ranges are like 0-10, 10-20 etc. I have to count the number of values which fall in certain rang

Answer 1

Or you can create logical arrays and then use element-wise multiplication. Don't know how fast this is though and it might use a lot of memory for large arrays.

Something like this

A(find((A>0.2 .* (A<0.8)) ==1))

---

Generate values

A= rand(5)

A =

0.414906   0.350930   0.057642   0.650775   0.525488
0.573207   0.763477   0.120935   0.041357   0.900946
0.333857   0.241653   0.421551   0.737704   0.162307
0.517501   0.491623   0.016663   0.016396   0.254099
0.158867   0.098630   0.198298   0.223716   0.136054

Find the intersection where the values > 0.8 and < 0.2. This will give you two logical arrays and the values where A>0.2 and A<0.8 will be =1 after element-wise multiplication.

find((A>0.2 .* (A<0.8)) ==1)

Then apply those indices to A

A(find((A>0.2 .* (A<0.8)) ==1))

ans =

   0.41491
   0.57321
   0.33386
   0.51750
   0.35093
   0.76348
   0.24165
   0.49162
   0.42155
   0.65077
   0.73770
   0.22372
   0.52549
   0.90095
   0.25410