How to use one data set to find the mean of another?

I have a data set (neighbors) and a data set (height) where I need to find the mean of the height of the plants that have 1 neighbor.

If say my Neighbors data set is 2,1,4,1,6,7,3,1 and my height is 12.5,17,10,4,16,20.4,13.2,9.4 . How do I compare these two? My thought is to use NON=find(Neighbors==1) and somehow use the designated spots to correlate it to height, but I don't know how. Please let me know if there is another way to do this. I've only been using Matlab for 1 week and have been using youtube a lot for help. Thanks.

NON=NumberOfNeighbors

PLCm=PlantHeightcm

find PLCm when NON=1

Error using find

Second argument must be a positive scalar integer.

Answer 1

[Chunru]

neighbors = [2,1,4,1,6,7,3,1];
height = [12.5,17,10,4,16,20.4,13.2,9.4 ];

% find the entries with 1 neighbour
idx = neighbors == 1;
% use logic index to get the heights with 1 neigbour and find mean
a = mean(height(idx))

a = 10.1333

% or in one line
a = mean(height(neighbors==1))

a = 10.1333

[Kristin Aldridge]

Thank you! That's the formula I ended up using and got the appropriate answer. I appreciate it!

Answer 2

[Jeff Miller]

NON1 = NON == 1;  % this makes a boolean vector that is true for the positions where NON==1
mean(PLCm(NON1));  % this computes the mean of the PLCm values in those positions