MATLAB Answers

Error with find function in a for loop

1 view (last 30 days)
Kafayat Olayinka
Kafayat Olayinka on 6 Feb 2020
Commented: TADA on 6 Feb 2020
Time, height, and temperature variable all have the same array size. I want find temperature at altitude greater than 6km. I also want 6kmtemp to be the same size as temperature. However, after running this code, the result was an empty array. t3 is 0*0. How can I make this find function work in a for loop. BTW, the find function worked when i didnt have it in the loop. However, the array size changed. What am i missing? Thanks
for i=1:length(Time)
t3=find(height(i)>=6);
6kmtemp(i,t3)=temperature(t3);
end

  2 Comments

Star Strider
Star Strider on 6 Feb 2020
Note that:
6kmtemp
is not an acceptable variable name, and will throw an error.
Consider:
temp6km
instead.
Kafayat Olayinka
Kafayat Olayinka on 6 Feb 2020
That is true. however, that was not the error. After running that code, t3 array is empty. meaning the find function in the loop didn't work.

Sign in to comment.

Accepted Answer

TADA
TADA on 6 Feb 2020
Find accepts a logical vector and returns all the indices containing 1.
The problem is you are giving find a scalar value so it's going to return an empty value when height(i) < 6 and 1 whenever height(i) >= 6
Did you consider not using find at all? Instead you can switch to logical indexing:
6kmtemp = nan(size(temperature));
atLeast6km = height >= 6;
6kmtemp(atLeast6km) = temperature(atLeast6km);
You should preallocate 6kmtemp to whatever value you want the "empty" cells to have, I used NaN but you can define your own constants according to what makes sense for you

  4 Comments

Show 1 older comment
Kafayat Olayinka
Kafayat Olayinka on 6 Feb 2020
The code above is not my original code. this is an example of what I am having issue. my original code does not contain 6kmtemp. this was for explaining purpose. thank you.

Sign in to comment.

More Answers (0)

Sign in to answer this question.