Can i find 'mean' of on column , based on second column ?

I have random matrix A 120x6. In last column I have only values 1 or 2. I want to find the min, max, median, and mean of first column for this rows, where in 6 column is 1.

6    8    2    9    5    2
1    8    6   10    5    2
1   10    2    7    2    1
3    3    2    7    2    1
2   10    8    3    1    1
2    1    4    6    4    1
10    9    2    2    9    2
3    8    5    2    5    1
4    3    9    8    6    2
4    8    4    7    7    2
10    1    4    9    7    2

[Wlmistrzow]

i tryied with this

for i=1:120

if A(i,6)==1

d = mean(mean(A(:,1)));

e = median(A(:,1));

end

end

disp(d);

Answer 1

[Image Analyst]

Try this:

m = [...
	6    8    2    9    5    2
1    8    6   10    5    2
1   10    2    7    2    1
3    3    2    7    2    1
2   10    8    3    1    1
2    1    4    6    4    1
10    9    2    2    9    2
3    8    5    2    5    1
4    3    9    8    6    2
4    8    4    7    7    2
10    1    4    9    7    2]
col6Is1 = m(:, 6) == 1
minOfColumn1 = min(m(col6Is1, 1))
maxOfColumn1 = max(m(col6Is1, 1))
medianOfColumn1 = median(m(col6Is1, 1))
meanOfColumn1 = mean(m(col6Is1, 1))

Answer 2

[Thiago Henrique Gomes Lobato]

You can first find the index where columm 6 is one, save it in a vector and then use it as a mask for your first columm, in this way you also vectorize your code, which runs faster in Matlab :

A = rand(120,6)*2;
A(:,6) = ceil(A(:,6)); % Values here can be only either 1 or 2

IndexToTakeAverageAndEtc = find(A(:,6)==1); % Find all rows where A(:,6)==1

Mean = mean(A(IndexToTakeAverageAndEtc,1)); % Take the mean only for the rows where the last columm is 1
Max = max(A(IndexToTakeAverageAndEtc,1));
...

[Wlmistrzow]

6 8 2 9 5 2

1 8 6 10 5 2

1 10 2 7 2 1

3 3 2 7 2 1

2 10 8 3 1 1

2 1 4 6 4 1

10 9 2 2 9 2

3 8 5 2 5 1

4 3 9 8 6 2

4 8 4 7 7 2

10 1 4 9 7 2

i must to have mean from values from column 1 where in the same row , but i the 6 column is number 1. in this example i must to have mean from (1 ,3 ,2,2,3).

[Thiago Henrique Gomes Lobato]

Sorry, I made a typo in my initial code in getting the value from the frist columm, just change the 6 for a 1 (I also edited the answer), this give the result that you want:

A = [6    8    2    9    5    2
1    8    6   10    5    2
1   10    2    7    2    1
3    3    2    7    2    1
2   10    8    3    1    1
2    1    4    6    4    1
10    9    2    2    9    2
3    8    5    2    5    1
4    3    9    8    6    2
4    8    4    7    7    2
10    1    4    9    7    2];
A(:,6) = ceil(A(:,6)); % Values here can be only either 1 or 2
IndexToTakeAverageAndEtc = find(A(:,6)==1); % Find all rows where A(:,6)==1
Mean = mean(A(IndexToTakeAverageAndEtc,1)) % Take the mean only for the rows where the last columm is 1
...
Mean =

2.2000

Which is the mean for (1 ,3 ,2,2,3)