Finding average using two input condition from a table

Hi, I hope someone can help me with this question. I'd like to find the average of the 3rd column of a table using conditions on the 1st and 2nd columns. For example, in the table below, I'd like to find the average z with x = 1 AND y = 1800 (this should be average of 1.5 and 2), and when x = 2, y = 1900 (1.4 alone), etc

x y z

1 1800 1.5

2 1900 1.4

3 2100 3

3 1900 1.1

1 1900 0.8

2 2700 1.2

3 1800 2

Answer 1

[Peter Perkins]

Several ways to do this, including findgroups/splitapply, groupsummary, and varfun:

>> XYZ = [ ...
    1	1800	1.5
    2	1900	1.4
    3	2100	3
    3	1900	1.1
    1	1900	0.8
    2	2700	1.2
    1	1800	2];
>> T = array2table(XYZ,'VariableNames',{'x' 'y' 'z'})
T =
  7×3 table
    x     y       z 
    _    ____    ___
    1    1800    1.5
    2    1900    1.4
    3    2100      3
    3    1900    1.1
    1    1900    0.8
    2    2700    1.2
    1    1800      2
>> varfun(@mean,T,'GroupingVariables',{'x' 'y'})
ans =
  6×4 table
    x     y      GroupCount    mean_z
    _    ____    __________    ______
    1    1800        2          1.75 
    1    1900        1           0.8 
    2    1900        1           1.4 
    2    2700        1           1.2 
    3    1900        1           1.1 
    3    2100        1             3 

[Harold Singh]

Peter, Many thanks. This works. Sure beats looping through the table, and computing the average.

Harold

Answer 2

[Harold Singh]

Sorry, I made a mistake with the table. The corrected table is:

x y z

1 1800 1.5

2 1900 1.4

3 2100 3

3 1900 1.1

1 1900 0.8

2 2700 1.2

1 1800 2