# Re: [Scilab-users] mean of elements corresponding element is "true"

```Le 02/03/2018 à 16:40, fujimoto2005 a écrit :
```
```In the attached code,"boolean_M" is a random Boolean matrix.
I want to get the average of each column of A whose corresponding element of
boolean_M has "true" as row vector x_V, but it does not work.
Where am I wrong?
n=10;
boolean_M=rand(n,n)>0.5;
disp(boolean_M)
A=rand(n,n);
disp(A);
x_V=mean(A(boolean_M),'r');
```
```

n  =  5;
boolean_M  =  rand(n,n)>0.5
A  =  grand(n,n,"uin",0,9)
A(boolean_M)  =  %nan
nanmean(A,"r")

--> n = 5;
--> boolean_M = rand(n,n)>0.5
boolean_M  =
T F F F T
T T T T T
T T F T T
F T F T F
F F T T F

--> A = grand(n,n,"uin",0,9)
A  =
6.   2.   5.   4.   6.
6.   9.   3.   6.   5.
3.   9.   3.   5.   4.
0.   8.   7.   0.   7.
1.   6.   8.   7.   2.

--> A(boolean_M) = %nan
A  =
Nan   2.    5.    4.    Nan
Nan   Nan   Nan   Nan   Nan
Nan   Nan   3.    Nan   Nan
0.    Nan   7.    Nan   7.
1.    6.    Nan   Nan   2.

--> nanmean(A,"r")
ans  =
0.5   4.   5.   4.   4.5

Samuel

```
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