# Re: [ferret_users] average values excluding zeroes

```Hi,
I think what you're doing looks correct.  What are you seeing?

One thing that may be going on is the region specification:

let temp=ci_data[x=65:95@ave,y=5:40@ave]

```
The context, x=65:95 and y=5:40, is being applied to the pt_in_poly expression and I think the x context is being applied to the arguments xci,yci
```
```
Try it with this instead - you have defined ci_data to be missing outside the region of interest, so it should give you the result you want.
```
let temp=ci_data[x=@ave,y=@ave]

```
Another small suggestion, is to make sure your polygon is closed. Repeat the first value in the lists at the end.
```
See the region,

yes? plot/vs/line/over/nolab/thick xci, yci

Ansley

On 12/3/2014 7:13 AM, Nitin Patil wrote:
```
```Dear ferret users,

```
I am averaging the area of interest and I am getting the mean, standard deviation which counts zero also to get mean. How to exclude the zero in the selected area grids and get the real mean value.
```
Here is my script:

```
let xci = {77,79,79,83,83,84,84,83,83,82,82,80,80,79,79,76,76,73,73,72,72,74,74,75,75,77,77} let yci = {27,27,25,25,24,24,21,20,20,19,18,18,17,17,16,16,15,15,15,18,21,21,23,23,24,24,24}
```let ci = pt_in_poly(rf[d=1],xci, yci)
let ci_data = if ci eq 1 then ci*rf[d=1,l=18050:18171]

let temp=ci_data[x=65:95@ave,y=5:40@ave]
let sum=MISSING(temp,0)
let sum_good=IFV temp then 1 else 0
let count=sum_good
let mean=sum/count

stat mean
sh sym stat*
let varmean = (\$stat_mean)
let varstd = (\$stat_std)

--------------------------

--
Regards,
Nitin Patil

```
```

```