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# basic code question

Asked by John on 22 Mar 2012

Hello,

If I had two vectors x1 and x2. How could I make vector x3 with all the elements of x2 except the first 3 elements and last 3 elements are from x1?

Many thanks

John

## 1 Comment

Oleg Komarov on 22 Mar 2012

Please give a specific title to your questions. Otherwise it's hard to tell wether you're double-posting or not.

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Answer by Thomas on 22 Mar 2012

Is this what you wanted?

``` x1=1:10
x2=11:20
y=[x2(3:length(x2)) x1(1:length(x1-3))]```

Wayne King on 22 Mar 2012

x3 = [x1(1:3) x2(4:end-3) x1(end-2:end)];

John on 22 Mar 2012

Thanks,

I'm trying to use it in this context but I'm getting an error for y2

Error using ==> horzcat
CAT arguments dimensions are not consistent.

but y1 and y2 are the same length and direction?

Thank you

for k = 1:length(files)
nrows = size(sch_cycle,1)-1;
x = sch_cycle(:,1);
y = sch_cycle(:,2);
h=3;
N= size(sch_cycle,1);
r=ksr(x,y,h,N)
y1=r.f';
y2 = [y(1:3) y1(4:end-3) y(end-2:end)];

Oleg Komarov on 23 Mar 2012

Concatenate vertically as I show in my example.

Answer by Oleg Komarov on 22 Mar 2012

If same size:

```x1(4:end-2) = x2(4:end-2);
```

Otherwise:

```[x1(1:3); x2(4:end-2); x1(end-2:end)]
```

Answer by Geoff on 22 Mar 2012

To get all but the last 3, use this:

```x1(1:end-3)
```

You can work out how to get all but the first 3 =)

And you already know how to concatenate vectors.

## 1 Comment

Geoff on 22 Mar 2012

Oops, I misread. You want to get the last three only:

x1(end-2:end)