# How to splice two separate Chain into one

**URL:** <https://discourse.julialang.org/t/how-to-splice-two-separate-chain-into-one/121357>\
**Category:** General Usage\
**Created:** [October 16, 2024, 2:17am UTC](https://discourse.julialang.org/t/how-to-splice-two-separate-chain-into-one/121357 "2024-10-16T02:17:57Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Yaozhong\_Liu](https://avatars.discourse-cdn.com/v4/letter/y/a587f6/32.png) [@Yaozhong\_Liu](https://discourse.julialang.org/u/Yaozhong_Liu)\
**Post date:** [October 16, 2024, 2:17am UTC](https://discourse.julialang.org/t/how-to-splice-two-separate-chain-into-one/121357/1 "2024-10-16T02:17:57Z")

</div>

Hi.  
I now have two chains. I want to splice them.  
I know function Parallel(+) can do that. But I don’t expect to get the sum. Instead, I expect to get them end to end.  
For example, Chain1 has 2 outputs:1,2. Chain2 has 2 outputs:3,4. I expect to get Chain3(1,2,3,4)

How can I achieve that?  
Thanks

---

<div class="post-metadata">

**Author:** ![BioTurboNick](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bioturbonick/32/6380_2.png) [@BioTurboNick](https://discourse.julialang.org/u/BioTurboNick)\
**Post date:** [October 16, 2024, 2:26am UTC](https://discourse.julialang.org/t/how-to-splice-two-separate-chain-into-one/121357/2 "2024-10-16T02:26:38Z")

</div>

I assume you’re talking about Flux.jl?

And sounds like you are looking for concatenation?

If so, something like this presumably:

`Parallel((x...) -> cat(x...; dims = <channel_dim>), ...)`

---

<div class="post-metadata">

**Author:** ![Yaozhong\_Liu](https://avatars.discourse-cdn.com/v4/letter/y/a587f6/32.png) [@Yaozhong\_Liu](https://discourse.julialang.org/u/Yaozhong_Liu)\
**Post date:** [October 16, 2024, 5:58am UTC](https://discourse.julialang.org/t/how-to-splice-two-separate-chain-into-one/121357/3 "2024-10-16T05:58:03Z")

</div>

Thank you for replying me!  
Yes! I’m using Flux and concatenation is exactly what I meant.  
I tried your method and succeeded!  
Thank you!