# How can I concatenate arrays in a loop?

**URL:** https://discourse.julialang.org/t/how-can-i-concatenate-arrays-in-a-loop/26043
**Category:** New to Julia
**Created:** [July 5, 2019, 3:01pm UTC](https://discourse.julialang.org/t/how-can-i-concatenate-arrays-in-a-loop/26043 "2019-07-05T15:01:50Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![Elmer\_Cusipuma](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/elmer_cusipuma/32/11958_2.png) [@Elmer\_Cusipuma](https://discourse.julialang.org/u/Elmer_Cusipuma)
#### Post date: [July 5, 2019, 3:01pm UTC](https://discourse.julialang.org/t/how-can-i-concatenate-arrays-in-a-loop/26043/1 "2019-07-05T15:01:50Z")

</div>

I’m trying to create a Array{Float,2} with a for loop

```julia
julia> r = [1 0 0;0 0.85 0.5;0 0 1];

julia> coord = [(0, 0, 450),(400, 0, 450),(400, 600, 450),(0, 600, 450)];

julia> t = [r*collect(i) for i in coord]
4-element Array{Array{Float64,1},1}:
 [0.0, 225.0, 450.0]
 [400.0, 225.0, 450.0]
 [400.0, 735.0, 450.0]
 [0.0, 735.0, 450.0]

```

Desired output:

```julia
3×4 Array{Float64,2}:
   0.0 400.0 400.0 0.0
 225.0 225.0 735.0 735.0
 450.0 450.0 450.0 450.0

```

---

<div class="post-metadata">

### Author: ![feanor12](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/feanor12/32/8212_2.png) [@feanor12](https://discourse.julialang.org/u/feanor12)
#### Post date: [July 5, 2019, 3:21pm UTC](https://discourse.julialang.org/t/how-can-i-concatenate-arrays-in-a-loop/26043/2 "2019-07-05T15:21:28Z")

</div>

```julia
r*hcat(collect.(coord)...)
# or
[r[j,:]'*collect(i) for j in 1:3 ,i in coord ]

```