I’m trying to unwrap a vector of vectors of vectors into one vector and my first thought is to

```
[k for i in vecs, j in i, k in j]
or
[k for k in j, j in i, i in vecs]
```

```
ERROR: UndefVarError: i/j not defined
```

Do I need to use a full for loop or am I missing something?

oheil
#2
Perhaps you mean something like:

```
[ k for i in vecs for j in 1:i for k in 1:j ]
```

Your `i`

in `j in i`

is an element and not iterable. Same for `j`

in `k in j`

.

oheil
#3
ok, I see vector of vector… ok, it should work, but with `for`

and not `,`

separated.

```
julia> a= [ [1,2,3], [2,3,4,5,6] ]
2-element Vector{Vector{Int64}}:
[1, 2, 3]
[2, 3, 4, 5, 6]
julia> [j for i in a for j in i ]
8-element Vector{Int64}:
1
2
3
2
3
4
5
6
```

~~Iterators.flatten(a) isn’t going deep, so it’s a bit tricky with that …~~

oheil
#4

yes! there it is! thank you. easy enough to iterate with flatten.