# Loop in dictionary definition
**URL:** https://discourse.julialang.org/t/loop-in-dictionary-definition/63951
**Category:** New to Julia
**Created:** [July 2, 2021, 5:40pm UTC](https://discourse.julialang.org/t/loop-in-dictionary-definition/63951 "2021-07-02T17:40:44Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Ribeiro](https://discourse.julialang.org/u/Ribeiro)
#### Post date: [July 2, 2021, 5:40pm UTC](https://discourse.julialang.org/t/loop-in-dictionary-definition/63951/1 "2021-07-02T17:40:44Z")
Hello,
I’m using a library that uses a dictionary to set variables along points, like so:
```julia
bla = Dict(
1 => foo,
2 => bar
)
```
I want to create that dictionary over a large number of points and that number is not constant. Something like:
```julia
bla = Dict(
for i in 1:N
i => foo[i],
end
)
```
How can I achieve this?
Thanks a lot!
---
### Author:  [@rdeits](https://discourse.julialang.org/u/rdeits)
#### Post date: [July 2, 2021, 5:46pm UTC](https://discourse.julialang.org/t/loop-in-dictionary-definition/63951/2 "2021-07-02T17:46:47Z")
You can use a comprehension for this::
```julia
julia> N = 5;
julia> foo = rand(N);
julia> bla = Dict(i => foo[i] for i in 1:N)
Dict{Int64, Float64} with 5 entries:
5 => 0.825488
4 => 0.308265
2 => 0.932313
3 => 0.495245
1 => 0.490559
```
---
### Author:  [@Ribeiro](https://discourse.julialang.org/u/Ribeiro)
#### Post date: [July 2, 2021, 5:52pm UTC](https://discourse.julialang.org/t/loop-in-dictionary-definition/63951/3 "2021-07-02T17:52:41Z")
> [@rdeits](#):
>
> You can use a comprehension for this:
Oh, that’s great, thanks!
How do I combine that with a defined entry? I never worked with Dictionaries before. Can I add a new point (say point 6) after `bla = Dict(i => foo[i] for i in 1:N)`?
Something like:
```julia
bla = Dict(i => foo[i] for i in 1:N, 6=>0.2)
```
Thanks!
---
### Author:  [@Ribeiro](https://discourse.julialang.org/u/Ribeiro)
#### Post date: [July 2, 2021, 5:56pm UTC](https://discourse.julialang.org/t/loop-in-dictionary-definition/63951/4 "2021-07-02T17:56:15Z")
Just figured out the merge command. So if that’s the way to go, I’m happy. Thanks again!
---
### Author:  [@rdeits](https://discourse.julialang.org/u/rdeits)
#### Post date: [July 2, 2021, 6:14pm UTC](https://discourse.julialang.org/t/loop-in-dictionary-definition/63951/5 "2021-07-02T18:14:35Z")
Yup, `merge` will certainly work. On the other hand, you might also consider just using a loop–loops are fast in Julia, and often the easiest way to do things:
```julia
julia> d = Dict{Int, Float64}()
Dict{Int64, Float64}()
julia> for i in 1:N
d[i] = foo[i]
end
julia> d[6] = 0.2
0.2
julia> d
Dict{Int64, Float64} with 6 entries:
5 => 0.825488
4 => 0.308265
6 => 0.2
2 => 0.932313
3 => 0.495245
1 => 0.490559
```
---
### Author:  [@Ribeiro](https://discourse.julialang.org/u/Ribeiro)
#### Post date: [July 2, 2021, 6:26pm UTC](https://discourse.julialang.org/t/loop-in-dictionary-definition/63951/6 "2021-07-02T18:26:45Z")
Ah, that is also a neat way to do it. Thanks!