# Interim values of Metaheuristics optimiziers
**URL:** https://discourse.julialang.org/t/interim-values-of-metaheuristics-optimiziers/104768
**Category:** Optimization (Mathematical)
**Tags:** question
**Created:** [October 9, 2023, 8:35pm UTC](https://discourse.julialang.org/t/interim-values-of-metaheuristics-optimiziers/104768 "2023-10-09T20:35:35Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@jcusick](https://discourse.julialang.org/u/jcusick)
#### Post date: [October 9, 2023, 8:35pm UTC](https://discourse.julialang.org/t/interim-values-of-metaheuristics-optimiziers/104768/1 "2023-10-09T20:35:35Z")
I’m interested in getting the interim population values for algorithms within `Metaheuristics.jl` at each timestep, for example Differential Evolution.
I’ve seen [examples](https://jmejia8.github.io/Metaheuristics.jl/stable/visualization/#Convergence) where the _single_ member of the population with the best fitness can be retrieved at each iteration using `convergence()`, though I’d like to be able to interrogate _each member_ of the population at a given timestep.
Is there a clean way to do this? I looked around but it doesn’t seem like `Metaheuristics.optimize()` provides the ability to give a callback function or similar pattern.
The hacky approach I’ve found thus far is to inspect `status.population` during internal calls to `Metaheuristics.stop_criteria!`, which is based off this example from [modifying an existing metaheuristic](https://jmejia8.github.io/Metaheuristics.jl/stable/examples/#Modifying-an-Existing-Metaheuristic).
```julia
global POPULATION [];
function Metaheuristics.stop_criteria!(
status,
parameters::DE
problem,
information,
options,
args...;
kargs...
)
# Allow for traditional usage of DE algo to
# set status and determine when to stop
if status.stop
return
end
# Record state of population
push!(POPULATION, status.population)
end
```
Perhaps there are other lesser documented internal `Metaheuristics` functions that
would be more direct in what I’m looking for?
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [October 10, 2023, 5:50am UTC](https://discourse.julialang.org/t/interim-values-of-metaheuristics-optimiziers/104768/2 "2023-10-10T05:50:06Z")
Hi @jcusick, welcome to the forum. I don’t know the answer to the question, but @jmejia8 should be able to help.
---
### Author:  [@jmejia8](https://discourse.julialang.org/u/jmejia8)
#### Post date: [October 10, 2023, 6:07am UTC](https://discourse.julialang.org/t/interim-values-of-metaheuristics-optimiziers/104768/3 "2023-10-10T06:07:04Z")
@jcusick - Below two approaches:
# Using a logger
```julia
function logger(status)
display(status.population)
print(status.population[1])
end
optimize(f, bounds, DE; logger)
```
See this [Printing progress to terminal when running optimization? · Issue #78 · jmejia8/Metaheuristics.jl · GitHub](https://github.com/jmejia8/Metaheuristics.jl/issues/78#issuecomment-1504465010)
# Using `optimize!`
Example at:
[API References · Metaheuristics.jl](https://jmejia8.github.io/Metaheuristics.jl/stable/api/#Metaheuristics.optimize)!
---
### Author:  [@jcusick](https://discourse.julialang.org/u/jcusick)
#### Post date: [October 10, 2023, 12:45pm UTC](https://discourse.julialang.org/t/interim-values-of-metaheuristics-optimiziers/104768/4 "2023-10-10T12:45:31Z")
Ahh those approaches look great – thanks both @jmejia8 and @odow!