# Minimum by key function
**URL:** https://discourse.julialang.org/t/minimum-by-key-function/56056
**Category:** New to Julia
**Tags:** question
**Created:** [February 25, 2021, 11:15pm UTC](https://discourse.julialang.org/t/minimum-by-key-function/56056 "2021-02-25T23:15:03Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@jzr](https://discourse.julialang.org/u/jzr)
#### Post date: [February 25, 2021, 11:15pm UTC](https://discourse.julialang.org/t/minimum-by-key-function/56056/1 "2021-02-25T23:15:03Z")
How can I find the minimum value of an array, but evaluating the minimum through a key function?
In Python,
```julia
In [6]: min([-3, -1, 2], key=abs)
Out[6]: -1
```
---
### Author:  [@lmiq](https://discourse.julialang.org/u/lmiq)
#### Post date: [February 25, 2021, 11:24pm UTC](https://discourse.julialang.org/t/minimum-by-key-function/56056/2 "2021-02-25T23:24:18Z")
```julia
julia> minimum(abs,[-2,1,3])
1
```
By the way, I found out this by using the “help” of the REPL, which is very useful:
```julia
julia> ? minimum
```
Uhm, I note that it is not the same! Sorry. I will keep searching ☹
edit: at least in Julia you can write your own function if searching takes longer than that:
```julia
julia> function minbykey(x;by=identity)
min = by(x[firstindex(x)])
imin = 1
for i in firstindex(x)+1:lastindex(x)
y = by(x[i])
if y < min
min = y
imin = i
end
end
x[imin]
end
minbykey (generic function with 2 methods)
julia> minbykey([-2,-1,3],by=abs)
-1
```
---
### Author:  [@contradict](https://discourse.julialang.org/u/contradict)
#### Post date: [February 25, 2021, 11:50pm UTC](https://discourse.julialang.org/t/minimum-by-key-function/56056/3 "2021-02-25T23:50:38Z")
As far as I know there is no built-in way right now, but 2-arg versions of `findmin` and `argmin` are [coming in 1.7](https://github.com/JuliaLang/julia/pull/35316).
In the mean time:
```julia
minimumby(f, iter) = reduce(iter) do x, y
f(x) < f(y) ? x : y
end
```