# Conditional sum in constraint

**URL:** <https://discourse.julialang.org/t/conditional-sum-in-constraint/71100>\
**Category:** Optimization (Mathematical)\
**Tags:** jump\
**Created:** [November 7, 2021, 2:46pm UTC](https://discourse.julialang.org/t/conditional-sum-in-constraint/71100 "2021-11-07T14:46:19Z")\
**Posts on this page:** 9\
**Page:** 1

<div class="post-metadata">

**Author:** ![Fabrizio](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fabrizio/32/30587_2.png) [@Fabrizio](https://discourse.julialang.org/u/Fabrizio)\
**Post date:** [November 7, 2021, 2:46pm UTC](https://discourse.julialang.org/t/conditional-sum-in-constraint/71100/1 "2021-11-07T14:46:19Z")

</div>

Dear all, the piece of code below works well with Jump until Ver 0.20.6, newer version of JuMP give to to me the error

LoadError: KeyError: key (1, 1, 2, 1) not found

The BRANCH set is a sparse set indicating the network topology of a power system, while TInBUS is a subset of BUS where generation is present. I’m using Julia 1.6.0. Any hint kn how to modify to make it work?

Thanks  
Fabrizio

> ```
> for h=1:hmax
> for r in BUS
> if r in keys(TInBUS)
> @constraint(
> MyMod,
> sum(pt[j,h] for j in TInBUS[r]) - nodeload[r,h] ==
> sum(p_flow[(l,k,m,h)] for (l,k,m) in BRANCH if r == m) -
> sum(p_flow[(l,k,m,h)] for (l,k,m) in BRANCH if r == k)
> )
> else 
> @constraint(
> MyMod,
> - nodeload[r,h] ==
> sum(p_flow[(l,k,m,h)] for (l,k,m) in BRANCH if r == m) -
> sum(p_flow[(l,k,m,h)] for (l,k,m) in BRANCH if r == k)
> )
> end
> end
> end
> 
> ```

---

<div class="post-metadata">

**Author:** ![trahflow](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/trahflow/32/30585_2.png) [@trahflow](https://discourse.julialang.org/u/trahflow)\
**Post date:** [November 7, 2021, 3:14pm UTC](https://discourse.julialang.org/t/conditional-sum-in-constraint/71100/2 "2021-11-07T15:14:49Z")

</div>

Hi Fabrizio,

to make it easier to help you, try to format the code you post. You can do so using [Markdown](https://en.wikipedia.org/wiki/Markdown), in particular by putting your code between triple backticks ```… ```. see e.g. [here for a reference](https://commonmark.org/help/)

This helps other people to quicker parse your problem.

Also, it’s usually helpful to paste the full stacktrace, not just the error.

---

<div class="post-metadata">

**Author:** ![trahflow](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/trahflow/32/30585_2.png) [@trahflow](https://discourse.julialang.org/u/trahflow)\
**Post date:** [November 7, 2021, 3:19pm UTC](https://discourse.julialang.org/t/conditional-sum-in-constraint/71100/3 "2021-11-07T15:19:36Z")

</div>

On your particular problem:  
It seems like it’s probably `p_flow` that doesn’t have a key `(1, 1, 2, 1)`.

You can get the keys of `p_flow` via

```julia
keys(p_flow)

```

to check.

---

<div class="post-metadata">

**Author:** ![Fabrizio](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fabrizio/32/30587_2.png) [@Fabrizio](https://discourse.julialang.org/u/Fabrizio)\
**Post date:** [November 7, 2021, 5:12pm UTC](https://discourse.julialang.org/t/conditional-sum-in-constraint/71100/4 "2021-11-07T17:12:54Z")

</div>

Hi, thanks for the answer. Below the full stacktrace. Indeed one of the two p\_flow (“in” or “out” of the node “r”) does not have the key depending on how is oriented, but the trick “if r==m” and “if r==k” in the _sum(.)_ worked just fine before updating JuMP to ver \>0.20.6

Any other hint?

Regards,  
Fabrizio

Stacktrace:  
[1] getindex(::JuMP.Containers.\_AxisLookup{Dict{NTuple{4,Int64},Int64}}, ::Tuple{Int32,Int32,Int32,Int64}) at C:\Users\Fabrizio.julia\packages\JuMP\klrjG\src\Containers\DenseAxisArray.jl:18  
[2] \_getindex\_recurse(::Tuple{JuMP.Containers.\_AxisLookup{Dict{NTuple{4,Int64},Int64}}}, ::Tuple{Tuple{Int32,Int32,Int32,Int64}}, ::getfield(JuMP.Containers, Symbol(“##8#10”))) at C:\Users\Fabrizio.julia\packages\JuMP\klrjG\src\Containers\DenseAxisArray.jl:250  
[3] to\_index(::JuMP.Containers.DenseAxisArray{VariableRef,1,Tuple{Array{NTuple{4,Int64},2}},Tuple{JuMP.Containers.\_AxisLookup{Dict{NTuple{4,Int64},Int64}}}}, ::Tuple{Tuple{Int32,Int32,Int32,Int64}}) at C:\Users\Fabrizio.julia\packages\JuMP\klrjG\src\Containers\DenseAxisArray.jl:259  
[4] getindex(::JuMP.Containers.DenseAxisArray{VariableRef,1,Tuple{Array{NTuple{4,Int64},2}},Tuple{JuMP.Containers.\_AxisLookup{Dict{NTuple{4,Int64},Int64}}}}, ::Tuple{Int32,Int32,Int32,Int64}) at C:\Users\Fabrizio.julia\packages\JuMP\klrjG\src\Containers\DenseAxisArray.jl:266  
[5] MyNetworkcns(::Model, ::Array{Tuple{Int32,Int32,Int32},1}, ::Array{Int64,1}, ::Int64, ::Array{Float64,1}, ::Bool, ::String, ::Bool, ::Int64, ::Bool, ::Bool) at C:\Users\Fabrizio.julia\packages\MutableArithmetics\0Y9ZS\src\rewrite.jl:279  
[6] SolveMyProblem(::String, ::Int64, ::Float64, ::Int64, ::Int64, ::Array{Float64,2}, ::Array{Tuple{Int32,Int32,Int32},1}, ::Array{Int64,1}, ::Array{Float64,1}, ::Bool, ::String, ::Int64, ::Bool) at C:\DATI\Codici\_Sorgente\ProgrammiJulia\UCOTS\_20211106\_newJump\UCOTS.jl:584  
[7] top-level scope at none:0  
[8] include at .\boot.jl:326 [inlined]  
[9] include\_relative(::Module, ::String) at .\loading.jl:1038  
[10] include(::Module, ::String) at .\sysimg.jl:29  
[11] include(::String) at .\client.jl:403  
[12] top-level scope at none:0

---

<div class="post-metadata">

**Author:** ![Fabrizio](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fabrizio/32/30587_2.png) [@Fabrizio](https://discourse.julialang.org/u/Fabrizio)\
**Post date:** [November 7, 2021, 5:23pm UTC](https://discourse.julialang.org/t/conditional-sum-in-constraint/71100/5 "2021-11-07T17:23:48Z")

</div>

I solved the problem by simply changing the definition of BRANCH from

BRANCH = [(Int32(BrancheS[l].line), Int32(BrancheS[l].from), Int32(BrancheS[l].to)) for l=1:length(LINES)]

in to

BRANCH = [(BrancheS[l].line, BrancheS[l].from, BrancheS[l].to) for l=1:length(LINES)]

---

<div class="post-metadata">

**Author:** ![odow](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/odow/32/28685_2.png) [@odow](https://discourse.julialang.org/u/odow)\
**Post date:** [November 7, 2021, 7:54pm UTC](https://discourse.julialang.org/t/conditional-sum-in-constraint/71100/6 "2021-11-07T19:54:24Z")

</div>

Hi @Fabrizio,

Can you provide a reproducible example that I can copy-and-paste?

Why did you have explicit `Int32` casts? It seems like JuMP might be converting `Int32` to `Int64` somewhere.

---

<div class="post-metadata">

**Author:** ![Fabrizio](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fabrizio/32/30587_2.png) [@Fabrizio](https://discourse.julialang.org/u/Fabrizio)\
**Post date:** [November 7, 2021, 8:12pm UTC](https://discourse.julialang.org/t/conditional-sum-in-constraint/71100/7 "2021-11-07T20:12:59Z")

</div>

Hi @odow,

a working example is quite difficult to extract for me and i don’t know why a former student did this explicit cast in the definition of the set BRANCH.

However maybe the problem was in the: “if r==m” or “if r==k” in the sum(.) below

> sum(p\_flow[(l,k,m,h)] for (l,k,m) in BRANCH if r == m)

If you take a look of the code posted previously the BUS is so defined:

BUS = collect(1:Int32(size(bus,1)))

and we iterate in the for loop “r in BUS”

the only thing i can stress is that there has been a change in the ver \> 0.20.6 of JuMP

---

<div class="post-metadata">

**Author:** ![odow](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/odow/32/28685_2.png) [@odow](https://discourse.julialang.org/u/odow)\
**Post date:** [November 7, 2021, 9:21pm UTC](https://discourse.julialang.org/t/conditional-sum-in-constraint/71100/8 "2021-11-07T21:21:02Z")

</div>

## Current version

The current behavior seems correct. If your index sets are `Int32`, then you need to index with an `Int32`:

```Julia
julia> using JuMP

julia> model = Model();

julia> S = Int32[1]
1-element Vector{Int32}:
 1

julia> @variable(model, x[S])
1-dimensional DenseAxisArray{VariableRef,1,...} with index sets:
    Dimension 1, Int32[1]
And data, a 1-element Vector{VariableRef}:
 x[1]

julia> x[1]
ERROR: KeyError: key 1 not found
Stacktrace:
 [1] getindex(#unused#::JuMP.Containers._AxisLookup{Dict{Int32, Int64}}, key::Int64)
   @ JuMP.Containers ~/.julia/dev/JuMP/src/Containers/DenseAxisArray.jl:18
 [2] _getindex_recurse(data::Tuple{JuMP.Containers._AxisLookup{Dict{Int32, Int64}}}, keys::Tuple{Int64}, condition::JuMP.Containers.var"#10#12")
   @ JuMP.Containers ~/.julia/dev/JuMP/src/Containers/DenseAxisArray.jl:299
 [3] to_index(A::JuMP.Containers.DenseAxisArray{VariableRef, 1, Tuple{Vector{Int32}}, Tuple{JuMP.Containers._AxisLookup{Dict{Int32, Int64}}}}, idx::Tuple{Int64})
   @ JuMP.Containers ~/.julia/dev/JuMP/src/Containers/DenseAxisArray.jl:308
 [4] getindex(A::JuMP.Containers.DenseAxisArray{VariableRef, 1, Tuple{Vector{Int32}}, Tuple{JuMP.Containers._AxisLookup{Dict{Int32, Int64}}}}, idx::Int64)
   @ JuMP.Containers ~/.julia/dev/JuMP/src/Containers/DenseAxisArray.jl:315
 [5] top-level scope
   @ REPL[18]:1

julia> x[Int32(1)]
x[1]

```

## v0.21.6

It looks like JuMP 0.21.6 didn’t respect types like this, and automatically converted if needed:

```Julia
julia> using JuMP

julia> model = Model();

julia> S = Int32[1]
1-element Vector{Int32}:
 1

julia> @variable(model, x[S])
1-dimensional DenseAxisArray{VariableRef,1,...} with index sets:
    Dimension 1, Int32[1]
And data, a 1-element Vector{VariableRef}:
 x[1]

julia> x[1]
x[1]

```

It’s a shame we broke existing code. But I’d regard this as a bug fix. I don’t know if we want to re-introduce the old behavior. The easiest fix for your code is probably just to delete all of the explicit `Int32` casts.

---

<div class="post-metadata">

**Author:** ![Fabrizio](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fabrizio/32/30587_2.png) [@Fabrizio](https://discourse.julialang.org/u/Fabrizio)\
**Post date:** [November 7, 2021, 11:53pm UTC](https://discourse.julialang.org/t/conditional-sum-in-constraint/71100/9 "2021-11-07T23:53:02Z")

</div>

thanks @odow for the explanation, and yes i don’t know if you want to treat as a bug fix, but it may be useful.

Regards,  
Fabrizio