错误尝试访问索引 [1, 0] 处的 30×26 Array{VariableRef,2}

Question

I am having problems when I want to assign workers to different shifts according to the satisfy the required. They can be in two shifts per day.

But I do not know why the array problem, I am new in Julia

empleados=26;
turnos=30;
requerimiento=[3,4,1,1,2,2,4,3,1,3,3,1,2,4,2,4,3,2,1,2,2,2,2,2,2,3]
costo=28;

using JuMP
using Gurobi
m = Model(with_optimizer(Gurobi.Optimizer))

@variable(m, x[1:turnos,1:empleados]<=1,Bin)

@objective(m, Min, costo * sum(x))    

for i in 1:turnos+1,j in 1:empleados
    @constraint(m,x[i,j] + x[i,j-1] + x[i,j+1]  <= 2)
end
for i in 1:turnos+3,j in 1:empleados
    @constraint(m, x[i,j]+x[i,j-2]+x[i,j-3]+x[i,j+3]+x[i,j+2] <= 1) 
end
    @constraint(m, sum(x[i,:]) for i in i:turnos >=requerimiento[i])

***ERROR***
BoundsError: attempt to access 30×26 Array{VariableRef,2} at index [1, 0]

Stacktrace:
 [1] getindex(::Array{VariableRef,2}, ::Int64, ::Int64) at .\array.jl:729
 [2] macro expansion at C:\Users\DELL\.julia\packages\JuMP\MsUSY\src\macros.jl:390 [inlined]
 [3] top-level scope at .\In[103]:15

Answer 1

The first error appears in this line:

for i in 1:turnos+1,j in 1:empleados
    @constraint(m,x[i,j] + x[i,j-1] + x[i,j+1]  <= 2)
end

In Julia, arrays are usually indexed starting from 1 (look for 1-based indexing). This is different from other languages like python.

This means that if your array is of size (30,26), you can only use indices from 1 to 30 in the first dimension and from 1 to 26 y the second one.

Your variable x has a size of 30x26 , but in your loop you are trying to call the element x[1,0] (because you are asking x[i,j - 1] and j starts from 1). Once you fix this by either reformulating your indices or your range, you will run into another problem with the part x[i,j+1] because you will try to access x[1,27] which also does not exist. You also need to fix the range of i, which currently goes from 1 to 31 in the first index ( for i in 1:turnos + 1 ). This is also going to break your code because your array only has a size 30 in the first dimension.

Finally, in the last line you are constructing

@constraint(m, sum(x[i,:]) for i in i:turnos >=requerimiento[i])

This will give an error beacuse you are asking i to go from i to another value, which doesn't make sense.

So you only need to pay careful attention to how you are iterating your arrays.

One way to make this line work is doing:

for i in 1:turnos,j in 2:empleados-1
       @constraint(m,x[i,j] + x[i,j-1] + x[i,j+1]  <= 2)
end

But I don't understand your model so I don't know if that is what you are trying to do. The best advice I can give you is to familiarize better with the indexing on the official docs using simple examples.