<h3>Question</h3>

i'm starting to learn GEKKO. Now, I am solving a knapsak problem to learn, but this time I get the error "int 'object is not subscriptable". can you look at this code? what is the source of the problem How should I define the 1.10 matrices?

```
from gekko import GEKKO
import numpy as np
m = GEKKO(remote=False)
x = m.Var((10),lb=0,ub=1,integer=True)
#x = m.Array(m.Var,(1,10),lb=0,ub=1,integer=True)
v=np.array([2, 2, 7, 8, 2, 1, 7, 9, 4, 10])
w=np.array([2, 2, 2, 2, 2, 1, 6, 7, 3, 3])
capacity=16
for j in range(10):
m.Maximize(v[j]*x[j])
for i in range(10):
m.Equation(m.sum(x[i]*w[i])<=capacity)
m.options.solver = 1
m.solve()
#print('Objective Function: ' + str(m.options.objfcnval))
print(x)
```

My second question is that there is a function called "showproblem ()" in MATLAB. Does GEKKO have this function?

thanks for help. new question that according to answer. can i write here this style(that doesnt work, if i can do it, please write working style)(i want to write this style, because i think this style is easier to understand.),

```
for i in range(10):
xw = x[i]*w[i]
m.Equation(m.sum(xw)<=capacity)
```

instead of this.

```
xw = [x[i]*w[i] for i in range(10)]
m.Equation(m.sum(xw)<=capacity)
```

<h3>Answer1:</h3>

Here is a modified version that solves the mixed integer problem in gekko.

<pre class="lang-py prettyprint-override">```
from gekko import GEKKO
import numpy as np
m = GEKKO(remote=False)
x = m.Array(m.Var,10,lb=0,ub=1,integer=True)
v=np.array([2, 2, 7, 8, 2, 1, 7, 9, 4, 10])
w=np.array([2, 2, 2, 2, 2, 1, 6, 7, 3, 3])
capacity=16
for j in range(10):
m.Maximize(v[j]*x[j])
xw = [x[i]*w[i] for i in range(10)]
m.Equation(m.sum(xw)<=capacity)
m.options.solver = 1
m.solve()
print('Objective Function: ' + str(-m.options.objfcnval))
print(x)
```

Your problem formulation was close. You just needed to define a list `xw`

that you use to form the capacity constraint.
If you want to use a loop instead of a list comprehension then I recommend the following instead of `xw = [x[i]*w[i] for i in range(10)]`

.

```
xw = []
for i in range(10):
xw.append(x[i]*w[i])
```

来源：`https://stackoverflow.com/questions/61881241/int-object-is-not-subscriptable`