questions about functions inside a function

[Duncan Booth]

"fdu.xiaojf at gmail.com" <fdu.xiaojf at gmail.com> wrote:

> In order to make sure all variables be larger than 0, I tried to created
> constraint function like this:
> 
> cons = []
> for i in range(N):
>      c = lambda x: x[i] - 1e-10
>      cons.append(c)
> 
> But when functions in cons are evaluated, the value in all functions are
> all the same(N-1, which is the last value of i in the loop).
> 
> What I want is, when functions in cons be evaluated, every function
> refers to a different variable in X.

So pass i in as a default value:

for i in range(N):
   def c(x, i=i):
       return x[i] - 1e-10
   cons.append(c)