How to set "variable hints" for Gurobi

Hi,
I have a MIQCP-Problem that I want to solve with Gurobi 12. It is a pipeflow problem with a binary variable indicating the flow direction.
I already know the likely direction of the flow, therefore I’d like to provide these values to Gurobi as variable hints. The variable hint values are read as parameters from an excel file.

Is it possible to set the variable hints in AMPL directly? I am using .run files, no API.

The advice from “Gurobot” ChatGPT was to use

# Assign hints to variables
let {i in I} x[i].hint := hint_value[i];

but it doesn’t work.

An alternative (also not working) suggestion was

for {i in I} {hint x[i] hint_value[i]};

Any hints would be much appreciated.

To specify hints, you can use the mip:start option described in our Gurobi Options listing.