distance is a turtle and patch primitive that reports the shortest distance between the current agent and another provided agent. For example, the following code would make the turtles who are close enough to the center patch (0,0) move one step forward, but if their distance to the center patch (0,0) is 5 units or more, they would not move.

ask turtles [
    if distance (patch 0 0) < 5 [ forward 1 ]
]

Things to keep in mind when using distance:

• We can only provide a specific agent to the distance primitive. For example, if we had a turtle breed named trees, the following code would show an error even if there is only one tree in our model: distance trees. This error is shown because trees will always report an agentset. In such a situation where you know that there will only be one agent in the model, you can use the one-of primitive: distance one-of trees.
• If we need to learn an agent's distance to a certain location, not another agent, we can use the distancexy primitive.

In the model example below, we use distance to implement a rudimentary path finding behavior for a lumberjack. The lumberjack has a "target" tree that they will try to move towards and cut down. Once they cut down that tree, they will set their eyes to the closest tree. We use distance to get the distance between the lumberjack and all of the trees so that we can figure out which tree is closest. In the case of ties, we choose one of the closest trees randomly.