in-radius is a primitive that reports all the agents within a certain radius of the current agent. For example, a turtle might like to know how many other turtles are within a radius of two units of itself or a patch might like to know how many turtles are within three units of itself.

ask turtles [
    if any? other turtles in-radius 2 [
        create-link-with one-of other turtles in-radius 2
    ]
]

Things to keep in mind when using in-radius:

• You can also use floating point values for the radius parameter such as in-radius 3.65.
• Both turtles and patches can use in-radius.
• Keep in mind that in-radius may report the original turtle, too, if you are using the same breeds. Be sure to account for that in your models by using the other primitive as shown in the example above.
• You can combine in-radius and the with primitives to narrow down the target agents but make sure to encapsulate the first with statement within parentheses ( ). For example, you can write a code like if any? (carrots with [color = orange]) in-radius 2 [ eat ].

In the model example below, we have an environment represented with green patches and a factory at the center. When the go button is clicked, the factory pollutes all the patches within a radius of 5, represented by darker green patches.