在看例子时有几个问题看不懂
新手，在看netlogo自带的例子时，有几行程序看不懂，希望高手能够指点。netlogo自带的social science--traffic grid这一例子当中，
globals
[
grid-x-inc ;; the amount of patches in between two roads in the x direction
grid-y-inc ;; the amount of patches in between two roads in the y direction
acceleration ;; the constant that controls how much a car speeds up or slows down by if
;; it is to accelerate or decelerate
phase ;; keeps track of the phase
num-cars-stopped ;; the number of cars that are stopped during a single pass thru the go procedure
current-light ;; the currently selected light
;; patch agentsets
intersections ;; agentset containing the patches that are intersections
roads ;; agentset containing the patches that are roads
]
turtles-own
[
speed ;; the speed of the turtle
up-car? ;; true if the turtle moves downwards and false if it moves to the right
wait-time ;; the amount of time since the last time a turtle has moved
]
patches-own
[
intersection? ;; true if the patch is at the intersection of two roads
green-light-up? ;; true if the green light is above the intersection.otherwise, false.
;; false for a non-intersection patches.
my-row ;; the row of the intersection counting from the upper left corner of the
;; world.-1 for non-intersection patches.
my-column ;; the column of the intersection counting from the upper left corner of the
;; world.-1 for non-intersection patches.
my-phase ;; the phase for the intersection.-1 for non-intersection patches.
auto? ;; whether or not this intersection will switch automatically.
;; false for non-intersection patches.
]
;;;;;;;;;;;;;;;;;;;;;;
;; Setup Procedures ;;
;;;;;;;;;;;;;;;;;;;;;;
;; Initialize the display by giving the global and patch variables initial values.
;; Create num-cars of turtles if there are enough road patches for one turtle to
;; be created per road patch. Set up the plots.
to setup
ca
setup-globals
;; First we ask the patches to draw themselves and set up a few variables
setup-patches
make-current one-of intersections
label-current
set-default-shape turtles "car"
if (num-cars > count roads)
[
user-message (word "There are too many cars for the amount of "
"road.Either increase the amount of roads "
"by increasing the GRID-SIZE-X or "
"GRID-SIZE-Y sliders, or decrease the "
"number of cars by lowering the NUMBER slider.\n"
"The setup has stopped.")
stop
]
;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
crt num-cars
[
setup-cars
set-car-color
record-data
]
;; give the turtles an initial speed
ask turtles [ set-car-speed ]
reset-ticks
end
;; Initialize the global variables to appropriate values
to setup-globals
set current-light nobody ;; just for now, since there are no lights yet
set phase 0
set num-cars-stopped 0
set grid-x-inc world-width / grid-size-x
set grid-y-inc world-height / grid-size-y
;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
set acceleration 0.099
end
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
;; and initialize the traffic lights to one setting
to setup-patches
;; initialize the patch-owned variables and color the patches to a base-color
ask patches
[
set intersection? false
set auto? false
set green-light-up? true
set my-row -1
set my-column -1
set my-phase -1
set pcolor brown + 3
]
;; initialize the global variables that hold patch agentsets
set roads patches with
[(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
(floor((pycor + max-pycor) mod grid-y-inc) = 0)]
set intersections roads with
[(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
(floor((pycor + max-pycor) mod grid-y-inc) = 0)]
ask roads [ set pcolor white ]
setup-intersections
end
其中定义道路的句子，如下所示，是什么意思啊？
set roads patches with
[(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
(floor((pycor + max-pycor) mod grid-y-inc) = 0)]
谁能帮我解释一下[(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0)是什么意思吗？
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