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[求助] 在看例子时有几个问题看不懂

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发表于 2012-6-20 08:59:43 | 显示全部楼层 |阅读模式
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。
' C: U7 h# n' _* K! b, vnetlogo自带的social science--traffic grid这一例子当中,
# F# t! K4 U  `globals* F. Q3 {* x9 J! o) T- F/ {9 O
[4 H/ b  ?5 `8 @7 @9 e
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 j1 k$ O$ O  z: D  grid-y-inc               ;; the amount of patches in between two roads in the y direction( W0 n& m$ ^4 s0 y* h! x
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 v7 g2 Q; w, x  n. I                           ;; it is to accelerate or decelerate, U4 k: T& G/ x. R
  phase                    ;; keeps track of the phase7 V4 R# _$ N  _& H8 O: w8 a
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) u: W, U; s! r3 {$ u9 d5 ^; f
  current-light            ;; the currently selected light- A: R7 l4 q9 p) @5 r1 n

7 W! w, |) m8 A7 {  ;; patch agentsets
# b+ B- ?* @7 B$ W8 q* T  intersections ;; agentset containing the patches that are intersections
5 X, l& ^- a! I  roads         ;; agentset containing the patches that are roads
. A6 |! n7 X* s% w7 \8 _]
7 T" b  ~7 Y9 j0 V* v8 x
  F1 i) T& C$ S) Oturtles-own
2 R; _# z8 u% Q% Q8 a$ r! h" f$ B. K[
; Y0 L- {* _2 N. n  \  speed     ;; the speed of the turtle9 J1 m( G0 x0 |3 M
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 |2 F; o0 ^, J! r0 b6 G0 n
  wait-time ;; the amount of time since the last time a turtle has moved2 m/ u, w; Q: Y! l- l/ W# n4 A( V
]
" X5 r- R* o, a% {; P* }2 J' J6 q& q+ P1 q: u3 I
patches-own
$ H$ V3 Q# N; ^8 c+ j[0 a4 D- V+ [( `; @, y6 z
  intersection?   ;; true if the patch is at the intersection of two roads
' z  P3 A6 D/ m  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 c; _, U5 Q2 s4 x7 a0 f
                  ;; false for a non-intersection patches.
* e; j* R) @6 {3 L- |# ?  my-row          ;; the row of the intersection counting from the upper left corner of the
/ \3 m- t3 Y9 S7 }5 u! g6 l  u                  ;; world.  -1 for non-intersection patches.
7 e0 V7 S5 s! v  my-column       ;; the column of the intersection counting from the upper left corner of the' v- I; A* n% }2 S  I' b
                  ;; world.  -1 for non-intersection patches., k6 H, k; ^: k4 i' v% L
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ b. l" J) N" _  }) \$ u" ^* _
  auto?           ;; whether or not this intersection will switch automatically.
' h2 D% R9 J) d, ^                  ;; false for non-intersection patches.
2 n0 q, Y8 k+ x; A: \0 T]5 s' @9 |7 y9 N5 p+ K3 t+ v% o1 [

; P' G/ O1 ?, s. Y
! F5 c/ p; _# t6 _% m2 S3 D;;;;;;;;;;;;;;;;;;;;;;
; d! G. k, S, i;; Setup Procedures ;;
: M2 T2 n0 w* l* B" O- C  h' a;;;;;;;;;;;;;;;;;;;;;;
) y3 l8 T5 _. u6 [
1 R: B. p9 U9 E+ x. y;; Initialize the display by giving the global and patch variables initial values.
8 M/ V5 p, P1 g( k: @/ o" L* [;; Create num-cars of turtles if there are enough road patches for one turtle to
5 ^5 [2 b! X2 S, w;; be created per road patch. Set up the plots.: ^1 }, O) b$ I
to setup
9 ~6 {" A2 P% q/ B1 _' V/ c  ca$ C  @& e3 r- x' ]; c) O4 k/ r
  setup-globals
; Q8 A  I- v' m0 g" {7 _
2 ~/ b& F9 H8 l, [$ F1 N" Q  ;; First we ask the patches to draw themselves and set up a few variables* O7 T* k; Q" A! i& Z: `) X) U8 L
  setup-patches
& \: y- o7 H! P7 r, [& B# J/ f  make-current one-of intersections% c+ l4 Z  u0 `1 N
  label-current( B0 N; ]5 ^0 Q0 L6 v* X

* |: ?! \# \- k- t% Z  set-default-shape turtles "car"
" q  n/ q9 J3 r
& C6 s2 }3 P  P* j3 n+ ~  if (num-cars > count roads)- D, w& @" @7 |& P! D  X- [
  [5 Y7 g, u2 j- Q
    user-message (word "There are too many cars for the amount of "* M! p: [8 E0 }2 p* j8 ?# Y
                       "road.  Either increase the amount of roads "$ l3 a# Q6 H$ \
                       "by increasing the GRID-SIZE-X or "+ L; l' o! w' [7 |$ `: u
                       "GRID-SIZE-Y sliders, or decrease the "/ s/ n/ E8 ~5 N: \, ~
                       "number of cars by lowering the NUMBER slider.\n"2 Q1 u, g4 |; d: X! ^2 W4 G/ i
                       "The setup has stopped.")5 @8 u5 D7 z) f- m" a# c- l! A
    stop
& a$ ^1 z1 x  Q0 T9 h# V  ]
. F  F3 z7 b/ L% ^' ]2 l( N  {/ Z& O0 N" _
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ a3 I, k% e9 z& Y
  crt num-cars
9 p% b4 m1 J: ~& |0 Z6 ]  [% S+ {) h, m- j- S7 q
    setup-cars7 O* b3 k$ o0 J3 U0 H/ A
    set-car-color
, M* B' E2 @9 q' C% X* G* r    record-data# a1 F0 w+ @" G0 B4 w6 r& @2 N# z
  ]
: D4 b6 Z  h8 m. Q! ]# r3 s% M9 G6 J6 ~2 l8 M2 _
  ;; give the turtles an initial speed# w% S. j6 {- b" H. X' k1 j
  ask turtles [ set-car-speed ]
: V- j1 e3 `: G( H4 T- e: x) e1 W: V2 r) G6 [+ Y
  reset-ticks
8 F# C/ d! o8 p. i: R1 [& oend2 g0 F4 \% E7 g/ w8 A# _: f0 H
) t% P9 V: `! m8 N5 ?
;; Initialize the global variables to appropriate values! P7 n$ g0 b4 V. \- M3 l
to setup-globals0 ]" k& _; ?! L# C
  set current-light nobody ;; just for now, since there are no lights yet
6 I% a/ ]6 O, T; r; E  set phase 0
3 d7 s2 P2 H8 p" j7 P  set num-cars-stopped 0' U/ `3 `1 @- J' D  P
  set grid-x-inc world-width / grid-size-x* _8 R3 V: e9 x* {8 j
  set grid-y-inc world-height / grid-size-y
' k9 U5 t. _7 B: y' s, J/ O$ ?- }4 f  w7 r3 l# l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 x) R0 a% B8 s5 @% X
  set acceleration 0.099
4 r2 }, C# Y/ y$ @6 j. z: Rend. ?! _) o( }: T$ s8 @! O
. e7 Q5 }% Q6 k4 Z! Q9 K
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* n1 _5 t/ }. h, `% Q* ?;; and initialize the traffic lights to one setting9 u7 `4 B1 b: A
to setup-patches
: V. C$ n0 Y4 Y, y- b  ;; initialize the patch-owned variables and color the patches to a base-color( d  {  J" X5 B3 O
  ask patches
7 R" f+ r, V+ e4 f) i& g# C; N6 I  [
# Y% p- `5 e( x7 w+ c    set intersection? false9 H  b: H  P+ U8 O4 w% {
    set auto? false6 F1 g  b2 ], H( t5 E
    set green-light-up? true
& E9 j: A3 O* B' A    set my-row -1
/ c/ v2 k0 Z( f& c/ Q    set my-column -1- M3 I1 o! Y% Z
    set my-phase -1; ~. ]2 }( R9 ^4 Y6 w# m
    set pcolor brown + 3, S( i+ `9 z# O  L: S
  ]; h3 u) U) @0 F% j$ C
" Z! C6 H/ z+ E' W1 l
  ;; initialize the global variables that hold patch agentsets, b3 b1 ^2 w) O
  set roads patches with
- C$ ]1 A, _, _( f" c  X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 P0 H1 p2 i! G, x& H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  X6 A  |/ p; X  set intersections roads with
  [+ L3 `; p9 _9 h! W0 G% |; X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  I5 R+ W' {! ]; T" A+ U6 B" {2 ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 |; _  n/ w' a$ V
; {5 b# M. ~: t/ g8 g/ ^; a+ N
  ask roads [ set pcolor white ]
- q. j0 n8 \) p% F% m    setup-intersections3 `7 u- }+ R9 B% G+ `
end" V$ u, X' s% a( K) p
其中定义道路的句子,如下所示,是什么意思啊?
- L2 A' e0 P; V set roads patches with0 v. u5 R( G) D$ x1 j; O6 A! V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" \' A# z# o( N$ L; [, V- U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" D% X  T$ a+ c3 q) |/ u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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