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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。
; T4 s$ O% ^  V1 f* j; ynetlogo自带的social science--traffic grid这一例子当中,$ u% D& n4 ~$ y, E2 _& ^5 z$ |
globals
( v, N6 ]* f4 K! K( F: W4 T[$ U0 v! p! ^! x" B: U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction& L. p5 B" W) j
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 L% N# n% G4 G* d9 I  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- x( D' q2 x  O7 B
                           ;; it is to accelerate or decelerate
" z2 ]" o5 J4 g  phase                    ;; keeps track of the phase" W/ {2 O1 o7 H7 y. k
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 b+ N, Q- q1 i, r5 l; C, K- A% g4 h  current-light            ;; the currently selected light& u0 p4 V1 |2 t5 k' l, j8 j

' ]0 `$ K. j5 I2 @' m. U7 n  ;; patch agentsets3 u* s, k' ^3 R4 v% t% E3 T
  intersections ;; agentset containing the patches that are intersections0 z/ _: Z3 H7 X4 U( ?
  roads         ;; agentset containing the patches that are roads
" I  j% X, z4 Z- s$ K  f) L( M]
% M- |+ O) C; {- k! `4 |% [, N- e; n. V
turtles-own. O, g  }5 C; |" P( K) F" M
[" m3 S2 d5 K( P& C0 ], R4 F
  speed     ;; the speed of the turtle
$ F0 v1 g1 P7 Y2 j! M( e1 ~  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 c) I% K+ F( A  W  Z( b  wait-time ;; the amount of time since the last time a turtle has moved
! ?) g. K3 d. _; p7 n5 Q* k3 A]
8 ~/ s1 o3 V% y3 a" \5 X- B. n5 T( W7 F3 z% Z
patches-own3 y" D7 s7 j. |# z) X; e  ~
[0 ^# O0 Z7 X3 l3 K) N/ u, C
  intersection?   ;; true if the patch is at the intersection of two roads7 N7 X6 q0 {( M4 ?
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 d1 z8 {! s" ?/ D& X, x                  ;; false for a non-intersection patches.
- V: Y3 {* S% }& F  my-row          ;; the row of the intersection counting from the upper left corner of the
- Y& y" \# E. N0 j                  ;; world.  -1 for non-intersection patches.' }8 p' R/ G( r( T- g
  my-column       ;; the column of the intersection counting from the upper left corner of the
( H. ~1 o$ N& M                  ;; world.  -1 for non-intersection patches.
. b- o9 o7 Y+ k  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 H! r( P6 n4 h0 e; D; l5 L8 Y  auto?           ;; whether or not this intersection will switch automatically.. y7 i# g  t3 u. k, \, J3 i, J
                  ;; false for non-intersection patches." k# ^7 A; G1 B" w* |
]$ c4 d4 Z  d$ S$ n' R

! z9 D1 u' }1 V$ V: u3 @6 R* @/ |; v9 }# i2 D  A* Z3 ^) n' c% K
;;;;;;;;;;;;;;;;;;;;;;" v" m, _/ E3 w- w) g# ~6 `. L8 \; v, ]
;; Setup Procedures ;;/ s) M6 L2 I4 M( L8 b/ n. W7 W
;;;;;;;;;;;;;;;;;;;;;;
# }3 v2 t% f& ^
3 Z: _! e" u8 \8 r) W- X" \;; Initialize the display by giving the global and patch variables initial values.6 Y) |- j6 `9 C7 V& t
;; Create num-cars of turtles if there are enough road patches for one turtle to
7 r1 V$ J1 {+ j3 ?# X;; be created per road patch. Set up the plots.
1 j2 w) u' J5 ^4 Dto setup
; {. L- j8 W+ s! X  ca
1 S* k  V( M4 M  setup-globals
. i# d/ h' B: S5 Y; `
  X; }+ X9 S3 D- _# `  ;; First we ask the patches to draw themselves and set up a few variables& U! n  g! Z# O$ O" |
  setup-patches
5 B; \) G, Q* l  make-current one-of intersections
' w4 C0 {% e/ J  label-current; V+ A" F0 E7 c. L

' y: C2 v( b/ I$ z5 @! m3 J  set-default-shape turtles "car": [' l: l1 h* m6 X$ m

9 M! `3 Z% p: G0 U' P+ o  if (num-cars > count roads)
" b1 f. `! h- `7 P+ x+ B& L! W  [
) P6 p) A% v9 _# Y' J' }1 V1 Z    user-message (word "There are too many cars for the amount of "# M$ z0 ?* Z! _2 j
                       "road.  Either increase the amount of roads "
5 |  F: K$ o4 D0 A. d& O( f                       "by increasing the GRID-SIZE-X or "
: {! p* S* K1 a* W) M8 x                       "GRID-SIZE-Y sliders, or decrease the "
( J- |- ]7 Y+ R                       "number of cars by lowering the NUMBER slider.\n"1 w& Q& |0 T- N( O
                       "The setup has stopped.")+ r! S5 B+ I) h# q
    stop
4 V6 U% D6 h3 K, H- X% L) U  ]# e1 r: b* m8 F. a6 e6 I

, @) \7 c. l9 K. O7 m6 V5 D  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ c. `' H& [; f, s& n$ V9 h7 K: j
  crt num-cars
7 I. v! ?+ e' j. f( f% {* H6 u  [. _- x- G& ~0 j! r
    setup-cars
+ }) v& d% _  O* [8 Z3 _9 q    set-car-color
! _' F" l$ l3 s' x; p    record-data4 U% `' g4 v1 ]
  ]3 ^/ b: n8 \/ \3 R5 `' k; K- R
9 Y2 z9 m1 ]9 q% b
  ;; give the turtles an initial speed
( _) {" s9 ]2 h, O  ask turtles [ set-car-speed ]5 Y% i. r6 [% t2 @# ?$ r, B; N% q
/ S; n# f" {3 @9 @  n
  reset-ticks6 P6 x4 ~: O9 {8 B0 Q4 e
end. b, s8 `. q6 [
- J5 ]) o' z3 J. D' j" ^
;; Initialize the global variables to appropriate values
6 r! l# h, t" n/ n, |) m7 [7 zto setup-globals" }& z; c- z  b7 `4 \( n% q. m  o
  set current-light nobody ;; just for now, since there are no lights yet- l: m# M, d2 N& ]
  set phase 0( Q* o: n) R6 e# i
  set num-cars-stopped 0
: L! m) X3 Y% d$ A  set grid-x-inc world-width / grid-size-x
( Z/ K+ s" C) A  set grid-y-inc world-height / grid-size-y6 D* [8 ?8 t! C& ^+ Q3 `4 z9 M9 p8 F

6 r7 Y1 U5 P6 `! m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, I. @" M6 [9 L) \) T' R  set acceleration 0.099
# y* H! y: L- Iend
6 ^1 t! i4 k9 Y) T
  x- C- p9 [3 Y  I6 w; h$ m;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, C; R6 Q2 E" u1 S;; and initialize the traffic lights to one setting
9 d7 G2 M+ l$ l& U& Cto setup-patches
! [8 B" s$ ?7 [8 E3 s  ;; initialize the patch-owned variables and color the patches to a base-color0 d, C" M9 X" Z
  ask patches. `1 T" I* K2 J+ V$ R0 ?+ m  J
  [3 d% g1 d; m2 O! U# |( A0 l# L& A
    set intersection? false& f; `( f$ R/ ~( ~; u4 ~: |
    set auto? false
. ~/ h0 w- r. k1 h7 w* l) `    set green-light-up? true# k9 ~% H4 _) y
    set my-row -1
0 B. b' L, p) e4 U9 L    set my-column -1
, [- s% @1 ^& Q  s) o7 P    set my-phase -12 M7 x& c) ]$ x6 k
    set pcolor brown + 3; U( N/ q" ]0 M9 g9 k, T
  ]! R, B2 d. |  g4 @, V# K* c) j2 ^4 r

0 z" U4 ^" c: L9 E  ;; initialize the global variables that hold patch agentsets
- d% W5 R6 V+ u, c0 Y* `; f4 L  set roads patches with
4 G7 t- x# k' {( l5 \, |    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 M9 R* C2 k( Z+ E# ~: w- N# r7 i  M, |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& F, }! w! g2 r7 ^9 r0 s' u1 X6 a, s8 W
  set intersections roads with
/ f0 q4 C. R/ Z( P& a! s: M' p0 L, P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 M7 O* K! O2 @% I* S) n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 J0 L8 ?  U$ q' X! e1 S  }, v
" H7 G+ ?  t0 Q; K0 ]
  ask roads [ set pcolor white ]3 ^9 N: u4 D% m4 a
    setup-intersections; s$ D5 [4 n$ D9 q5 h
end
7 E, y  a& b1 }1 q- J1 D2 A/ }, ?其中定义道路的句子,如下所示,是什么意思啊?- b3 r8 M9 \6 F8 y0 U7 m- L5 w
set roads patches with
' d6 V5 a% n" y/ M: p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ @  U5 C# m1 W: Y$ g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 x1 z9 F4 _9 _' c1 \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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