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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。" r9 c  ~  V- v" u/ C  y
netlogo自带的social science--traffic grid这一例子当中,! _0 m/ f% ^. `+ k! I1 U1 ]
globals' I1 ~8 f! f" l0 t! y* L) d
[
* N8 Q6 T% J( V+ k- z4 N" _+ |  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: F* f, r- s1 D- l- J  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 l, P) o; c3 N0 I+ I/ }  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 A, ^$ e) [* a- J8 k' H2 b& b
                           ;; it is to accelerate or decelerate
. t7 Z' X; I- W" T4 R$ k, [  phase                    ;; keeps track of the phase% O& ?$ J1 p2 d  B: m) S
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 r# S# f$ Y9 ^
  current-light            ;; the currently selected light
  k8 y3 v" w7 p& @
# h5 C  _  O# A' b) A) `  ;; patch agentsets
* X# h! x2 }1 E+ y7 f- Q: K  intersections ;; agentset containing the patches that are intersections
$ T/ V2 c- {6 V$ D  roads         ;; agentset containing the patches that are roads0 j* S) D) z0 T+ H- X# O3 n* D
]8 Y3 [2 d4 Q: |

2 k( U" U# L& b3 qturtles-own
: ?7 ]& T7 _* @" w- @& q5 \+ J' t[
2 \; ]0 D9 B" A0 a$ J, }& F+ {2 P  E  speed     ;; the speed of the turtle* I+ C6 c0 R( [$ i
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- |" h' N# s, |) O) e  wait-time ;; the amount of time since the last time a turtle has moved
+ U- J+ \  E' Q+ s]
" p8 @! ^' Y9 p; w4 l, O3 N; G5 e0 `/ Y! n! G4 ^; B. V
patches-own
6 ~* v; p8 N- f' \6 ^/ Z6 T9 E9 y/ b[
, w8 r4 Y; R  g* b+ a. ~8 q  intersection?   ;; true if the patch is at the intersection of two roads
$ T6 {- K* u! _, s; d6 y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 ?* L4 \. b* |
                  ;; false for a non-intersection patches.
, d8 z5 A# P/ A# a, @9 n  my-row          ;; the row of the intersection counting from the upper left corner of the4 G2 u; A# r4 `: |9 ^% Q. ~
                  ;; world.  -1 for non-intersection patches.7 S" t" V9 L. q3 N& n
  my-column       ;; the column of the intersection counting from the upper left corner of the
  Z7 Y8 B  O4 p. S3 v7 D7 _* Z/ M                  ;; world.  -1 for non-intersection patches.( z1 |! h1 r( W' o0 Q1 V1 G+ l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 a! s3 a  j: e/ a; s  I
  auto?           ;; whether or not this intersection will switch automatically.1 G$ u4 Y. U* F/ S9 E
                  ;; false for non-intersection patches.+ I2 T+ U3 T3 J. p) _& }
]
, v5 Q" w1 w5 r8 {! M; I- R0 D6 w3 \1 E! j' k8 {0 r
. w$ c# a( ]( I
;;;;;;;;;;;;;;;;;;;;;;
; M* K. R! F" `7 {* _;; Setup Procedures ;;9 ^$ P1 z3 y: M" u2 Q( @
;;;;;;;;;;;;;;;;;;;;;;
' ~. g6 k4 ~" Z6 O
- J9 ?- _; M' u8 m8 l9 B! b;; Initialize the display by giving the global and patch variables initial values.
  n  N1 i4 I7 e, o" V1 x) H;; Create num-cars of turtles if there are enough road patches for one turtle to( B0 W! Q% R% v) [' B0 B4 e( T+ X
;; be created per road patch. Set up the plots.
( J( z9 \8 P$ Z/ Gto setup+ U# e& Y  Q' B, b* F4 H
  ca6 ~2 D# H% I: r2 v: {5 U
  setup-globals2 z* S" W* Z6 B2 H' Z

- U: F+ t% D  C  c" q! Y* U/ A0 ~+ O  ;; First we ask the patches to draw themselves and set up a few variables3 `. s: {# U5 Q0 z4 T
  setup-patches
$ e  o% M' H, j4 K' ?6 T; |  make-current one-of intersections$ _1 b# Z, S% e; b
  label-current5 e  a, ?/ I! T3 U- ^) ~
6 J  z. J5 H, _0 T& b6 t
  set-default-shape turtles "car"! A  N! A  [5 L/ o4 J; H4 I- B
6 r. p4 b, l1 ?& u# `' K' c% \) |
  if (num-cars > count roads)
$ }$ z7 \1 P) l+ k4 [3 E9 O/ h  [
4 }" O: |+ ^2 g1 {* p, M! S    user-message (word "There are too many cars for the amount of "3 J: p. b: O, s) j/ }9 z& w
                       "road.  Either increase the amount of roads "1 J- r7 T$ i0 E6 i$ Q: m
                       "by increasing the GRID-SIZE-X or "
' a0 y/ }* ?- l8 [1 u3 w                       "GRID-SIZE-Y sliders, or decrease the "5 b: H" L1 o$ W4 s% ~9 J' V
                       "number of cars by lowering the NUMBER slider.\n". x1 j; V2 V' C( O
                       "The setup has stopped.")5 B: d5 @6 |* i9 F+ M. K( i: u' g
    stop
$ K. E. A. z: [7 e4 `( ~6 H  ]& j2 W  C3 O2 ~9 [9 v
2 j3 }' |, ?! G9 ~! ?  Z3 T
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 p! O8 L. S) R; \: G  crt num-cars
& ]! [. ]9 X9 ]  [
' }0 }& R; ~- p0 O; Y1 n' S; L    setup-cars
( e6 ^( ~+ H1 V0 m" c    set-car-color  h3 p6 C. W" j* C
    record-data
. z( S3 N9 ]: Y  ]) P& r3 r) g+ Z

7 O  C& `8 C4 l* d& a4 S  ;; give the turtles an initial speed2 W( _4 S: d7 p3 l
  ask turtles [ set-car-speed ]
: k& J0 W& L0 P7 o/ O; |" A0 @  E% ^2 P; u& Y7 l: `' y+ _( q8 n, ]
  reset-ticks( K9 H, k6 T9 n1 p3 v7 w" c
end
/ U0 Q- Q. @4 ~* a  ?) ~* p  S2 U# r$ s7 C+ Q, V
;; Initialize the global variables to appropriate values$ U7 ~/ c* D( M/ u! F2 y! _& [
to setup-globals
/ v! x% {5 n+ F% h& Z# h8 |  set current-light nobody ;; just for now, since there are no lights yet  |# M1 s" A8 o/ ]9 A9 `
  set phase 0
+ i+ f/ n" U& N( p% v) |& t* `  set num-cars-stopped 0
+ }" b$ N7 B9 T7 u1 [6 B  set grid-x-inc world-width / grid-size-x, C: g. }3 S' b6 [4 j' d  U$ `
  set grid-y-inc world-height / grid-size-y
" W5 a+ j; g2 e$ ^6 \: w+ ~4 D( K9 O# X7 ]2 z- m% p2 W" s* D( l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# V: n$ O. f' ~4 e8 Q2 `! O6 H$ q" T; I  set acceleration 0.0998 y) \" [$ m4 J
end& s! T. Z; |% ^& }2 C4 h

9 [1 X( p" N/ i$ v  W+ [- d;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' J' V& V# N. A
;; and initialize the traffic lights to one setting
8 `  r' m8 t; [5 x: W  F8 zto setup-patches# Z+ Z: y: }: s. `
  ;; initialize the patch-owned variables and color the patches to a base-color
3 k5 E! r' G) A9 [3 `' ]  ask patches. h: |7 h- }5 ~  V3 y9 W  c
  [
# N: D  g( s; R( p    set intersection? false; o2 I& Y. M. v3 m- y7 N6 M. \
    set auto? false
6 s4 S6 W2 t" ]$ Y! n    set green-light-up? true
0 o% R; P% [% a8 W/ o0 F/ R; X- z$ j/ M    set my-row -1
& Q) r5 l# U/ P, h3 c' n# h' E    set my-column -16 t1 Q: ~# O$ k# c5 W$ G1 u
    set my-phase -1
2 N; F, R# n, D1 T4 `    set pcolor brown + 3
4 E" B$ s; O6 T6 Q* ]% e9 q  ]
& ]5 f: K0 V& _* [2 |
" q+ ]# e3 A2 a  ;; initialize the global variables that hold patch agentsets& R% T6 ]1 L$ \; @  w; ?
  set roads patches with
. r/ Z7 v" o+ J2 z; }" d* t6 b7 u- Y7 w3 U3 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* q' N! p+ w' }9 z; v4 J$ Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* p2 V, H7 x, ^0 u! ]0 \  set intersections roads with
# n. F* y! D8 I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 q. n# Q- ~: `. h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% W. y0 l+ G% C# E; b* q+ ?
7 l! S8 Q( F5 C- `/ d  ask roads [ set pcolor white ]0 X3 }* a0 `0 V9 D/ }" t2 X
    setup-intersections# D6 r3 e7 ~/ o5 l6 v$ O
end3 S2 z) T2 x. C) t* o
其中定义道路的句子,如下所示,是什么意思啊?0 X: x* h+ g2 Y6 H  j8 _
set roads patches with
& v, U4 M8 n0 H% Z0 q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- b8 F3 X1 D+ J) t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  I; I' Z9 G8 N/ k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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