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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。
) I0 V, D# b) m7 G  \9 c9 Onetlogo自带的social science--traffic grid这一例子当中,
9 t+ O- |/ C1 Y& y* ~8 Z; l$ |globals6 r, y) B4 }/ T; P, ?
[# _9 X4 m, D1 r; Z; J' X' X
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 A. W9 ~: K* ^( R8 V3 k' |  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 |; g  @+ ~# \9 i  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. r' X" S) @" Q7 O                           ;; it is to accelerate or decelerate
. e* S/ m) q# h0 m4 g: \  phase                    ;; keeps track of the phase
  n" Z2 n, A1 i' s; k" |+ {( @7 u  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ f5 _% W" S+ @! W3 S5 w
  current-light            ;; the currently selected light
% V# U' I" X4 {* K; J' f: R% |0 y% e9 S$ Y/ U: n  r9 a
  ;; patch agentsets
% t# o3 X& }1 k3 f2 X8 I3 g  intersections ;; agentset containing the patches that are intersections
5 N" g" i7 r( j. t$ M  roads         ;; agentset containing the patches that are roads8 C- |7 q. ]& s* z' c8 y! o, w
]; [. e4 ~7 U5 D) {* T- F: {  ?
+ y  A4 ?' v- H9 A; B
turtles-own- f7 x  J: ~5 b- e
[
# H. B, _+ `" _- A& `  speed     ;; the speed of the turtle
7 q' {9 V0 c4 Y: d7 ~" _  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 i9 P# y# ]8 A" v  B: I  wait-time ;; the amount of time since the last time a turtle has moved# E( c' V, u2 ]4 w- T
]
* i* ]/ Z7 J- o* Q' z7 b7 F  O  W( u: f6 I
patches-own
0 n$ X5 V! s- A! O! I[( g  R, F( S& A
  intersection?   ;; true if the patch is at the intersection of two roads$ \( K% X3 L( }4 f; ~
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 S/ O* C9 E) _! \
                  ;; false for a non-intersection patches.$ x4 L4 I/ r" g* O9 r; J: l
  my-row          ;; the row of the intersection counting from the upper left corner of the+ @2 ^9 s8 ^, _1 B" C& |2 b
                  ;; world.  -1 for non-intersection patches.$ u4 r2 h$ Z3 Q- _4 F( q% ?
  my-column       ;; the column of the intersection counting from the upper left corner of the
$ S' B6 p% [8 `( ?+ o                  ;; world.  -1 for non-intersection patches.- E1 N7 W" q6 k
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: _! l2 N5 `1 s  auto?           ;; whether or not this intersection will switch automatically.+ J- _* A5 _; G3 E5 g. ]# m) r# M
                  ;; false for non-intersection patches.  g# o8 ~; |6 x3 L
]* M' t) Q  N& C. e% g9 C2 D

! Q+ d2 P, t4 d* k* O2 X/ @2 O& o. R, j
;;;;;;;;;;;;;;;;;;;;;;( R, }# f5 V; y  `+ ^3 }' A
;; Setup Procedures ;;/ `9 H+ E2 ?* d1 b; f/ `6 }! a
;;;;;;;;;;;;;;;;;;;;;;
% X7 D- ~2 e& D1 m
! f9 n2 g7 {" \/ ]7 g, E;; Initialize the display by giving the global and patch variables initial values.
* q- y5 q% j) c8 C( ?  ?5 k;; Create num-cars of turtles if there are enough road patches for one turtle to2 _; D6 q! e) l+ E# F
;; be created per road patch. Set up the plots.0 p: ~' T8 o; L- Q1 J, E$ W
to setup
8 {5 U0 @$ p8 v  ca
6 `! ?* R5 F4 A! ]4 n  setup-globals
9 K6 W: E1 k" l# }# l" i9 E7 x  k" z! m0 y9 K
  ;; First we ask the patches to draw themselves and set up a few variables
& h7 |# L; n, v6 r4 a  setup-patches$ _& s+ A* k, a" X. H3 W
  make-current one-of intersections0 ]" p$ k4 c7 O6 _1 l+ V  |$ s) Q
  label-current+ E3 @* @) A6 J0 b  [. B
6 o( A! n+ f* U4 Y
  set-default-shape turtles "car"4 H( }1 o6 M, J4 e: L. u

/ E( r  m5 s0 }8 s) Q. C  G  if (num-cars > count roads)9 t) H" w! T4 g
  [
4 ~! s+ n* h2 P; w& n' U    user-message (word "There are too many cars for the amount of "* J; l* s( q/ L: r/ b. m% `5 G1 _. O. m
                       "road.  Either increase the amount of roads "
' Q) f  I$ m1 e& J8 q                       "by increasing the GRID-SIZE-X or "! e" C$ q- N/ j
                       "GRID-SIZE-Y sliders, or decrease the "
& y# K2 `0 f9 f/ a                       "number of cars by lowering the NUMBER slider.\n"
6 X; [9 c3 X; \! n. W$ Y                       "The setup has stopped."); J; R) n/ E" z. T) W
    stop
; D6 e. c) U$ G! L$ I  ]! ]+ F% m' r, `2 I
5 |4 v$ F2 E4 U
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 ~$ @% _, y0 j1 B" \5 v
  crt num-cars4 \& w6 T( M  i  \$ |
  [$ K  h) g$ u, n1 u# d8 i6 Z- x* j
    setup-cars
3 J% ~" W6 t8 \1 R2 M" t6 U% o9 C    set-car-color- w1 k/ u8 {; ?7 L% E1 F0 ]
    record-data
6 z" x3 ^$ [0 H2 w3 g  ]
$ E1 H- x# L( p' p5 D0 j/ c, i: T2 Q$ S
  ;; give the turtles an initial speed" D" B) R# z2 y- K/ w0 e4 ~( W
  ask turtles [ set-car-speed ]1 W: d7 m0 {* m. w

7 S  k0 ~8 X2 u6 t- a  reset-ticks
: u* p! \. P6 O2 K+ Nend
; `) H& P* K+ A/ {" L/ z
1 y6 c  I8 G+ U0 F9 T! I7 g' ?5 m;; Initialize the global variables to appropriate values
9 a: ?* q) A* p" _- _. h: {3 Qto setup-globals# l# e/ J- R" s, X5 L8 ~
  set current-light nobody ;; just for now, since there are no lights yet7 X# k3 b0 j' ^
  set phase 0% Z0 ^: Y1 D- g  \8 ^# V! M9 c- Y
  set num-cars-stopped 0
: R* \! Z# c# D, v- x8 J  h  set grid-x-inc world-width / grid-size-x
( U* l4 ?& b/ z! y, e( N  set grid-y-inc world-height / grid-size-y
5 F- n9 h$ R3 P
) D. H$ K# M3 }$ h, B' G  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ s, v3 |' A3 I5 G- l
  set acceleration 0.099
- U# t; N, o: X2 wend! k- ]% C* r  |6 e6 `6 v

" t. M* ~6 S' s/ u3 d;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 m6 \* f  H$ u5 r/ o;; and initialize the traffic lights to one setting' y' M: ]) k; p+ i
to setup-patches: k& }) ^: R" x( z4 a9 |1 K& U
  ;; initialize the patch-owned variables and color the patches to a base-color( V+ u: K! m5 [' N
  ask patches
6 d0 w5 _3 R. u' S  [
9 J$ P; Y9 _3 O* V* G' @    set intersection? false
6 Y* K- p/ U; e' C  P) f    set auto? false9 a( U' w# b- ?9 V9 z3 j
    set green-light-up? true' C$ \' ]( v- x
    set my-row -13 U% M0 v1 I( L$ B' q& ^/ h& ~& ^
    set my-column -1
; D) F  `# a8 V    set my-phase -1* {3 Y8 P' q5 h6 l3 {+ \" R
    set pcolor brown + 3; v1 G+ a9 G1 }7 b
  ]0 I7 z5 P7 ?; ?: b/ ~$ E0 Y

( J& {! R3 o; Z2 f% F  ;; initialize the global variables that hold patch agentsets9 z; B* V' T' a% W# ^9 k
  set roads patches with; G; y( K( ]9 j- P- c- k; x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% T& T' g6 k5 ?( ]8 A) P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 ?% P4 n7 `! L* a8 P  set intersections roads with" T6 v  _3 q. E" J, [  ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 z( S/ _5 k- G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ ?# O2 `5 D, G/ q+ y4 r
; @8 D% Q) }" l& S0 n  ask roads [ set pcolor white ]
8 i" z9 p: e* |: J  m    setup-intersections
7 s# n! _2 B- B; R4 b3 ^end
5 D% l( T+ |6 b0 B, f7 y- X其中定义道路的句子,如下所示,是什么意思啊?* O6 `- ?, Q$ S6 d) K  ~* D
set roads patches with
% I, g5 h+ |7 V# o7 j9 B+ O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. v8 f! p1 m2 p0 y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; u) T* P1 s$ }7 [: ?6 m  Q+ J
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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