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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。
  {5 \% _# D+ _; _) Z( ~5 fnetlogo自带的social science--traffic grid这一例子当中,
( C2 K; y7 g: n# Gglobals, U+ k4 q9 y9 c+ ^4 T
[
8 {3 y! p( Q9 {9 o  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* z0 v. R0 x3 u0 A6 d  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 E. D/ A* |% |  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 _# V) Y7 @9 s( ]  c8 [* D0 C
                           ;; it is to accelerate or decelerate' H/ i% e" H6 m: H
  phase                    ;; keeps track of the phase6 G$ {8 h' U0 O3 q* D- A3 G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ U/ V. v2 {3 E" G  x  current-light            ;; the currently selected light* V0 A* i2 ~2 v+ R( I+ O$ b

) G' M2 p* j7 `# L  ;; patch agentsets
$ O" z( w9 B9 h4 o. A) A* w  intersections ;; agentset containing the patches that are intersections
$ O, K1 j. Z8 ?  x6 t5 n/ m  roads         ;; agentset containing the patches that are roads8 W0 x! ~' v" S7 j, t+ V$ z9 f+ e
]
$ x1 z: ~" h, Y5 R) s7 F) S$ }% {
3 Z, l  E6 u/ cturtles-own
7 S$ |1 ]+ m; u- M" r: L$ R[/ v  q, }0 U2 i( Q1 M+ g: h$ v
  speed     ;; the speed of the turtle
8 W8 ^# G' t) r" X- s  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 U- d- i* Q) B9 B; [# d  g' {( Z+ }
  wait-time ;; the amount of time since the last time a turtle has moved& L# `9 E2 k% H/ |9 o  ?" H
]
0 H( l# J* ?& l: T/ n, ^# `
2 j4 [! ^2 G; ppatches-own, N/ N( A" R) L- B9 H/ `" R
[
! D8 I0 f5 ~0 ]$ K# C! Q  intersection?   ;; true if the patch is at the intersection of two roads
& _5 x7 ~- C0 Q* @7 U: e# |  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( R5 r- U$ Q7 X; @) w5 Q                  ;; false for a non-intersection patches.
) P$ T& n% o. h& n6 F  my-row          ;; the row of the intersection counting from the upper left corner of the
- \4 ~9 v) ?& K% S& L                  ;; world.  -1 for non-intersection patches.
/ C$ h% Y1 ]& y+ T  my-column       ;; the column of the intersection counting from the upper left corner of the6 x6 h, b) c# [1 ~2 ~' _+ N7 p9 {
                  ;; world.  -1 for non-intersection patches.
  z5 @4 I, e) H( W  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) L( @: c* K5 I0 t, c3 ^7 r/ u6 t( D9 R
  auto?           ;; whether or not this intersection will switch automatically.5 G/ E( H; F& y# `% Z6 K- Q
                  ;; false for non-intersection patches.% u. w9 f1 @; n2 i' @
]- g+ p" h. |$ J. K" f
5 {% C- u1 E# `# N0 n5 b5 N3 y
9 Z2 U' j0 U' c! f$ I
;;;;;;;;;;;;;;;;;;;;;;
& f8 T8 u4 a5 j/ G% ?$ E* O  p;; Setup Procedures ;;
2 f# g# D  Z8 B7 `' R;;;;;;;;;;;;;;;;;;;;;;
  z4 ^' F# {- Q3 L. N/ G5 Z9 I# o: c, l. j( L
;; Initialize the display by giving the global and patch variables initial values.
5 s, R+ J" X& J; A: Y1 m$ c; D;; Create num-cars of turtles if there are enough road patches for one turtle to; Q$ \; F3 V5 j* z/ q, m
;; be created per road patch. Set up the plots.
: m/ h! f, L2 V  j5 G& M2 hto setup7 e+ W0 J# ]) ~0 S" F
  ca/ x: J1 R7 M5 i# [& y9 q
  setup-globals5 J$ u! S6 ?/ E1 v: q

! h, y( ~  _- d1 e! E, \( B  ;; First we ask the patches to draw themselves and set up a few variables
# y1 ?3 d% `: D4 [) d+ i- }  setup-patches2 e# n1 E1 [9 R+ Z6 W
  make-current one-of intersections
6 l5 t0 W* X: y! |2 k  label-current- A; _. G5 h0 G! E

1 W$ k0 v, e; P! x+ L, ?0 H" B  set-default-shape turtles "car"% Z+ d3 _! q' O! e, u# @4 ^

6 y" C4 e/ J* I4 _+ I  if (num-cars > count roads)
% J! x# ^$ \* T, O. M8 ]  [8 |& P6 b* u% J: G, ?/ u
    user-message (word "There are too many cars for the amount of "
! s# @8 e* C  L/ I  _                       "road.  Either increase the amount of roads "
* @: W; P7 d& j8 X4 m( B; F                       "by increasing the GRID-SIZE-X or "
- \8 D9 _* Z) j+ k) @                       "GRID-SIZE-Y sliders, or decrease the "  i. [3 J+ w1 F2 c) e
                       "number of cars by lowering the NUMBER slider.\n"
% [% l: h$ m; B7 ~* q: [                       "The setup has stopped.")
) u! \: }2 b% }" m    stop3 T; v4 k5 Z3 t2 L( q0 t4 T0 d( }
  ]
' p- D5 A" |! a- ?& k% F
& x, o' m; i0 C) B9 d: G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
; v* D+ m8 l  ^9 ?' P" Q" A  crt num-cars
: L- f, U8 v* l1 G1 c6 ?  [; o& v0 l. [5 U2 Z4 I6 O4 h
    setup-cars1 v7 Y3 T6 Z. f- U7 ?
    set-car-color
) h! `  ?+ S% d- O, Q, r+ s+ D    record-data
% a( K2 ?; \9 {( U# C* M: w  ]
8 {. ^2 @! U  ?' {
( C4 \; @; F  }$ {7 N  ;; give the turtles an initial speed" b' ~" [6 @$ ~3 z% Q; h: J* c
  ask turtles [ set-car-speed ]
  Q0 p/ r) ?: E. i1 B& S2 `3 \, _* F' M; ~  j2 I5 X& o1 Z
  reset-ticks5 X* I3 f5 g, N' ~  ^
end
* p( H9 w: y# d) @$ Q: \  K& o: Z' E3 k( B; u6 r6 Y+ d
;; Initialize the global variables to appropriate values3 }4 a4 I5 g4 l  z
to setup-globals
1 l7 L* z. V/ Q* K) w9 k3 n  set current-light nobody ;; just for now, since there are no lights yet+ f* e0 c7 e) E/ z: y2 p
  set phase 00 ]5 f9 ?; V' v" D/ y
  set num-cars-stopped 0# \/ S/ U! B1 E2 O/ p# T  e. @/ o
  set grid-x-inc world-width / grid-size-x! x/ L$ i6 g: {" O2 c8 p
  set grid-y-inc world-height / grid-size-y
1 ?9 d+ S- _7 L/ d* R. F
' `0 Y, R- Y+ H% j- o, z+ Y  R4 g, E  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 [) I( k/ Z* h5 s  set acceleration 0.099. K! O  Q4 J/ q. i" c
end. ^' C, c% m3 f6 ~2 c6 X& p
/ z- j! S3 j+ E  F
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, w4 s' z. h# O5 l;; and initialize the traffic lights to one setting
1 J- r' T- C7 f# L( j( `to setup-patches2 I$ o$ v8 x1 \( e0 e
  ;; initialize the patch-owned variables and color the patches to a base-color
2 |7 f% S( p7 y; s# S0 L5 k* X  ask patches
1 C- j% ?9 b, o' w  [- b' S+ Q( K, \3 i# a
    set intersection? false
8 o  g9 X, Y3 T    set auto? false; W2 d2 l0 y. s, q  h; a5 q
    set green-light-up? true
7 }! z$ D  b9 O; w- j; I* G8 u    set my-row -1) s) c" b- y. e3 }* W5 Z
    set my-column -14 u/ ?- X5 j. n2 H2 u' D6 \2 D
    set my-phase -1
$ X7 T7 j, X# S& x    set pcolor brown + 3, w" U# G& x0 o/ W2 ^- r2 {+ \
  ]/ e" d7 A0 X. g/ D; `: ?) C
! T9 `$ _! @- s* f+ g
  ;; initialize the global variables that hold patch agentsets
0 d# _- r, T- o" K4 I  set roads patches with
* B8 H; @3 {& m$ `7 l! Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: p4 i* G: V) p7 h2 L, d  ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) U9 b+ s) k& C$ y9 x! M$ ]  o- F" Z
  set intersections roads with
$ R" r. ?8 g$ O2 r/ w5 _% x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' K: ^+ M% P* L1 n( e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 Z2 ]; H. Y. }7 }, F! e% u1 j7 V8 N! W( h1 ^" F% K! H
  ask roads [ set pcolor white ]
9 \' k2 x( S* K; _, {! K" Y  n    setup-intersections3 j, |4 i5 T5 T4 a0 B
end. V: k/ T0 P% H' B
其中定义道路的句子,如下所示,是什么意思啊?" z- e" m) j, O
set roads patches with& |0 Y' Z& m# \2 |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 {" _1 `1 S0 h" K7 s8 T& \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! V8 T7 L& b" o+ ^
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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