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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。
- J4 y! M4 m0 T0 |6 rnetlogo自带的social science--traffic grid这一例子当中,) ~  }* G$ r  w/ P
globals5 i6 ~: ~7 |4 {* D
[
  T* I, P1 C8 Q  X  grid-x-inc               ;; the amount of patches in between two roads in the x direction% A' s' a7 P0 [5 _6 T6 R
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 C) O/ T+ Z+ ?3 q$ o& S% O6 e  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( V/ ]: `/ M- U' j. d                           ;; it is to accelerate or decelerate4 {3 s; _& s7 Y# ?8 ?) I9 J2 r& w
  phase                    ;; keeps track of the phase6 d7 ?. ?* l0 y6 k) N
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 N% c9 ~* \' @' E" ?5 L$ E  current-light            ;; the currently selected light
$ a! e* W% [0 s9 `7 ?& D" U" x  b7 f. E5 l, v' W; _4 ~1 j: r: z/ n
  ;; patch agentsets
$ {, u2 ^, q) k0 C- ?: x  intersections ;; agentset containing the patches that are intersections
) w+ K! r) f4 O  roads         ;; agentset containing the patches that are roads
3 h1 E/ Z$ ^' h2 X- {* }% r]$ g( S- L9 d4 l0 N7 g+ `

. [" v( X4 G: Y3 K3 B) ^2 kturtles-own
) \# X/ A  L4 E2 ?( a9 m. e[# t6 ~$ y" B7 o9 G* S
  speed     ;; the speed of the turtle
8 j# f# y! Q/ d5 P/ Q$ \  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
) E+ p9 I, l; R0 E  wait-time ;; the amount of time since the last time a turtle has moved, R5 E; }1 H2 u% o
]# Q7 N1 p" \$ [6 w  k  ?
' t8 ^) w4 u, @7 c; Y- Q
patches-own. a5 s5 f4 W' J
[$ }2 L8 o& l# L$ d! s* F: I
  intersection?   ;; true if the patch is at the intersection of two roads
% D8 U9 F. E# u$ g7 y$ w  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* w: Y' s; i. y" z  S$ [
                  ;; false for a non-intersection patches.; s- f" V: x0 u* L. L- f
  my-row          ;; the row of the intersection counting from the upper left corner of the& A9 J: N/ m( }
                  ;; world.  -1 for non-intersection patches.
& P% U  g2 W$ e  my-column       ;; the column of the intersection counting from the upper left corner of the5 _: X5 G; ^0 Z4 ^) I! ^! \# V
                  ;; world.  -1 for non-intersection patches.
0 u' T/ m$ _+ u* ?9 ]1 l  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- ]% v5 p) o% Y( p& s. @- }2 |/ r4 ^  auto?           ;; whether or not this intersection will switch automatically.6 E8 v, F7 y% I7 |: _
                  ;; false for non-intersection patches.0 W3 x! O5 G7 g, P
]
- y+ W6 x/ N) _- A- l( a7 u- \  m  }

" y% s; C2 N9 Z# W;;;;;;;;;;;;;;;;;;;;;;; C  h0 [- w% t7 I7 M1 x! |
;; Setup Procedures ;;1 L) D, U! ~8 J( {
;;;;;;;;;;;;;;;;;;;;;;
, ^4 a8 q8 ~* V1 q9 v  p" ~7 {+ }) R- S( L* q
;; Initialize the display by giving the global and patch variables initial values.
  Y! N, p3 C8 b% e3 a6 r;; Create num-cars of turtles if there are enough road patches for one turtle to
1 A' g# y& n  Q, W;; be created per road patch. Set up the plots.
1 d$ i+ D5 c7 b  ito setup) Z, U' M2 |! H# o5 n5 D9 ?" g9 W  k
  ca
4 v) f$ z7 `$ a/ c! j+ f  setup-globals3 m9 o2 C1 J$ y& {  D0 p6 S# x

9 m8 t4 n! m# z+ I% i: Y  ;; First we ask the patches to draw themselves and set up a few variables
$ ]( L: l# {! g& n! _' _' `: j- v  setup-patches
0 W: r" e3 X& l8 M/ D/ C6 x  make-current one-of intersections
2 s, K; ]3 d/ c- _+ r/ b9 q  label-current
; T" k! W& H. B
" E0 A# m' N* C" \- d  set-default-shape turtles "car"- r* g- G1 T. q9 s1 Y! j! I3 R2 z

: Y& S0 j2 G3 O+ s! D  if (num-cars > count roads)
6 E* E: R. Q4 B% L$ A5 B  [
  p  \! v4 ]) v9 w+ i% Q1 u3 l    user-message (word "There are too many cars for the amount of "
7 |" ~& i; Y" L' s+ g$ V: Y                       "road.  Either increase the amount of roads "6 n$ C" |9 a/ z3 x, L
                       "by increasing the GRID-SIZE-X or "3 W: x' v. g1 y1 i4 u
                       "GRID-SIZE-Y sliders, or decrease the "3 P$ S0 @& L# |$ r8 z% a
                       "number of cars by lowering the NUMBER slider.\n"+ U3 ~8 p5 `; ~( P
                       "The setup has stopped.")
: P& S: E' p+ `# O8 D2 r    stop
  y, j0 ^  R2 Q# Q0 \  ]7 X9 r, D$ W& Q- T
5 D. p. [# _4 ^( Q- e: ?5 e+ o3 y
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; {% @( C) k7 x$ g! C: D
  crt num-cars
6 b& j) B0 I& B0 u0 s" I# Q/ b  [
1 A6 H$ Q) S8 A% [8 I% m    setup-cars
8 b% W( ]& u% ?" \" N    set-car-color
; S$ ?. D) d1 q& Y! l" K. D" o    record-data
$ u' k( F4 a$ v+ M# e, Y! E  ]3 B4 l* v6 N& g7 P+ h( X2 h
8 N- v1 {- O6 N8 L0 G
  ;; give the turtles an initial speed
/ |( y4 {5 N; {& U/ N* G6 |  ask turtles [ set-car-speed ], C. p' L4 A; W3 n" t
0 w; [* Z7 B9 \; ]% Q
  reset-ticks
+ m1 ^2 B+ L9 Q: q7 |0 Vend
+ J7 P* e9 E+ ~. ?$ k3 K1 `# k7 N! f8 l% n
;; Initialize the global variables to appropriate values
3 L2 K! d; v  R* K+ Q* jto setup-globals+ I' ?% P7 w  |' A) S- f
  set current-light nobody ;; just for now, since there are no lights yet- b6 E; R+ X7 m$ r4 x: V/ B
  set phase 0
; I6 F0 z; a2 |' V7 l; `5 S+ N# M' M  set num-cars-stopped 0% M, w$ G; J+ f2 ?' \, R% |! w
  set grid-x-inc world-width / grid-size-x& @8 A' D, I4 H$ j0 E
  set grid-y-inc world-height / grid-size-y8 W/ Y1 P  ]6 X$ y2 y  |
1 W' P9 \1 K2 \; k% G! J: v
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( S* o  }" b6 W# x6 [0 E* y  set acceleration 0.099+ s9 ?# R( q. L0 j  [! ^2 e- Y
end0 x5 t' k6 M" D- S

% O1 Z: t0 Y9 ^5 j;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 s6 r4 X. G. p$ L
;; and initialize the traffic lights to one setting
. p9 Z- \. p( T9 V, h( rto setup-patches
2 C" {4 k) H, }- O/ J  ;; initialize the patch-owned variables and color the patches to a base-color
" {- F# F  {2 u6 V+ V; S" P  ask patches
! `- P/ d3 j+ X* h/ r& g& @; u/ C  [
8 M2 L8 ]8 k* u3 V8 [6 z) H    set intersection? false
+ \1 X0 i% X$ ]. x2 X; u    set auto? false
4 ^2 F2 R6 A4 m% L9 r    set green-light-up? true2 A% Q+ U$ P, |- V/ `
    set my-row -1# s# k4 a- `) ]9 _; N: ^; E
    set my-column -1: p# q6 H7 j8 g2 S5 n, Y; n$ a/ e" _' ^
    set my-phase -1( l6 f0 I' @+ l! s" P
    set pcolor brown + 3
# y; M4 A" c7 d6 K- n7 I( Y  ]
, J, g' x, ]$ n! Q6 V" j; O5 h# K8 d  I/ r8 U: y
  ;; initialize the global variables that hold patch agentsets( Z. }  @: Z- ^, E: n5 \
  set roads patches with# S$ m5 `5 `8 [0 [% I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( i1 Y! [- t* g+ i8 W2 ^$ _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ ]3 h& `1 U* H  set intersections roads with0 Z$ j: X5 j$ O, F% e$ K- D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: j2 a: R" J" a: ?4 G. b( i2 t, f) J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 A  y8 o7 b& ]6 J5 p! I) O4 N0 t% F( E5 j0 p
  ask roads [ set pcolor white ]0 n2 y( P8 p9 v- [; K
    setup-intersections
* X& u1 A9 Y2 e: s) vend1 E- }* }5 \  K$ C# F: h
其中定义道路的句子,如下所示,是什么意思啊?
$ l( g6 I: I& V' \( j set roads patches with2 E% s: ]" w# n9 [* d0 G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ `7 m, I5 ^6 t# g/ B; n& k# B: W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- n8 B3 n. o. a) s& N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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