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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。
6 w6 J  _( I! g8 k2 R9 M  ~' Y' T2 Znetlogo自带的social science--traffic grid这一例子当中,
% ~& Q5 b# o1 ~globals5 T+ l1 K, j  ^0 f9 _
[3 m2 [# H5 B$ b! u- S4 J" |* `
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# B' `1 \5 b; H) J
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 A4 x' }& a- s
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 U* F& b1 g6 Z% H1 i
                           ;; it is to accelerate or decelerate( v- E/ l& V6 ~( }
  phase                    ;; keeps track of the phase
6 ^) d8 [3 e" o7 V" e9 v7 W# k  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 d) G$ m6 ?: q5 W4 b6 O
  current-light            ;; the currently selected light
4 g. l' T0 o' C% |) N  _" d  b# E; I# p0 }; K
  ;; patch agentsets
0 A! v3 z3 W# R3 n% @  intersections ;; agentset containing the patches that are intersections
+ n1 B5 y2 \3 ]2 O  roads         ;; agentset containing the patches that are roads
5 r: a% B; k8 E. Z7 p; T]% C/ a4 n7 `7 _1 {/ a! K

+ a0 @6 t- D9 W* d) v7 y( nturtles-own, ?0 W' N  m2 V# m, G( L
[: t( w: N& m0 k7 D
  speed     ;; the speed of the turtle
! b; I2 {! z9 R9 v( ?) b, }$ S; L8 Q; a4 |  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* w* y# G, v& t+ `" s  wait-time ;; the amount of time since the last time a turtle has moved$ @# E' e$ l! X. M; s
]( }: n# y6 |9 g# h: w5 A% F/ C# U0 @

1 I1 N2 {, X$ ?/ C( g* ~patches-own1 ~& |) |% P4 m+ E
[
* x$ M. E- j# N* x- ?6 U2 ]& w  intersection?   ;; true if the patch is at the intersection of two roads8 |  u' P* Q  W( }9 j, ]: ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ h, o) k0 M* w8 n3 j                  ;; false for a non-intersection patches.
! L. ^+ I, l/ L- J: ?( e) j  my-row          ;; the row of the intersection counting from the upper left corner of the
  Y" @$ u0 m# Y8 b; N) T+ r                  ;; world.  -1 for non-intersection patches.
" t4 q6 p6 X2 \# c+ c1 N8 N; [; S  my-column       ;; the column of the intersection counting from the upper left corner of the  Z- S) b. A' K$ S/ [: i4 U
                  ;; world.  -1 for non-intersection patches.
4 _# z9 [; V# I, Q+ M  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
, ]' ]. }. `, h: z2 q7 W$ X' {2 X  auto?           ;; whether or not this intersection will switch automatically.
& G  x, n4 P, g; J                  ;; false for non-intersection patches.  b5 d( C" Y8 G
]
5 _8 Y5 n* f5 j1 k' }' ?4 t& c. b; i7 c2 X* _5 \( {

; [4 j' s/ [; d;;;;;;;;;;;;;;;;;;;;;;
6 _7 Q( o7 h1 p;; Setup Procedures ;;
. w( n; e) c2 L$ s( U* r;;;;;;;;;;;;;;;;;;;;;;
" M) J; F( |, v* \/ ?$ B& q9 K
/ U; M- N/ ?, {* }" S) U* _' ~9 b" C6 X+ V;; Initialize the display by giving the global and patch variables initial values.$ j$ }* `' e# D$ [
;; Create num-cars of turtles if there are enough road patches for one turtle to# l- _: n$ i+ n+ B7 C' `: a: Y9 c% h
;; be created per road patch. Set up the plots.0 g9 \9 s' A9 ^( l2 F# u
to setup# ?  P; A+ r' {- K2 a
  ca
1 t+ Y, G5 E/ m, a& }( p2 k' q  setup-globals
* e7 B2 w& m6 m. |: s  H) ?, R9 w$ g( S; P4 x
  ;; First we ask the patches to draw themselves and set up a few variables" _+ X& C0 A4 P5 O2 S+ p
  setup-patches
" m! ~3 J+ S5 [8 J+ K( s  make-current one-of intersections
! Z& ^; G9 q" S  label-current: U) C+ \; d, A+ ]- ^

2 Z( Y/ g7 c& I" N  set-default-shape turtles "car"
$ c$ |9 P* ]" @! F2 k9 D
. X7 p2 @+ F& W$ V  if (num-cars > count roads)  Z2 C! ?+ @7 U1 |) ~$ ~7 W
  [- j$ @# W& d' T1 A! b( |
    user-message (word "There are too many cars for the amount of "% T& `& H7 L8 s; k) L2 ?" k
                       "road.  Either increase the amount of roads "
# Z* y, W( [+ y0 B                       "by increasing the GRID-SIZE-X or "# |9 `9 C# j' {
                       "GRID-SIZE-Y sliders, or decrease the "
' \, O& `$ l9 C* i& }4 J                       "number of cars by lowering the NUMBER slider.\n"
* t) g* m& E8 a) O( @                       "The setup has stopped.")6 |2 V+ D5 W; M% ?/ D* s
    stop
+ n3 d* r# m+ w- `  ]6 p/ R9 y; n2 c* X+ N4 E, m

  }; A) \" T8 R" T  Z( m, k  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% ]6 p# q' I0 K+ R+ H% e  crt num-cars
0 D" f3 v4 [; I0 d: R$ N  [  E- s  N; `7 X" \0 x
    setup-cars2 z" x! t" |3 I( s
    set-car-color
: P5 j& q* c, L! R5 R% @    record-data
5 [1 U6 N1 w+ m% w! G# v2 T  ]( u; O5 }' @9 g- @# K( U% w7 T
, j& z8 {# U! Q+ F& V
  ;; give the turtles an initial speed; }* m* H/ U3 D  b6 X- J( @
  ask turtles [ set-car-speed ]$ D  |0 \: m- Z1 [+ E7 i

$ V# h& b' w" [3 `0 o  T  reset-ticks
# o$ J3 y- l2 [* Y7 l$ \9 b' lend
8 S# Q% K0 g% u
2 {9 c6 b1 s5 u& P5 t- {;; Initialize the global variables to appropriate values
4 x: ~6 x1 k' H# xto setup-globals' C7 l5 \3 {# V5 {  B
  set current-light nobody ;; just for now, since there are no lights yet) }, `3 N& O6 P
  set phase 0
) X$ |) p4 {# S3 d% n& e1 R  set num-cars-stopped 0
) p; h! U1 i7 c  set grid-x-inc world-width / grid-size-x
+ V1 F1 ?6 A, p  set grid-y-inc world-height / grid-size-y1 q! r7 U5 Y7 O% p2 Z7 l

4 L! i& s9 n# s, V  f  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 J0 |! i% C& ~
  set acceleration 0.099
$ x, k9 N& ?$ h9 u* s9 hend
! B  g6 P8 G) x; ?. F; X7 p
1 q  q7 \$ w$ Q+ T0 {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 B) H2 ~* ]8 o* x6 Z. w% z, I: T;; and initialize the traffic lights to one setting# b/ ?; C0 ~+ i7 ~* }6 s
to setup-patches
4 J# m6 j8 `0 V5 R2 Z# a1 u  ;; initialize the patch-owned variables and color the patches to a base-color
5 u9 H, G; a2 q6 F, S) a  ask patches
* u. m6 x$ |6 g" \7 d3 J1 C5 _3 J5 G: H  [7 F3 p0 X  u& g1 U
    set intersection? false
( M& {% L2 X* r1 I% i! S6 G    set auto? false% C) r! H% U) u2 B& I  o2 x8 o
    set green-light-up? true8 s7 r5 Y; E+ n' |
    set my-row -1
' f3 r3 L* B4 g5 s' w9 o$ x7 _; d    set my-column -16 x9 {  S/ G# g# o" ]2 w  _
    set my-phase -1& r5 O9 }  P) g6 V
    set pcolor brown + 3/ q: m+ Z8 x! y
  ]) |( ~; }8 g) W
3 j+ M- ?8 o) i$ p3 I$ z0 m6 J
  ;; initialize the global variables that hold patch agentsets: E0 l$ ], E9 i7 A$ t4 {
  set roads patches with# n, z" E% T$ `0 N+ k! N* O0 M; w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 X9 ]* A$ z& k: V9 ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# u) ~8 f6 ~( S- V, ]- s
  set intersections roads with) I2 D& G! W$ U/ Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% J: V8 i6 e) Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 Y! |0 ~/ i9 N

( O6 Z. j4 X) e6 B: q8 I  ask roads [ set pcolor white ], `% x( n3 w) O$ J2 F' [3 J
    setup-intersections+ ~* L. N; G4 T" N; T
end
$ k. @( H- o1 F% k# H8 H# i其中定义道路的句子,如下所示,是什么意思啊?' u4 n' e- p% f$ L/ y
set roads patches with
4 @1 N6 ]7 u# f0 V# F9 T  Z2 Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 f: d) M3 `9 q1 R( h3 @% y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  A) Y! ]9 A+ Z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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