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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。: H1 G" t! H* `1 c. `! ?- d
netlogo自带的social science--traffic grid这一例子当中,
/ x1 Z0 x+ }1 \- `1 `globals1 p3 Q1 F- |+ f' P
[; T) H4 m9 \( H# o0 x  C- n# E
  grid-x-inc               ;; the amount of patches in between two roads in the x direction* W, R+ @" T, C8 V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: c: e. n8 K+ U  x, M  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 F5 Y% o& H4 y$ Y. p0 M                           ;; it is to accelerate or decelerate
$ l% q: B$ }5 V6 |2 {: {  i  phase                    ;; keeps track of the phase5 ~8 f/ }( L+ ^. @0 r# p$ O* n
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" ]8 r5 S+ ]! {. K4 l" L
  current-light            ;; the currently selected light9 J8 b$ _. g  ?3 Q

* G; k2 m$ q1 u# a  ;; patch agentsets
+ I$ c' P: w  c6 _1 a  intersections ;; agentset containing the patches that are intersections
3 i; U5 l. |. R1 f: K/ B& v  roads         ;; agentset containing the patches that are roads6 s: d. |5 B# U
]
  ?6 b& y! w1 M7 A7 u+ t
2 e) C) p. K" N. Hturtles-own1 J+ Z9 B2 l; l7 V; p
[& s. l, W5 C" c' B+ L' |- w
  speed     ;; the speed of the turtle( S7 _5 v+ n1 H3 @
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* ~7 A- s  A4 S$ A
  wait-time ;; the amount of time since the last time a turtle has moved
2 Z3 j  S. v9 P]8 S" ?9 }" g5 J0 C: G$ S

+ {( V' y. F9 Spatches-own: b6 w" B" B8 X/ h, t, \
[- T) j9 F5 G6 V5 ~( J/ d
  intersection?   ;; true if the patch is at the intersection of two roads
5 @6 V- W4 w9 O/ Y& ~  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ x# x  G) f7 }+ I" q* I
                  ;; false for a non-intersection patches., V3 G: U. X4 n
  my-row          ;; the row of the intersection counting from the upper left corner of the
! B6 q1 O  M/ [' Z                  ;; world.  -1 for non-intersection patches.9 k5 D) t* N( e) V/ x# H
  my-column       ;; the column of the intersection counting from the upper left corner of the
. M0 N0 S. N, {6 g% H                  ;; world.  -1 for non-intersection patches.! |' q% ?5 J, A4 J6 ]/ {& t
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. q2 V% M5 \8 q/ |
  auto?           ;; whether or not this intersection will switch automatically.5 I5 N+ L8 k3 V5 ?. G: t7 x
                  ;; false for non-intersection patches.
, L; D) j# q" N. B9 c9 Z! l! W]
9 ^/ K$ b: p) C) }8 \- f7 e& x, [; M8 u! p
" U$ d6 D$ G+ ?1 g
;;;;;;;;;;;;;;;;;;;;;;
4 r2 }% h$ Y! z5 \  S;; Setup Procedures ;;
% E( r  o) r2 v3 T1 @0 M;;;;;;;;;;;;;;;;;;;;;;
- [4 I' w6 d# L; ]! A* }% W% \& Q5 @$ _3 i
;; Initialize the display by giving the global and patch variables initial values.
5 h( z! c) i9 z0 A;; Create num-cars of turtles if there are enough road patches for one turtle to: ~* O8 v. j- p; f
;; be created per road patch. Set up the plots.( K0 |4 r: U0 ^4 R
to setup  H* W* d6 D: G; {
  ca
/ U' v5 c6 l5 J& [4 ?1 W. V  setup-globals
. n; s" n* S9 U6 y4 L4 q
- i' X/ n" a# M4 C9 g. _. {; a  ;; First we ask the patches to draw themselves and set up a few variables
3 S9 M$ X0 A" @) E- l2 k  setup-patches% E2 U& B) N) b# w* O# P
  make-current one-of intersections, S9 Y8 H) Q3 w0 H. W8 o% H
  label-current9 z0 w# O! U- D& C+ s: l/ b2 B+ g8 k( M
8 w9 o) ?! L% h
  set-default-shape turtles "car"' t' ^: }# |! \+ _9 Q# X

$ f( G- y: _- a" u9 [: k  if (num-cars > count roads)
2 B7 ~" n, I/ O! d/ \  [
4 Y! y* j: g( Z. @$ I! P# C    user-message (word "There are too many cars for the amount of "' }8 u3 T" i. |- C
                       "road.  Either increase the amount of roads "
  ~( g, d$ R; ?% x/ t# \) ~                       "by increasing the GRID-SIZE-X or "
6 B% _' i+ Y/ |  e) ~& C8 @' N" U                       "GRID-SIZE-Y sliders, or decrease the "
7 V2 Y6 d( c) p5 Y$ U4 n                       "number of cars by lowering the NUMBER slider.\n"
' l$ R, ^5 p0 s5 H8 p: R5 |4 g0 q                       "The setup has stopped.")
. f4 V/ s5 K3 ?% i    stop" @1 y" E; a/ n3 B3 k
  ]
7 n9 b+ A5 W9 o( i' I+ f/ `+ R+ @! k- j( k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: G$ t4 A" j+ a  crt num-cars
; z) C$ \1 p: \' X6 e& M5 }$ U  [# S# ?! N0 s& d7 G2 l* G6 _
    setup-cars& ?5 R& s. D1 B' A& h+ F
    set-car-color5 s; L0 U6 M: S: }
    record-data
+ l7 f* C8 \# h: Y  ]
. x; i! A3 U" u" I& c) f* g
- _% K6 k; j4 O- k* d1 h: e9 m  ;; give the turtles an initial speed
2 ]9 Q% b( e7 e5 _0 {  ask turtles [ set-car-speed ]* @* [$ _$ @. O
$ D8 `: W- M) N; |5 ~
  reset-ticks# P- t/ `9 g- [+ [0 Q4 ^
end! y( G  B; S. L2 K. Q7 N
# @! M/ m2 u3 d/ o( |
;; Initialize the global variables to appropriate values# H; T5 j3 j: F$ E- ]
to setup-globals
9 E& C- W! i, d6 D5 d  set current-light nobody ;; just for now, since there are no lights yet
" k8 _" B4 R$ t- Y  set phase 04 Z4 Z4 `' B; ^- t" Z
  set num-cars-stopped 07 g4 Q. u. {1 X0 {! [
  set grid-x-inc world-width / grid-size-x# W% f9 J" o: v# D8 P$ u
  set grid-y-inc world-height / grid-size-y( p- b$ F. ]) o) p. m; \
/ @# v" r/ E4 I- I! L' Q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) Z% b! X, p+ T. r9 |; L
  set acceleration 0.099
5 ?# {1 w% e6 |/ A. ?+ f9 mend9 o8 M- [" O3 ^
3 b( }; S/ l- p" a! _/ v
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# s: x+ s! i9 E, s& @! @; {: X;; and initialize the traffic lights to one setting& u9 t" U2 F! E2 q
to setup-patches7 w' w: e! F0 n
  ;; initialize the patch-owned variables and color the patches to a base-color# f) v" W& i( F1 q* D, P: N
  ask patches
+ r1 g! z* R0 S8 s* q6 y  [" s* e0 J# k/ g
    set intersection? false; o. z' Z+ I9 m4 K  }4 x, v% q: W
    set auto? false  u/ y8 t6 s6 ~! G3 @! }
    set green-light-up? true& ^1 Z- ?+ R6 q* l) @' s; t" x9 Q
    set my-row -1
7 T$ \4 a, O; \" d2 B( P    set my-column -11 N. `8 f5 g- ~
    set my-phase -1
# d3 v* d% N3 d1 W+ Z- o    set pcolor brown + 39 z: k" Y" b/ K, U5 Q5 K5 H% q
  ]0 S( Z8 R6 b5 \) S7 A" u$ K( O

6 `2 Z1 {* i4 R/ G- @, ~  ;; initialize the global variables that hold patch agentsets+ m% z4 M7 G/ }& F
  set roads patches with. o+ f# |) o5 H3 j3 W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  L6 E" k5 v6 O' \, E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 s$ w6 d/ c; z1 \  set intersections roads with
/ K3 }) z$ U% l% @* u# K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! M# Y( d8 B+ c) m4 c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& l4 Y5 U+ X# I) a$ H
4 x. E( ?0 y% Q9 l$ t! o4 w$ x  ask roads [ set pcolor white ], S: U, s$ L/ E0 C% b
    setup-intersections
- K) o* b2 p" z% F1 U$ aend
9 ^% `& C; `8 H& C其中定义道路的句子,如下所示,是什么意思啊?
! i/ w% U+ H0 G# R' Z, Y set roads patches with
/ a2 x$ g* v  M9 R  y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ }8 m  A. q* n1 I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 t3 C+ ]* C% N8 C( v. U$ l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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