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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。
7 [# T! C  `* B, Z7 c. hnetlogo自带的social science--traffic grid这一例子当中,
: u: ~3 W8 x) n- R" Lglobals
) Z9 N$ d# {8 ^; O$ d[3 V5 _  i# G% f
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. B- `5 E( J& q2 t) ?6 b- {. P  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ X$ q  l# S' Z1 ^- _- o) _
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 W( m% ], o; G3 t9 P8 F
                           ;; it is to accelerate or decelerate
' D. M5 Z# Z- p% m; |0 T  phase                    ;; keeps track of the phase
/ B# U2 D# E2 O/ _4 k4 ?$ @& i  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, _2 a. ?# ~8 }' Y8 p! z( o" a# @7 l# d
  current-light            ;; the currently selected light
+ u: W$ A( X; y6 T3 b3 R0 G. r' o$ S+ g2 W5 V4 P0 I# U
  ;; patch agentsets
* C+ _: G8 {/ N$ _, P0 _  intersections ;; agentset containing the patches that are intersections! |, Y( v1 z  y  E9 H6 G( l% @
  roads         ;; agentset containing the patches that are roads
& }$ Y. d# E$ d) H" X]! T, r# J+ T( i" A' Z% M; E( c

, J& G# X& Y& J2 L5 \3 Iturtles-own! v  A0 U5 N* J' `
[5 T6 l7 W: ?& O$ m# `
  speed     ;; the speed of the turtle# d, c+ B# L% }  Q8 L7 U( L
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ Q( _( e& U$ }0 @8 R  wait-time ;; the amount of time since the last time a turtle has moved1 C) K2 ?8 g. O0 ^
]
( F  E" h# M  r$ P# x9 D; e+ L" x6 B; u# K  H$ B# s, {
patches-own
3 C, i" ~5 A: Q' F, X$ S[, ]# E- R4 {' x
  intersection?   ;; true if the patch is at the intersection of two roads& L& f/ G. R9 R1 ^0 W9 \
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: f9 H; B( C) p
                  ;; false for a non-intersection patches.% x) K  B6 v, w( A1 `
  my-row          ;; the row of the intersection counting from the upper left corner of the/ h% _# m. A. Y, k" P% n
                  ;; world.  -1 for non-intersection patches.6 S, F, \% l( q+ |
  my-column       ;; the column of the intersection counting from the upper left corner of the! ~9 a' m5 y" T) V6 w5 h
                  ;; world.  -1 for non-intersection patches.
& C, r* l0 N2 M! J8 B  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
2 Q0 |& _7 o8 O  O0 a- H6 I, o  auto?           ;; whether or not this intersection will switch automatically.
" m3 e" I6 e5 j2 A                  ;; false for non-intersection patches.
+ m, a0 ~- [- K5 o]
% `/ t1 _" ]# W# c$ g" A7 N
9 Z+ g) u% _6 v2 k9 {: V7 {; Z/ s1 d9 X% d
;;;;;;;;;;;;;;;;;;;;;;
3 d8 |$ r5 d$ L; i+ M% s$ _) O' W+ W;; Setup Procedures ;;
- ?; i4 B  R! l4 [, K* Q;;;;;;;;;;;;;;;;;;;;;;
  t  I3 R# J0 j3 n1 r# T: l/ y
  C# x6 h) h$ _;; Initialize the display by giving the global and patch variables initial values." z. n3 I) r* Q' j0 ?
;; Create num-cars of turtles if there are enough road patches for one turtle to
$ E& O" `. _% ?* ^% g4 c5 M;; be created per road patch. Set up the plots.
( [1 n* L: }( s! v- y6 J( L, u9 ?" pto setup
8 Y$ a. y# t1 r& ~  ca
$ S7 T, I4 f# M% U/ G0 s  setup-globals/ {, o* E/ G) x) N6 z; `
; s' u9 j, V3 a. m+ ?4 m
  ;; First we ask the patches to draw themselves and set up a few variables
9 |! M1 ~2 p' @" ~2 A  setup-patches( g' t2 S; ~4 A
  make-current one-of intersections
2 w+ a1 G7 F! z5 @8 Z8 x4 {7 |  O5 A  label-current
+ P1 V/ J, k; n5 q
0 P! ?5 ^2 t9 M- ^  set-default-shape turtles "car"
5 a* @3 ~) y5 d, F& `
0 j- a# @7 H5 L$ C: N  if (num-cars > count roads)
# m2 q9 @, S% M  [8 ]6 y. S5 E  J
    user-message (word "There are too many cars for the amount of "
1 W$ t' j  \/ O: _+ s                       "road.  Either increase the amount of roads "
  I: \4 ~2 ]6 O* q9 M) Y: E; m( G                       "by increasing the GRID-SIZE-X or "
9 j3 _$ U" K9 G                       "GRID-SIZE-Y sliders, or decrease the "- c3 z1 g# F. j- c( p! {. [
                       "number of cars by lowering the NUMBER slider.\n"* T* l) D$ }5 Y% n2 M9 {  I
                       "The setup has stopped.")0 V) Q! E6 H" d9 B% |
    stop0 \1 U& ^9 k3 m; E' Q" N8 I
  ]! ]" l4 X. n. F7 ]1 B( P# h' b

8 v  L$ H/ r/ L# j  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: t7 A7 A- K& l* L0 O# Z. T
  crt num-cars
0 o5 i  j5 ~/ u6 g8 Q7 A  [
6 H5 P5 q1 _; Z2 S, {- @# s; b    setup-cars
: w: ~  [/ H0 d  |7 Q" f    set-car-color. @" o3 d9 _2 g* [4 P
    record-data
. Y; J. X6 b% Y# a  ]1 h1 m& S- y! |) `6 O: |4 {
" W4 h6 z+ Y' j1 ^9 A
  ;; give the turtles an initial speed
2 ?" O6 M9 }  ^) `  l; r1 u( m  ask turtles [ set-car-speed ]& x/ T4 f9 p( y; l4 V9 U
; }* G+ ?$ h6 M# R8 P+ w# Y
  reset-ticks- u7 k3 Y) B2 D) o2 y( }& X
end
# J( v2 D( a8 x/ O, ~
5 B% d+ x( ?8 w) D7 X6 }) S;; Initialize the global variables to appropriate values
* _$ s+ Z4 ^6 O9 b& ~* y# F: tto setup-globals2 ^6 N. h" I: ]! T
  set current-light nobody ;; just for now, since there are no lights yet
4 c# j: P9 ~; K. l  H  set phase 0+ \2 u( x7 z0 k0 k- j5 A) K
  set num-cars-stopped 0
, @) _. `8 g( l* W/ _3 p  set grid-x-inc world-width / grid-size-x# D4 M; ?$ g( p" ?$ A1 N% x8 F1 B2 k: A
  set grid-y-inc world-height / grid-size-y* Q5 y- @' O# l+ {

# u$ B1 d' u, y7 H6 w  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- u* h/ {9 Q  n" P% \, I% `7 A  P
  set acceleration 0.099
6 h, ?0 c2 P1 E6 F. ]7 ?end
- o0 ~3 a2 d% [( r2 k9 B8 n4 }2 m! n; ^; T1 m% ]" }, ^0 ~4 t$ f
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' ^7 }2 _0 t4 @% ?
;; and initialize the traffic lights to one setting
2 P& @$ s  Q8 w8 X+ c: q* [( vto setup-patches& f; e' b+ Z3 g5 `8 h
  ;; initialize the patch-owned variables and color the patches to a base-color
" c3 r- }* G* @& v  W  ask patches6 A1 `  I# N# R
  [
+ t+ I  z, W% p5 n    set intersection? false
( @7 d1 e3 {, U$ t+ c    set auto? false1 Q) S8 i% B0 A6 w1 M
    set green-light-up? true
2 _$ x9 T5 _/ w4 s    set my-row -1
& I3 D# ~7 G4 X% M5 D( p, u    set my-column -1, x- c1 _  T. R$ }# p
    set my-phase -10 c  ]% w: u  Y
    set pcolor brown + 3( o! f( g5 {0 f( _
  ]
  @! H! D, U" Y3 N8 L
: O, ~8 k7 d2 M  ;; initialize the global variables that hold patch agentsets
2 L; A6 x' ]- E) G3 r, X  set roads patches with: m; Y- Y! M) L6 {% e# Y/ N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 W( Z4 p+ Z4 Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 u. Q# L! E9 s. c$ c: ^0 I5 b
  set intersections roads with& T- A* ?& B8 ]; C6 G0 S2 X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 ]+ C6 J6 V, d; [8 U; B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 U/ @, S6 ^) [, T2 Y% x
3 w  G6 _( X8 M0 ~& {6 S4 n  ask roads [ set pcolor white ]& \, P- C5 ~0 b. t5 e& N
    setup-intersections% F2 {0 f1 S5 @5 z6 `1 L
end0 f3 H' z4 @2 n
其中定义道路的句子,如下所示,是什么意思啊?
5 q7 M, U  c9 P# P set roads patches with
7 {6 ^9 ^2 \# [$ X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 c1 p6 f& l4 O2 [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- F% Z+ X- r) O5 U
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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