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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。, w4 E% b2 a$ F- Y6 j
netlogo自带的social science--traffic grid这一例子当中,
3 Y/ K$ u) d2 q4 ]. m2 ]globals+ ?" x  v6 K0 \3 [* b( Z
[
2 D! t6 X" m3 u$ L5 y1 a8 e& L  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% B+ Q3 O  c) o1 q  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 }4 h  Q& K$ z
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ ?: U6 [( t  o                           ;; it is to accelerate or decelerate
" I2 j; ^/ J7 J# M4 Z% R  phase                    ;; keeps track of the phase
; I& a( E6 A" G9 V3 n: \5 N! `  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ P+ t9 C. r% E% d- @, h
  current-light            ;; the currently selected light% n' ?4 c: U( T1 ~) Z
) D" d& j" J' o7 ]
  ;; patch agentsets
0 \0 C" K0 ?4 z) b5 M4 P  intersections ;; agentset containing the patches that are intersections
! i$ U; W1 V; J7 {; K. k  roads         ;; agentset containing the patches that are roads
. b) J1 W& A: D) g- U7 j, h]& w# D% V; M0 r  l# ]/ c9 l; K/ q

: G7 i- p+ M1 a+ K# z1 e  Mturtles-own
5 J! k3 w- Y3 L$ c[4 @8 g6 |  Z5 c5 J4 w+ u
  speed     ;; the speed of the turtle1 @5 i. u3 e& S) b( u- L
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ p( a4 Z4 n. k: Z/ g  wait-time ;; the amount of time since the last time a turtle has moved
+ X9 _* e/ ]7 M! o* D5 t]0 @$ T$ R& J; ]- m/ w

/ a6 `6 Y+ @8 Q8 V+ y& k' e# i+ lpatches-own5 e/ ?7 N  ^4 ~5 J
[5 g, t9 _2 ~& h) x3 ?/ J
  intersection?   ;; true if the patch is at the intersection of two roads
7 o' C" A* W; k  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" [: K& b& v& g  ^4 F' |* R9 v                  ;; false for a non-intersection patches.9 r- L! q- r+ ~9 D
  my-row          ;; the row of the intersection counting from the upper left corner of the  s9 b. y3 W) @4 m) C; }# ]) X
                  ;; world.  -1 for non-intersection patches.
9 p4 L3 w) Z- G& i# g4 G3 ~8 F  my-column       ;; the column of the intersection counting from the upper left corner of the) ?: B% z  x; a/ Y  i4 A' x
                  ;; world.  -1 for non-intersection patches.
. [; L1 c' ]- D$ T* R6 ^! }  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; _1 l6 {; W* F) z& {( ]4 [/ N7 ]  auto?           ;; whether or not this intersection will switch automatically.7 _, l9 G; n3 V3 f/ @7 F
                  ;; false for non-intersection patches.
* M1 t' P- g/ _  Z7 C]9 |4 g1 s  P$ w! A3 m4 _
/ g5 n  i. W# r4 w) l% v; W& P
3 m  f( G6 f0 l8 @
;;;;;;;;;;;;;;;;;;;;;;! \- s1 s. i% f2 V
;; Setup Procedures ;;
$ c. x+ ]6 W% v! {& Q6 r;;;;;;;;;;;;;;;;;;;;;;
) A/ e2 X7 j; I% b6 h& h, C1 D7 o6 m8 Q# z% Q: N
;; Initialize the display by giving the global and patch variables initial values.
5 R2 M8 _* A3 C/ N;; Create num-cars of turtles if there are enough road patches for one turtle to
3 i% f$ \9 z$ Z: W;; be created per road patch. Set up the plots.
8 p- U- R# B6 Lto setup2 @( l6 g$ v+ ]* Z3 l
  ca- I- q- M; g# w! }5 y+ s: |
  setup-globals
; ?7 e. K& Q7 ~9 X. n
6 W+ B# |) E; g$ B9 K, e  ;; First we ask the patches to draw themselves and set up a few variables* F; h8 @6 X! N: v: l' N* b
  setup-patches
8 o- u7 q6 r  h( f2 F; \  make-current one-of intersections1 k  w# ^" D0 [2 F8 r+ v- Q
  label-current
, |) t( H4 W. r# p# b" T
! r$ E6 [) G% M) p# h$ Q- x- [  set-default-shape turtles "car"9 C# }1 {( ]0 X1 y* I6 J
$ e- O/ I* \/ L6 X$ j4 n/ @) w
  if (num-cars > count roads)
0 y: m/ Q, b6 n1 v# ~! T( G. c  [# C# r+ v8 q# @& I" S
    user-message (word "There are too many cars for the amount of "# V9 h. w) T6 g2 S! S' Y
                       "road.  Either increase the amount of roads "0 c$ w% N) h3 |( p6 n7 s# ]. d2 Q
                       "by increasing the GRID-SIZE-X or "0 b/ I0 t4 b; z8 ^# t
                       "GRID-SIZE-Y sliders, or decrease the ", L  h* |8 L8 L6 M9 B. F; |
                       "number of cars by lowering the NUMBER slider.\n"4 u/ _! `! l/ O) Y! [7 p
                       "The setup has stopped.")8 ?; c3 O% E% O/ o& r7 Q& H
    stop8 P5 d+ T& f1 i. H( Y7 T
  ]2 ?& N  N! ^# V7 d5 M) h
* e6 s& G! Y' w  w
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color  P4 S4 e/ R3 b+ v8 n' p3 U0 F
  crt num-cars
7 N6 d) L! U5 j5 P9 i  [
5 H8 B" j+ x$ L& o) D2 u    setup-cars
; c% v# k* i* t/ n# r( `' B+ F    set-car-color
. I: d+ r8 \, ?" F. M$ A    record-data
; `5 P# k) s# r- {  ]: j3 ?5 m! ], O; _
9 U# q$ W+ ?4 i, U6 U! `
  ;; give the turtles an initial speed3 b$ l( V  m$ f- _, p
  ask turtles [ set-car-speed ]) x- P5 v& `; _6 f, V

3 K$ l. L, W: ~  reset-ticks, S& }4 E  b6 d, @: A1 Y; F1 ^
end
$ i4 X- [; j8 j* U" \
: b/ u4 K* W) V;; Initialize the global variables to appropriate values
" \6 l' h# Z6 u, B  S, P+ jto setup-globals+ t$ T* ?5 U8 H* g
  set current-light nobody ;; just for now, since there are no lights yet
: ~3 |+ B. G6 M( t  set phase 0
+ L* }6 S. N% ~' t  q6 l  set num-cars-stopped 0
% i1 e2 `  P9 `; c  set grid-x-inc world-width / grid-size-x6 ?. t: r2 u3 H0 |7 ]3 L7 ]
  set grid-y-inc world-height / grid-size-y1 S' n" x! j: x0 ?/ _* z2 d% U

5 M4 W% f+ E, E7 n5 q  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  Z# G' r- E' v6 M+ b: @2 {, K( V  set acceleration 0.099
% ]" _1 t. l& l5 ~end
' ~, i1 j, B3 G1 V1 ], S
3 Z) e  G/ w- V+ H;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 L! z$ N* y0 D;; and initialize the traffic lights to one setting
9 x8 v. y8 o* G/ S" I$ T/ Qto setup-patches2 |. [* r4 ^: w8 M6 r
  ;; initialize the patch-owned variables and color the patches to a base-color
) X8 D% c6 W2 ~  ask patches
' D) A  j7 U2 }5 X$ S9 d  [7 x. l7 W% [3 z7 P: J1 h! X3 R
    set intersection? false2 B9 }: ?0 V/ N% u1 n
    set auto? false
; i. q; e# l: i+ w    set green-light-up? true' f! B: `7 Q6 z# W! c( p! r
    set my-row -1. [' l: z0 T) A; E8 l9 c/ x
    set my-column -1- y) `9 F4 p, J, M! S! ^2 P
    set my-phase -1! r2 `' C" Q( r: [% Z
    set pcolor brown + 37 A7 \" n- g4 j
  ]& t1 a3 G% m, |( O/ p- y

, o0 P# N& ]. o' D, }. P7 n  ;; initialize the global variables that hold patch agentsets& I' G  \* o4 f, H
  set roads patches with
% B1 t8 w. C  I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 Z7 V8 h/ W9 a2 A# B( D$ s* E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 {' I9 p$ [3 A2 N# D5 T2 b  set intersections roads with
; r1 D# I, a, o/ v( Y4 i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 u/ w) X6 v& h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  S5 L. e) T( @/ V
+ @8 p1 g" V. x! g
  ask roads [ set pcolor white ]  r5 ]- a: l% S$ G
    setup-intersections
* o5 I2 n- u% P9 ~5 |. `end) Q, t  _' |. L: {# D6 f
其中定义道路的句子,如下所示,是什么意思啊?% o; c# Z9 I- h" g' Y6 Y
set roads patches with% @5 W( S( ]9 W8 f6 Z2 @) M, R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: D$ A2 p& `! S, a  P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 m. k2 l' g/ U3 @% R7 Q
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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