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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。
$ Y0 v$ C8 c0 mnetlogo自带的social science--traffic grid这一例子当中,
; V& z/ c5 H" c# s$ |globals9 d- i+ a* r& p$ a* ]* |
[7 _$ y, {! ?! h# s$ ?1 L
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% Q7 N3 V" R) B' Q  grid-y-inc               ;; the amount of patches in between two roads in the y direction* D( z" C" }: c7 y# Y6 e
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. p( o: L1 W2 {
                           ;; it is to accelerate or decelerate0 h# g0 d# n0 B1 Q, x
  phase                    ;; keeps track of the phase6 [% _5 E+ \% y5 l  Q  l
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ V. x' V) L+ s  current-light            ;; the currently selected light1 _9 {: F# y5 {+ Z; U  O

# `% e' L$ A8 G/ |  ;; patch agentsets
1 B/ W  ^& g/ U9 E  intersections ;; agentset containing the patches that are intersections( D" G3 a. w9 k$ |5 W
  roads         ;; agentset containing the patches that are roads
7 {1 _6 F2 ]# o, c]
+ e$ S9 V& Y, E: D
' A( g+ r, V2 c) E7 T' b$ cturtles-own2 d2 p3 T1 [1 [
[
! h$ |7 ~  r! T9 r# s' D( l7 P  |) c8 Q  speed     ;; the speed of the turtle/ ~2 m4 l" u) R  |) |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ n: O9 ^) i: l; R. [: s
  wait-time ;; the amount of time since the last time a turtle has moved
5 z1 Y0 v. |/ x" s], Q9 O- J3 W% L4 c0 ~
3 Z" }9 d5 c# _; M' ~' u8 U
patches-own% o4 C4 C" ]4 Q/ h
[
5 ^2 F6 l$ V! ]  intersection?   ;; true if the patch is at the intersection of two roads: Q5 n# u2 d% X  l2 k6 ~% C* y: q
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.) n9 X* T, X8 J$ i
                  ;; false for a non-intersection patches.
+ j, c1 ^! w# A( T6 R2 ?  my-row          ;; the row of the intersection counting from the upper left corner of the: c- O6 k' @3 L! I: Q
                  ;; world.  -1 for non-intersection patches., U; w4 X2 _% P  \1 |. t2 s. u
  my-column       ;; the column of the intersection counting from the upper left corner of the) H" A: Y8 l! f3 f
                  ;; world.  -1 for non-intersection patches.
2 {. M# y! i# ^8 A% t  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 @7 e7 l4 ^2 L/ }0 T
  auto?           ;; whether or not this intersection will switch automatically.& [: S: b1 y* D5 m1 E2 m5 f
                  ;; false for non-intersection patches.
) F. h* _* O; O# `]
; u( h) j2 t9 h2 C: X/ W2 F( Z5 a% I1 B- z# O) \

9 g# O$ a2 A. _;;;;;;;;;;;;;;;;;;;;;;
: S$ ]5 @: m4 u& z* T;; Setup Procedures ;;% z7 h" K5 G4 H7 N' W7 j# r
;;;;;;;;;;;;;;;;;;;;;;
9 a( R8 l& n+ O/ d  x; g3 K+ o/ x3 B6 N% ^
;; Initialize the display by giving the global and patch variables initial values.) Z' D) G+ z2 `! b6 \* w
;; Create num-cars of turtles if there are enough road patches for one turtle to( f' i. c6 n: b* ^# H/ N* j  S
;; be created per road patch. Set up the plots.
7 {; a9 ?4 k7 ?, r3 Oto setup5 `- s. _8 z- c3 ?8 }/ J
  ca
8 F" \5 p' a# |+ C  setup-globals
1 ]/ Y1 k$ k( C/ x! z! y' p% [
* y9 l& O2 @$ o) b. u  ;; First we ask the patches to draw themselves and set up a few variables
& `4 k- q$ s! K. E* I3 F6 h, H$ [  setup-patches  F; O9 j3 n; ?. R$ x( \' l4 [# g
  make-current one-of intersections, e2 M1 }$ u# \1 C
  label-current
/ T/ ^% ?# w" [; X+ a( E6 I* U! h) T" ~! z1 N
  set-default-shape turtles "car"
& Z: H7 \: T. p' ^9 ?
1 ]' |* h6 `" X# t* D  if (num-cars > count roads)' D5 U+ W" J& Q9 b
  [
. n9 m; r7 L4 R    user-message (word "There are too many cars for the amount of ") {  P8 Y" E/ P1 K  ?
                       "road.  Either increase the amount of roads "* s! u# @- }1 d0 i9 Z  g" T5 N$ T: V
                       "by increasing the GRID-SIZE-X or "
; {0 K4 g  q6 U+ y) S2 a. x4 G                       "GRID-SIZE-Y sliders, or decrease the "1 _! n- ]* R1 a# r" e
                       "number of cars by lowering the NUMBER slider.\n"
' D% A5 T# c3 t2 P! R3 R                       "The setup has stopped.")' |) A0 E& T( m* [
    stop9 o- A  z2 @) k3 |6 a% d
  ]% g; b7 X; b8 o  ~0 |
7 W. _. O7 h- O6 A% r+ f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. I; i$ s4 J4 d% w
  crt num-cars
4 a4 j) S$ Y; Q6 i! g  [6 T& O" j1 l( w; u' n
    setup-cars
# S1 P! o* W3 _/ d  R7 v0 L    set-car-color
- b; P) n; R. p6 U3 |    record-data
& j. A& P: ?, O+ E* U: |  ]
8 ?1 E' O& |5 |- v6 C# M5 \  {# N$ {- ^( ^% N7 S
  ;; give the turtles an initial speed3 O) ?0 d- z# {- t* b$ c9 }
  ask turtles [ set-car-speed ]; p& J* n1 J5 j% s* L
0 ^. k" B/ S( H
  reset-ticks
) k# J' ^* j8 fend0 i, w) \* u, i8 O$ F

) D6 g6 Q( `0 T- a* J# t;; Initialize the global variables to appropriate values
4 _" Q" ~$ Q6 K) s, h8 f* Fto setup-globals( y5 O% H, b6 K6 a: w' e, g0 X4 q
  set current-light nobody ;; just for now, since there are no lights yet
$ U: {2 A2 P3 X- H( Q9 D  set phase 0
; e  d1 W8 c) _! x) V% Q6 m  set num-cars-stopped 0
' ]2 {  o) F. a6 Z4 P3 \  `  set grid-x-inc world-width / grid-size-x0 `1 @' L- ^6 ^0 E3 o
  set grid-y-inc world-height / grid-size-y
. j2 m8 S+ h3 @1 L/ C- b" w' [& V# z! p$ z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 l  k  Z1 r9 m( D! p
  set acceleration 0.099! h$ e. s  O1 ?
end% G5 Q6 F$ S5 B& p+ I  S
2 i0 P6 E. A: U0 Y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" D$ Y6 o4 g! p# l;; and initialize the traffic lights to one setting# b- Q7 ^/ D8 {3 n! ~' z. }
to setup-patches! S% N8 a( V# n" L
  ;; initialize the patch-owned variables and color the patches to a base-color
3 T  c& \, n) F  ask patches& v' K2 Q7 e+ y% ^
  [
( c4 @4 x/ X1 J- u: y/ ?$ F; o) W    set intersection? false1 e9 q0 N' c  k2 ~0 X
    set auto? false
4 V1 C9 X9 |/ E- r    set green-light-up? true: }5 W: y/ Z6 n- f4 y
    set my-row -1
* g3 s* ?) C7 v3 l    set my-column -1
  j. F/ s5 ~/ d" f    set my-phase -1' I$ N' t2 i( y" v5 J7 \; K* C
    set pcolor brown + 38 O5 Y' G; Y! \& \
  ]
8 f0 [4 m8 t5 Q7 ^+ b$ O4 k4 ]9 t# \! f0 k
  ;; initialize the global variables that hold patch agentsets
3 y8 r8 C2 @, ]' D4 W0 f  set roads patches with
$ L4 F5 A6 ~* K  M  T( K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# `# J/ q; V& G4 F/ n, ?0 Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* D5 [% C/ ?$ N2 [4 c6 ]! d$ B
  set intersections roads with
% v! X7 m, i2 Y' G0 J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) w  |. R2 ^( N. o; j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( @! O2 {- J( R. P! I" N1 C4 M
# e5 j* |. b7 k  ask roads [ set pcolor white ]! I! S! f+ `5 `  |
    setup-intersections% k% Q4 }7 q) K2 S2 {
end- e: @& w3 M1 U' e: K+ }# L
其中定义道路的句子,如下所示,是什么意思啊?
* R$ r* L2 P9 [, s- j; L set roads patches with) b9 T2 g  W* Q& i- ]& h& Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" p; e1 O- q- P7 V# V7 G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], b) [% d# R' Z7 `% T( [
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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