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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。' g0 s% G8 N) l* C6 l
netlogo自带的social science--traffic grid这一例子当中,
/ U. W  q& d6 F$ hglobals
  `1 D& w, A- q9 T  O% [[3 U' g* f; A" ]* b& Z9 l
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 x* A. `1 ~" j9 y2 |$ h
  grid-y-inc               ;; the amount of patches in between two roads in the y direction- W9 N3 X! @) }# M
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 v, c$ P. K! q
                           ;; it is to accelerate or decelerate) V( W2 d! c9 t2 e- X2 d
  phase                    ;; keeps track of the phase0 m2 U  `: o6 u# ~! q# @. x
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 O1 _) w' e! ?  I& r. D8 i9 X" V& e
  current-light            ;; the currently selected light* x! n$ ^9 K* ]9 Z- H" C: T

- @  T' h# z0 S' p6 p  ;; patch agentsets+ S0 x, v1 C: n8 f" ?; `8 ]
  intersections ;; agentset containing the patches that are intersections
" t' C2 Z4 |1 y" D0 H9 q  roads         ;; agentset containing the patches that are roads
# T, x. e( q. |/ U' b* t]
& E. q  n$ v0 h6 A( c8 j! O+ u0 \
. v$ Z0 I1 R6 ~6 w# n# Fturtles-own
, t  o1 M- Z; X+ _2 ~[
5 f, A% D& z9 a+ [  speed     ;; the speed of the turtle
0 e) i; o% a) a$ ]  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 L7 ?3 W' P3 F% Z- U; D% g
  wait-time ;; the amount of time since the last time a turtle has moved
# r* e+ C8 i! h6 P4 I) Q]
- S! H7 ^& [! _  |$ |" O
* ~: E  n/ ^* {) V$ S. Dpatches-own
9 u$ D% Z' M9 {& g* L* O6 G+ p[
9 \  t( j, O1 g4 M+ x  intersection?   ;; true if the patch is at the intersection of two roads, U& Y" @2 y1 X' A7 M
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false., r; r/ ~+ M( U9 M" ^7 H
                  ;; false for a non-intersection patches.
0 {0 C7 p: p0 |/ E! f2 [3 T  my-row          ;; the row of the intersection counting from the upper left corner of the
+ R3 F$ P" N, L                  ;; world.  -1 for non-intersection patches.( u' R7 j( z; o+ s! _
  my-column       ;; the column of the intersection counting from the upper left corner of the" z5 S! n9 ^3 X3 E' [
                  ;; world.  -1 for non-intersection patches.8 Z+ z# P: Z% Q/ R; R
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ Y" Y1 N6 v" c$ R7 w! z5 c
  auto?           ;; whether or not this intersection will switch automatically.% K. E  G1 W) A3 G* W8 v% t& c& R' r
                  ;; false for non-intersection patches.
3 s: ?8 H9 j6 m1 t0 l]3 y- W$ y. K! I$ A4 u8 Z& C
: v, T2 |3 I; a# S! ]3 O, K
& U* h: ]0 A9 T& N4 L
;;;;;;;;;;;;;;;;;;;;;;- _1 b+ ]* P& Q' h5 Y
;; Setup Procedures ;;% _; K1 u* W" L7 c$ b; A& ~* f) f
;;;;;;;;;;;;;;;;;;;;;;" [: S9 k2 [: i' J
; P. j! R7 [$ q7 p4 i
;; Initialize the display by giving the global and patch variables initial values.3 O% {& U  X$ K
;; Create num-cars of turtles if there are enough road patches for one turtle to
. J; a- [( z$ K; l;; be created per road patch. Set up the plots.* d% y9 x- `" |5 b! u' Y
to setup8 t9 B; a+ T) p: P6 \
  ca+ R. c0 u/ B" W% L! @) H' {4 I: u
  setup-globals) H, c' k6 I$ y) j

) C3 L) A% Y4 z/ K  ;; First we ask the patches to draw themselves and set up a few variables
0 b/ [" l  Y" K8 K/ P  setup-patches
* O. P9 c  v  I* v! a  make-current one-of intersections
- b3 g& g5 V' G* Z; o% o  label-current6 q0 l1 o& {6 U0 P  D. r6 u" a
& q: _, B# O2 [6 O+ E
  set-default-shape turtles "car"7 R0 ~) L( }' d, n
0 a0 W0 l2 {& w3 _( r  d8 i& A" |
  if (num-cars > count roads)
2 ^! Z  Q) ?# e4 ~  [& S, B- w# I4 o, f
    user-message (word "There are too many cars for the amount of "4 v- N* Y) t, w/ m; V: E
                       "road.  Either increase the amount of roads "
' c) W  d# O8 |- j- X  i0 s5 y8 ~. [                       "by increasing the GRID-SIZE-X or ", y! I' {; ^" p1 g
                       "GRID-SIZE-Y sliders, or decrease the "  ]4 M, F' W, y3 U. q( |
                       "number of cars by lowering the NUMBER slider.\n"
9 }& m; D% P: D9 p                       "The setup has stopped.")( f2 N$ L$ N! z, P
    stop
) \. r( C; j( F7 O# s9 l0 s  ]6 _" C3 t$ p6 ^9 W8 W5 o

  H$ c4 o) D% k6 U' \  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* t& a: k, s/ p0 o0 V1 d; j  crt num-cars/ k/ ]* \' m, |3 r% y
  [
% ~& o7 T4 z+ R0 i+ a  h2 a" ]    setup-cars. @+ U- A" e" n; M' @, u9 @
    set-car-color
( E3 a4 i* U1 @0 `# L2 t    record-data+ U3 R6 A' P# N: t8 v6 B
  ]
0 H2 I' T! h( R8 p/ x8 }7 N2 g' u3 q/ L, K
  ;; give the turtles an initial speed& X! K8 ?7 G! g" u8 z
  ask turtles [ set-car-speed ]; I2 \. O9 w' B4 M+ N" r# ]9 x  ?

/ D2 }  V' U/ y! v8 R7 e2 z  reset-ticks+ b  Y$ |- b/ Z5 H4 s7 m
end
5 Q4 v  m) |9 P( z* ~4 q; V
- f1 v! |3 {9 j* q) B;; Initialize the global variables to appropriate values
: T0 p+ d4 A* ]* O7 l% Z6 u' r# Zto setup-globals
7 L1 Z* i% c0 C5 S/ D8 P7 U  set current-light nobody ;; just for now, since there are no lights yet
0 w5 z3 J( O! l- x5 ~9 n  set phase 0
- n6 ]) F  Q( n& G, m: C6 q+ B  set num-cars-stopped 0
- d9 A" n) k; k7 ^  set grid-x-inc world-width / grid-size-x
* t. p' x9 p7 @' H6 t  set grid-y-inc world-height / grid-size-y0 ?/ e# s: V" ~& x0 Z8 }/ U. @+ {

8 y' c/ w8 x5 H/ Z9 v& s/ t; ^  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) A. c! `4 q: }/ w* W( U3 L* ?
  set acceleration 0.0996 f+ r- {& Q9 }4 X
end
# X" z  g* J, P# e! m/ i( {' W2 {7 ?- X" Z
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; G6 K! j% k, s" v;; and initialize the traffic lights to one setting' B3 e2 M" q3 c, m0 A, Z
to setup-patches! O/ ]7 D$ B: W+ Y3 A
  ;; initialize the patch-owned variables and color the patches to a base-color2 `# H* W: O" ~1 S5 ^, H
  ask patches
1 j5 L) g  x- s8 G4 G  [
+ J" F& O: T- d: F    set intersection? false
: T( g; \2 a0 L& y( E2 w: z# \! m    set auto? false7 a7 R) j: I2 X$ i
    set green-light-up? true0 `: |" L3 i6 ~3 x$ n+ o
    set my-row -1
9 {5 ~4 L8 a0 O* S3 Q1 n: W$ x    set my-column -1
, E2 H0 X* F) L. o" h! E, ^    set my-phase -1
% Y1 u2 Z2 x0 N/ n4 a    set pcolor brown + 3; @# ?& U2 H! [6 g$ c' u  B  \
  ]
; }/ I; t6 k  v( P2 R
. D- \" V2 s( z. V+ T, d  ;; initialize the global variables that hold patch agentsets
: \/ K0 L# z: U: Q% T7 ]& L  set roads patches with
6 G6 Y, A( h7 t' P, v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& G6 G# p  _, }% Z( k( U0 j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 Q, a% h, L7 N* \, i
  set intersections roads with
4 R5 E7 T' `9 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ p" }% b7 d& X- S$ M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ \3 h6 w' Y6 u& s" ^+ `
8 ?! E. Q# J9 x2 y7 r' h" T  ask roads [ set pcolor white ]! N4 G5 e# L3 k2 @. U' ~
    setup-intersections5 r8 `/ k, @: C3 l+ f0 D+ ~- O
end- @% {: q" e4 o- w
其中定义道路的句子,如下所示,是什么意思啊?
, `& J  ?9 h. i set roads patches with
  l1 J7 c' D8 B! L2 g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 U6 y7 u; D: T" _1 }+ O* a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* f! `% Z0 N7 v1 ?, x
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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