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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。! v8 l' L; o# ]: v+ L0 Z3 Q# w
netlogo自带的social science--traffic grid这一例子当中,4 D3 x) m$ I8 f) w$ u. g# E! o! ^
globals' D9 m- j2 k4 L$ N. J7 T! _
[
: i$ R) e9 T3 ]* M- d  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, U; H2 R& G- z8 z* k  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 Z2 t) _% ]0 _' d  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 m9 o* d8 W, C! V0 Q" j                           ;; it is to accelerate or decelerate7 g* I: A& [" b
  phase                    ;; keeps track of the phase
# `9 u. n- A# j  Y* W1 l% b# U+ k  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 ?0 x2 W# L6 K0 e
  current-light            ;; the currently selected light  f/ g) m: \; F

' L6 E3 F/ c) z4 Q* i) {7 J  ;; patch agentsets  D/ J1 i& e4 x$ k/ S3 M2 c
  intersections ;; agentset containing the patches that are intersections
+ u( |4 H# `5 _- W, F9 n  roads         ;; agentset containing the patches that are roads0 z, x- v9 a/ u. p" x. N( c  w
]
2 ~4 O; y; j: Z, U: C. Y9 S8 x0 S" D+ R" ~4 q
turtles-own
9 I' O9 `" ]- \  Q" S1 K2 I[) D, ^8 x% ^( K3 }, j* K$ L% n  x
  speed     ;; the speed of the turtle
7 z. g& `% C; s; w' n2 F, K0 C. j8 v/ w, b7 F  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 y# _. C# ~# }1 ]0 |, `
  wait-time ;; the amount of time since the last time a turtle has moved4 l2 ^, }/ V- \# g; ^0 F& @/ E
]
, x8 A8 x; `  D- q, E. p, w% _; @2 N8 \: t; x3 [: n
patches-own
+ A# s1 [9 `9 O$ j% o9 u[
2 c2 N7 p* \# Q2 i& W1 t8 {* m  intersection?   ;; true if the patch is at the intersection of two roads2 u3 p' `9 M/ R
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! A- F- Q6 e+ K8 R                  ;; false for a non-intersection patches.- Y/ C4 b# u8 ^
  my-row          ;; the row of the intersection counting from the upper left corner of the
" ^- d+ O0 u. ~) p& Q% w4 U                  ;; world.  -1 for non-intersection patches.
. H: M) l( q0 A# a0 y! r+ d8 x$ c% _  my-column       ;; the column of the intersection counting from the upper left corner of the
' E* p& V  U, v) S, p* L                  ;; world.  -1 for non-intersection patches.
% s8 \' m2 O8 F+ ^, D  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( z3 |* T5 H$ L$ d8 i& n2 G* ^  auto?           ;; whether or not this intersection will switch automatically.6 N2 Y+ E$ ^" Y3 R$ w% O
                  ;; false for non-intersection patches.
- h3 z- |1 w6 x( p& N]5 R, `- V" c. t; ]! H- n

8 u- W# G2 V! p, E; ]( F' x/ P( Y' b7 E* h
;;;;;;;;;;;;;;;;;;;;;;
5 T  a7 C6 t# ^" a;; Setup Procedures ;;+ s& Y. M, h8 z$ @
;;;;;;;;;;;;;;;;;;;;;;) ?# S$ Q4 m& W+ b0 x4 F

$ l' f) \8 r5 d+ w;; Initialize the display by giving the global and patch variables initial values.
& m) I2 V' s9 e& {7 k;; Create num-cars of turtles if there are enough road patches for one turtle to8 E$ u+ g- O, H; I
;; be created per road patch. Set up the plots.
: a% u) `; b' \2 }to setup- S7 T& s, n$ s5 W- S
  ca/ Y3 \6 x( ^2 j, y2 }9 x& |# a! \
  setup-globals
8 g! I3 J$ f, L9 l
: n* a  ?" V& y4 u/ i5 R7 x  ;; First we ask the patches to draw themselves and set up a few variables
3 T* F" r* X. f! q) e) E' E# ]  setup-patches
: H, ~% ]" ~' n5 ]( L/ M5 o  make-current one-of intersections
% y, c$ M, }; I% G/ T  label-current- C" c0 T9 O+ Z$ E
5 f3 k9 w3 [6 P4 X8 W9 k3 T
  set-default-shape turtles "car"
5 @, q/ v; H( U& B- S1 U0 R# E1 q6 a3 i. [
  if (num-cars > count roads)5 F7 Z# ]7 W5 f$ N  C, [* w6 A
  [4 }* _( E* Y. W" P
    user-message (word "There are too many cars for the amount of "- }% S7 ~$ Y- ^; [/ m3 ^
                       "road.  Either increase the amount of roads "
5 T) M* q4 z. j/ D: U                       "by increasing the GRID-SIZE-X or "+ _0 A9 E8 @+ i1 h8 I) v
                       "GRID-SIZE-Y sliders, or decrease the "3 \$ p- ?. @; K
                       "number of cars by lowering the NUMBER slider.\n"" ]3 }6 ]* b" F5 E% D# S- G( w
                       "The setup has stopped.")
8 a& V0 H! d) J( h- c' A  J! x9 |    stop
# _9 O" a( C, N% l8 }7 `  ]# \% l8 K9 ^- A& r9 T

. t- B2 _# A1 \; r5 C2 J$ W  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% w+ O3 ^& u  D
  crt num-cars
# A# P" P* i( t  [# x  Q5 z( u- e6 U
    setup-cars, V, n+ D1 J) @
    set-car-color! n* z( T* u/ i5 m
    record-data0 a- O2 \. l% k" O2 {; a/ x" k4 J; X
  ]
& n5 g; J( }3 c: l. Y( U. Q/ v6 D! V1 |9 j8 n( p
  ;; give the turtles an initial speed
5 `6 o5 F9 M- e- Z* c8 r  ask turtles [ set-car-speed ]
2 B3 U1 a9 m9 `7 k( q
. K( N8 X$ K4 f) V' a( D  reset-ticks/ n+ u1 K4 J2 g
end
8 ]( M7 Z  P4 G: p# N$ ^' K/ _4 }6 V( M# y; |. [3 [+ r
;; Initialize the global variables to appropriate values: c  j6 ]0 V# v" C. |
to setup-globals6 I! C9 v% t2 {/ l
  set current-light nobody ;; just for now, since there are no lights yet
$ A5 |- B% {+ ^3 g! U* L  ]  set phase 05 R- ^1 {7 M  n0 H4 M; z
  set num-cars-stopped 0- Q# U& e1 D) w6 [# r1 R
  set grid-x-inc world-width / grid-size-x+ {3 U% z& U4 C: b" x" k
  set grid-y-inc world-height / grid-size-y
) U  a! {5 ], Z7 w% Y" F) _' F% g) x; S
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 B( \/ A5 O9 C8 w- v! v* l3 g; f! G/ g4 [  set acceleration 0.099' }9 {) B" h5 j% r, A, W$ ]" [
end3 X, R/ R0 i4 m. v9 K8 p

' O/ g* F% w5 F; M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 K1 a% q% E3 i& S;; and initialize the traffic lights to one setting
2 Z1 x( w4 {* ^! Y5 b& Cto setup-patches
- P0 V' b4 [1 P0 w7 _1 _  ;; initialize the patch-owned variables and color the patches to a base-color8 s' `& n$ ~, N0 u; p
  ask patches) x: A$ y* l1 }# M# \
  [4 S( m; R+ v" ?
    set intersection? false0 J4 Y% r$ @4 w4 ^: M( V
    set auto? false2 F, T7 T; i" y8 Y  x8 x
    set green-light-up? true. R+ p$ ?, ]: n' u4 h/ |
    set my-row -1
9 o, T/ @* B" v  q1 D# i    set my-column -1# f4 k. e; }. N: h# ~! p& s
    set my-phase -1: }' \3 J  P% x- I: p7 v; x
    set pcolor brown + 3
7 U% g5 N, \0 f& X6 x  ], e6 g$ {; j7 z$ X$ e
$ s( z- C; k3 L
  ;; initialize the global variables that hold patch agentsets
/ a8 u) k5 T3 g4 \2 J  set roads patches with
) H4 i+ L# p5 y- [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" M+ M/ Y3 g1 d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) r" k7 ?. M" F) t2 r2 \/ H
  set intersections roads with
% Y4 N. i( G! W8 N) d9 y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, O/ `: e0 i) n0 F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* y6 f8 u, s6 q) W! N: \/ ^4 I
7 c2 e) a1 t3 ^# Z  ask roads [ set pcolor white ]
+ n: h# l5 d* {1 g2 R4 S( X( O+ W7 j: z    setup-intersections, l5 |& C, a9 X  Q$ l
end
9 ^- n! z8 W; f6 @' R其中定义道路的句子,如下所示,是什么意思啊?
3 q: s+ ]: T7 \5 V3 C. R# o set roads patches with# T# p+ a9 V% N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ m; I, ?, v& ~! z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 X- J4 a* v* w! B
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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