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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。4 v; u% ~7 H9 O7 j8 P" R9 o  P4 Z# |
netlogo自带的social science--traffic grid这一例子当中,
; k. K8 x$ T1 H$ `globals
- y0 @: ~; W2 \/ V" d+ u[
+ ]) s  w0 e( A# b8 m  grid-x-inc               ;; the amount of patches in between two roads in the x direction# Y) j% V+ b, n% C( f! ~, R) Q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
3 |# r5 V* H5 K2 \6 p. Q+ L  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- |# j  m/ R+ M/ x8 i                           ;; it is to accelerate or decelerate( p& |# L3 w& T, X. f: C
  phase                    ;; keeps track of the phase4 r5 W- G7 j' h# [# }, t
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 j7 T0 X0 U! H  current-light            ;; the currently selected light3 p8 {4 D) e- j8 g1 ?

. e* f3 M4 g1 r4 H  ;; patch agentsets
$ g. S8 p3 ?) ~9 }4 X9 t; q  intersections ;; agentset containing the patches that are intersections
! P! w1 A! y5 y4 }  G4 j8 ?  roads         ;; agentset containing the patches that are roads
2 c" c5 z4 q& m7 |" F]
7 S) ~+ u1 U7 v; r7 F* l) b  C; Z
turtles-own, \5 w: z" j" z, T' p5 n
[
- C% I" Q6 i6 ~9 ^5 {3 s% O  speed     ;; the speed of the turtle$ V; N0 x$ A- h3 `
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' n9 z1 }1 E2 d: _' `$ }, Y* K9 p
  wait-time ;; the amount of time since the last time a turtle has moved. }: j' O/ G. C* z( `4 C
]& q+ Y; I* Q. l' O: l

" }* l! l5 _) v6 ]7 y! Apatches-own
4 u. d* `8 o2 w- o7 W1 D  V[
/ b. z+ E; R+ s# S4 M  intersection?   ;; true if the patch is at the intersection of two roads
; h, J  y: L  ]  F! W! x  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 H7 R( v6 O8 q" H
                  ;; false for a non-intersection patches.
8 ~* x! d$ B' m1 l6 P/ m9 ]0 F  my-row          ;; the row of the intersection counting from the upper left corner of the. X6 n; k2 \( S
                  ;; world.  -1 for non-intersection patches.. B" c- m. N2 U8 n4 ?
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 ~. k- t. P! B" d. v' k0 n                  ;; world.  -1 for non-intersection patches.
' H; Y4 ^+ {5 {! [9 [$ R& u' U  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 o$ Q0 m5 u& N2 t* O& {
  auto?           ;; whether or not this intersection will switch automatically.1 }! j3 n/ V4 i* W/ z$ ]$ K
                  ;; false for non-intersection patches.
3 F' i) g, j! g5 a4 T) x]
5 w6 K# _. a3 P% `( W. e; u( S# r, j( C$ W" K- y

+ _- k* Y( g9 T/ b8 ?: ];;;;;;;;;;;;;;;;;;;;;;
- U$ c% @0 ^# H;; Setup Procedures ;;) D# m6 \  M0 V
;;;;;;;;;;;;;;;;;;;;;;4 {$ l1 B2 A( }

( \7 E$ H* S& z: ~. P- ];; Initialize the display by giving the global and patch variables initial values.
" C1 r& |. ^7 U2 b* B& H;; Create num-cars of turtles if there are enough road patches for one turtle to
1 V0 I2 y0 R, ~* |7 @% w;; be created per road patch. Set up the plots.
2 O) E- T. e2 d. H' M5 C- T2 f2 mto setup  V' x; }% ~+ T- o9 @; ?( X
  ca
' s7 c4 N- V6 s" q9 s4 m, X  setup-globals8 l5 {' M  d3 y; w  o" B8 @
/ A1 G! X" ?$ v' I8 P1 q
  ;; First we ask the patches to draw themselves and set up a few variables
6 N% c$ }+ |. C* c# `9 p  setup-patches
! w+ w+ o9 r1 A+ S  make-current one-of intersections
. m2 ?% z5 [, q- K* o) Q  label-current
. t4 T2 ^! z) H1 S5 B0 R7 s' q
$ V6 E0 u8 j+ m# Y8 ?& Q1 B  set-default-shape turtles "car"% {7 K# F+ ?2 o" o8 A3 F+ D
; D4 l6 \% [& y+ k, w
  if (num-cars > count roads)/ H6 c' \% u* O4 ?2 O) [3 y: j
  [  Y% [4 {9 W4 B- w. p+ {3 P
    user-message (word "There are too many cars for the amount of "
: n/ L* V6 z: D. g                       "road.  Either increase the amount of roads "
$ l  |! \7 J, S0 D9 D# c4 `! _                       "by increasing the GRID-SIZE-X or "
% G+ F  L2 l$ X                       "GRID-SIZE-Y sliders, or decrease the "
; T6 h' l/ l8 K4 d3 _                       "number of cars by lowering the NUMBER slider.\n"  ?- r1 C* H2 `0 D& n% \7 m7 E
                       "The setup has stopped.")
) L" s" t3 L. K4 B6 ]. V3 m    stop
, U% S0 E+ U  v* t5 ~  ]
: g6 \+ x6 C: {- D# z+ @. W6 r1 I) f9 G5 Z0 J1 w& Y$ u) z# m
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ u2 `; m3 K- \5 a* Y0 A) S
  crt num-cars
& K- r" A- d1 c  b7 I  [# t" Z, \/ v! h
    setup-cars
/ r5 Q4 k9 \6 G) L    set-car-color
1 H3 J8 z; R5 c* u    record-data
+ L4 {9 D6 x" s( m0 |  ]; Q( {1 R2 b; S

0 X8 f7 S, B4 P4 j' N  ;; give the turtles an initial speed5 h0 ~4 ?5 Y% a% ]7 U
  ask turtles [ set-car-speed ]
2 Z. @3 }; i1 p2 `2 S; l2 l, k2 F1 `  C, G
  reset-ticks
3 N, p, ~& P8 s1 _end. t9 p5 T% K( H: G2 m. H
7 `1 M. J! [1 l) }5 A6 `/ @- V
;; Initialize the global variables to appropriate values  a' t# R, `+ |/ o
to setup-globals
0 V; g9 [3 G1 ~  r6 A' T  set current-light nobody ;; just for now, since there are no lights yet
( j7 m" f: U* `* X3 D$ i( ^  set phase 0
8 z& y7 f: b# F% V* F  set num-cars-stopped 0
* V. r! X$ i/ Z1 C  set grid-x-inc world-width / grid-size-x
$ E7 [& C+ Z, F& Q6 {& }8 }# O  |  set grid-y-inc world-height / grid-size-y
0 v* G; C% t9 ~' ]4 w1 E! A- r3 f0 }8 V' j9 |' h6 @: {
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; r% K& D/ v8 N4 j% _% @% Y/ S
  set acceleration 0.099
- O- B8 U: R0 g/ M  Pend
& Y3 L0 ^. q7 C2 k# g, D1 j& `8 G+ w" q: v" b) U% U
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 G% _) d$ P' k# M6 l1 l
;; and initialize the traffic lights to one setting
, ]# W; ^; s+ Gto setup-patches
2 w2 J" d6 k+ g4 y  ;; initialize the patch-owned variables and color the patches to a base-color3 J. ^) u$ P, f
  ask patches
  n3 U2 u# |- ~0 L. `- e" I  [: |/ m- @# f( o( H7 Z+ w" {/ c
    set intersection? false/ }# X$ _3 E9 g- y/ p3 L
    set auto? false
% s* \  a- F6 g. S6 K    set green-light-up? true
- P5 A& e! \! `2 W' M3 N7 @# X* e    set my-row -19 F! L- Y& F+ i/ i( H2 s
    set my-column -1
5 Z3 {0 {2 P' U. V    set my-phase -1
4 {3 I) Y& i1 q# q- }    set pcolor brown + 3) C5 k3 h3 n, I# p" a
  ]
9 ]- F+ m# _2 X7 D; o: `! v6 G8 k" ~# i+ I
  ;; initialize the global variables that hold patch agentsets
8 C3 u4 _9 C9 t" g  set roads patches with
7 k  A5 T& V/ }9 \, c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ R& \& z5 }' \% o- [" {* S* |, z# c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 }) q: H$ q" u* n4 u, ?
  set intersections roads with% Y* |3 N4 E& s9 J
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: R$ \* I1 P0 {/ P9 H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 @4 s* g7 y9 m( D8 l6 n, ~- U, S2 c, e
  ask roads [ set pcolor white ]
7 N' [" w  s- d$ P0 g$ J    setup-intersections
4 R7 ?) h: q! u& M3 jend" v& c- F% d& K  b
其中定义道路的句子,如下所示,是什么意思啊?9 h( _) h6 F: M4 n) b% R
set roads patches with
- j- x+ l. M0 O; h) r$ }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& }$ H9 ]# j6 H/ F% y! D" B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], J) N9 b. F% p, T" j
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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