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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。
. x+ `9 r/ n0 M4 a# Knetlogo自带的social science--traffic grid这一例子当中,: ?+ o$ H4 @+ U  [4 B& ]/ f
globals4 X2 ?" }4 V5 ~4 T+ D" H; g6 {& Q/ Q* _
[1 j2 Q1 `" ]% \
  grid-x-inc               ;; the amount of patches in between two roads in the x direction; r5 \  M7 Q1 g- {% V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 f3 G  \8 K8 R  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, h8 j' {8 D2 F! p& N# I+ T
                           ;; it is to accelerate or decelerate) t6 \) [8 R$ R' V' p+ _' g1 H& k
  phase                    ;; keeps track of the phase
& _7 z& @0 s/ O0 Y5 V: U) a0 V  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 R% d7 n8 E. {
  current-light            ;; the currently selected light
+ j/ }% t) e% o1 d$ a3 H; l. ~
% D, S4 O" C/ O+ ~" r% I" r. C* p  ;; patch agentsets
& s! o  z0 }# ^6 w$ m! ]7 Z' R  intersections ;; agentset containing the patches that are intersections4 |/ a4 Y* ~! m$ ?
  roads         ;; agentset containing the patches that are roads
0 M* s( ]4 ^" ]0 T: j. f  O% D]+ A4 p0 z' a# d1 f
! m6 V3 `) v. c0 I
turtles-own
4 O/ y+ x; @; ^0 q[: @0 T' B( L+ }8 S
  speed     ;; the speed of the turtle8 u: E- Y# L0 u! j6 P. v
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& S' T+ w: N5 p# z3 u) w9 g
  wait-time ;; the amount of time since the last time a turtle has moved3 n1 E. ?  ~! X* c$ c" D: b
]
0 b. J2 g8 }7 F
8 U& p* j% y+ p. u, ?$ k! M. Vpatches-own
$ b2 o( r1 v+ @[
! x3 |" u0 F' Y: a  intersection?   ;; true if the patch is at the intersection of two roads
4 p- c7 I2 t5 s( a2 h  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 v; L& u" F6 z, U4 ]9 G5 G
                  ;; false for a non-intersection patches.
" j* e4 h! ^& N* ^4 |! t7 o0 S  my-row          ;; the row of the intersection counting from the upper left corner of the6 g9 V( j) ^4 `
                  ;; world.  -1 for non-intersection patches.
2 v% B9 |( [) ~5 O  my-column       ;; the column of the intersection counting from the upper left corner of the. K/ \" Z4 X1 d: b
                  ;; world.  -1 for non-intersection patches.
* h4 X8 y# |+ W; A  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( o) w4 ^) o# Y7 z2 ^2 U. G! ^0 h3 e9 }- X
  auto?           ;; whether or not this intersection will switch automatically.
) I/ K4 Y+ G0 M  U9 A- ]& B                  ;; false for non-intersection patches.
2 b" b. X9 q8 @) M& {$ I, h0 Q]
- A9 @9 f- [0 o+ [) u& T" n+ \% {) W* r9 H

) h- Y" |$ b& j. W+ e;;;;;;;;;;;;;;;;;;;;;;5 l9 H1 b, A4 ^* I
;; Setup Procedures ;;
; n+ e4 F: d5 O& N: c0 L7 |;;;;;;;;;;;;;;;;;;;;;;9 {: ^* X; v3 D$ W  x

; F5 ~* A8 y8 J, m9 s;; Initialize the display by giving the global and patch variables initial values.
. x* I! C0 x) H/ ~$ W7 W7 j2 U;; Create num-cars of turtles if there are enough road patches for one turtle to) ?$ g) H; O: n9 h
;; be created per road patch. Set up the plots.& a) B& F" |! b% [& V
to setup
- b2 D8 C8 Z7 D# l2 Z& S! z1 f  ca) X' C- _7 I9 @
  setup-globals5 ^! J0 D( o/ g& x
1 @; g. D5 p. P* H5 Q  }0 E
  ;; First we ask the patches to draw themselves and set up a few variables
! P) F- S0 @; O5 \! T. p, {4 g# Z  setup-patches
* ?0 ^' j5 I1 [  make-current one-of intersections
  h0 ?, a6 A* r" q7 t  label-current
/ t+ ?+ n; }+ z0 ~% E2 X& S. h8 Q- P8 g2 m
  set-default-shape turtles "car"
: a5 i% z7 {$ Q2 k* |- H# |5 q& |
' c# Z9 L3 N$ n1 w' a9 n- c  if (num-cars > count roads)
9 a0 m- C- [  Y$ y& h  [
( F- v  o) [* T4 E5 D    user-message (word "There are too many cars for the amount of "0 c* V; @1 z' d: f
                       "road.  Either increase the amount of roads "
8 n; x8 U- `8 R" ^                       "by increasing the GRID-SIZE-X or "- m$ X7 d; o/ @# \/ C
                       "GRID-SIZE-Y sliders, or decrease the "
5 Z5 C( `+ P( Z6 J) g                       "number of cars by lowering the NUMBER slider.\n"6 \4 j; z" D( O/ Y  q, B
                       "The setup has stopped.")  U0 A2 }  u5 r% p9 s1 S
    stop- m/ r* O$ A! z" ]# O1 ^3 @; K
  ]. R# s5 W, b/ e, u3 G$ m

# a) |; Y9 W* ~' O& D$ V" t  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
; T. p: u$ X1 O  crt num-cars4 ?) s8 r+ U2 s$ P9 U( \8 m
  [
* E$ a# K/ W2 m! x& V    setup-cars% X8 a) @) e, p* H( N! ^2 ?2 @
    set-car-color
0 e$ m3 c) W( w, \. M    record-data
9 }+ n& {' j8 N$ _3 v  ]
/ c/ G$ `! s: h9 D/ b  F
+ [7 t3 l6 s, }$ v- s0 C& x% y1 S  ;; give the turtles an initial speed# z0 T* ~1 t. N# n, N
  ask turtles [ set-car-speed ]5 k; z, V# M4 Y4 S- w' `

9 F6 O% Y3 ?+ \  reset-ticks8 A4 k% A- K6 R, s! A: b. b$ a
end8 W& G4 M' u% Y7 h
" F# ^) F" F* v: W& F
;; Initialize the global variables to appropriate values8 g) y5 S( g. u4 B9 [
to setup-globals
' X6 N8 y- y  D  set current-light nobody ;; just for now, since there are no lights yet' y% |! Q: z" z7 ^
  set phase 0
& ]. N0 ~5 f: H" T3 j  set num-cars-stopped 0
7 p; Y: ~. I2 |5 z! H  set grid-x-inc world-width / grid-size-x# Z8 j" J2 T) E. o; s9 I  K0 O- s) j
  set grid-y-inc world-height / grid-size-y) M" c. f( P6 x/ N+ s! G

! E' p0 q2 y1 w  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! B: I8 a. j5 H0 v
  set acceleration 0.099
. l5 {( P% W& Oend
2 g( i. o/ L. |+ ]4 F/ M  z
, B; w  e( e0 s+ d# p$ a: y, w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 ]$ J6 k+ E, ?% G1 Y;; and initialize the traffic lights to one setting3 r- K9 C$ n6 O1 F) H! ~
to setup-patches3 s0 r4 Q2 a+ Z! [( _5 F( J8 I2 F$ I
  ;; initialize the patch-owned variables and color the patches to a base-color0 L6 W$ g2 n) [) r+ g, v
  ask patches3 x' L5 f3 W" V
  [
2 \( {5 T, l8 u9 l6 b    set intersection? false5 H% r6 V& j% x) A. K& i* o# R
    set auto? false
  j: b' ~6 ~; d  C* Q- A: w    set green-light-up? true0 @7 V; v# H- G* H% u% m7 T. P
    set my-row -1) N# B: l/ {+ ~1 I/ v
    set my-column -1
! f3 ^6 k/ S' I% e9 |7 O! f    set my-phase -17 d- Q# `! c* Y+ f- O
    set pcolor brown + 3
+ P" ]0 W* C7 G5 r+ l# c( J! |  ]. J" V& P' w8 g5 E$ f

8 n% r+ m. {6 L$ G' |2 D& H% e1 \5 y  ;; initialize the global variables that hold patch agentsets5 ]1 W; |% B. H, Q- ^7 J; C
  set roads patches with
1 f' m5 ~) u+ ]4 q% O" w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% a" B+ H# c, h; }' n* p, ?+ T# P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ a# p: ]6 D- d9 M2 ^/ ?" o  w
  set intersections roads with5 {' o; {- H- e( Q4 z3 {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) ]2 g. j' [) `8 _6 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 p" Z* H# h' v9 \- `9 b1 T& S

2 |# u* u1 o# z3 u  ask roads [ set pcolor white ]
0 D9 u7 N; ^! R1 M* Q    setup-intersections) K, L8 _" [* Z  ^) F" h1 q
end
4 j, S4 _6 t" a3 Y$ y7 M其中定义道路的句子,如下所示,是什么意思啊?
# v6 a# g- N0 L+ v+ o  }" O$ V set roads patches with" S+ V; ~$ D  }, k8 k2 S# X2 ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 f' o1 P2 y  Z( `4 V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 \9 M$ q( p+ L0 ^; m# D
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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