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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。
+ X9 X! d" a( f0 U0 nnetlogo自带的social science--traffic grid这一例子当中,
$ D! k6 M# K; D6 B  F4 h& zglobals8 {; l; T3 d& {* v, P
[# P8 F) E4 i9 G
  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 C, W7 p3 |$ u+ X+ a: Q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction( N5 Y0 X5 N+ z/ S! w
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 U  {. m. c7 f. y5 h  h                           ;; it is to accelerate or decelerate) G% X4 O- c8 P+ q
  phase                    ;; keeps track of the phase+ ?% Q7 ?! t8 N7 P
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 R/ S: {' p9 G$ R& P
  current-light            ;; the currently selected light- h$ c; k) S" T0 k+ \( F7 D

* \9 s% P6 g4 m$ W  ;; patch agentsets
; Y. Y+ j1 Q& R( ^) t: {5 R  intersections ;; agentset containing the patches that are intersections
- A0 p) d; S4 ~9 k3 y, L  roads         ;; agentset containing the patches that are roads
7 ~  C" `+ _  o  Q$ s' E9 i% K; k]
  }- k+ t. ^: `: v% @- f( B% B( ]- I1 s" S1 A* k$ F
turtles-own
( _" |$ Z" U1 z2 h9 m" r) U( m  z[. l, e+ |. p. s6 a( Z$ M/ F( w
  speed     ;; the speed of the turtle
; @2 t" ]1 U& [$ A+ b  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ \3 S% Y, k: u! L  \! w2 I2 O
  wait-time ;; the amount of time since the last time a turtle has moved
2 n; `  b) e" h6 _* j2 l& d8 P]
( n- M( R7 j8 D( i6 W
. N$ a4 [) C$ p5 a) j( Fpatches-own
  M% f8 X) z" S7 m6 ][4 K4 C& u3 _2 Z- z) l8 t! O
  intersection?   ;; true if the patch is at the intersection of two roads4 e( \( {; T7 |4 ~) }( p
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' ~) z% e, A$ \9 z( j                  ;; false for a non-intersection patches.
8 W. I5 ^( Z4 w8 e  my-row          ;; the row of the intersection counting from the upper left corner of the6 y3 Z3 s- P, i! @
                  ;; world.  -1 for non-intersection patches.* ]6 U* C- p3 N# x6 o& B4 w
  my-column       ;; the column of the intersection counting from the upper left corner of the) H4 `" J( E) F7 k/ A( B- O
                  ;; world.  -1 for non-intersection patches.
' d4 ~, v9 w9 b# ^. V3 C; M+ _0 @( x  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( T  F; D% t# V6 B, O  auto?           ;; whether or not this intersection will switch automatically.
& b" v7 p# `3 v                  ;; false for non-intersection patches.+ }% q2 r4 f2 O4 W' H5 I& i& w
]
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) s' r9 }+ `; h$ s5 |5 v& C# G5 g
;;;;;;;;;;;;;;;;;;;;;;$ c/ F7 c$ {( q5 h" C- i9 l/ \* D% v
;; Setup Procedures ;;" W7 k! l/ b! g! _* T9 W( G
;;;;;;;;;;;;;;;;;;;;;;) k( C8 {4 x" d% c. d
7 a/ [" M5 z& |0 J  `
;; Initialize the display by giving the global and patch variables initial values.
# e: K0 j- z4 n, N) A  _;; Create num-cars of turtles if there are enough road patches for one turtle to/ y# t! Z) b1 r; @. F8 `: w
;; be created per road patch. Set up the plots.
+ e- N: p: g/ q. o! H- R( i% gto setup; W7 H8 ]' F4 f$ _; i$ H/ u. U
  ca
  S3 c) K* L7 [$ \' e  setup-globals6 m* M$ F4 W9 G4 K8 \) {

9 k  J- y: J% Z0 w8 L  l, Y' I  K  ;; First we ask the patches to draw themselves and set up a few variables' n% v0 T0 c8 d1 y' ]- P
  setup-patches
4 [6 ^( \/ s% ^+ |) c+ A  make-current one-of intersections7 ]0 n' U+ W- v# H2 [+ t
  label-current8 {% s, d* C' J! T: Q

$ t& F, f7 }; E' _# t6 J  set-default-shape turtles "car"! m  D' j8 O* p' T/ p
' {! g; b9 ^' D) a: c. b& W3 i) p
  if (num-cars > count roads)
, t, @% X. ^. v) d4 j3 ]  [# y; o, _" U6 B: w! e
    user-message (word "There are too many cars for the amount of "
6 `( x* x9 j3 e6 U3 o9 g$ c                       "road.  Either increase the amount of roads "
! |& s1 V+ t# a3 ^! h                       "by increasing the GRID-SIZE-X or "
6 e4 A8 }$ u/ G                       "GRID-SIZE-Y sliders, or decrease the "
% w; M/ u3 x& L5 ~1 L                       "number of cars by lowering the NUMBER slider.\n"
# Z3 x3 p- R$ M4 q  k9 _4 C$ h5 d( b                       "The setup has stopped.")& |# @, H# [: s" j4 u% o
    stop
  o, T( [  T" `- H) P  ]
: R# M% t/ p8 D* H( P# A0 v4 D/ D& X4 Y/ i' h3 {
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 b& g5 A9 K, i1 w& [; q
  crt num-cars
0 v6 m% e% Y, U: ^1 K' A  [; {9 P. ~8 S2 _8 s* _
    setup-cars
8 V. |4 D8 s' ^    set-car-color8 P- `$ P/ o6 {% G* G
    record-data
; q$ W# F* b9 h  |6 S8 b  ]
2 {" m' U! v/ R: k4 h# i1 U4 J  K7 r1 j% I, V
  ;; give the turtles an initial speed
& \3 D' ]( X9 t, y/ [  `  r  ask turtles [ set-car-speed ]
6 S# [# O3 C1 _' l$ ^& W" e" z* h( a5 Y9 b- L
  reset-ticks
- y1 ]5 g6 N# Q* q# q# z( Jend
. v7 C5 `# ~, u, r- U1 u. G( ~* Q3 q/ M
;; Initialize the global variables to appropriate values
! b$ v- |! Z0 f4 H; e8 R% Qto setup-globals9 h, C: d/ I; _/ K/ h4 i$ l* X
  set current-light nobody ;; just for now, since there are no lights yet4 l3 G  Q$ I: M: |0 Q0 J9 H, ]0 q
  set phase 0, A( h* j/ s! u
  set num-cars-stopped 0
9 _% X5 F9 m5 {% L" X8 A  set grid-x-inc world-width / grid-size-x# _3 U9 i" e9 K/ N
  set grid-y-inc world-height / grid-size-y
( }0 Q2 E. [2 d; m  u0 Y  x8 ]5 i" d& t7 c& M; }
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary2 s0 W, v7 t. e" D2 W& L- b/ u# Y
  set acceleration 0.099
- }- r7 O5 d& `( _. rend$ i. ^  b7 B% |$ Y  Z; [

  D$ {4 e6 T# b) l0 y& g$ v4 ]3 I;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 l6 I6 j+ p$ Z7 n* T. f5 Q;; and initialize the traffic lights to one setting
  `( B0 I% t8 O: l9 T4 V8 E/ oto setup-patches" `0 h" m1 d9 v/ @: F' l3 M
  ;; initialize the patch-owned variables and color the patches to a base-color
: [( V9 _1 ^) d4 ^  ask patches$ i0 K% |( q5 U
  [# s% G+ v9 E+ Z4 m  _
    set intersection? false' \1 E  U! E% i3 @, |
    set auto? false
* l* h+ B; k! A    set green-light-up? true
3 I0 [) l& [% r8 F6 a9 r    set my-row -1, S/ o, r% R# S0 R; G3 ^
    set my-column -1+ D% _' {9 T4 f" o6 k" I8 d
    set my-phase -1
- q7 L7 Z( y( x    set pcolor brown + 3" p9 M- m) @3 p" N$ M
  ]$ F7 W$ f$ Q6 ]

( C/ D- [- X  J7 A( O$ y; I' z  ;; initialize the global variables that hold patch agentsets' r: a9 C) m8 S- q; d: I5 i. y" I
  set roads patches with
3 _1 i- m" L3 N! v' E# o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 @  B/ K" A% j! m' h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 ?. |- b- w$ ]0 {$ O8 M
  set intersections roads with9 Z/ |  C! q0 y2 ?" w3 f  A4 V" V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 ?) P: r4 V+ H# f, L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. c! A8 B  D2 O* u8 }2 F+ D! o' H4 L" _' R7 L2 Q
  ask roads [ set pcolor white ]; k; x: M8 A) H" ~
    setup-intersections
# ~2 b3 z* H' R( Y0 mend
7 |& @9 H; _+ p' I9 {0 a2 Q其中定义道路的句子,如下所示,是什么意思啊?2 S' r# b& F* C, v8 ]# F6 K
set roads patches with
9 h4 U4 s1 W: C4 m) r( P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 `2 J, Y4 Y2 K* m  d* y- G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 ]/ n" K$ L2 v" L! `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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