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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。9 I2 H8 n5 m$ j4 \, t) L$ ]
netlogo自带的social science--traffic grid这一例子当中,
/ R7 Y  v* n  [7 O0 R& r) X6 Tglobals
: ~; {- ?8 E# a5 K+ s1 W' M& b[
+ I6 |1 |4 e! o: \/ E& _9 d  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ n( x" F; M9 I6 q( [) m5 x3 s  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 y1 ?" l' ?. k' f
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  t0 n- A$ o& R
                           ;; it is to accelerate or decelerate
6 j+ b' ]/ e+ O5 U& q( y  phase                    ;; keeps track of the phase7 d* X' }4 K2 F1 C  Z8 b% r2 `) R
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 Y7 M) l) F, m9 Y  current-light            ;; the currently selected light
- J- a2 t, b2 p4 f* F
) r& y4 O! Z4 l# Z7 y  ;; patch agentsets
! S" r' D" \& T3 C  {  intersections ;; agentset containing the patches that are intersections
: F; C- X& _$ a. a  B  roads         ;; agentset containing the patches that are roads- E% `' v! d2 P! R/ K1 U# T
]
3 T( Y% [3 v) M0 m: Q8 W! j) e( i$ h' J* c5 m5 [/ y( P
turtles-own
6 l. N) X  i0 }# c* s: f6 X; \2 q. @[4 v* A& c7 e" E9 E2 A# ^6 E
  speed     ;; the speed of the turtle
3 t3 T7 G) h* F5 [3 \  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 G& _% a. S: \. L0 k
  wait-time ;; the amount of time since the last time a turtle has moved
& x% I4 _3 B% O1 T  p]
- \9 w; _! ]. V2 V2 D* G
, V5 X: ^$ j( jpatches-own8 S2 F9 N( _1 B3 C. N
[
. b. }) T  K' f* T  intersection?   ;; true if the patch is at the intersection of two roads
( D1 E6 P$ K( G3 G4 i  y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# u0 x4 m  P. v7 Z$ k; J
                  ;; false for a non-intersection patches.3 O3 q/ {4 L) X; n# H( W! }
  my-row          ;; the row of the intersection counting from the upper left corner of the
" J' @# h1 [2 E; B& h  h                  ;; world.  -1 for non-intersection patches.# f( s. u) l! f) y0 l6 S& Z# b
  my-column       ;; the column of the intersection counting from the upper left corner of the" l) M/ t! N$ J$ J4 H
                  ;; world.  -1 for non-intersection patches.$ ~. b; n) x. K
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! ^. d" f& v' y; Q
  auto?           ;; whether or not this intersection will switch automatically.  `0 T% j, U3 y( L( N4 n! c
                  ;; false for non-intersection patches.
& g! w  ?( x9 N6 U0 I( v0 P]
5 m! j* R! D  j: K# c, |/ Z" }1 ^6 D

- s; b1 c) w6 ]) b;;;;;;;;;;;;;;;;;;;;;;
+ d0 U' |+ E. |% @9 Y  z;; Setup Procedures ;;
+ ]& B+ [: Z( R( h* Z, w* c;;;;;;;;;;;;;;;;;;;;;;
' y6 g4 k2 F6 v' J
# F% x) g3 f- F6 h. p( Y# d) f;; Initialize the display by giving the global and patch variables initial values.: N5 M4 s; c0 Z2 @1 R  {
;; Create num-cars of turtles if there are enough road patches for one turtle to
( E% p, x: F+ U7 F;; be created per road patch. Set up the plots." E8 L4 p: K4 \& L9 p( [% T
to setup! S, k2 W6 v- F4 S4 w
  ca
" Z& ~5 p- Q) `/ g' I) ?7 g  setup-globals
( K% g+ M, R: I8 h7 h: @3 r1 t) R: a+ D# N$ W- N
  ;; First we ask the patches to draw themselves and set up a few variables
. b: b) d( b  ~) h7 r+ I  setup-patches& j5 T( N/ h& x
  make-current one-of intersections1 n: @9 n: C" y. }% @$ e  _$ C" l
  label-current
$ N* j4 [/ J' O, C8 m; s# O. Y/ ^4 W$ F
  set-default-shape turtles "car"6 G  W1 l1 N9 C' {
2 p3 |8 Y0 M, Y
  if (num-cars > count roads)$ s0 b& Z$ v' C% e
  [- U1 s, e' U/ f0 r2 }3 v
    user-message (word "There are too many cars for the amount of "' i% M. o- \# _4 e
                       "road.  Either increase the amount of roads "9 e8 V& D  W6 q; R6 Z! K
                       "by increasing the GRID-SIZE-X or "
$ @* h) |0 }4 p5 P4 R: L  W- h                       "GRID-SIZE-Y sliders, or decrease the "
% a0 c/ X3 K- F" j% b* X/ o                       "number of cars by lowering the NUMBER slider.\n"3 B8 a) _( @" [+ }0 S8 ?
                       "The setup has stopped.")& g* u  k% s. U* R* Z7 }
    stop
8 ^- Y: B! h& e  N7 f  ]  O7 D' w# P' }/ U" ]

5 J$ j- f( E+ {" R# @  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 ^4 e  M. C( ~* |- G: |' O  crt num-cars
4 y+ I( O" s  g. }4 K; s3 w; e- S  [
/ u+ {0 T; l& E' p8 o    setup-cars
" z$ o1 T+ _/ `    set-car-color* u$ r0 D) j0 C7 q, H
    record-data& [, _- k. ^0 ~& \( G! d1 O* T9 r3 h
  ]
& ?9 V1 L3 y9 b8 k
9 s: L# f+ h3 r' {  ;; give the turtles an initial speed# B! @2 S( d7 o6 k5 ~* B
  ask turtles [ set-car-speed ]
  v+ w& _# u  C! G/ o3 L1 K6 ~& D5 y/ a. i$ J* Q5 _
  reset-ticks
2 y  Z5 w; A5 B# Tend
2 r4 Y6 V0 b5 u( k1 Q# N" {# B0 m% J" p1 c- t* g- l
;; Initialize the global variables to appropriate values! j+ H" ?. I8 n1 T
to setup-globals
- s2 u  X( e( \! j% {  set current-light nobody ;; just for now, since there are no lights yet; C/ m7 w8 m3 Y( Z9 V. v" k
  set phase 0/ e+ D1 T* Z2 t& i' {; S7 C
  set num-cars-stopped 0, p2 ]# i1 x: i2 L( }# @
  set grid-x-inc world-width / grid-size-x
: P; O. @: `6 Q2 J/ _  set grid-y-inc world-height / grid-size-y. P/ n6 [2 S0 A! F4 y: @# Q! B* `

& L! ~: u8 _! ]4 _0 y$ k% ^9 G6 q! f  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; }/ {. D0 q" r, J7 u$ F- z  set acceleration 0.099
6 P2 \! I) k  }end
( E- d; }; u4 U# w9 G; B8 v8 _8 P( ^0 m
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: H5 k/ z. P9 V6 c3 A+ _. E8 s7 c
;; and initialize the traffic lights to one setting
/ D4 _3 ^4 m; l7 h# Q4 f# yto setup-patches; @% V% P& N8 A- _9 S
  ;; initialize the patch-owned variables and color the patches to a base-color
0 a. n) ]0 m  ~2 z$ W  ask patches" f! j: y) G/ i5 y' N, i
  [
* w. R% X# ]9 C- K0 m    set intersection? false
6 D9 [$ [2 [) N% v    set auto? false
# V* s9 S; l$ s    set green-light-up? true  J* g" C; c: z1 K( C0 f
    set my-row -1
2 _1 ^0 x2 f# P$ Z( L5 F( D1 k    set my-column -15 v+ g' `. q- m; D* Y( ]) v+ _# N1 @4 q' z
    set my-phase -1
) j4 S, D0 h4 d/ y' T    set pcolor brown + 3
* y3 L- `0 w/ v6 s) Y  ]  Q1 M. ?0 g! }( f$ s
9 S' {5 _6 G* G: N5 `7 J
  ;; initialize the global variables that hold patch agentsets
) v( t5 r, V6 K1 D  set roads patches with; b& \4 O0 x" k( T% U9 ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# G2 D  z3 F& q/ k$ H" q9 Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 g+ R9 \* g7 j3 l- j! R
  set intersections roads with
+ [6 l. W: R; t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 b; p2 G* v+ q6 Q3 O/ g% k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 N& A1 U" m0 \- o. s* w; _) Z# x* N0 A3 f! c9 g$ d% p3 T, {8 L
  ask roads [ set pcolor white ], @: c! H4 ^' v6 ^9 H( D
    setup-intersections
: j( n# R$ R9 m4 K$ n! vend" N6 [5 J7 h+ ~; H
其中定义道路的句子,如下所示,是什么意思啊?
& y) l, ]) J7 K+ z3 k: x set roads patches with5 f; b& l. d+ ?, {6 |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; Y: Y8 l9 i6 B: Q' F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" ~) g% P9 _1 C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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