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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。( ~; c; J" i; T* }3 g7 L
netlogo自带的social science--traffic grid这一例子当中,
: Q5 C2 z: T; I1 aglobals/ b  e0 ?7 |  H7 m/ n9 y
[3 A' S, J( X* G& ]/ k5 H' m1 Y) D
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- J% L# _7 f" K  grid-y-inc               ;; the amount of patches in between two roads in the y direction( @* b0 y8 t. A; v9 w' }$ a, ^
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' j4 W8 m; T6 h, C& n4 Z1 S
                           ;; it is to accelerate or decelerate
0 |: j$ y6 P  A# [3 i  phase                    ;; keeps track of the phase
7 @4 f2 c) o& L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% ], J3 I9 Y4 R, k! Z
  current-light            ;; the currently selected light
$ ^& L: ~' v3 D$ l0 i+ J
, e$ i4 N. n5 r' r. ]  ;; patch agentsets
! X: S: ]( r0 n$ D( g  intersections ;; agentset containing the patches that are intersections
+ V" D1 H& ?, p; S# b8 j  roads         ;; agentset containing the patches that are roads5 B! g  F' |, v- p
]
7 e6 j, N2 q+ D2 Y
( b3 R' C6 y/ b5 R5 W: |& F# Wturtles-own& f2 y/ u8 c( P- r% Q/ D
[$ v: S# x4 R0 Z/ [8 ~% @
  speed     ;; the speed of the turtle
% W4 O, R2 N' f& k  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 n! {" I4 l/ H* t) Q( t% ]  wait-time ;; the amount of time since the last time a turtle has moved0 n! A: l1 s, \9 t6 F
]6 Z  X4 b, ~5 x' k) W3 d  M
9 f7 _; p2 i2 u0 _) |; z/ y% n: _
patches-own* b+ O  g& a4 M7 M( c
[
  N, x& m2 \2 C" L+ {  intersection?   ;; true if the patch is at the intersection of two roads: H7 Q8 z* n- \  z) @* ?5 E
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: U1 @9 D$ y& R  Z2 C( h; n
                  ;; false for a non-intersection patches.
) x2 q) p5 d' A2 a/ s5 f+ h  my-row          ;; the row of the intersection counting from the upper left corner of the
  x" e# X/ ~" F; y9 ?' W2 p                  ;; world.  -1 for non-intersection patches.
: w# n. L  g% V- \) Y  my-column       ;; the column of the intersection counting from the upper left corner of the
" Q, e- X& Q" [; L  e                  ;; world.  -1 for non-intersection patches.
" W3 x5 o3 {' _* ~/ M% a  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  m6 m8 ?7 |/ q( Y  auto?           ;; whether or not this intersection will switch automatically.( n: ~2 c$ P. ^- V
                  ;; false for non-intersection patches.
0 n. r; l& d: v6 ]/ O]
) q9 G# A! J1 ?1 H7 U8 E
0 S3 }6 x- L1 }
: t: g- l6 ]0 b/ E0 N;;;;;;;;;;;;;;;;;;;;;;
; ]% \/ \8 N4 F3 Y;; Setup Procedures ;;
/ `; X3 R8 F  ~;;;;;;;;;;;;;;;;;;;;;;
3 C" b# I& w* ~
! ^8 y4 d) V& `+ {, `4 t9 V1 x7 `;; Initialize the display by giving the global and patch variables initial values.4 c1 L; h$ m& O5 U6 _* k- F& {& W
;; Create num-cars of turtles if there are enough road patches for one turtle to; X, t1 [4 v* g7 K9 B( t9 G* A
;; be created per road patch. Set up the plots.
, v: K5 G3 f% U4 i% fto setup
& t! {% a- v/ A8 Y- z# t1 r! i  ca/ Q) y& s+ t- L3 K
  setup-globals" ?, d4 [0 R8 y& r! ^9 v

  i5 \, J2 m) L* V' `6 R2 L, n  ;; First we ask the patches to draw themselves and set up a few variables9 x; F- Y5 G3 r* s
  setup-patches( k3 ?7 o$ F8 O  r* }9 A1 ~
  make-current one-of intersections
; V% B+ S/ X- J4 c1 L6 j  label-current3 ~6 H* V8 P% ^
8 w  s; A" u" E( j6 X% W
  set-default-shape turtles "car"
+ H6 g1 r) b+ X; r$ d3 L8 u2 \" b- ?: G- l3 D. l5 f
  if (num-cars > count roads)5 t1 b! r- D& j* g
  [) C+ r+ k/ E* E: j( m" s
    user-message (word "There are too many cars for the amount of "- L9 x  J# W, e! L6 T  ?
                       "road.  Either increase the amount of roads ") k5 @# x0 I9 b7 w9 W
                       "by increasing the GRID-SIZE-X or "
3 i$ }# n3 z' o9 T( m" X                       "GRID-SIZE-Y sliders, or decrease the "
1 T( {$ Z0 Z* X7 i, F# q9 s                       "number of cars by lowering the NUMBER slider.\n": w( F1 ~1 q7 t
                       "The setup has stopped.")+ b! u) B$ [, h. p
    stop0 u8 n! A% p( H8 y7 H/ L. @+ s* B
  ]6 A: I; p; d' y: P8 L" D/ H% X

6 i( s6 ~" N- ?7 x  }  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 S, R$ u+ X' U: J) B) C
  crt num-cars
+ g; R8 p7 F* v0 [: I6 h  [8 V$ B% O9 Q& F
    setup-cars
$ M$ _. Q! ]- e( M    set-car-color
" d9 L3 F+ c" ]1 K( L    record-data
' x, j% g8 W) l  ]( I5 h% ^: ]5 ]2 j. L' W6 g- p
; Q; H6 {0 T" D6 G5 ?4 ]1 }
  ;; give the turtles an initial speed
. o. B0 R7 q0 }; o  ask turtles [ set-car-speed ]
8 s$ `4 l5 i) H- C: [2 C( J* s( [
/ N# J& e. A! @  m  reset-ticks
- \. M0 G7 A+ L# U: Q' `end3 e! s; s* Q& O, K# i3 `

- I. e! W# p& e$ E;; Initialize the global variables to appropriate values
$ Q6 D3 L* H  ?3 wto setup-globals( }8 h5 ?. w$ v8 ^$ @: }
  set current-light nobody ;; just for now, since there are no lights yet
' R8 o0 N6 _! c" K$ z0 ]8 J  set phase 0
- l5 |( {& d6 N  set num-cars-stopped 08 H1 E& p5 m8 [/ Q
  set grid-x-inc world-width / grid-size-x
4 Y! V. i8 W1 R  u6 F% w  set grid-y-inc world-height / grid-size-y
! q& Q! a4 o: [8 c: O3 F8 D% |: k- y$ D: A
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary" Y( D9 Z, C! Z  N) P  ~
  set acceleration 0.0996 p! z7 c4 i9 v. L- I8 |% C
end
6 u7 t0 p6 i% J3 t0 [) x. x* k" P6 h4 W
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# y+ p5 |% E; m+ W5 Q, C;; and initialize the traffic lights to one setting
) d2 Q' ~; s1 z5 U- w& @- a8 ^2 \# |  Ito setup-patches3 G% X" i+ G3 _2 j3 L0 a
  ;; initialize the patch-owned variables and color the patches to a base-color
/ p  @/ e: R& Z* k# Y  ask patches
5 G, S0 @2 f$ w9 P1 E. o  [
' a( y: ?' K0 i1 z% V" O' p0 B5 X    set intersection? false3 n  w6 ?0 }, {; G
    set auto? false
; b  p7 r0 M7 c9 {5 u8 K* J' A; A    set green-light-up? true7 Q7 v' d/ b) {' q+ a: U
    set my-row -19 {7 G" @" _) i8 U# c. s% U
    set my-column -1
* |8 F$ ]; ~1 s6 v    set my-phase -1$ I0 x' i9 {( P* P: O4 e
    set pcolor brown + 38 U8 j* s0 `6 u7 M3 r- N% ]
  ]( K8 I& q7 _: S) B1 j
. R* f5 L" m8 k1 k% D  l& H* q' c
  ;; initialize the global variables that hold patch agentsets
) Y! H& B' ~9 G8 p/ v  set roads patches with
7 F) D4 Q. a3 H  k' j! R$ q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( \8 @' e" p0 K9 ]5 I; O; l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ B3 D; Y" K* z  set intersections roads with
) L4 P5 v, a0 _1 r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' [2 L- {2 H$ J( P2 D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- s' b. `1 ?5 V% e" f! ^( \8 N3 B
) F1 z0 J6 S& h
  ask roads [ set pcolor white ]
) N4 J9 \3 [& y' ~' U    setup-intersections# ?2 `7 u3 k; K! P4 F' A1 h
end
( h, y: _+ |7 E其中定义道路的句子,如下所示,是什么意思啊?+ z. |: }9 |& E8 ?% l5 J8 [% g
set roads patches with1 Z9 [$ ]+ S& D8 }5 x9 M- n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 d& w  R  e1 ?$ b3 f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 p3 u3 M+ t5 }3 c( Y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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