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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。$ O  h. H. Q2 x: i' w  e# L
netlogo自带的social science--traffic grid这一例子当中,1 P  w0 }) C! w) R0 U( L7 `
globals
% j/ I8 p7 P; [' Y( K[5 U4 p$ d0 {9 {
  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 }" S% s( q" Y" e1 R6 F
  grid-y-inc               ;; the amount of patches in between two roads in the y direction: {5 I5 e- D1 A9 E3 L* c9 p5 v
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 Q/ l& Y! y& d: K" `! o7 ~$ J" h
                           ;; it is to accelerate or decelerate
- P: t/ L6 S2 v* y0 ~  t  phase                    ;; keeps track of the phase
) Q* j8 |% Q2 R' J- j* c  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* h$ X( K7 L2 b8 K$ N! z  }4 T  current-light            ;; the currently selected light
  |! n8 T0 s; `# _4 O
9 |5 G  w: F" H3 A! {$ r  ;; patch agentsets7 f/ r8 f; |% f2 I
  intersections ;; agentset containing the patches that are intersections
+ i. c# S! [& a- v- \" v  roads         ;; agentset containing the patches that are roads& D  `; a" J7 y/ M
]0 K+ J' n% w- F
9 i0 h  n% j+ E/ V' J  L+ l% E
turtles-own
9 ?1 Y( J3 k& V* D5 d[/ D7 X# K4 V" h' c* u* m4 ]
  speed     ;; the speed of the turtle
3 R) E0 O7 x" Q5 O' G  up-car?   ;; true if the turtle moves downwards and false if it moves to the right% I; \! E; [+ M# T5 J& W5 k
  wait-time ;; the amount of time since the last time a turtle has moved
# U0 g( [7 r$ R( w& Y5 }3 p8 L]/ h/ G  Z) z' Q* ], K. r
: R' Y& t) K' L( c
patches-own
; Q/ E5 u# ]- c7 G[! s0 P7 l7 K- F' I* S( z7 U- |
  intersection?   ;; true if the patch is at the intersection of two roads' E. w) s& O. c+ I
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! C* T. M5 g; }3 N% S3 W                  ;; false for a non-intersection patches.: J2 j6 C, r. j& J$ B
  my-row          ;; the row of the intersection counting from the upper left corner of the# w* L! ^. h, ?8 x# u
                  ;; world.  -1 for non-intersection patches.
# R: j; n2 m$ F* D. E) m3 j5 s  my-column       ;; the column of the intersection counting from the upper left corner of the" O* J' w! u" g: @# m
                  ;; world.  -1 for non-intersection patches.
7 G  ?" l+ P2 ?$ n& I# r# n  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- O. x% X  g0 w" P3 J9 z+ l  auto?           ;; whether or not this intersection will switch automatically.  W5 z$ g1 L0 P' J
                  ;; false for non-intersection patches.6 _" x2 R6 Y' e  A& V
]0 B# y0 C9 q; f4 a7 {
" I8 j4 s5 B9 N, x8 H  @* F  `

) k; b/ y# P, F7 V3 q2 _;;;;;;;;;;;;;;;;;;;;;;: b; Z. J7 d- l5 A; T. M( |
;; Setup Procedures ;;- o+ i6 j8 y  g9 g- T1 C7 T
;;;;;;;;;;;;;;;;;;;;;;3 _' v1 D/ g$ ^6 b

$ s! Q/ J, y. N8 y+ j0 L' ~* I;; Initialize the display by giving the global and patch variables initial values.8 ]0 ]$ M& k: {- B; z: G4 @& w
;; Create num-cars of turtles if there are enough road patches for one turtle to
' t1 k4 S7 m+ g; E% a* H& W;; be created per road patch. Set up the plots.& Q# D( Y1 J( _0 ]1 {9 P/ I
to setup: n5 M- l. S2 \! i. G0 C! R
  ca7 R, s& D1 X" s8 b6 k
  setup-globals
! ?" n4 s: V% e# n, S1 E4 p1 Z8 X( {- n8 g; v4 _' G: s
  ;; First we ask the patches to draw themselves and set up a few variables
4 Y6 I% E2 J  |* a9 K" [  setup-patches0 F/ X0 ~0 y# A
  make-current one-of intersections
, K: k! `# q6 I: C! m  label-current
& ~- u6 V- |" ]+ p* c3 A
' G9 |% j$ ]4 S: C1 s. }  set-default-shape turtles "car"
# Z9 q0 J4 V9 x7 [
( c' q4 y7 h; L3 w# U9 e5 {  if (num-cars > count roads)
5 q1 j) V+ @7 R0 @# m4 b- a# Y  [
3 M, q, V) ]2 b; S( ~    user-message (word "There are too many cars for the amount of ": Y9 }/ R- W7 e3 W8 R
                       "road.  Either increase the amount of roads "
. W2 l2 a$ Y# _% P3 z. D% e                       "by increasing the GRID-SIZE-X or "
( c% v9 F* ]  Q) k: J                       "GRID-SIZE-Y sliders, or decrease the "
( W% q" C: A6 \2 F) f  R8 e) p                       "number of cars by lowering the NUMBER slider.\n"
9 n2 u" y/ e9 Q3 z. n' S                       "The setup has stopped.")
7 \6 L7 T/ K3 {    stop
5 ~9 e# c' r  I# ~  ]/ n, c9 j& x+ S9 a

3 ^0 Z4 x6 N/ e! u& p% D  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( }4 M+ T# \  n! I4 }
  crt num-cars
0 `# ]. ]" |/ R# s) I  [
7 K0 f- M0 n# O& p, s# h    setup-cars
4 B1 L$ L4 M4 G; v    set-car-color, j* A$ J, ~# l+ n" B' ~0 O0 L
    record-data
" l. ~+ v" o( W' z1 x  ]
# ^2 M9 E- S+ I" _3 u! W( g/ _" y( @( ]0 i
  ;; give the turtles an initial speed+ d$ J1 f" K. H9 g2 @% n
  ask turtles [ set-car-speed ]- O, b( U  ^+ q4 a' [1 s
9 e/ l) V1 C" ~' @$ d1 {8 e7 g, t
  reset-ticks: V( j. W# p* f2 M
end/ ~4 a. S) ~. ?+ i- o- ]
& a" W1 s6 x4 `* v  R/ a
;; Initialize the global variables to appropriate values" V; l, ^- j9 v5 C
to setup-globals
1 ^. x8 L- T* P+ [% D, H  set current-light nobody ;; just for now, since there are no lights yet2 s; K# [* u2 L% V$ v
  set phase 07 S- \7 J' H: g5 `: v; O: x4 X
  set num-cars-stopped 02 \3 }# [) r* }3 d) ^# d1 c
  set grid-x-inc world-width / grid-size-x; [! }. J1 I& K( I" g+ u
  set grid-y-inc world-height / grid-size-y$ P' M9 g+ u2 @, ~4 T3 s+ m
' Q9 v# f" }, }
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, Y. A: G. h( x1 y1 g
  set acceleration 0.099
; g0 r3 ]+ p2 I  B2 J( B. lend1 v1 [! K5 {& z% w

$ T& q. N+ i3 D7 _* t$ T8 u;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# I# |1 f/ q# k3 f$ L;; and initialize the traffic lights to one setting
# N9 y. ^+ W( o7 D* p% k2 Oto setup-patches8 o" [0 d* j! _
  ;; initialize the patch-owned variables and color the patches to a base-color
9 P3 m6 z+ N) r& B  ask patches
8 h8 b! `6 r9 L  [1 ^0 m, @) X6 w$ ?9 N. r3 S: J
    set intersection? false& H: T4 f4 R  d$ Z+ Z  V
    set auto? false) K- U& p/ g# R: O- Y! A
    set green-light-up? true
. d! ~2 h' _: T' y! U- D7 J7 t    set my-row -1, F* \- m$ k5 R  l9 u- z% a
    set my-column -1  h  g: r+ h! ]# a6 k" f6 S3 s9 `
    set my-phase -1
: F# N1 ~/ D* }' t4 }* N) E    set pcolor brown + 3
9 X( {( k2 O9 z+ w( o  ], T* m8 I' U# t2 t
1 ~, n0 b3 Q5 W, F
  ;; initialize the global variables that hold patch agentsets
8 Q8 R# t- g- I  set roads patches with
9 [9 E* O2 a1 n3 s% S+ E- W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  ^0 m3 M* l5 ?. i: u! u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; k0 A# X, A, X" @
  set intersections roads with8 [* z4 {9 v. B; C2 @6 s: e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, r3 J. ?# j1 g# J+ R4 i3 F; k3 _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, H, U9 ^. E& p8 N6 R4 T6 Y- F& u+ m& p* h/ r8 a) w0 i6 d% R
  ask roads [ set pcolor white ]
2 i0 Q. d+ |3 ]6 b2 a4 a    setup-intersections
6 c: E  W+ G7 V' s. G" E8 qend
5 F7 G  i0 j5 m+ I3 r8 E其中定义道路的句子,如下所示,是什么意思啊?& ?( @  w+ y( [
set roads patches with
: a5 ^+ {2 M& J: }: b6 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& H) v& I% g1 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) V  C0 r7 S* 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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