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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。& Q( g! c6 N! e$ z* k8 m& @1 g
netlogo自带的social science--traffic grid这一例子当中,& f8 l+ Q! v! t
globals
$ j$ x& n8 F* t* @  a9 ?" b[% R  @/ [# X$ j7 d7 V+ T
  grid-x-inc               ;; the amount of patches in between two roads in the x direction* g# b0 T3 {; B$ U; _
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 k- u! y3 i  i
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 H7 Y' N7 @0 i
                           ;; it is to accelerate or decelerate; F6 `' s  K7 y& m. C
  phase                    ;; keeps track of the phase6 j" q" T% l( W0 Y% G1 j
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) j8 H1 |9 D1 ^3 ~) Y* V; z. ]: }. U2 x
  current-light            ;; the currently selected light
$ Q0 c6 w& v, I# s( ?6 c* y4 x8 b" v0 i# B, l8 `
  ;; patch agentsets1 b  r/ K% ?7 p- S& j
  intersections ;; agentset containing the patches that are intersections
" t2 n4 N7 ?  k# L  roads         ;; agentset containing the patches that are roads
7 w4 t) p* r, E]9 U  m3 s* G8 v5 n6 |6 b; ~1 g

& Y9 s- P$ [* ^& r8 p! C- A# ]turtles-own
% z4 y0 A/ X3 @[
3 T0 y" B* ^3 z  ]- B% n3 p  speed     ;; the speed of the turtle% p. m( {& v- @5 H# H) D# ]
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ c: K7 ], n, f0 t) t% [
  wait-time ;; the amount of time since the last time a turtle has moved8 ^- a* Z. y: {% j+ V* [, Z+ M
]
, M+ p& e& q) }0 b% E
7 h* a% R  e0 k- F( R3 a1 j" G3 t# Ypatches-own4 p! q; o' [: d3 n
[1 @/ S  Z9 S6 v) B  l+ k; m  L
  intersection?   ;; true if the patch is at the intersection of two roads
8 \$ @2 g5 r& @6 t, r' Q  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 ]0 Y4 T" H' S- ]* o                  ;; false for a non-intersection patches.
' b3 E# A; w0 z% r) R  my-row          ;; the row of the intersection counting from the upper left corner of the* z/ B- x) r( ^. ^% m
                  ;; world.  -1 for non-intersection patches.
1 a$ ?, \1 V- d) w3 J  my-column       ;; the column of the intersection counting from the upper left corner of the
3 o/ D/ N; [" H) y( ?4 W5 r& _                  ;; world.  -1 for non-intersection patches.; |0 e. Q6 Z2 e# @9 ~8 }7 y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ o# |# L  F! S3 o  auto?           ;; whether or not this intersection will switch automatically.) {4 X, z: b$ T& f# m: T; N
                  ;; false for non-intersection patches.
$ c& N* Q2 o! V" \" M$ g# h- G]' J' X4 G1 P; S  Z, A# {

) Z0 |4 u* }1 y) x( ^7 r. q! m
2 O: _9 g, T. m' U- m;;;;;;;;;;;;;;;;;;;;;;
1 h5 `/ m2 Z0 v;; Setup Procedures ;;
' W! L/ \/ c( U4 [! J;;;;;;;;;;;;;;;;;;;;;;
! e  _+ q  j" _& H, G
1 v7 \' `3 e0 ]$ y; n. D;; Initialize the display by giving the global and patch variables initial values.  j6 U) l5 f) H0 G/ y( a
;; Create num-cars of turtles if there are enough road patches for one turtle to  q, P+ Q) D' ?4 G0 c' j
;; be created per road patch. Set up the plots., u" X  s) m2 V% t. D8 o- f8 ^
to setup2 _! }6 b! V- U/ T! r
  ca
& ^  g& ^2 Q$ g( O  setup-globals  I) ?- j. E3 h7 M" F

( ]* q7 r* B/ D0 y$ ^  ;; First we ask the patches to draw themselves and set up a few variables
: {2 X, F; X2 P! J+ w8 d9 C  setup-patches7 w! _' p/ V/ n6 i9 k, A( H! ^
  make-current one-of intersections; j" w5 l9 i) c. e- U3 _
  label-current
8 x) U. N, w0 [' f5 X+ ?/ Y2 o) O7 N
  set-default-shape turtles "car"
% D0 W( e& ^. h3 w! ~" D& C6 u9 D. a$ y; N" {9 T
  if (num-cars > count roads)
0 [5 d/ V  A1 r+ H, f1 E  [
+ g8 N/ `: _  q% q    user-message (word "There are too many cars for the amount of "
; ]5 m/ J3 R* Z# s: b% y# ]                       "road.  Either increase the amount of roads "! M( z$ Z; V" q; i+ }/ x& k4 ?3 Q
                       "by increasing the GRID-SIZE-X or "
/ g' j* ~/ N& |                       "GRID-SIZE-Y sliders, or decrease the "
" [6 i% Z# P( N% x" c, Q% F                       "number of cars by lowering the NUMBER slider.\n"# @# Z& [( \9 ~6 |; I/ x2 t$ Y4 B
                       "The setup has stopped.")7 T* a3 w: B7 \; {) d. w
    stop9 s, j* I& V  Q
  ]6 H8 i6 t1 \( D* T  e( ?

7 }: d2 y) D' ^' w- Q9 G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  v; c, }5 N7 O' D  crt num-cars# b9 N1 `' P6 c$ r* K- L1 q
  [$ t7 Y1 @/ R  t% S! ]
    setup-cars
8 ~2 c3 @+ p+ S" n    set-car-color
. N  c2 R) I: T( ~* B3 N    record-data( q2 p3 F, [  |4 J% R
  ]# j" w# R5 Z8 C; i4 h) Y& z6 q
" I2 f$ c: ~! p8 b( L, G
  ;; give the turtles an initial speed
0 W, j: }' M( A2 p0 [  ask turtles [ set-car-speed ]+ `% m; |6 w( n7 g  V

5 ^/ A) \8 u" q( L  reset-ticks" \% P$ Z) n' a) g9 ]& |9 @: |
end4 ^4 A  {$ o; {1 V( N( a/ n' h

% X' v2 A0 @! m$ ?5 E5 j;; Initialize the global variables to appropriate values
: E7 [0 E3 O8 {8 Eto setup-globals
8 @/ k' V$ t4 `7 Y  set current-light nobody ;; just for now, since there are no lights yet
4 d: A% U- _7 ~  y4 u  set phase 0
8 j0 k( g8 K# t) i; I  k  set num-cars-stopped 0: l1 {% l0 z) X  n& H1 g
  set grid-x-inc world-width / grid-size-x
" x! E. D: d* P' M4 F$ ]' s* ^; M  set grid-y-inc world-height / grid-size-y7 x8 P+ \% l/ L8 B0 l% u
" s! D7 g+ L5 q5 S- S. L7 N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
. h1 i* I0 o( F% T" P% v4 [4 C  set acceleration 0.099
% @; E3 p9 F* Qend' q! Y; G' @: Q! b/ J9 H
& a6 _0 `. x/ \0 D
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 y; U9 y( ^% {) K
;; and initialize the traffic lights to one setting# O! O) i  q) X) K" K
to setup-patches: L6 L" X: M2 k; u
  ;; initialize the patch-owned variables and color the patches to a base-color+ `) H4 M% E% f7 R% r6 L5 l5 }8 c2 b
  ask patches
+ W: b' o$ W# W; I  [
$ ]; f2 x1 y* w  L    set intersection? false
' s" N( P: B1 B; A1 ]# x4 u3 W    set auto? false# M3 K- J) M7 k% K
    set green-light-up? true
& A( v, f  ]4 ?7 f; {' f    set my-row -1
/ y' u/ J- |/ k; ?& x! q( g    set my-column -1# f" l" S2 f/ o& u
    set my-phase -1
& B+ L# K" Y6 x5 f  L/ P    set pcolor brown + 3
* x" k8 X2 A4 b7 W% B5 H! s3 z1 d  ]
( H) E' k+ O$ N% `% D; @% j1 R$ B
  ;; initialize the global variables that hold patch agentsets0 I% `' q; R8 ~6 e) ]0 T6 }
  set roads patches with& L) [# F, P& a( c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! K: v# e* s- ?% Z/ o/ [2 l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 j0 D% U1 y5 O; k: g5 V
  set intersections roads with! F* a. y# {% h/ P/ A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 O( [) Y, D8 H1 B6 L5 p7 Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 S! \/ r8 s3 j; d- B* r* H
  m& z/ m& \2 U. o% B  ask roads [ set pcolor white ]
! x0 \5 e6 w5 o    setup-intersections
+ Z4 k6 ?4 n1 K1 \6 U6 B2 mend
# z' `: f, i$ q; D" h其中定义道路的句子,如下所示,是什么意思啊?% Q) O8 r( d- u+ f& V# m7 x
set roads patches with
) ]) M( ?" I* u) R% ?6 `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* w  X+ G: i1 `- m$ h  D4 y0 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' {1 O% W6 ^$ K$ @; n* W1 _# G
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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