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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。3 Q  M8 N+ v) i# g  h1 P
netlogo自带的social science--traffic grid这一例子当中,
9 ~/ E$ [- L1 e% rglobals6 [6 L. x/ }% n$ `! G6 S
[' u9 e  M* |, R; D
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  a) T9 i5 V' L/ s4 f+ a  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. K; ?' G: P* n. g* C0 Q; H  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 k! S" n+ I# b% ?# r2 b/ |% ^2 }8 r
                           ;; it is to accelerate or decelerate- R  G# D8 s4 w$ N/ W* g% y8 y3 o/ z6 b
  phase                    ;; keeps track of the phase
+ H7 e; ]; _6 ?. ~7 z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, }* r5 P- r- f6 \0 H
  current-light            ;; the currently selected light3 v! ]3 N  z/ W/ I  d- x# V
+ ]+ w* }* e* H; u. |
  ;; patch agentsets+ O6 L& K) {/ r* ?, D4 Y
  intersections ;; agentset containing the patches that are intersections  Z3 ?9 O6 M8 I# p
  roads         ;; agentset containing the patches that are roads
" _8 O  {- l# }) L. s/ w! z]
; V/ }0 d. {% P& O7 \/ z
9 X  p/ G) r. `3 r0 nturtles-own
+ D! Y& I+ H6 g- Q  A  u3 I! }[
1 k( p2 s  T( _  speed     ;; the speed of the turtle
: M  C7 @$ t& D  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( @2 @" |3 t$ x0 }! d; ~
  wait-time ;; the amount of time since the last time a turtle has moved) Y( r5 H5 Q3 K8 u/ R1 O
]
7 `- |3 K  p) N+ h$ m
3 R) ~  @( V* u, ?) g! y. `patches-own& o  S  M4 \/ t; o
[
5 o& [9 t2 q2 {  intersection?   ;; true if the patch is at the intersection of two roads4 \! L- |/ P2 h
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: ~$ c) U9 G& J; U; J* }  a                  ;; false for a non-intersection patches.% T2 @( ]( L! T1 Y9 T: c) Z% u
  my-row          ;; the row of the intersection counting from the upper left corner of the- g. r( @5 Z' u" I6 ^+ Q
                  ;; world.  -1 for non-intersection patches.- _$ r, u8 Z8 @- ]' y1 w
  my-column       ;; the column of the intersection counting from the upper left corner of the! _, S' e4 T9 F' V
                  ;; world.  -1 for non-intersection patches.5 t  o! ~0 l9 L; [# t3 d' F
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 z! I, i) b" ^' B7 Y# `  auto?           ;; whether or not this intersection will switch automatically.
& W' s3 }$ }3 k" J6 i# G9 l                  ;; false for non-intersection patches.
$ n% w# c6 f* u, h) }4 O+ _]0 F5 P& M# M( }2 {3 v8 W
  J( t. H2 |1 y8 U# p; b. G. s
% k  y  M4 ^9 E8 ^% W) y
;;;;;;;;;;;;;;;;;;;;;;
7 Z8 ?, I2 T7 s* L) \# e) }+ y% a! `;; Setup Procedures ;;5 e* T7 U; ?4 C( W7 L7 E- S$ Q
;;;;;;;;;;;;;;;;;;;;;;; z' q) D" x8 S  M# C  U/ W4 n

1 S  a" t  F3 @! o) |;; Initialize the display by giving the global and patch variables initial values./ U! s7 f  H- b2 H  d% D. S6 c
;; Create num-cars of turtles if there are enough road patches for one turtle to9 N5 d# o( X+ R& W7 \
;; be created per road patch. Set up the plots.
3 _/ F- `# u6 D/ \0 Kto setup3 {$ }# J& _& f8 C% W
  ca5 S9 T0 v7 F* V; _- k6 O% ]
  setup-globals( B' D4 A+ a( j

2 Q- [% T  }" p3 @  ;; First we ask the patches to draw themselves and set up a few variables& |  G' Z/ f% ?6 A8 b3 e4 k, n+ X
  setup-patches. h4 R* F% _% V& u! Q( ]
  make-current one-of intersections
0 C" E& e. g8 i+ n, N+ \9 W  label-current
  E3 L+ p. }0 h! D. k8 v: v; t* s+ e+ s# u, Z2 U9 i$ j2 I1 H
  set-default-shape turtles "car"+ R% |8 @' k3 D  [! z
7 o: G% h; Y' [5 q
  if (num-cars > count roads)8 y; k) i" C/ {
  [
7 }" k8 Z, [" @  R/ r, t+ A    user-message (word "There are too many cars for the amount of "
8 Q4 T* E9 b6 a6 ]4 p                       "road.  Either increase the amount of roads "2 }# ^0 q1 ]. o! M% L
                       "by increasing the GRID-SIZE-X or "
! C9 {+ G- R" B1 r! h4 {+ U% o6 r                       "GRID-SIZE-Y sliders, or decrease the "
. A& g% a8 m, Y' d/ r! G8 l                       "number of cars by lowering the NUMBER slider.\n"
$ ~5 I4 u% w2 w  H  B                       "The setup has stopped.")
' V- p/ J6 d0 n: s6 {2 j    stop& g7 z% Z8 j: w& w
  ]
5 Q( t) t3 k. \2 q8 k
8 Y: s3 O% O$ q5 f  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 _/ {0 n9 ^- z+ Y# |7 ]
  crt num-cars
7 P( n4 I7 @/ L7 |! q8 X- f  [5 f$ `3 G# D2 o7 y" P& m
    setup-cars' |) O, N4 l* r& X5 g, Y" V
    set-car-color
- z  @8 x+ J# y' J* D    record-data
" n- O6 G4 S5 t' ]: L% l* o. `  ]
1 j3 {3 `; q. j
$ T! c: A) ~' c$ h  ;; give the turtles an initial speed8 q' G+ @* T% g. i" F% ?5 j7 |
  ask turtles [ set-car-speed ]
( a% Q! c* x! ^6 o/ m" E) u9 n8 i
, [: A  f, }5 w# J) L! G, K  reset-ticks/ o% F; N+ J; y" G* r# e
end; F, `1 M" l. C9 w3 I
$ ]; ]9 z+ f1 `, h% }7 Z5 R. z' z
;; Initialize the global variables to appropriate values! }2 P& o4 @! Q4 Z* f) w1 M7 F
to setup-globals4 E9 u1 k8 I! B' [% D
  set current-light nobody ;; just for now, since there are no lights yet
: I+ {, s# N$ D2 }- T/ E. `: A: y* s  set phase 0
  U) s9 e  ?6 u9 q. e  set num-cars-stopped 0' r4 b  F, a( {! @5 Q$ |$ j/ V
  set grid-x-inc world-width / grid-size-x
* x0 G) A, P5 S# A8 q  set grid-y-inc world-height / grid-size-y' ]2 N& I- v, @+ U

* ^  i( f) n  s: O; h* O9 d$ @  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( r& ?; B' K# \2 v  set acceleration 0.099' j, b  P) e* ^3 |1 G7 a* @9 x9 ^
end4 O" N5 U* G6 `
2 b% O* A) U% @$ i
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& `" u, V+ L  s6 U! J) ]
;; and initialize the traffic lights to one setting4 ]; b' e0 `4 I/ |
to setup-patches0 J/ h& i0 |0 g$ _- I
  ;; initialize the patch-owned variables and color the patches to a base-color
& K7 X% d& }% ^5 |/ V0 J1 q  ask patches
! [/ G+ \: K1 c6 Z' _  [9 I6 m- p1 @" Y8 B: {  r1 Y
    set intersection? false
) Z5 R% S; U0 w- @0 J3 c    set auto? false: w. C2 m" F2 r8 e: `+ Y& u
    set green-light-up? true' }) l$ y! `3 h8 K
    set my-row -1
+ j6 Z! J* O/ t) k8 B& W9 A    set my-column -1
$ W# g, {0 S' T0 `' j/ x/ y! u    set my-phase -1" A0 ~3 @" R% b/ Q  W2 p2 ]1 f0 G
    set pcolor brown + 3% r; H" O3 O; l# E$ ]( u: ~
  ]( ~5 q. f" [$ F; X

% b, u, d$ `; D( ]; J, @  e; D  ;; initialize the global variables that hold patch agentsets2 V) Z! |; W* _& O* @9 O( D
  set roads patches with7 F: p; {$ j" p& G' d( k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% D" G8 @" {- _0 I8 f; W4 ?" h8 m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 N/ q6 ^( R0 r, w/ r6 H
  set intersections roads with' V" ^, i& [7 R6 Z  _7 e( u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 x' c" h' ?. j0 _! @7 W7 p3 \- B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! G5 \0 A! |( ]- a

& W0 J: [6 V& H2 U. p  ask roads [ set pcolor white ]
  C/ o6 `; w5 q    setup-intersections. k/ C) T, i8 y% K, I& K
end7 s  Y/ ^% |* u* ^- o: D: N
其中定义道路的句子,如下所示,是什么意思啊?
5 e" U1 \3 N+ a5 F" ` set roads patches with
* t7 h+ P& Z+ S8 J% }4 ~! P8 L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ ~+ U0 g" j+ W) L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ G! V6 M) }. z1 I0 r
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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