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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。
- Y- }8 F, L$ u- ]netlogo自带的social science--traffic grid这一例子当中,
' v, ]+ f/ b3 a$ _1 J4 L1 w; Jglobals$ E( H1 g. b. _$ E7 v6 I
[" F) O. A( ]4 Y& f9 D' M
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 t8 _3 E, O& z7 V8 ~6 I  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 a" S3 r& N9 }  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 ]7 r; W7 W& N8 V# D9 R- l                           ;; it is to accelerate or decelerate" M/ S; J! [5 `3 d/ x( V
  phase                    ;; keeps track of the phase
  s( S+ X( C: _" X/ Z- |  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- ^3 ^! l8 h# m
  current-light            ;; the currently selected light, L: f6 ^) d8 ~3 z* R) j0 b
6 F, M: H9 }/ D6 b1 G& S, c
  ;; patch agentsets1 L& H# Y" z! p7 L" h$ p$ |
  intersections ;; agentset containing the patches that are intersections
" N6 I+ O( e# U  roads         ;; agentset containing the patches that are roads
  l3 L# r9 S/ K]7 B8 P! i2 N9 P! J

( T0 k$ I! `# M8 k; {turtles-own6 X+ D& H& p# z3 Y2 u
[3 {) v9 C7 _; x
  speed     ;; the speed of the turtle
. _- j+ @+ J* X3 }, t* y( y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- l, G0 n* m/ |) ~7 R
  wait-time ;; the amount of time since the last time a turtle has moved
9 o1 e" t$ W" X- F# V* ]* N], e2 f! Q8 P! j0 F. l+ g2 j
& X7 r+ ]' r, b* [5 i0 w
patches-own5 o5 j- \8 f; f. m" E
[
! ^1 |" ?) D' E4 g4 D; Y  intersection?   ;; true if the patch is at the intersection of two roads+ p  C2 T' e9 q
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) n' H: I4 \+ {  c" Y                  ;; false for a non-intersection patches." r3 @, U$ P: O
  my-row          ;; the row of the intersection counting from the upper left corner of the/ C) n9 F( y, A+ J: x+ ^
                  ;; world.  -1 for non-intersection patches.
5 K- ^* x5 ~: K+ u3 ^4 d4 m7 ]  my-column       ;; the column of the intersection counting from the upper left corner of the
; F( ^& U1 e) Q4 x( I                  ;; world.  -1 for non-intersection patches.
& b" y+ Q/ G& T" ?  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: B7 s/ g8 q3 L8 [  auto?           ;; whether or not this intersection will switch automatically.  z" a/ c2 i* z4 V$ E
                  ;; false for non-intersection patches.
+ C; p# Z, i( A1 B]
/ t8 Y" K/ v: \# F* G; F9 ^
# k5 m. s+ b% [) Y+ H9 s' x! Y0 {6 j( m
' k+ @1 x4 W; D2 u' X5 W" A;;;;;;;;;;;;;;;;;;;;;;
( q9 l2 m" }" m/ Z;; Setup Procedures ;;: C  K7 Y5 Y/ v* j
;;;;;;;;;;;;;;;;;;;;;;3 D  I8 B( {2 b6 [9 y* Z
( b: I( A9 D% R' A4 @) a" Z3 U2 f+ a
;; Initialize the display by giving the global and patch variables initial values.3 M( s( A9 ~1 }  V
;; Create num-cars of turtles if there are enough road patches for one turtle to
1 k& ?6 ^! h1 \% w& E# j) d;; be created per road patch. Set up the plots.8 B7 ?( i+ J, u7 L4 B
to setup
1 n- O1 @) W: v, b7 S  ca4 i2 @8 Y2 _) h# v# W5 |
  setup-globals5 |3 f% U! H- v9 Y/ B3 a( o
- {7 a+ d2 v$ Z& z1 H/ O1 X3 P" r
  ;; First we ask the patches to draw themselves and set up a few variables9 l' n" ^& L- C9 E3 ~, X. N
  setup-patches
' G8 ]; s, a) }! _3 u' w  make-current one-of intersections
. }; ?' V. b# Y( @1 C7 T( Y6 N, y# p  label-current
% l" U, a( F  X# |& J; _8 T$ p. U) f$ h
  set-default-shape turtles "car"
& l  c5 H# d8 O& s5 `' z* F/ v- l( m, ~5 q
  if (num-cars > count roads)" e9 F1 x# Z* E
  [
$ C( u- i, ?, s' W& H- F    user-message (word "There are too many cars for the amount of "
' L# v$ ^8 h( K/ j8 q7 I' J6 @# p                       "road.  Either increase the amount of roads "# B& T& Q7 o: p/ n
                       "by increasing the GRID-SIZE-X or "
' Y% }' s6 t) a8 m                       "GRID-SIZE-Y sliders, or decrease the "# [# Y$ k$ z. F' k3 t  |0 k1 l
                       "number of cars by lowering the NUMBER slider.\n"0 c1 N8 Y3 a) P* _9 l
                       "The setup has stopped.")) u* T# S$ |  w! A( b  e/ g  i4 ^
    stop
9 C3 u3 E( T1 O$ t* V  ]
! u- ]3 ]; _. c, `9 b' c- t" P+ ^& K, o1 v* w9 X
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 F/ d% M# q8 }9 s/ Y  crt num-cars3 J) Y9 M( ~" X1 ]( A
  [
) A  r! A6 k) G" m: ]# R0 b& J    setup-cars, h1 C( o: w- p, O
    set-car-color
/ J2 M1 u6 O9 {6 a: Z( X1 Q    record-data0 V* Z( |8 s4 W* k: H, b5 ]
  ]
( A6 ]- [; V5 n( Z4 C0 N
( F) }( T% H) r* n! k8 t+ F1 k  y  ;; give the turtles an initial speed
& c3 n5 f# r* {# z9 \, I  ask turtles [ set-car-speed ]
3 T1 ^2 b4 f1 y' A" ^" J  Y3 T6 V+ R. M
  reset-ticks  p4 g% N/ g6 E' Y: z) D
end, C  d3 Z; [  C2 b% X, C( ~2 _/ g
1 l; {8 _8 E/ e, I+ @
;; Initialize the global variables to appropriate values$ H% H; N% q" P/ {3 h  q
to setup-globals7 x* P* v3 P6 g7 S- K
  set current-light nobody ;; just for now, since there are no lights yet" Y& Y/ p& A5 j$ T1 g
  set phase 0- ]* z1 z; n$ `
  set num-cars-stopped 0' E! `1 Z4 |( ?' A7 h, B
  set grid-x-inc world-width / grid-size-x' g8 d3 F; t5 x7 f, U, Q3 T* o
  set grid-y-inc world-height / grid-size-y; x1 ]8 T: Z% U4 K9 i( s$ [
! t' p- a# @* m$ u9 E
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 V. s* O$ _' m$ s% {5 T  set acceleration 0.099
- D+ `6 c& U" H/ ^9 D9 C# qend7 K: S( ^4 Z) H6 u# f2 R3 K) T* ^

. Q7 {( U9 y3 d( w. C  C0 j;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 c5 W) Z6 z8 V6 W;; and initialize the traffic lights to one setting* \) P1 z/ P6 x8 f+ v! d
to setup-patches+ H# Z; h6 x# k' R
  ;; initialize the patch-owned variables and color the patches to a base-color
* d' V5 T% l- z- f  ask patches
8 m: B! ]! H2 K9 u7 r" R/ v4 ?  [
9 H6 n" {; X$ ~  b2 T    set intersection? false  p# y2 D! v3 `; h9 c( g
    set auto? false- d5 \4 l$ v1 q4 u& E. _( p4 R/ e
    set green-light-up? true# L$ j! }) |& n6 L
    set my-row -1* Y4 i2 m! E0 u  q& ^2 C
    set my-column -1, s) y; l5 X8 [
    set my-phase -14 c/ d* Z6 |9 A4 ]0 V6 T( x
    set pcolor brown + 3& r& _$ G) [- ?" Q4 T( I4 {. v
  ]
& |& Q  U% ?6 {. W9 H1 Q, {2 W& g& S0 i
  ;; initialize the global variables that hold patch agentsets. U0 _# J5 \) J
  set roads patches with! ?3 {" N6 f2 V! A; @& Z; c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( i% K$ B+ e  R% a! c$ C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( D. [4 a- Q+ Z2 `& M
  set intersections roads with
) O5 z. a# t& q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ e) p* T5 G. y) W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) K1 ]% D9 D! {0 P$ T' N- z
5 U& n4 |6 S; l, B/ M8 W/ U
  ask roads [ set pcolor white ]
" P/ R2 |7 A; Y& b    setup-intersections
5 [4 \+ t. |# |, ?7 V* ]end" }- j1 V, _; y: d6 E. X5 X2 v
其中定义道路的句子,如下所示,是什么意思啊?
1 F' g: j! x1 f, U set roads patches with7 N" q; U8 b) {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  y) P& D2 Z) V5 ?' `3 }( F+ m* m5 e& x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 h/ A# y# f8 e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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