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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。
' u  E/ t2 e8 {3 o+ Enetlogo自带的social science--traffic grid这一例子当中,
; s4 p2 y1 J8 j) a7 P" Q' Wglobals
1 ]* S0 x6 k! e) d, P[- W( [/ C' y& b5 ?5 A% ~
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, I7 i  f  N; d! m  S3 O  grid-y-inc               ;; the amount of patches in between two roads in the y direction
3 u$ ?0 m% V$ `  ]( I  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 _: K7 d- y, c
                           ;; it is to accelerate or decelerate2 t5 @9 k2 t" _+ X( @
  phase                    ;; keeps track of the phase; N$ {! V7 D+ `1 G$ K5 b$ {7 X/ b
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: ]4 f& U6 O% Y
  current-light            ;; the currently selected light
2 z  t: j+ @. ]& k8 w" a
- [' q5 W# b( I* E* {6 L! \  ;; patch agentsets4 ?8 R3 C8 _# J: t; A: C) W9 ^2 g8 J
  intersections ;; agentset containing the patches that are intersections1 r. i$ y6 ^  N+ C
  roads         ;; agentset containing the patches that are roads. a" o) V1 G- F1 x' Q
]
; w6 ^! _/ Z3 N; `5 ~8 \3 e1 f* F2 U6 u  Q
turtles-own
7 O% S1 j" l) O  b6 b[
- {! n4 q3 w+ `) F: Z+ u/ b  speed     ;; the speed of the turtle
* R" D; d1 J' V+ i# d  @, Y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; ^$ E$ F# U; f" V
  wait-time ;; the amount of time since the last time a turtle has moved( T+ V- \, E- J( X9 T! `% B
]( m6 c& h1 r4 X. ^- G6 ]% P
# o% ~; \6 W4 ~
patches-own
3 q" W! W: h, {8 a( }+ Z[$ S1 f  `% |/ c- i0 T  h0 D
  intersection?   ;; true if the patch is at the intersection of two roads1 R8 @, z2 s7 @) u3 S
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 Y1 W5 [! {# n( B! K                  ;; false for a non-intersection patches.) ^3 a! U4 k& i& R
  my-row          ;; the row of the intersection counting from the upper left corner of the
8 H) `6 B$ ~( `1 [+ }7 R4 v                  ;; world.  -1 for non-intersection patches.
- @  \# D# x. T* H" l5 ^) v  my-column       ;; the column of the intersection counting from the upper left corner of the( N: @( ]6 f" n8 T2 N' h6 G. n
                  ;; world.  -1 for non-intersection patches.
- M# M2 X7 [  F- `  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ V8 X' _; v" Q  auto?           ;; whether or not this intersection will switch automatically.0 F  ~' O& ~! L- ^
                  ;; false for non-intersection patches.
$ q* C/ H# T" e8 ^( S5 U]1 q* w( t1 l' k
! G3 T: Q7 X4 e; p" }" V
% v/ Y# |$ \) M& f
;;;;;;;;;;;;;;;;;;;;;;
# y" C  @+ g3 m8 R6 v+ F6 @& Z;; Setup Procedures ;;8 L5 l* n5 x3 u5 K
;;;;;;;;;;;;;;;;;;;;;;
% Z  l, A0 B, }; Q
& V" ^+ D7 s( e- z2 m! E;; Initialize the display by giving the global and patch variables initial values.2 [. g* B+ K6 f( E
;; Create num-cars of turtles if there are enough road patches for one turtle to1 u; E; x6 C7 a
;; be created per road patch. Set up the plots.3 M7 _0 m  ?. W
to setup/ n1 U+ o) u% y: ~5 |5 T% h/ }
  ca
* U1 z  P9 s# t* d6 N! T/ T  setup-globals( F5 v7 F& h/ E  x3 ?0 Z3 F

# f+ V% u8 i0 l' E  ;; First we ask the patches to draw themselves and set up a few variables
$ H8 x, F% ~  e8 ]2 p  setup-patches
* x5 n$ B% m! Q3 s9 m/ o7 M  make-current one-of intersections) N. m0 F" w3 _' I& Q/ k
  label-current
0 T) ~& M5 `# q7 Q
  q* k/ m. R% t( B( H. A, G  set-default-shape turtles "car"
% p  J" u& k% h& C# E" [; Q! p9 R! A* o* O/ G
  if (num-cars > count roads)
5 r. R) k" x* j' o# s  [) x, y2 Q) k8 j) j6 \' Z, `$ m! p
    user-message (word "There are too many cars for the amount of "
( O$ J$ y+ ^2 R4 q$ c, J                       "road.  Either increase the amount of roads "
1 s* c( U2 \) q; _                       "by increasing the GRID-SIZE-X or "
+ F* q2 |7 b0 l2 E) _                       "GRID-SIZE-Y sliders, or decrease the "
1 J$ ]3 Y7 a0 p9 }  }- W8 s5 `                       "number of cars by lowering the NUMBER slider.\n"
! z, v. D/ d& W( l, R2 V4 z                       "The setup has stopped.")
: _! ~& g9 ]2 c0 H% q    stop
1 v& K/ a- G; Z! M) L  W% Q  ]
6 F+ Z; ]" ?  |5 o# T+ J+ I2 K* v$ |* R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 `9 `4 a/ K9 h8 C5 s' X' d; f  crt num-cars
7 S% W$ P+ N6 z1 {, l  [/ J9 T2 {. t& P  p2 ]- u! c5 A
    setup-cars" U1 P. @& Q- P1 g' F% I
    set-car-color9 m- w* F/ K0 ]7 \- v
    record-data
/ P" n! C! f7 x+ E  ]
5 l. e+ M8 @2 G1 N: L2 a* Q9 P/ `$ C
  ;; give the turtles an initial speed
7 f" R/ m) s$ W! ^3 g) A  ask turtles [ set-car-speed ]1 ~- ]' O0 v' K6 W

$ C& K# N& T3 I  reset-ticks
( f, ^5 h1 }8 |, b8 S# |1 m* xend  G  d; e. I) h( D

6 n/ n  k5 @6 V* l. {4 Q( I;; Initialize the global variables to appropriate values
7 i2 e2 g3 F3 x1 Q! Y( x4 |to setup-globals
8 m  J' D+ f' q1 x2 J! P; M2 Z  set current-light nobody ;; just for now, since there are no lights yet
/ S" w, L) @$ q  set phase 0
1 c: }  W4 G; f& ^  set num-cars-stopped 0+ D6 @! n# C( c( g
  set grid-x-inc world-width / grid-size-x
6 D/ @2 e5 ~) w8 a3 F. x  set grid-y-inc world-height / grid-size-y2 @; ?0 a9 \3 T' p
0 o" s5 Z: u8 x8 e# ]2 [( J9 `
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# e: U& B6 }7 K# j! e9 H: d  set acceleration 0.0992 u. ^" H  q/ B" d5 ?
end% T' N8 x  j9 a5 D

; ]! p, O$ U7 U0 [;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( Z/ W9 D2 U7 O( l5 u9 h
;; and initialize the traffic lights to one setting* _) S) C, K% `0 Z  P2 ?8 t2 m
to setup-patches
0 M& y0 q3 @  v, g: ^) f4 `  ;; initialize the patch-owned variables and color the patches to a base-color) f/ q* H9 C/ ~, I
  ask patches
5 ^& V; c1 m' W* C4 `  [
6 t# r8 `3 v1 z9 g    set intersection? false
' y9 x/ U7 Y4 u/ a1 t1 u9 \( H0 `7 s# C    set auto? false
  p6 _1 r$ P6 J# r# L    set green-light-up? true
( P; N! j, Z3 ]3 v9 H    set my-row -15 p: `4 l/ x- W+ ~6 L3 F
    set my-column -1
3 f+ b1 x0 O5 N; V3 t    set my-phase -1  h$ U8 \% G$ G. `+ b! l
    set pcolor brown + 3
" m& @% s: n: L, h0 T  ]  e; ~6 S6 X: P+ i! p/ ^* C

2 B  @! b% M5 u( ]% @4 p  ;; initialize the global variables that hold patch agentsets2 u2 J/ N. V" c/ b
  set roads patches with
* i' [* @3 Z6 I% Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ M* l3 ]4 y  _7 i# q  @- X2 z/ J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 K& M. J! o$ f( H$ [( @9 `, u. h  set intersections roads with% y( j1 Y- }* q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 b8 W3 l" |+ h( i( \+ N8 m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 \9 g2 u0 |+ I3 Z

# u" H8 o4 B3 Y4 \* g  ask roads [ set pcolor white ]5 P' c2 R9 X- i5 c) @/ Z
    setup-intersections
- z4 b  r- N% x+ f8 d* B3 _) Wend
1 y/ _( q. c3 p其中定义道路的句子,如下所示,是什么意思啊?5 a4 s" o" d  Y$ M& d$ [
set roads patches with- N$ u& f4 d; Q1 y3 U3 j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 H. Z' t/ ~& S! J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 l" k/ I5 x: D$ n
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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