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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。
+ M( F) q/ \6 Y- y/ e$ y' Znetlogo自带的social science--traffic grid这一例子当中,
4 D9 p7 v  }  Y# r7 aglobals3 a4 T. c4 \/ j- C) H
[
& J, s. S) \) ]  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 D- v  S2 L/ h( m# J! h
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
- @9 N! N1 j- l+ k, E  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 ]) w  \2 `% B9 y$ e. e% W
                           ;; it is to accelerate or decelerate0 N3 O5 e( q. e; O3 @1 C( n6 m
  phase                    ;; keeps track of the phase
! b3 d7 ^1 R% S; _  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 P/ o+ d# u% E
  current-light            ;; the currently selected light2 q4 s2 {+ Z0 @

% q- p/ Z* w9 \! ?  ;; patch agentsets
  Q: ?, v/ W( B8 ~7 x  ?$ X1 O1 u9 Y! |  intersections ;; agentset containing the patches that are intersections
8 S' ]4 A. S& x  roads         ;; agentset containing the patches that are roads) z- t8 `  W7 @" X- A6 g
]
# g; k0 r9 F- t7 b8 w* [" D1 d# r
turtles-own
0 {/ c; `% x/ {9 N) ~0 x) N[
4 H. q5 b4 |- a0 R8 Z! r, v- Z  speed     ;; the speed of the turtle0 g* P9 p3 \7 Q+ E: D. O
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 I/ M/ V& q7 r; p* U6 u2 Q, `
  wait-time ;; the amount of time since the last time a turtle has moved4 H' `! ^1 {; }
]
4 |0 j4 t6 _! I, W, U$ Y% M- Y$ q0 }, i! M# s' C+ C8 M
patches-own
, {7 Z) d9 r* u* z: ][) h% I1 v, L* w; F
  intersection?   ;; true if the patch is at the intersection of two roads. l6 [1 w  O/ p5 \! {
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; L: j; ]- T( d  V
                  ;; false for a non-intersection patches.
: K. q; h; G* _! R$ \  my-row          ;; the row of the intersection counting from the upper left corner of the% m) A6 @/ u5 s( M
                  ;; world.  -1 for non-intersection patches.
, W8 c( m9 F) `( J: S  my-column       ;; the column of the intersection counting from the upper left corner of the
7 b. q, F' E1 p  ~6 Y# X9 q                  ;; world.  -1 for non-intersection patches.& i2 w1 S, r% E9 M
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) K2 x. t3 {, X* P& U2 o2 q# ]  auto?           ;; whether or not this intersection will switch automatically.! R) r' [- Y* a  }' B( r3 r
                  ;; false for non-intersection patches.* P. P, e8 G' F' M- ?
]
7 Z: R' _, I) i! c7 t7 s0 U
7 l) E% s: V* Q0 Y1 g8 j0 L+ k! k- V
;;;;;;;;;;;;;;;;;;;;;;
$ g+ c. L" W8 X3 g;; Setup Procedures ;;
; i# h: u8 }8 O1 Y;;;;;;;;;;;;;;;;;;;;;;' k6 u+ `- E. q( L
6 E6 L  Z; q$ ?8 l& k4 S4 v. |  B
;; Initialize the display by giving the global and patch variables initial values.2 R+ @3 v4 d- ~( J9 H7 L- {
;; Create num-cars of turtles if there are enough road patches for one turtle to- G1 h* C4 c; t1 Q( e
;; be created per road patch. Set up the plots.7 I0 I3 r: E; g* o' j" F+ z
to setup* M' z' W# @" ~6 v6 T7 C8 Y
  ca+ t" P6 h  q  Q8 C+ n5 L5 }: q
  setup-globals
1 A0 F7 y' {# c' ^) N! O* E4 s; c& I# |& h
  ;; First we ask the patches to draw themselves and set up a few variables) m* v: f$ }/ n0 l' d8 o$ l$ O
  setup-patches
5 i1 b4 P2 V/ g/ N' r  make-current one-of intersections
% r1 h$ X& T% |9 R+ @0 |  label-current
0 c% T4 c# f  X9 V2 j, u6 _6 |; s) M6 j! U: B5 c
  set-default-shape turtles "car"+ h; ?' I+ j8 H0 p4 w3 |( O" \9 N4 E1 Q

9 G! r7 B& l& n; M9 Y) A+ w  if (num-cars > count roads)
( p" v" r  T- X  [
+ j) ~7 o( D7 z9 j$ z    user-message (word "There are too many cars for the amount of "7 h! R5 W, Q5 F6 g7 \
                       "road.  Either increase the amount of roads "+ A, Q: D& J8 o# X( `
                       "by increasing the GRID-SIZE-X or "1 k/ L0 c4 N3 e' z
                       "GRID-SIZE-Y sliders, or decrease the "/ J1 m7 u5 B/ J$ c9 z
                       "number of cars by lowering the NUMBER slider.\n"
2 i0 ~- ~: i- H- s                       "The setup has stopped.")
, ^0 j+ |; m% @1 s- ]2 J; u8 O    stop
4 r# N; {. v% y  ]: x6 F' _: Q: J) v. _4 O
  @3 |' _+ ?6 ~, h0 T4 M9 `; e! e2 O
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 o* y) N% a/ I/ x2 K2 e
  crt num-cars3 W; `1 I# G( m' O3 u
  [$ d, v/ w% }1 K  R7 U9 y! b& |- H7 V
    setup-cars
( B* A1 b9 T  F7 g2 g; b7 h    set-car-color
* K$ I8 {1 l, l+ P    record-data
, p$ P* u+ f* z7 S" r& K  ]; ]! p- T( O2 j7 n# h; J) ?
% _- G) P0 v$ n$ ~1 M8 s
  ;; give the turtles an initial speed
! M6 `" a; y& o' H  ask turtles [ set-car-speed ]0 V: O9 Y* W: y+ ^1 _' I5 @4 u

' K3 _) ?0 |7 K0 C( N2 N6 M  d5 [7 V" c  reset-ticks
, L1 Z! @  ?2 ]) |( oend& R+ A9 V9 C  f- w- d* L

; I' q0 ^2 o: D4 Y  D$ A;; Initialize the global variables to appropriate values
- D/ x+ ], ?: Z, eto setup-globals, z, g  `# U' f) O
  set current-light nobody ;; just for now, since there are no lights yet
# g- `( G" [$ K  set phase 0
8 w2 o6 q1 L4 }1 [% P$ \  set num-cars-stopped 02 s, W- W( v. B  H/ C
  set grid-x-inc world-width / grid-size-x
) s  @& U1 n: @" B% l+ X( R  n  set grid-y-inc world-height / grid-size-y1 n% g! ~/ R8 o- }
* ~9 r/ l6 r' l$ g- @/ {
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% H5 ?& }0 a/ y  set acceleration 0.099
4 i+ O- y7 ^% t( qend
" \5 d: l% l! g$ I8 M
5 W5 m, D/ i3 z: F! D2 x;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( o1 i' x& r/ q. o( k+ R;; and initialize the traffic lights to one setting# n4 j$ K. u/ J' k6 r4 ~+ I# H
to setup-patches
4 m2 W8 }/ Q2 \6 H9 O8 _0 r& a  ;; initialize the patch-owned variables and color the patches to a base-color
2 L, P% s! Y0 ^4 W7 V# l8 X$ N  ask patches% j  z- t' T6 f7 \3 o, D
  [
# j$ a" W) |3 Z( e0 h    set intersection? false
4 G* }6 e; r& U6 E0 U9 N6 e* t3 n    set auto? false' p( K, L: R# ]. Y9 |) }
    set green-light-up? true+ F, e3 Q% g9 K2 X. y% n1 C5 p+ \
    set my-row -1
$ m" v. b8 ]2 g0 O/ q  X  \/ i    set my-column -1, Z) }9 M& F4 o& Q  ?( a  ?
    set my-phase -1& z) S3 l# T: |( a$ |
    set pcolor brown + 3
5 f+ l9 q+ q  u9 Y/ I  ]
1 N5 s& f* r8 L& D" H8 n- S; H# D/ q7 V/ E0 i$ O+ F
  ;; initialize the global variables that hold patch agentsets
4 @  e7 _$ s1 U! {5 H  set roads patches with. [* H; R% o/ [* [) ~8 G- P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& K% d" h6 @- J3 A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; J1 t+ F9 u4 Z4 e* j+ @  v  set intersections roads with
$ _7 W' P2 J  ?* r8 t: f: z, ^1 b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 m" x" Z7 j. @; @: k: N+ R5 U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 a9 _; Z: Z% K7 r- ^' C
2 [" Q. ^% M( e. t. u9 E  ask roads [ set pcolor white ]
- x- u8 ?+ v( T. p    setup-intersections
! I0 n0 [  r5 z4 F9 L4 f. nend; U5 T: [" v9 n9 Y. D
其中定义道路的句子,如下所示,是什么意思啊?$ D. ~! o5 w9 p6 X
set roads patches with
" L% i8 L; N  z4 V' c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 j3 }0 H) X2 h" v5 L7 G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 t( A( Q6 ^* ~
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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