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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# h9 t) E/ q' M1 g; Pnetlogo自带的social science--traffic grid这一例子当中,0 H& k9 \  C6 m
globals
# P7 x' t1 y  B6 a* M7 H/ }- _[2 z/ X1 ]1 k- ]5 h' r/ h4 r& Z
  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 |* g4 R6 Y6 M) N" w
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, N* m' r0 ~9 s/ N9 O+ A4 F  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: |/ f3 f2 M: G8 }# j1 I
                           ;; it is to accelerate or decelerate
2 W  b6 O+ _# `% A8 Y  phase                    ;; keeps track of the phase% m) Z5 C. B; v
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' D' t$ Y+ y7 H% e. a
  current-light            ;; the currently selected light
5 b& v: c" t2 P
4 y9 C. {# `7 p/ s2 t  ;; patch agentsets* m' N- h" p0 w6 ]' G
  intersections ;; agentset containing the patches that are intersections$ l1 m% H/ R) T
  roads         ;; agentset containing the patches that are roads
" L9 K( Z+ [' \) ?6 ]% E]$ v5 k8 N* t7 p4 x) n- v

- F7 A2 Z7 C/ U3 i0 j% Dturtles-own
/ X2 h) a% G/ q. c' X8 d! @[* |% Y% j. u+ H5 Z* r
  speed     ;; the speed of the turtle! r. l- k+ A. x2 X3 c- w# j
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% R& a& n* n7 w' ]  wait-time ;; the amount of time since the last time a turtle has moved
; z% T' N7 n2 y7 K( _$ H; I7 a]
2 g) g; [/ B( Y, u9 x' N- A+ D
8 T4 N* p6 e2 {" x4 R2 ppatches-own
  d# _! E1 b; {  p[; {5 ?) f8 K; P9 u$ B2 ]
  intersection?   ;; true if the patch is at the intersection of two roads- C, D% j6 |& T$ C3 t8 ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ c& m. r) a3 ^6 F# a+ g
                  ;; false for a non-intersection patches.
0 R* n: y3 G, N( e  my-row          ;; the row of the intersection counting from the upper left corner of the
* [* S6 `& S+ k" H                  ;; world.  -1 for non-intersection patches.# \# }% _* ^" }
  my-column       ;; the column of the intersection counting from the upper left corner of the
) w4 u: S8 b( a4 n) q! R# i7 u- ]0 `6 F                  ;; world.  -1 for non-intersection patches.
1 p6 Y$ }4 J1 e0 `( s  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ p; g* k; S: M' s  auto?           ;; whether or not this intersection will switch automatically.
% {9 X) M" H3 L3 \4 G                  ;; false for non-intersection patches.
: F; U6 B- K+ M" Z. O. w]
% @% \7 U, N% Y6 l! \# x9 |- I" D
( P7 N7 u! Z6 }4 i6 ?6 b) N: G2 K
;;;;;;;;;;;;;;;;;;;;;;4 J9 @  x7 ~) e0 T& I2 }/ g
;; Setup Procedures ;;1 b4 Y) v  n# j
;;;;;;;;;;;;;;;;;;;;;;
7 {) e. o6 M) F  @% D8 I, o1 F$ q
;; Initialize the display by giving the global and patch variables initial values.
, d6 K  q6 B) F- v;; Create num-cars of turtles if there are enough road patches for one turtle to
6 v! f7 _  B4 F7 D, o/ V;; be created per road patch. Set up the plots.
( ~. A9 n) o3 Q8 Lto setup1 X4 p- ?6 I$ z$ {
  ca+ @# B# j$ ~' }0 y" w" A
  setup-globals
0 l$ p2 [; \; \4 e$ r& s7 Y0 z3 V3 x  y5 \$ l, n! e
  ;; First we ask the patches to draw themselves and set up a few variables
- I! W2 F- b0 ]" K* y9 _  setup-patches" ]. W2 i/ j' e/ w1 \* `" D# r
  make-current one-of intersections
& K8 V7 t3 ^# u5 K" d7 M1 F  label-current  `4 M. ^+ f2 H# {" C4 \6 a

( v9 m' H5 I& T8 ~5 X2 ]0 `  set-default-shape turtles "car": a' _% Q, r* C7 \. a; Z

: q/ i. S. i+ i, v4 l2 S( R  if (num-cars > count roads)
5 N' A5 ]+ ~. `  [
3 ~) ?! @& o4 o+ y    user-message (word "There are too many cars for the amount of "
! v) ^" C4 s9 [                       "road.  Either increase the amount of roads "
% b6 D9 G7 r% Z" ]$ e$ O                       "by increasing the GRID-SIZE-X or "
/ M" A, B& E  }/ Y6 i# ?1 K& P                       "GRID-SIZE-Y sliders, or decrease the "
1 C# b  H, ?: ]                       "number of cars by lowering the NUMBER slider.\n"' l" q* o7 {8 k% E
                       "The setup has stopped.")& r5 R, Z  c  t2 _* _8 {2 Q
    stop
5 f$ u  _0 G2 Z' M5 }( I; ?& l  ]" |$ p$ }+ z: z+ v8 s9 E

6 M- A- e* ^3 |& l# u* E  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. l$ J: d+ \8 t  R5 S  crt num-cars: ~- s- n8 e, d- g8 z0 h2 C5 l
  [
' O' t% B6 k1 z- J5 X6 h( ?    setup-cars; G3 M8 _: T* }+ @. |
    set-car-color, [4 ^- k" L& V2 F$ ^% `; X- \; p. b4 s
    record-data
9 \8 m' ~( J: [  ]
( L2 j7 A# I( k9 Z' o- \% e& q: q3 C: e. U# K( `
  ;; give the turtles an initial speed
2 U; ^/ s4 U+ U1 {  ask turtles [ set-car-speed ]2 ]: S7 O* L" P( T8 k  B$ B3 B

- i6 J5 ?0 F% z+ v% K1 ^  reset-ticks
1 M6 Q! i, b& Gend) S, c, s: R% b& j
& v  F# `* {0 T1 a! Y- v
;; Initialize the global variables to appropriate values
" H( e; r: T4 y& N- f7 P6 y5 D" I' qto setup-globals
! `8 ^+ F* l; K) A  set current-light nobody ;; just for now, since there are no lights yet( r- n1 i8 E- A1 e
  set phase 0
% I9 \  k* n4 c! A  set num-cars-stopped 0
- Y6 D  `& w. R/ I+ W3 ^7 k; H  set grid-x-inc world-width / grid-size-x
: n9 s$ L, I0 }1 i, Q  set grid-y-inc world-height / grid-size-y% w9 j8 f) u- f2 g7 `

6 X; ^% d1 B/ r& z/ ~  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 J0 O0 D; j& I* e6 }; `: V  set acceleration 0.099
) F1 x+ }6 J9 ~5 r) R  M2 L0 cend# l8 l8 i# Q6 J8 |) p

$ t3 J0 ~! ^0 f% x  C) R9 o( p4 _;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 i( m+ f$ S' W2 U8 v/ \
;; and initialize the traffic lights to one setting4 W# j% K8 j$ f
to setup-patches
; u5 Q  _, c* A( e, a  b6 P  ;; initialize the patch-owned variables and color the patches to a base-color
4 M' y4 n* A( ]# @: q  ask patches
" d: Z0 I+ g7 T  [+ g$ M, m7 L. ]0 y
    set intersection? false
" G: M- V$ Z" n) g9 F: a$ p/ K* j    set auto? false
) I  R; z% m$ y, S  X    set green-light-up? true4 [1 C8 F$ ~/ n+ @& x
    set my-row -1
; U. V9 H/ f5 x    set my-column -1
& A  ]/ g% H! M* F. v! e    set my-phase -1# Q5 @% M$ k+ V: Q- b
    set pcolor brown + 3
' ]2 @  n6 f$ z: U7 z: N, V. }$ g" p  ]
$ O/ _7 O6 c. P* A* N0 s6 b% ~# F" c) D, B( b8 Y& F3 z
  ;; initialize the global variables that hold patch agentsets- i0 ~" j0 ]  n6 J. P' t  Q. @+ a9 W
  set roads patches with
7 ]1 B- R3 R% ]" c3 T- d: Z3 ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 }. f# c1 F" G6 `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 r7 p/ F9 V8 r4 ^. P
  set intersections roads with
4 `) v0 p5 r5 H# O+ p* K- o9 K0 i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 |( B5 S/ e+ A6 o5 O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& n  C# r8 e% E4 E
& F. X4 f6 I2 o5 C4 N5 G
  ask roads [ set pcolor white ]2 X( ?( C! A5 {; q
    setup-intersections1 v' u  K2 u1 ^
end% z6 x' [3 J" L9 T! x" t
其中定义道路的句子,如下所示,是什么意思啊?5 ]4 f; A0 R5 O5 m0 u9 c
set roads patches with
" x1 l3 O- r$ H  V  {$ [  z/ ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! W& v% u% g/ q+ T; A+ I) R# v9 \/ w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 P3 O5 ?  B8 J8 [! A5 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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