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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。
4 F8 f7 s0 o) j9 Q4 _% @1 znetlogo自带的social science--traffic grid这一例子当中,7 E; E8 `: a3 S2 ]. p
globals, g) v7 T; ]3 E2 ?- b4 t/ a' n
[
6 }$ l' R  w$ @# @; }1 V5 I. v  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ H/ h: L2 u; s' d' j7 o  grid-y-inc               ;; the amount of patches in between two roads in the y direction
9 L9 U7 @, x: Q' I! ~1 [  acceleration             ;; the constant that controls how much a car speeds up or slows down by if" B$ ~0 d( O* j5 {1 |( l. Q- n
                           ;; it is to accelerate or decelerate
4 S5 v  h# Q6 U  phase                    ;; keeps track of the phase
5 k8 @8 ^4 {5 z0 v  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* R) C9 q! `, `# m  current-light            ;; the currently selected light9 B! B( q: `1 I% s
- w* q0 {8 H/ W1 a
  ;; patch agentsets
  I2 X5 R% m& b1 D+ ]  intersections ;; agentset containing the patches that are intersections
! @  Q# Y* G- t  }  _: s: l$ K  roads         ;; agentset containing the patches that are roads: c8 \/ ^0 k2 h" L7 P& @. C
]
& i, s, ]. f) \* F: }* |" a. F$ T; g% l/ O0 E, w' _
turtles-own( Q; M; Q& V1 b1 x. ^) y
[' t) c: i0 }& S7 w2 w# ~; \
  speed     ;; the speed of the turtle# J4 _% ?5 _+ i; F. d% k+ J8 }
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# V  p) z% N2 s/ H* I. }  wait-time ;; the amount of time since the last time a turtle has moved
" `, {: a6 z$ S; ]]
1 T) s- D+ u3 S4 I! Q% X# E6 Y5 H! [' Q- [! C
patches-own' x0 W8 Q5 E+ E2 g, }$ _
[
$ b. }' h# e1 o# A  intersection?   ;; true if the patch is at the intersection of two roads. Z9 C8 ?( O5 C
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: l% w6 W7 K6 ]0 K0 D0 p8 [
                  ;; false for a non-intersection patches.1 E: l- y' U4 J. @% I+ G
  my-row          ;; the row of the intersection counting from the upper left corner of the. O2 X' I8 z8 d
                  ;; world.  -1 for non-intersection patches.& w; V; i& p. x) w& ?
  my-column       ;; the column of the intersection counting from the upper left corner of the
1 Q- x  @7 L1 N  o                  ;; world.  -1 for non-intersection patches.
% _% ]1 V! {$ @5 C3 g* W7 c  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 R( h3 e  ?- }% {. h
  auto?           ;; whether or not this intersection will switch automatically.
9 a8 |" B" {; L2 s5 D                  ;; false for non-intersection patches.
3 A5 p5 m8 q& y0 `+ G9 h: {]
7 Y/ J0 U+ A7 k, P# S- v
5 G: Y4 W( e/ ?6 [3 y
* v& z: @1 t, P5 a;;;;;;;;;;;;;;;;;;;;;;% c0 g7 v: V3 X3 z# G9 Y
;; Setup Procedures ;;2 j2 }% F' Z" L4 B' C
;;;;;;;;;;;;;;;;;;;;;;
1 x  b% }6 f9 H1 D! P( o- h% @0 |. Q9 r
;; Initialize the display by giving the global and patch variables initial values.  D# W- I; n! r6 b
;; Create num-cars of turtles if there are enough road patches for one turtle to% M9 {" Y% |/ o/ ?, E4 O1 r
;; be created per road patch. Set up the plots.
+ [% g3 G$ O7 J. k, F" H* Mto setup
2 H- {9 F4 }3 g' S  ca: s4 C- Q, n( c0 y4 k
  setup-globals5 h, e# k# @; L) E  [- C$ s

2 P9 Y( V8 G  m% j) H( D  ;; First we ask the patches to draw themselves and set up a few variables
. Q4 v* @8 H* ^  setup-patches
0 {8 T( J5 F6 f- ?# R  make-current one-of intersections1 I9 R8 Q% T" ?5 R. s" s: o
  label-current
9 t0 z( t; z, L8 M& |+ x4 c) ~5 I' w+ D# i8 R0 Q
  set-default-shape turtles "car"5 ^$ w  W# A& i1 }
! }; ]3 J8 H* w) E& D: X& I$ t0 O
  if (num-cars > count roads)& w& y1 }: p- ^* X9 Z) }
  [
/ w7 F1 x7 T% j    user-message (word "There are too many cars for the amount of "
' C4 \! d5 s6 X$ k0 n! w                       "road.  Either increase the amount of roads "- w; i! A$ \6 E# {0 m
                       "by increasing the GRID-SIZE-X or "
3 M3 o/ [, Z$ T% `+ d                       "GRID-SIZE-Y sliders, or decrease the "7 v6 B: U: f4 S
                       "number of cars by lowering the NUMBER slider.\n", d7 X( f/ `$ r" e
                       "The setup has stopped.")
5 k) Y6 G2 A, z" p# p3 b    stop
3 c* o$ n6 X8 F- \& \0 I  ]: t4 m' Z7 E* q# K; t

: ]% b8 B! w; T' S& W  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* C" [/ Y6 `7 O1 E( f$ g, t
  crt num-cars
" S" X7 {: e0 B" H- Y( K0 a3 q  [; _/ a1 j% A6 E  _4 N5 A* \/ L9 {
    setup-cars  D* z0 ~! X2 ?: v! @* `
    set-car-color/ y$ Y7 `/ ]. a4 e( {9 c6 d, D  m9 s
    record-data& ]8 g9 i- q. D- b) D* C
  ]& d8 G/ I' Z. G' {; X0 Q

' n3 X, R! f. @. K  ;; give the turtles an initial speed8 t( ]8 M) u3 w
  ask turtles [ set-car-speed ]& X# T3 O; f0 P- L9 F
3 u( g5 k2 z9 L$ a
  reset-ticks- K( N* m' ?6 h* E2 C" q/ C
end8 D$ _) X. r3 w) y
8 r# p1 e' i( N- w' p
;; Initialize the global variables to appropriate values
. J0 Y5 f9 \8 @- ]to setup-globals) {  t% `3 T5 f
  set current-light nobody ;; just for now, since there are no lights yet
) o3 B; ~- n- x. Z: `$ j  set phase 0* L& a; }  Z% \6 F) [
  set num-cars-stopped 0# K/ {6 ^  S% f
  set grid-x-inc world-width / grid-size-x
' V; g8 _1 a0 C* S2 D) }7 d  set grid-y-inc world-height / grid-size-y
  i3 z. U4 ^& G6 e) u, Y4 o& g8 u; E# Q+ B8 M6 m
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. X' x. `% A( }+ M! \9 f
  set acceleration 0.099/ l7 b& W  T* J) y1 r
end
  R/ D# B# ]5 X
6 K. m7 z  `, P- R& l: W;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 P- \& Z) w: `2 R6 D
;; and initialize the traffic lights to one setting
; ]6 v' n; d# j* Q8 [; l8 n3 ~to setup-patches
% E$ ]" ]2 _- h. m: U  ;; initialize the patch-owned variables and color the patches to a base-color
' m; h: B+ i0 B( Y& X; B  ask patches
( N) y8 v0 z) k2 y3 r  [
5 B2 N$ v5 ?; S7 e4 D$ b    set intersection? false
  e  R. Y$ f6 y  _" U    set auto? false3 n, U. q8 z3 C$ j- a  R  P$ n; Y
    set green-light-up? true; E" E( b9 q9 K2 ?
    set my-row -1( p3 m  o: a  ?& i& w2 g4 B
    set my-column -1
7 O4 V' C& T- Y4 y) H3 x, M    set my-phase -1# J5 R4 A, m8 I
    set pcolor brown + 3
9 K- |- T* y2 h  ]$ r' w0 _8 ~! k4 c. {

( a# d5 j7 ^( ~+ i- l) b0 q( ~+ i  ;; initialize the global variables that hold patch agentsets2 d) x: y$ r, y
  set roads patches with
8 H) Y. B6 G  j0 Q) i! `/ w5 l$ B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% P6 |9 a. l8 E+ z/ V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' R8 h  S# z7 q4 `6 H9 m0 N! @; i
  set intersections roads with
& s1 \7 q1 m+ S, i: u* R% _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ D) b; {1 q- d* R3 c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& s. g) e  \* v0 N0 ?
( F* t4 x2 G! S' Q& o4 \0 K% ]
  ask roads [ set pcolor white ]+ q, N2 ?  j; J8 d! L
    setup-intersections  s$ _) D. _) m# e
end
6 {( d1 o  `0 i' a其中定义道路的句子,如下所示,是什么意思啊?
  }" o9 @5 P  j  p! U, P' h set roads patches with1 ~: Q8 _! \- N' V. j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. \6 d# {, [; s( a7 S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( \: B& J/ m! H/ W7 S+ 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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