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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。) @% t8 L# N4 ~! o
netlogo自带的social science--traffic grid这一例子当中,
! B: u" i9 t  X/ H6 {globals9 k/ }: ~5 [: O$ p
[
7 E* g; p# W# O" M0 ?' M1 Q$ r  grid-x-inc               ;; the amount of patches in between two roads in the x direction) d) z1 B# \, g$ ]3 N
  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 g% W  Z' c' G( ?
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 Q- U; b5 u  ^) J. A1 U
                           ;; it is to accelerate or decelerate+ F" D; @2 f. m! S9 E0 w8 J
  phase                    ;; keeps track of the phase
: p5 ~2 B9 b; y6 L) U2 Y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 \; o5 I% [+ H3 E( W  current-light            ;; the currently selected light
9 x  J9 y; C6 }9 m# i) ?% r2 s* R& [+ Z+ }* F$ N
  ;; patch agentsets3 q! Z# E" T/ l! M6 L
  intersections ;; agentset containing the patches that are intersections& O: Q( [: l$ h) i7 g$ a
  roads         ;; agentset containing the patches that are roads
% }; e8 o4 Z; t3 m. N8 Q3 p]" ^# u5 I+ W3 [" Y$ c% K4 A
3 ?; a' L- Y' Z6 }6 j3 u
turtles-own
$ r5 n, x& `* x  l' b8 A[2 }. ]- [) H9 Z3 l1 k. F* r" u
  speed     ;; the speed of the turtle5 @$ U/ X) Q6 ^# u# |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right$ `% w. ~3 `4 c1 R
  wait-time ;; the amount of time since the last time a turtle has moved# }( G" O: _8 _3 ?9 q4 w! E) P
]3 q* [* a9 o1 B" R0 a
- T! Y# ~  |1 w  c% I
patches-own
, }! I3 j3 `1 m' s7 f' I[9 y. R* V5 g# f0 J+ T% r
  intersection?   ;; true if the patch is at the intersection of two roads4 _% u+ s: D1 [# i% P8 B
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 W3 K9 w' c. X6 P5 T                  ;; false for a non-intersection patches.+ G( ]( b( D7 _* H, y. z
  my-row          ;; the row of the intersection counting from the upper left corner of the5 d. I# e2 [6 g, S
                  ;; world.  -1 for non-intersection patches.
4 C4 r0 {7 u4 K2 L$ E  my-column       ;; the column of the intersection counting from the upper left corner of the4 \7 V& W8 y9 t, T- J9 k2 {
                  ;; world.  -1 for non-intersection patches.1 S0 Q0 N/ [! c3 e9 \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- `) v) {/ \. Z! n
  auto?           ;; whether or not this intersection will switch automatically.
7 E5 V; @  |% L1 U0 \! D0 w- ~, Q                  ;; false for non-intersection patches.
8 L2 [9 j& |2 ^% \% F2 ~; U]) i8 O" @2 I6 ^% P6 Q; J

, h' @8 f: H$ t# a
( O& l+ s7 q0 q% C2 P. E( l/ m;;;;;;;;;;;;;;;;;;;;;;
5 i3 ]% @) m/ o) x/ H, [- z;; Setup Procedures ;;
- G6 r, b+ S7 y+ @! M- @;;;;;;;;;;;;;;;;;;;;;;
8 O8 `1 `# s- ^& N4 d: c1 @. s; H) M/ i
;; Initialize the display by giving the global and patch variables initial values.9 v0 e# I7 T/ S4 E+ y
;; Create num-cars of turtles if there are enough road patches for one turtle to% v! J! g4 d# ]1 I! r% e+ o
;; be created per road patch. Set up the plots.
8 ~$ Y0 x6 Y% u5 y8 lto setup
$ @" L; K/ Y. u, e  ca- `1 }" V% M" N+ U( ^( P, f. G
  setup-globals- v2 H, ?8 x) T& {8 G( @' s

& x2 a. M. ^* m0 X; H/ I5 @  ;; First we ask the patches to draw themselves and set up a few variables
, e) p3 H- i3 h5 x5 a  setup-patches" Y/ L- z3 _6 w6 N
  make-current one-of intersections. i. |# J6 e" e
  label-current. o1 K7 L0 o+ e( w. q, ]
; p0 S8 X; c3 D2 N! R  i/ A1 ]# P4 B) S
  set-default-shape turtles "car"
& o* x% y$ a6 Y: z
* c4 q' o0 d6 l7 W  if (num-cars > count roads)' h0 |9 K( E9 r
  [* L4 k9 o8 h" O; \( k
    user-message (word "There are too many cars for the amount of "
+ G0 e5 @- {% C9 i                       "road.  Either increase the amount of roads "  T$ o- Z; w8 z" Z7 m$ [: x
                       "by increasing the GRID-SIZE-X or "
& c, j1 M& X2 n3 s4 p- d# x+ q                       "GRID-SIZE-Y sliders, or decrease the "9 Z4 M; X9 r1 z  p, Q6 n
                       "number of cars by lowering the NUMBER slider.\n"- v. Y1 K! E) a8 Q, j# Q
                       "The setup has stopped.")
% j& `6 l. Y4 R/ ]/ B/ [    stop
/ H1 v# C3 ^  e/ ]( i# x! ^* h  ], X! d# I1 P! p; J9 t

* h$ X& }6 k4 S) [- I1 g' A  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 C/ z3 ]0 z6 P! ]
  crt num-cars# }) ?" \4 k: C3 Y! Y9 S" ]2 L
  [
: N$ ]4 }7 G- G* `3 ?    setup-cars7 y7 x# V+ }* E) x6 ^5 {
    set-car-color
: s8 n0 e# q5 @! {    record-data
/ L6 R4 |/ l# W3 K5 V" d- a2 F  ]7 c5 R* b  \# \8 k* n& {2 z4 @

; ]* O3 v$ O6 E9 T2 v9 F  ;; give the turtles an initial speed
$ r' ]  f( L9 L6 d1 N* {  ask turtles [ set-car-speed ]
8 K: P* _3 C. b4 s9 c1 x$ d" ]/ }
- @3 d, b. i2 o9 b$ i  reset-ticks3 e+ s3 w( ^  ]2 Q7 F
end; W2 r4 }3 ?; K6 \3 Y. F2 P

7 M. J; J# L) E;; Initialize the global variables to appropriate values+ v% d/ @: q0 \1 |
to setup-globals
$ `6 s' T& M- e# e$ L" m  set current-light nobody ;; just for now, since there are no lights yet# a9 T2 s5 C) t8 d! c8 Z
  set phase 0/ B) J1 g. k( ^* i4 W  U' _: C- B
  set num-cars-stopped 05 s  S) C2 @) Q: H
  set grid-x-inc world-width / grid-size-x
4 v8 G8 G0 W; s* _, V1 m  set grid-y-inc world-height / grid-size-y
8 W1 y( q! f& Y1 X' o: F3 t5 I. }. S# {( W
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ [, Y0 z% Z9 B. |. n
  set acceleration 0.099( D  ]+ j) S4 W& ?9 z
end7 @% w  L) e! W' F) i  m; [
' G# F' F: E3 F+ I. c" |
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,% [* i) o) j7 H3 n, f
;; and initialize the traffic lights to one setting- X/ P! f4 h# g& B& b
to setup-patches
: J9 z" c: A' k! ?. K  ;; initialize the patch-owned variables and color the patches to a base-color5 k/ Q8 K  `  `: v4 A' x! [+ X
  ask patches
, J( D) ?7 _: t# K% l2 j+ k, b6 `4 _  [
, ~. P3 f/ q  R& a9 ]% ]+ c; _2 S+ `    set intersection? false
7 B( f* z' b5 q9 I  g" P; c+ \    set auto? false2 R4 i+ v: U  c4 t- }7 w& t
    set green-light-up? true& L* X$ i2 x# n! l* R, |+ z% ^% W
    set my-row -1
8 b) o: ^2 [! y$ r% U- C    set my-column -1. k) ~% j, Q( L0 @
    set my-phase -10 \4 g- @. D$ q, J! d
    set pcolor brown + 32 c  L5 b& ]5 f, v, v
  ]
' b, r7 l$ H; W  }9 s( F6 v1 u. f2 D
  ;; initialize the global variables that hold patch agentsets2 F: Q* q/ A& Q/ L
  set roads patches with
! n* v( d# P+ |  }! a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* X. h$ D) s' x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) k/ o3 n% ~" U1 F, `9 v
  set intersections roads with
2 O3 ]& l  o' Y- j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- ?( T/ d) n1 i  @6 D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  ]3 ~9 S6 p1 q. o; s, s; ~# \

3 d$ D6 Z, Y3 W. P  ask roads [ set pcolor white ]
' i% S& X& O2 O    setup-intersections" |  N0 @9 W+ U
end
7 D6 P4 ~: \2 b# _: E" G. I其中定义道路的句子,如下所示,是什么意思啊?/ h* e7 k$ M; _, L7 a* ?3 `
set roads patches with
) C8 \; k% O/ z- t: J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, J$ z! y% u7 f" s( U3 W7 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; Z4 N9 O8 V  @
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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