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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。- j% Y# s  }, r" B8 g7 d( v
netlogo自带的social science--traffic grid这一例子当中,5 o* z- a: m0 d: a: E: _
globals
% U' J* J! j. t  b* L[" a+ z2 }; S3 n+ i* |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 y  r; v( h' T* `8 K
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; M1 N8 ~5 n& v0 Y2 M  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ r! b5 F0 w# \' S1 n                           ;; it is to accelerate or decelerate
' ~) }! {- S1 F  a! E, I; r5 b  phase                    ;; keeps track of the phase$ E# i& J" w. T8 n- b
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
0 Q% ]# q9 M! y+ P5 v: {  current-light            ;; the currently selected light
6 D' u* V$ k: |' M" B. v' d) K* e# j7 E, M) N' O$ t. r
  ;; patch agentsets
' k" _' L' |  y7 n2 D/ G* s  intersections ;; agentset containing the patches that are intersections( U& H* x7 c; u3 i! F
  roads         ;; agentset containing the patches that are roads, }  O$ y& v. _2 [( J' B% r
]6 y- G- b" f  B' n& c: t: I
% O. N' Q) ^, F
turtles-own
, l5 _& N, P  B$ ]8 @[( ~3 T( w' A3 b2 x9 J. L
  speed     ;; the speed of the turtle# t( F+ T0 C9 m# o2 B+ C: o/ x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- G/ f" D, r$ r1 `$ F% M5 M2 K  wait-time ;; the amount of time since the last time a turtle has moved
, @* F6 I  m, n! O2 Y' d! w]
/ s9 a0 n: \8 W( ~4 x1 C9 _) J" r9 s% s3 \. u* D6 h- L; D
patches-own& B3 M; n  [8 i7 Z7 w
[
" Y4 l- J% t2 _  intersection?   ;; true if the patch is at the intersection of two roads  S% B6 ^: i* c& u& V; S
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. U$ N0 r% h2 D/ [2 w                  ;; false for a non-intersection patches.
, u) r2 G# D3 i/ Y  my-row          ;; the row of the intersection counting from the upper left corner of the
" D" |1 H6 D2 Q* v                  ;; world.  -1 for non-intersection patches.7 L0 d; a) w  q3 j
  my-column       ;; the column of the intersection counting from the upper left corner of the- z; ~* i6 }! i
                  ;; world.  -1 for non-intersection patches.' K+ p/ k% c0 h; `# _
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ P8 |0 W+ Y; P$ m% t2 M' `  ^9 O
  auto?           ;; whether or not this intersection will switch automatically.
2 ~0 M& n, r$ j# |* h1 _                  ;; false for non-intersection patches.
9 A: r0 h3 }0 u  |$ q; Z]
. v( e) k6 u6 r
% b9 k8 d+ ]* T/ A7 Q# O7 k/ q. w/ e, J; d4 Y
;;;;;;;;;;;;;;;;;;;;;;
0 }" U, {2 {3 _# [;; Setup Procedures ;;
) ~# b& Y( F+ J8 i;;;;;;;;;;;;;;;;;;;;;;
3 c+ b+ N- O2 `" Q4 V2 z: e2 v% b2 {4 q# O. ~! X) X
;; Initialize the display by giving the global and patch variables initial values.
, A8 w$ |5 k+ d;; Create num-cars of turtles if there are enough road patches for one turtle to) v) X. u/ a4 y$ F1 ]7 U- e
;; be created per road patch. Set up the plots.
+ q; X0 z2 o7 [) d4 b  oto setup
3 e& y  w' D) U/ V1 ~  ca% {. }8 }4 _# `3 P' e
  setup-globals
5 d$ I" t- l. q& P5 ]1 u7 a1 R& y% w4 v$ A+ A
  ;; First we ask the patches to draw themselves and set up a few variables
. u( u! r8 k- J  setup-patches
/ @9 s/ Z" ]( [7 [- o& L! t2 Z  make-current one-of intersections
& h3 \# q. }( V  label-current
+ t9 t4 K% @2 |5 |+ [. e- n# X) ^; R" t- r
  set-default-shape turtles "car"
# D5 d2 @3 c: F: g- ?) k( u7 p
& ]* S; y6 {$ L' H: k$ }0 @  if (num-cars > count roads)
3 B* g3 [( Z1 z: g  d# \$ n$ D  [- Y: R* L& b7 w0 G( @
    user-message (word "There are too many cars for the amount of "
8 L# |) z* {/ b# w$ v4 {                       "road.  Either increase the amount of roads "6 c2 [- m" V- L! q" r- C  _+ h
                       "by increasing the GRID-SIZE-X or "
8 a! ^" h/ j0 m& O" X                       "GRID-SIZE-Y sliders, or decrease the "
' b# q7 t2 _1 v9 [                       "number of cars by lowering the NUMBER slider.\n"
9 _5 `7 j8 E( R* i" w                       "The setup has stopped.")
: m/ C& W- `- x3 \6 m( Q    stop% l  U) J1 k5 X$ D* y9 M
  ]
# |1 s; {6 A0 v2 |7 a* p. v% y. R% x' g7 q9 t; _2 R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; e* E! C, G! V. c; K6 r
  crt num-cars
: I3 ]5 H3 t- a$ h, K  [
4 e. J5 e- d. B( A$ l    setup-cars& y& c6 W1 ^/ w+ G( d
    set-car-color
( b0 U# S4 I, a/ ~" d/ ~    record-data* T! O$ [4 H$ h: n# Z7 I4 b1 }
  ]  }) e! E0 o& |& n! B

0 R' t- Y, {: w2 S+ C  ;; give the turtles an initial speed: y4 V  N+ r: e+ b
  ask turtles [ set-car-speed ]4 J: S9 |. \2 G: Y. S

1 g! t, u% J+ O7 Z! j* s& W$ x6 w0 }  reset-ticks
+ w0 S; x9 \1 I9 F; ^end: y2 ]* C* w! s' @  m
9 x- O, p. j2 H0 n
;; Initialize the global variables to appropriate values
1 l# P+ }8 M0 M" I  ?8 Y. ?. ito setup-globals
$ r1 C# Y( j- I  set current-light nobody ;; just for now, since there are no lights yet
! t: u4 E8 F, W/ d' O  set phase 0
  w' O- b, b0 G# l4 |  set num-cars-stopped 0
% t# _( o& M. {# N2 ^" w  set grid-x-inc world-width / grid-size-x
% {; r% B! ?( v, Z, x" x: m' t  set grid-y-inc world-height / grid-size-y
/ U4 \, J- e3 L: H( A9 |3 S8 {, @5 C5 a  K+ K2 J8 d- L
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ r8 d% I% i. p$ p# R: T  set acceleration 0.099, S0 m" O; O- A
end
- x' s1 D$ C2 x/ ~
7 ]2 ^/ i/ {4 s;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ Q* s8 N- C6 R! Y' S' ~: A
;; and initialize the traffic lights to one setting
7 {4 _$ L$ Z  [" e2 F( m8 ?to setup-patches$ f0 }; N, r/ S
  ;; initialize the patch-owned variables and color the patches to a base-color
& I( m/ R# X0 U9 a& N! R  ask patches
7 ]* D6 H9 N6 w7 {  [
# k7 T8 F# X4 D, e    set intersection? false' I5 |2 }8 N$ i5 B0 g
    set auto? false8 R5 S: J! R1 `
    set green-light-up? true
9 k' h  \- d2 c$ o    set my-row -1! x. `, @+ ]: m0 W/ `& ]
    set my-column -1
* p# c& x/ n# }! n/ E    set my-phase -1
. x1 o. U( F# y# A    set pcolor brown + 30 i" f$ ?: E: p8 Y
  ]$ ?9 |* B& q3 w2 h6 l% x
3 {. F8 Y; ~4 T' s' G$ R% U1 A) D
  ;; initialize the global variables that hold patch agentsets2 e, Q+ w$ ?7 v! i; S
  set roads patches with) {) Z# \- g, _! i/ a/ h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% ^" r, A) L4 h+ Y7 ~5 t5 @9 W% |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 D) J8 ?, _  g5 n. H$ Q& w  set intersections roads with
8 L" p: O1 E! c$ u' ~& g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 h" Y% f9 L6 {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' Z2 t: V. u' n: Z$ K" _8 U: T, I
- Y$ D& \2 D, O) M5 Q
  ask roads [ set pcolor white ]
% F2 X8 `# }8 ]0 A' L    setup-intersections
& g. ~( c) J3 c6 v9 A' u& Mend' S/ k- J# H' Y" `
其中定义道路的句子,如下所示,是什么意思啊?
1 ~' Z5 X4 J) ~  T2 G set roads patches with
, w5 ]. i7 a" y# C) g; X) Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. n, {  J6 N, r* n8 p' l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 o7 [' }( v4 J- H& D3 p* M
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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