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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。5 O! {% J1 P' G7 P# w+ Q; c2 L
netlogo自带的social science--traffic grid这一例子当中,
' T+ X2 L" O4 D3 d/ k& gglobals
: H; W2 |5 H7 E: W0 B[! [$ ?+ T9 Q4 M6 z4 C
  grid-x-inc               ;; the amount of patches in between two roads in the x direction% ~2 N5 ^% f2 x% P- a8 H1 R
  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 ]; W3 Y) j0 F& ^6 v
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! C! r8 W- b7 R                           ;; it is to accelerate or decelerate6 E) B  k% D# H
  phase                    ;; keeps track of the phase5 I4 r8 E* G$ v6 E! s  N
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* g9 T( k  t. @# w, \
  current-light            ;; the currently selected light
$ J5 Q$ ?- N8 n* O" j' k: l1 }# h- E9 |$ V: }* y
  ;; patch agentsets9 N6 M) t2 @* x9 q& R( o7 ]( @
  intersections ;; agentset containing the patches that are intersections3 P3 v$ w; {0 j$ E% }5 k
  roads         ;; agentset containing the patches that are roads
0 `; H+ ]  q! z0 e]
/ E! p7 \* H' t( [2 f  g$ P% \$ N2 [
* @# {  x3 A1 @; q) i, \turtles-own0 L7 d" h9 l+ c+ E8 f0 h8 L
[
9 i; x; F$ u5 P" @! m  speed     ;; the speed of the turtle
' U: D2 M4 o$ d" B% b0 e- \4 C$ _- X  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 A/ o# X) k& ~& h- l1 m) B' N  wait-time ;; the amount of time since the last time a turtle has moved
5 Y$ W: ]" i2 r/ o' q7 q6 k]
; J$ Z6 E  A' D
- P. m* D) }2 ^! D7 z! m( [patches-own$ t, a3 j" Q& ~. F. p$ d
[
+ T7 e2 V- v( W+ @) C  intersection?   ;; true if the patch is at the intersection of two roads
8 M% m" S5 R. {; N3 T  ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" d- \, y8 E3 ], U9 I: {                  ;; false for a non-intersection patches.# m, I7 q3 r2 t  y
  my-row          ;; the row of the intersection counting from the upper left corner of the
# |5 ?3 U9 e+ e# a                  ;; world.  -1 for non-intersection patches.5 o6 G; T, \6 N# C. ]- P
  my-column       ;; the column of the intersection counting from the upper left corner of the
4 E( g6 X0 w  G% R. y' F. }                  ;; world.  -1 for non-intersection patches.
! D* ]5 B) t' L4 W# ?4 p  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 E5 e- M" y5 z$ P
  auto?           ;; whether or not this intersection will switch automatically.  I8 }; G" {* T/ B+ F
                  ;; false for non-intersection patches.
7 u2 ^' g8 g* A]9 v  n6 q. `% N( E$ R6 Q, u' B

! n$ _: O. s# t9 u8 \  v% o$ _3 u5 _- S' ]
;;;;;;;;;;;;;;;;;;;;;;
6 L/ ]& F1 m( E;; Setup Procedures ;;
2 F0 s/ x& F- G# x/ B  L;;;;;;;;;;;;;;;;;;;;;;) A0 F$ i% P9 e2 i" g/ |& L
7 Q$ v2 V9 G2 V* x3 }  b8 Z
;; Initialize the display by giving the global and patch variables initial values./ [' C; u0 N; T, X3 |
;; Create num-cars of turtles if there are enough road patches for one turtle to
1 F' J! h, \  U, a" C;; be created per road patch. Set up the plots.
2 a$ ?+ h; X% Oto setup
& Q! F1 q1 c, D2 X+ F* O* b# T  ca
/ J& ]8 L! F& ~  setup-globals' p6 N% R) C4 Z$ ~. I! @- _

7 Q2 Q; H+ m  u$ `. @  ;; First we ask the patches to draw themselves and set up a few variables
! m4 W1 C3 i3 q0 L+ z$ B) ]  setup-patches
+ M- _' i; k# [0 H# R! F! p* @  make-current one-of intersections( I' h5 l8 m  f6 O
  label-current
9 H+ A4 e' e) i6 [' i+ S  m- U$ d& S' |
  set-default-shape turtles "car") W7 W9 X* e/ O. [& z

. I) @" j% A; a. H' P  u  if (num-cars > count roads)
! M9 E, p, y* v2 `% `0 E) h  [
' Z" O& a" e  m- U) E4 \: M    user-message (word "There are too many cars for the amount of "
+ v: u, K2 \8 h. h( {                       "road.  Either increase the amount of roads "
& ?! S; ^& ]* r6 l                       "by increasing the GRID-SIZE-X or ". u  W9 j# D1 H8 P
                       "GRID-SIZE-Y sliders, or decrease the "5 C7 ^$ w" c3 s6 o5 h, B: h8 K
                       "number of cars by lowering the NUMBER slider.\n"
8 d1 @- r* S& n" H0 r                       "The setup has stopped.")- V* n4 }/ K3 J
    stop9 b. R) F1 Z6 [0 [% w
  ]
& `) N  E% x& n
6 }/ Q1 F$ Y" s1 a0 E; S" N  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color- h" `" [7 ]$ z4 s
  crt num-cars- l: P+ Q1 Y2 Z7 f
  [- ]& ~* G, {  g
    setup-cars* D. Q4 Y$ J4 f/ ~3 X
    set-car-color2 j) d7 ?2 ?! G) [" L( K
    record-data
. q9 X8 x4 h- Y7 Q/ r5 X  ]
# b( X$ Y  x. S/ H8 }
. s; \- n, R9 \  ;; give the turtles an initial speed1 k1 G  d. }8 J& M3 {& {: w/ n& h
  ask turtles [ set-car-speed ]
" _) Y! R7 c: U+ s0 Z. N) a% C5 D2 a! K
  reset-ticks
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5 W% f5 u( e5 D0 K8 [' d: G7 ?
;; Initialize the global variables to appropriate values
! i" d) M& M) r! o2 eto setup-globals7 u5 p6 i' Y  r1 w
  set current-light nobody ;; just for now, since there are no lights yet; Y4 Q: E9 L8 u; p
  set phase 0( L2 H6 g7 V4 _# l# X' Q1 l  v
  set num-cars-stopped 0
  T2 _, q' p, W1 u/ {6 Q  set grid-x-inc world-width / grid-size-x
1 q9 L1 \9 @8 a4 t8 d# D- ]* B  set grid-y-inc world-height / grid-size-y
: F, {% q& f- \, t! R  b  ^8 b/ s/ `
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ v: f% a. ~: G+ ~
  set acceleration 0.099
% W) _, h. z3 S  P# F4 G  ]) eend
$ b0 S0 U/ I# F' Y4 g( }8 X+ l! p; ]
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ g0 l& {0 P% c6 K" E2 o% P
;; and initialize the traffic lights to one setting8 P% G- K! N; I  ^
to setup-patches
- R3 c) K, O9 j+ n. V  ;; initialize the patch-owned variables and color the patches to a base-color  ^+ }5 v! @- Y9 I* g
  ask patches( U" y( X! k$ T6 P- O- ^
  [) J3 J7 \; D  w1 D0 Z
    set intersection? false
/ a6 w( f5 q) w! F    set auto? false. c) B5 {! v+ J
    set green-light-up? true
/ a5 c+ j- Q( e; i+ s8 t4 x' I' D    set my-row -1; R. j6 \/ b" Z1 u  q
    set my-column -1
5 u# C- h; D9 o    set my-phase -1; U' a+ K( i8 p! M
    set pcolor brown + 3* N+ f5 K4 A6 C
  ]
* m- c5 C1 w) p" W& N3 w. G+ w, G) W' T
  ;; initialize the global variables that hold patch agentsets  Y/ d" A2 P  j5 l  }2 `1 V8 W. I
  set roads patches with- [0 M( ~2 Z4 q( B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 g" ^9 Y3 Q7 f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 _" o/ |5 b; W; E2 r6 b3 Q
  set intersections roads with2 E/ q1 Z8 M# o9 I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& ?+ W9 m$ m5 [4 w, H& O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ ]5 A- z+ n; u& a' v  ^4 y
' ~  h0 h( {0 K7 l9 H( c* X
  ask roads [ set pcolor white ]' i- I* M) J# _* T
    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?
3 t# R0 E) \3 b set roads patches with9 _  d$ [4 U6 l7 e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# T6 m$ r* [% a1 a0 l4 ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 q( u9 v: J* s3 Q: z
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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