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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。
) Y5 w, M- d2 {) p( w7 {/ W" Nnetlogo自带的social science--traffic grid这一例子当中,# Q- ~4 v( t0 ~7 K4 K
globals; I! P# f0 W9 _4 w: _% L; D8 I3 \
[
( z& ^9 X' N9 Q/ T: z  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 ~) c- p$ n2 I6 T
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 M- ?" @/ t" l& \  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( F8 p) `: j( j* B: c
                           ;; it is to accelerate or decelerate
- N: }+ G6 k; p* K  phase                    ;; keeps track of the phase  ?* F  x$ ?3 H$ K
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: h- l( P2 C0 x* Y
  current-light            ;; the currently selected light
# \/ w) {, l( Q6 g0 z6 a6 D7 w9 A( ]# K- w" B4 h4 c
  ;; patch agentsets7 P# Y  D& _! d/ e- e
  intersections ;; agentset containing the patches that are intersections
' d, c8 k# ^$ t  roads         ;; agentset containing the patches that are roads
3 d+ H2 w0 y/ Z3 c) a" `]) u2 T* Y# |) p
" o7 e2 o5 ]2 _. Q- ]. I& v
turtles-own
4 y" e& B; }% |1 V3 p( ^: b8 g[
; }! v9 X' f, A* C1 d, b  speed     ;; the speed of the turtle
* V7 e" D' m) G0 V1 Y) ^  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
' b) N2 A* r, t; l* {" w- Y  o3 i  wait-time ;; the amount of time since the last time a turtle has moved2 z7 \& Z! _# {/ |
]( I' e$ W, z% ^# g

  Z9 U/ ?+ }7 D" Epatches-own& a: [5 N9 h) Y! E- K
[
- U. q8 Y$ c5 D  intersection?   ;; true if the patch is at the intersection of two roads
. t2 c$ \$ G* z2 @: S& d) _$ {$ s  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." {2 D6 g1 c0 J
                  ;; false for a non-intersection patches.
; c# c) B$ p5 j  \4 _7 R% U* u  my-row          ;; the row of the intersection counting from the upper left corner of the
0 V# \; u4 y$ G3 T# T! z9 _, d                  ;; world.  -1 for non-intersection patches.
. {7 a. ^6 m; _3 r" F& l$ Y' @, p0 F& `  my-column       ;; the column of the intersection counting from the upper left corner of the
! S/ K) a2 G/ ?7 s& \' g                  ;; world.  -1 for non-intersection patches.
, ]1 L0 c) T3 Q: f! y# Y  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- ^( T3 ]3 J# I; ~; q
  auto?           ;; whether or not this intersection will switch automatically.
/ F; w& `/ f% e4 a/ Q1 T1 y( o                  ;; false for non-intersection patches.
) C0 |0 k) z+ _# s8 e; d]. t" w7 @$ x9 E# X+ y) B
* a( i4 C" g9 Q  W) ], g; G; a2 _
. z4 j% ], |! c- g- g
;;;;;;;;;;;;;;;;;;;;;;
; d$ N# n# o9 s7 P& k, G;; Setup Procedures ;;
) O+ B$ c- ^' ~;;;;;;;;;;;;;;;;;;;;;;
9 o8 G* Z) U7 f
: `( M+ d% w4 p' [;; Initialize the display by giving the global and patch variables initial values." D& Y, a% d% l+ q: t7 _
;; Create num-cars of turtles if there are enough road patches for one turtle to- O$ \+ g9 \: D4 N% ], @
;; be created per road patch. Set up the plots.
# B4 E# Y  L% ?) R& z, s; e$ V" C6 n/ Hto setup4 ^" M+ B2 P+ u$ a  _* C9 U
  ca- O- R  B3 k7 Q! L  X* {# ?
  setup-globals
0 G) n, }7 T0 c) s: @
3 v( h, M, M: |3 d  ;; First we ask the patches to draw themselves and set up a few variables
% v; M. A! ]7 L7 {4 @- ~  setup-patches
9 b' v5 }' k" f  make-current one-of intersections& w3 }+ R. h  R0 j: F
  label-current/ k. g, o2 q' b6 }$ A0 ~

$ Q$ g( O2 V: G) c  Q  }  set-default-shape turtles "car"
: M$ D# ]" X+ Y
  E" T- c" I5 `$ X9 |# c  if (num-cars > count roads)
) D4 U4 P7 p7 [( J  [% ?% L, N% G: s2 A' q4 d
    user-message (word "There are too many cars for the amount of "( J% A( Y; }$ Y" S* j  f0 A. o' j
                       "road.  Either increase the amount of roads "1 Q& A1 S8 x1 e# j
                       "by increasing the GRID-SIZE-X or "
/ j$ ~) X) D: A/ M9 s' d/ ?                       "GRID-SIZE-Y sliders, or decrease the "
. V, Q$ e; R% P$ b                       "number of cars by lowering the NUMBER slider.\n"
. V* J! n4 q7 e# N# x, `                       "The setup has stopped.")
) v8 f: w* G. K3 h* ?& }    stop
* o- @: w9 z0 c) A) D8 A  ]
/ _$ L, c  ~( G5 l# i3 ]( F" j
0 L  Q7 ]5 ?' u1 P+ }; R  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 j7 ]+ R4 U) S$ F! [) |: o6 @% z  crt num-cars
3 P7 D( s  I) Y$ W  [
# \. H$ H. n  t' t$ J: B1 w    setup-cars6 p+ S6 \/ J& m/ {7 F6 k" k
    set-car-color7 j* `) w) x2 I* J# t: y! y- i
    record-data1 `2 Z3 j$ Y/ ?3 n5 J/ L
  ]
+ f) ]$ z# W0 D$ t$ k( G
# a( X0 W* E  \2 ]$ V1 O$ ?  ;; give the turtles an initial speed
& y! ^. I# ^+ M# L' |  ask turtles [ set-car-speed ]$ {1 I6 x' J/ r, P7 r  z6 @+ k
& C: ^6 [- d1 m, b" y
  reset-ticks; Y; x8 x- r) V* T
end
! A1 M4 ]% T+ r: d( Z6 t" J
5 H, r' `7 c! Z5 Z7 v" `1 T, Q8 z;; Initialize the global variables to appropriate values$ F+ ~& ]+ Z/ V. l2 O
to setup-globals5 ?, D) a' a6 i8 u+ l, ~) C
  set current-light nobody ;; just for now, since there are no lights yet( q  i9 {' g8 r/ V* o; W: f
  set phase 0+ |& w5 R0 }0 y: n: @
  set num-cars-stopped 0- W( Y% u$ }$ G- i. a2 ~
  set grid-x-inc world-width / grid-size-x
& c) B$ t6 B1 E7 O' b  set grid-y-inc world-height / grid-size-y
. p* D9 C; `7 w7 o- r+ z* C- H, e
* Y1 n' e. ~) O" ~; j  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
. e5 S; K; h2 q  set acceleration 0.099
0 @# r$ G$ a7 U2 z. Send+ E7 k7 {) m& [% |3 e6 Y0 ^9 F  z) U
9 I2 P7 z2 }9 R) w" Q5 B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ w4 w5 ~6 h3 r# i( ~7 y
;; and initialize the traffic lights to one setting
* }" T# F4 E: z$ C" Xto setup-patches' e  _0 A, l7 q0 v! M
  ;; initialize the patch-owned variables and color the patches to a base-color
$ l( G- @. F3 P1 o  g  f  ask patches
) E+ O/ W! {$ l6 v$ k: l$ R+ K' o  [8 B& W. b! Q. v4 w+ ~2 g! K& P
    set intersection? false6 n2 k" Q/ ]& C# K8 Y: i5 G
    set auto? false0 D, O% I* ~, b- `8 F
    set green-light-up? true7 v' |/ r- R3 K* W6 W! F
    set my-row -1/ f/ ]7 ~& a0 u/ z& W- B) z
    set my-column -18 z* ?: Z) n/ {- S$ p4 p7 x
    set my-phase -1/ |7 B! Q' P1 S7 Y; n
    set pcolor brown + 3. ?$ ^/ T0 ?% P# d3 u( X- P
  ]0 V  @$ {2 V4 a0 ~5 J! f8 o6 h* p. d5 F

2 i) w6 z2 u0 L# }  ;; initialize the global variables that hold patch agentsets
  N' h$ @7 G+ J# q% V  set roads patches with, l' d, P3 W5 C" C. Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! m  j7 w0 a& E) w' Y- l% a" T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ s/ \  k" X0 D6 i8 J+ ]$ r  T5 A  set intersections roads with/ X: f6 \- t7 P7 ^( N- X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! H8 o1 ?7 z2 C0 d7 d+ A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 N+ D; ?. y% [5 @( l+ z$ q& @$ U$ H+ h$ y* q# _+ P& r6 Z
  ask roads [ set pcolor white ]" Z5 J, J+ F3 S9 q- _
    setup-intersections% l  A; O$ j: p0 q4 ~( s  y
end4 F3 [/ l3 L# y
其中定义道路的句子,如下所示,是什么意思啊?1 I. K9 k9 n; R0 N; h& s! s
set roads patches with0 K  j  R; b/ _, N( ~* m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( N. y; I8 u& u8 N4 |' L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. \3 a* X( K+ B( v, Y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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