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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。
: B5 `! l. J( ^! C, \netlogo自带的social science--traffic grid这一例子当中,
9 {: _- t& S) t( n, k2 [globals
: A8 E& v6 p2 p- o3 c& {% B. b[
; K4 f/ F: s1 Z4 B, _  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 L( \9 L2 P7 c/ M( x3 g  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% m- u. q( Q9 ^" Y! }  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 L/ o4 V7 |( [8 e7 H  P! w' D
                           ;; it is to accelerate or decelerate
, H; v: a: X, g9 `( ?, `  phase                    ;; keeps track of the phase3 u( c9 n" ~4 _+ Y7 i$ Q* e* O9 m
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) E' N+ |, f. H& R% K" K  J8 p
  current-light            ;; the currently selected light$ ]2 {; ~9 }) X" s# H* @9 X

: g6 Q! c2 F) W! y( r. s  ;; patch agentsets3 S) k* U4 v, A
  intersections ;; agentset containing the patches that are intersections1 E" `/ `5 |1 G4 P% J. o
  roads         ;; agentset containing the patches that are roads
) x; i: L% Z4 d: P]. l3 k6 e$ ?) S+ c8 \8 j# ]

% |% N$ c* @& Rturtles-own
% [) g' C- ]1 c5 t8 X3 P[8 N# Z5 `/ G/ s1 T7 y9 O: {& g
  speed     ;; the speed of the turtle! Z' A/ p2 Q7 H1 W, p/ p0 g
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 A3 d4 `; H" i2 Z( V: \! T2 V% Z  wait-time ;; the amount of time since the last time a turtle has moved% ^8 R- A$ s. O$ H* b" F% f
]
" A, a; V- b* j8 r
  ^. F5 X1 f+ v6 ~+ G! wpatches-own+ f; m" x0 v& c4 q8 w# n( f
[
/ I! c6 B0 x: [  intersection?   ;; true if the patch is at the intersection of two roads
+ _: r. k# \4 o4 L+ b- b  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& Y: D% S' {! Y& o) K: a                  ;; false for a non-intersection patches.
+ [( t' M2 O" F  my-row          ;; the row of the intersection counting from the upper left corner of the& O: r% ?$ [0 B$ v6 j6 V! N
                  ;; world.  -1 for non-intersection patches./ H7 H9 y- Y+ y7 G. r5 g
  my-column       ;; the column of the intersection counting from the upper left corner of the
3 y; {: k. @* N4 Q# i% \                  ;; world.  -1 for non-intersection patches.
  x3 c+ L1 D( v. j3 i$ ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ F' B8 b4 K) I4 Z; G8 W! f* ^
  auto?           ;; whether or not this intersection will switch automatically.8 @. r0 x9 o0 k& B  ?: t
                  ;; false for non-intersection patches.0 `' \7 |- _+ q, y& j! F
]  x7 o4 [: I: E+ d2 g  }
- A  ]5 P7 @( S( E5 e# v7 w7 C

. m5 s! l8 m: T- V& J4 C8 o, `/ U;;;;;;;;;;;;;;;;;;;;;;
2 [* q/ H/ ~& x5 W) ~;; Setup Procedures ;;- u/ W* E& L) w0 [  V
;;;;;;;;;;;;;;;;;;;;;;
2 x- u0 e6 Z  w# r' ^
+ [) ?; }3 N! c" p/ [;; Initialize the display by giving the global and patch variables initial values.
$ W" R( M! `$ S9 E;; Create num-cars of turtles if there are enough road patches for one turtle to' A0 {0 X8 T, r7 l
;; be created per road patch. Set up the plots.+ _& u% f2 @& x0 ]" U! m6 Q3 c) T
to setup
) S2 ?" W$ o9 D1 L( ]0 o  ca
8 ~0 i6 H: ^' ?8 y1 U% H  setup-globals
8 Q9 f% M5 L0 I, }* f- }' x
( Z0 j* E4 I! ?# d  ;; First we ask the patches to draw themselves and set up a few variables
$ n+ C+ E4 I& ^  setup-patches( R8 r% |+ |' S" q. L
  make-current one-of intersections( f% i, c) C/ J) C& X  n4 T, L
  label-current
* _0 p8 ?" _; [: |& g: S! u5 \4 m# y, {6 e. d+ C
  set-default-shape turtles "car"' Z7 Z* {8 t7 v7 G5 E
, x' D. a) q* [, v
  if (num-cars > count roads)3 t& D2 d* u7 Q; |: @; Z
  [$ \; C: g5 X9 ^) Q$ B7 u& x% ?; s
    user-message (word "There are too many cars for the amount of "9 H: Y! @2 B& C9 M. c1 F
                       "road.  Either increase the amount of roads "7 G5 d5 z: L! Q( h% Z: x$ u" Q
                       "by increasing the GRID-SIZE-X or "% p$ i) G8 `6 U4 q# f
                       "GRID-SIZE-Y sliders, or decrease the "
. b- M# C+ s9 ?: {6 {4 \+ w3 d                       "number of cars by lowering the NUMBER slider.\n"# Q% D" V/ p0 d' O
                       "The setup has stopped.")" V0 Q) O7 y# o2 J8 q$ {
    stop
6 b$ q* q% L2 f8 E/ e/ B  ]& V( q, O, D8 @/ E

4 B8 H+ G% P! [- V  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' e+ _# h2 H; e  crt num-cars2 U* u! s$ [9 X8 i
  [  _" q# m, y& }: l
    setup-cars2 Y" X. a5 D1 N9 c9 M# ^7 C
    set-car-color
& |7 X8 ~5 O4 W) S( g) v6 r    record-data
5 U( O8 p8 _( W6 M' E0 ?  ]
9 v; K! H5 G7 e/ q) d5 T8 w
, j( a- E2 B5 i  ;; give the turtles an initial speed; }$ t( J' y( l: F" I7 g9 f) c
  ask turtles [ set-car-speed ]
$ {0 B3 D: S2 _6 y; B
5 P# C: K8 S' r7 E/ ?/ ?  reset-ticks) O0 N% \% w2 F
end
! E- T0 z+ d1 w
6 X" [' z- W, v( N7 n;; Initialize the global variables to appropriate values
# b+ ^0 I# B, [; Xto setup-globals
: L/ y' Z! U" H% q) {  set current-light nobody ;; just for now, since there are no lights yet
: T* x3 v( Q5 l: l; d  set phase 0/ e' U* Q- l4 q
  set num-cars-stopped 0
% ?% x6 d% l8 \0 B) O+ e, g8 g- x! s9 ^  set grid-x-inc world-width / grid-size-x
" l  T: ?/ z/ ?+ E' D  set grid-y-inc world-height / grid-size-y
* V$ s7 }* r$ G2 M, q
+ k' Y$ i$ N/ E. l" ?* Z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 f1 d5 U; j+ J* ~( [
  set acceleration 0.099
% |& \7 R. x+ ?* C: y2 m. Xend1 d; G8 M; N2 R0 ]9 z' M

0 u2 q+ `" Y# F( i' X  N! f5 D;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ O( d3 t6 S) C5 ?( L3 c
;; and initialize the traffic lights to one setting
9 _1 i# A+ u  ]2 tto setup-patches' H- k$ U" N% p5 S) Y4 m$ G4 K* Q" [
  ;; initialize the patch-owned variables and color the patches to a base-color- z# N2 j3 o+ e( j# Q
  ask patches! \. l  T) A7 ^8 o! v
  [
: i) t2 t7 B2 k* ~/ S    set intersection? false1 m; i+ o; I8 |  p3 P- ?' l
    set auto? false: B% G& d$ _6 ]- S
    set green-light-up? true
5 o8 ~) P2 f# {0 \7 B6 k8 O    set my-row -1; }) x# j. D( a- Y
    set my-column -1
3 ^7 P3 x8 I* V, p2 z# @* d' i    set my-phase -1# l& K5 W) a6 E  \* H8 }
    set pcolor brown + 3
' x4 ?+ H: ^+ W4 k  ]
8 A0 Z: [5 n5 B/ x4 _
$ g& V0 V* s* r! u  ;; initialize the global variables that hold patch agentsets
) z: I* y5 I; B' B# `( n  set roads patches with  q% C6 s! [9 ^( H8 B- k2 O& h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: B$ L6 U  C) v( {1 J- s/ Z& B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' i1 V4 p3 P, R& g  set intersections roads with
0 c+ r9 |1 m  w) r3 B$ }9 S/ V- q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
# t8 O# Z; k- [, e( ~7 U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 y7 _8 h" o8 U, w" \' e$ @
0 {0 Z6 _% O% \  T2 b' N
  ask roads [ set pcolor white ], A. o$ I4 D* i$ o
    setup-intersections+ Y9 y' W' n* o) y) P
end  A; _7 w  e: q, N3 M
其中定义道路的句子,如下所示,是什么意思啊?& Z" F2 U' H" ]
set roads patches with
* o5 A) e% n6 {3 ~4 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ W+ k; K- S) Z. I# ~/ {7 L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! r7 V0 Z9 A2 _# Q0 i7 K6 |) t4 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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