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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。# J4 \: [+ b( E
netlogo自带的social science--traffic grid这一例子当中,% g8 t" M# U% C+ L
globals# K6 m  K1 D) W8 O
[
7 y) A) L/ M/ @* I( J  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) t' K1 h5 c# K) f  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ [* t: f# W1 G! ^
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) J3 @) w/ Z; F& T7 o8 c: d( y
                           ;; it is to accelerate or decelerate+ |$ ~5 `9 j9 F
  phase                    ;; keeps track of the phase1 ^( l" B2 S% y' I
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. U' w& N: w* y: r3 ^6 x, m
  current-light            ;; the currently selected light0 F/ `) ?% i; a% x' d/ d' ^

$ E3 J# [' g6 a9 s/ D  }: A7 p  ;; patch agentsets, ~4 c: ~/ i& z- a* e, T6 Z& e
  intersections ;; agentset containing the patches that are intersections$ f+ ~9 W/ k/ j% i* ?+ V4 Y
  roads         ;; agentset containing the patches that are roads6 p+ k# @, M7 Q* P
]9 U' \. e  D3 H6 \

) g2 ^! Y# L6 g4 G  X# F/ K/ _3 Mturtles-own
- [! A- l9 e% y8 M" X0 z[' g# c8 {6 u' K
  speed     ;; the speed of the turtle
/ o8 w2 Y- @& ^/ s6 ~- y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 ]( n* j1 i" }$ z2 i" S  wait-time ;; the amount of time since the last time a turtle has moved' F( c9 a9 C( P* ?
]
" i: j: ~/ O8 ?7 C6 b1 {( X) \1 Y5 J, |' _5 |
patches-own; _( S' _( {) p, E+ O0 q/ \4 W
[
( y( g7 w* \$ K  intersection?   ;; true if the patch is at the intersection of two roads/ n6 ^% I: @# U  M# B+ ?
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; W) F+ _  s' w* u6 h- p5 E( T- ~$ U$ A
                  ;; false for a non-intersection patches.
5 w* D5 |* l* Q  c$ t" |* s  my-row          ;; the row of the intersection counting from the upper left corner of the
1 f" `5 x% T' e) A4 o# l: \4 }                  ;; world.  -1 for non-intersection patches.
5 {8 x. }' S" s8 X: F) g  my-column       ;; the column of the intersection counting from the upper left corner of the! u8 y  d- @" \  n
                  ;; world.  -1 for non-intersection patches.
9 s5 Q3 t0 G8 |9 |( Z/ k! L& J( N  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." B9 k# I" }0 b! T- Y3 Q
  auto?           ;; whether or not this intersection will switch automatically.7 T6 L0 K+ a: G( Z1 |' c. V
                  ;; false for non-intersection patches.% O4 f0 Z! l8 z( H* R6 u
]
% @* H# W' f7 ?( ^- o% g7 m% {. W4 \% y

# C. Z, A( L; W( };;;;;;;;;;;;;;;;;;;;;;
9 R( a1 X9 s) x$ E! }0 M3 Q7 n;; Setup Procedures ;;2 j. k+ ?6 j6 S% K
;;;;;;;;;;;;;;;;;;;;;;
1 L: o6 p2 ^  x, d& M% G/ H5 S  r  Y& z* n& V3 p7 s
;; Initialize the display by giving the global and patch variables initial values.( _( f8 C# m: z* n: P& Y% G
;; Create num-cars of turtles if there are enough road patches for one turtle to  s4 I3 S5 z' c+ B  I; e
;; be created per road patch. Set up the plots.
0 I7 q  O; z$ R4 t! q9 qto setup8 {- J  F1 ]" L. ~3 {
  ca
: H, Q6 x4 U0 y) \, j  setup-globals
' ~; q6 V; c9 E/ j! w" N4 y# ?# h* t& B$ h. u/ J, g
  ;; First we ask the patches to draw themselves and set up a few variables
, i- U1 g% K7 s, V. M) [2 M. \  setup-patches
2 s1 Q; w* t5 O- I  make-current one-of intersections
  ^  L9 x# l+ |  label-current
* ^0 t+ D4 x5 G: c7 Z8 X" m( b. t9 n  o
  set-default-shape turtles "car"
1 f% t  P  {) O) S, O$ }& `: z% M( m% N$ i6 Q
  if (num-cars > count roads)
8 Q; L9 {2 b/ O8 {. }$ N  [
* n2 J' C" O3 [$ ^( `7 [# M    user-message (word "There are too many cars for the amount of "( s! g- p7 p0 s1 J: {& i3 X
                       "road.  Either increase the amount of roads "$ ~+ h  L* S$ p/ }
                       "by increasing the GRID-SIZE-X or "8 J: B$ y- o7 ]" E5 x+ n) {
                       "GRID-SIZE-Y sliders, or decrease the "
* ^3 {! z# f, V& c; c  A  q                       "number of cars by lowering the NUMBER slider.\n"
0 Q- K, X" A7 F& _                       "The setup has stopped.")$ m* O6 s: V3 e& ]; b
    stop
+ C* P: N4 ?. G# c8 E- T  ], _) M( y. |: n/ J5 m) p
( G/ `, b7 m8 Q& V
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 o! [" k! L7 \/ v
  crt num-cars
" o5 H% J# O/ D- b5 l; Z8 b! j  [7 T8 a6 Z- [1 b* ~; _3 X) f2 v
    setup-cars
5 B& z" K: |8 M* ^5 x, |    set-car-color
% O& o8 ~# C% q/ Y1 r; z    record-data. v4 [. z" E8 p. X/ {2 ~
  ]. R$ f5 C1 b" }, m; U! G
4 F/ A) F' T3 N  G6 M! g
  ;; give the turtles an initial speed- r9 Z$ v- G' Q7 f; O& Z
  ask turtles [ set-car-speed ]
6 k, o7 M1 h1 e. H% ~6 c1 o* i
0 R* z3 ^* M0 t) F, q5 d/ G7 ]4 j" i  reset-ticks9 t9 ^2 {! \. S
end
9 z- N9 ]$ u+ z' h( A5 A% F
1 l% h$ }0 A) ^% T; P;; Initialize the global variables to appropriate values
' \1 @8 v- L% \  l) Q: I3 kto setup-globals
( F# R0 V7 r" T6 q  set current-light nobody ;; just for now, since there are no lights yet
: T) D( {% y1 [7 F  u7 E  set phase 06 x  L- y* t" B# y3 N" `7 L3 y
  set num-cars-stopped 04 v9 n$ ]: U) n
  set grid-x-inc world-width / grid-size-x
, p7 S4 U, O) d' r! c/ B  `  set grid-y-inc world-height / grid-size-y
; r' z( V3 E6 ~: X3 }
* X3 h; W& ~9 U  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary* k1 r, K3 i& n5 F
  set acceleration 0.099
% u1 L" n: j1 v' M0 ?' P1 Wend
# v- N/ x' [! w7 c- U$ D, ^/ V1 q, z5 @) b
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- _. P$ h/ ]) [4 T$ t;; and initialize the traffic lights to one setting
$ A& L! `; b7 ^% ^: [to setup-patches0 U: }) R5 ^$ e+ R$ r4 V! z" z
  ;; initialize the patch-owned variables and color the patches to a base-color# ~6 _2 K# x/ n# N
  ask patches
  O8 R( e+ I9 T2 o, v5 F# w  [
0 e8 }( j; r+ _+ y8 E" M0 l    set intersection? false% n  w6 d' c  m" [: Y: v- U4 [$ `1 _
    set auto? false  _& M3 W  y1 Z. d8 T) }
    set green-light-up? true
) E# o6 b+ c7 z5 N3 R    set my-row -12 O! E) u6 T5 z3 N7 i
    set my-column -10 g( g( |& h+ ^2 q/ F4 n$ r
    set my-phase -1
5 \1 K' E1 u7 Y) r0 W    set pcolor brown + 3
3 g2 _% z- G2 m" x8 C  ]
1 N$ x$ X8 ~. ]0 J' Q7 E3 ^2 Q* Z0 E
; _2 C# T) T6 J9 j! o  ;; initialize the global variables that hold patch agentsets
" N: M2 Q8 q4 R4 e0 V  set roads patches with
; b3 S: U9 f' N0 o% a: Z/ b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; r$ E5 J# \/ r, f! O/ M7 T+ y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% Y" c9 \/ F% V  {1 `( D) y0 F+ V  set intersections roads with% Q, i( a* p/ L2 W0 S- X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! q; b4 i. l1 G$ h5 ?( \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 f7 I- B0 n0 r5 k
* |$ I- ?! _# t6 P" p& z
  ask roads [ set pcolor white ]
& J! {# v9 o: G7 W% c% J    setup-intersections
9 U; J1 N$ E& G0 I5 cend. O  A# R; ?, g4 T2 j0 c) g- }
其中定义道路的句子,如下所示,是什么意思啊?
- K; x4 ~8 w7 W9 i- u9 _( o% M set roads patches with0 B! M6 s- N0 I# D; p' D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: R7 Y9 ~0 R6 W. Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; q- a# ~8 A; L% a. S7 b+ ]% p
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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