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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。
* P) H' c" M; A7 r5 J0 U- _8 Knetlogo自带的social science--traffic grid这一例子当中,
$ n5 r  L  w7 Iglobals
9 q( O4 t" y! ~! J, d[
" W. p2 N4 d. F- r  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ T# k+ C* x  T+ Q  grid-y-inc               ;; the amount of patches in between two roads in the y direction( i' {2 d/ G9 t  M
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& ~2 W# }& H- w" d# Y                           ;; it is to accelerate or decelerate- X  @4 o# j' z! c: L
  phase                    ;; keeps track of the phase; [- Q. Y( {  {2 q5 N: ?
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 ?/ C. f% _! i8 N. n  i3 o
  current-light            ;; the currently selected light% ]4 ?! s) b! j4 y" p2 d" h, A! T

; S0 T  I) }  x: R  ;; patch agentsets' f' f' v4 y: L# c
  intersections ;; agentset containing the patches that are intersections0 }* _3 j, Y% S/ J% M! Q& J- G
  roads         ;; agentset containing the patches that are roads7 c* t6 ^0 V; b/ X  U" g- A! F
]
( c  |' }' X. p
; F8 T; y. O; \+ t: }turtles-own8 o7 k+ l- ^3 h  f, t/ H7 \
[9 P8 K) B( h0 {: `* @: v
  speed     ;; the speed of the turtle
% s# ]) W1 m+ ^  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 t' I( F$ @3 i. w! b$ x" w8 _
  wait-time ;; the amount of time since the last time a turtle has moved
( r  h3 [  w4 O. I# c+ N% U/ M]3 Q  D5 B7 X) E! o. `7 L2 y

' c9 c0 n& r1 Y0 U3 }patches-own5 ?) X" l9 H- [; P% ~0 [. _8 S
[  E6 y1 E: [: |7 A) m- H8 y
  intersection?   ;; true if the patch is at the intersection of two roads
' ]  \. }9 W' b7 I! y/ j  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ _" I  B6 }& m) j# F# A5 Z( G
                  ;; false for a non-intersection patches.
' b! E% D. F/ ~* K& H4 y  my-row          ;; the row of the intersection counting from the upper left corner of the
# H& |9 E7 Z" q                  ;; world.  -1 for non-intersection patches.' S& |+ N' A+ h! L0 u
  my-column       ;; the column of the intersection counting from the upper left corner of the/ n# y- x7 j% g) U- L' u
                  ;; world.  -1 for non-intersection patches.
8 e. b# H. ?7 o' K0 j% k, X+ q* y- I  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
, q: Q( O# D" x) }, i; e  auto?           ;; whether or not this intersection will switch automatically.
' ^/ O6 s$ B. k/ Q+ g+ o1 V! F                  ;; false for non-intersection patches.9 z+ @1 r) f# e- Z
]2 P: U8 a* y+ R' N/ `5 l
3 p' p, o* q' T* P
& ?1 ?# M/ e% G. Z3 g- `
;;;;;;;;;;;;;;;;;;;;;;/ R9 O) I& I5 ^( T3 @
;; Setup Procedures ;;$ g9 J+ H; b. l  @7 t6 s
;;;;;;;;;;;;;;;;;;;;;;5 @- g" |" f; W1 I# H0 F# i+ i8 l" B

7 R9 J( P# e$ K8 Y) U- `;; Initialize the display by giving the global and patch variables initial values.
/ r; K7 i& H9 p4 p;; Create num-cars of turtles if there are enough road patches for one turtle to
6 D1 b7 Y6 l1 p0 b2 d1 y' L;; be created per road patch. Set up the plots.
( \; ~; }4 i' J* M1 C$ O2 P) Sto setup: W2 `6 f( r  d
  ca
# \  S+ w- A! e  setup-globals
/ `! T0 C( P+ }' ~1 A7 c  D9 ?$ V9 I. J
  ;; First we ask the patches to draw themselves and set up a few variables
: s# ^, z0 }( X# Q& |" ]# N  setup-patches
: i0 l$ f$ A/ P( Z- N% s- w* `2 l  make-current one-of intersections! F2 F# Y( V- H6 c, t, H
  label-current& T2 [+ o+ ?2 ^. d- t2 ?) u
1 Z! L7 T6 J0 G; e
  set-default-shape turtles "car"0 @  T; f0 f; R  x8 O

- ~$ J9 {6 \0 i5 g% t% v: w  if (num-cars > count roads)
- U) k8 u" _) w' }* K& l* E  [& N- d+ ~. h9 G7 d3 Q
    user-message (word "There are too many cars for the amount of "8 K- ?" r! I* C; \
                       "road.  Either increase the amount of roads "
) f. \' R, g! B0 S                       "by increasing the GRID-SIZE-X or "
6 v1 L! z; A" y7 }+ `8 l/ W7 v                       "GRID-SIZE-Y sliders, or decrease the "
! W3 z/ {) o; u2 N8 N" V                       "number of cars by lowering the NUMBER slider.\n"3 B# n  L: C/ O; Z
                       "The setup has stopped.")- X3 T( b! _) P! U5 K) O
    stop
) u" j7 |7 ]  S1 z' P, w  h  ]
* `" Y4 j4 \) x- K- u' o( y- k/ G, N1 E5 u( k* X  s! I9 D
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. U1 L+ ?) q3 H$ ~$ B' {3 i8 u
  crt num-cars9 q" d- X. L, S$ G) Z! E5 P
  [
  ?. ?  K0 R; H( q( K0 j! S    setup-cars
4 M1 ~- @; f$ P2 H4 D6 G0 h    set-car-color! P  p1 n: W# ^
    record-data
" W( y1 o8 C$ u. U5 L  ]
+ \- e: {  w) D8 ^! ?( r- O8 y# F9 O$ h% J0 F2 }# B3 t* @7 M) K0 r
  ;; give the turtles an initial speed
6 X6 u' [5 x8 U$ Q# _. F  ask turtles [ set-car-speed ]+ o! @% W  `, A  z6 Z. Y, E# K
- g" }+ F' o' V* b2 o( n9 W
  reset-ticks
% a- w7 c4 o; Y; Oend6 C' L! `& b& f% O

2 d+ T% b" `5 U0 r  {;; Initialize the global variables to appropriate values0 N# e. B% K" `6 A
to setup-globals
+ M9 i) ]$ K' }3 F" ^  set current-light nobody ;; just for now, since there are no lights yet
7 e1 }! v4 N8 v7 N  set phase 0( q: W2 Y( H- f8 y
  set num-cars-stopped 0' ^' \1 W: n* l! z* q& m
  set grid-x-inc world-width / grid-size-x
5 C6 P9 d8 @+ J: q  set grid-y-inc world-height / grid-size-y+ z# [& z) r- [% h6 V4 e
  e5 E, d2 L8 e3 h
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) j$ C0 U4 \" I: T: I  set acceleration 0.0994 V+ P! P4 V) e
end
) T  {  g3 [9 e4 \
: j6 Y, ~: Y& {3 S;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 ^9 j- ~# Q' y. q( I" p;; and initialize the traffic lights to one setting
% K9 d7 X2 k9 H- j4 d$ Ato setup-patches
+ X  ^' k4 A, D) q# {  ;; initialize the patch-owned variables and color the patches to a base-color( j: _+ s* i2 q. P( Q$ c
  ask patches2 G# c( r+ A' G$ V9 {2 E6 {
  [
; {# z1 t7 Z- t8 i    set intersection? false5 ]1 i( R6 c2 R5 p1 w& A
    set auto? false( c! g! Y% J( F1 A
    set green-light-up? true
3 y4 V5 N, G* E3 @    set my-row -1  F/ C: C8 I. E7 y, H, R+ ]. {
    set my-column -1! p; o. c* ~0 P4 b% X! Y4 p
    set my-phase -1
7 r$ x4 i7 U3 T+ C$ m6 ~5 p    set pcolor brown + 3
! }2 y4 s% K" d% j7 ?. p  ]/ ]- F9 x/ V4 N9 R# q0 A2 X+ Z

7 n0 n) {  v0 [5 ^5 {  ;; initialize the global variables that hold patch agentsets
( ?& ?+ O5 A) G. d& O# c2 t* T. H2 g  set roads patches with
& y, u+ {8 q- L) ]8 q. K+ L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 ~; }: ?* s% T8 o% K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 q- Y1 ]! N1 @$ ^! a, ?2 X  set intersections roads with9 V' {1 ?, e% [' G. F+ k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ E8 k6 E8 {: ?7 R6 B# H8 C" k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( ?' i  }( {$ C, i) v, A% V, ~4 W* x

! }( `: q+ k' U$ Z! \  ask roads [ set pcolor white ]. T5 [5 j6 l6 O6 }9 w
    setup-intersections5 E$ S* z9 D' g% a3 U
end
& H' N( E5 P; V其中定义道路的句子,如下所示,是什么意思啊?; N) u/ h5 q' m! i
set roads patches with
  [. [5 _+ e2 V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 q6 g. i# L& s+ \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; u8 s& W1 q3 i7 ?& [
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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