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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。& {6 h1 o" Y8 l( V
netlogo自带的social science--traffic grid这一例子当中,7 X- P, J: j# Y/ i% S! @3 T5 J
globals2 C0 r* f* z4 X, G* q
[( L1 J* A8 m0 [' [6 c* E% G
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. T" ]7 ], E# u8 w" o5 E  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ D: P# W+ j9 y% v" P2 @$ v# {
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: N5 ^3 n: {, Q+ X" D6 g' n  b0 |" Q) W! h
                           ;; it is to accelerate or decelerate
* d1 w5 Q- s. P& g- \0 @  phase                    ;; keeps track of the phase
9 I+ O" M' _4 I  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* ^/ P7 n: F' V, E" U, u  current-light            ;; the currently selected light' b9 ]1 V5 ^3 ~' r

7 y* t/ |1 t8 U) i+ ?  ;; patch agentsets& A/ F4 t1 f$ G, |" Z9 m
  intersections ;; agentset containing the patches that are intersections% j  k+ N, `8 [
  roads         ;; agentset containing the patches that are roads
2 f3 b2 X3 K; }% c& Q, w2 x! M" U]
& c' G7 W# z2 K: |
/ _9 H+ \3 P7 D2 {- M5 mturtles-own
' D2 ]9 v$ I! o. t! u* P[
4 V  I  P6 R6 ^$ [) Z  speed     ;; the speed of the turtle& N& Z, Z4 B2 q( R6 P. U% H
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- d* g* O! @+ e3 W( h  wait-time ;; the amount of time since the last time a turtle has moved
, d8 h% [0 `5 p; V9 B  c: ~]1 i# c0 X! N; c( `0 x
. `6 H& t3 H; S0 f
patches-own: c2 G9 K9 @6 \+ C7 U
[7 n5 ]) S( h/ q% U
  intersection?   ;; true if the patch is at the intersection of two roads  i, |9 m0 j  _1 x' L
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ E; i2 c2 U0 s( x4 c                  ;; false for a non-intersection patches.
& [. u$ o$ j/ u  my-row          ;; the row of the intersection counting from the upper left corner of the
" s* U7 n, ^$ v+ H/ p, Z                  ;; world.  -1 for non-intersection patches.; a/ }: B! Z; {3 Y; y
  my-column       ;; the column of the intersection counting from the upper left corner of the, A+ T& T0 V' h+ a
                  ;; world.  -1 for non-intersection patches.' b2 {; _1 R7 I- W4 R
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 f. ~) h; a0 {! A: h  ?
  auto?           ;; whether or not this intersection will switch automatically.
7 N/ |. e) L* l: x/ h4 g" N# M' R5 [6 G                  ;; false for non-intersection patches.
' l1 y7 M- ?. c9 r. j  P# t]
" T4 o/ u% l% ~4 D. ^; q- x. Z8 a6 ]
# a& l- o" \; e4 G0 F8 c' h
" a! I8 ~( s; [;;;;;;;;;;;;;;;;;;;;;;3 O- [$ g( ?2 G
;; Setup Procedures ;;" o: [4 z) T6 p( a5 h+ W7 z
;;;;;;;;;;;;;;;;;;;;;;
& L1 w6 g% R' F8 F6 l/ ]& c1 m; N! z; B; g( w
;; Initialize the display by giving the global and patch variables initial values.0 h; q$ A. p# K  o& t
;; Create num-cars of turtles if there are enough road patches for one turtle to
* \$ G! ^3 s- ~' F! {;; be created per road patch. Set up the plots.
! O* T# c: Z: \1 S$ d. wto setup
4 L4 y+ l# N$ }6 y4 d; N0 ?  ca  f! n& I; O- y8 T3 Y" q
  setup-globals
# G" j3 J' b3 K4 J+ l: `9 ?  f3 E( J) c
  ;; First we ask the patches to draw themselves and set up a few variables
/ i. T6 n: j) a9 @" L& w  setup-patches
2 }0 `+ a7 u) X4 ?3 B- d! V4 j0 D- G  make-current one-of intersections5 B" h8 A- _* S7 Y: b
  label-current/ [, s- d8 K& @7 e- e
  c$ r, f! l! i' C: }
  set-default-shape turtles "car"
0 U" S5 d; ~% G! D
- J; Z  }- I2 \  H/ H8 p  if (num-cars > count roads)3 e6 ~1 ]- i( N7 O$ G' E
  [
( v) x2 G9 }$ @" L    user-message (word "There are too many cars for the amount of "
' ?% `$ ]2 ]* ?% r4 K, g                       "road.  Either increase the amount of roads "7 [$ u1 g5 {, Y& N
                       "by increasing the GRID-SIZE-X or "
( D+ z8 ?; |1 e& F. [/ d7 d1 a. s                       "GRID-SIZE-Y sliders, or decrease the "
) n% J" x% Q1 ^5 c9 R+ Y                       "number of cars by lowering the NUMBER slider.\n"5 t: z  ]+ c, e' _  ^9 [
                       "The setup has stopped.")5 F# g0 L5 S& @3 Q5 w6 S9 U/ o
    stop2 s3 v* i2 K! ~
  ]
6 x# ^0 t3 e; `5 `
1 _- r- J/ h) s2 m' p  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 v- U5 A7 B: W1 x( x* j# r% N& X
  crt num-cars2 ]8 ^1 m5 N  q$ m3 W
  [1 M- Z$ S' U7 V' U1 e# P
    setup-cars
5 \' m& l4 d, [9 X' J    set-car-color% O) U. P5 g, P! G) k  f0 X  U
    record-data
& q" C5 J4 C  s. D* o  L0 F1 H  ]
6 t* Q0 ~. _8 [- E& U6 m$ O/ f9 Z& I
  ;; give the turtles an initial speed
( ~" y1 X& ^  O# H9 _, j  ask turtles [ set-car-speed ]5 R2 Q+ _9 w  g5 o

5 }% r, f! g# N: i0 ?' Q  reset-ticks
) E8 q! ?5 C+ M7 |3 p# E# R4 c/ bend( Y+ R+ ~  P8 b5 L5 \$ k5 d

8 c. G. B' a+ d/ ]8 K8 h;; Initialize the global variables to appropriate values
# H9 K" |0 i0 {$ Bto setup-globals
; C, a1 P  W; `* B+ e) p! e  set current-light nobody ;; just for now, since there are no lights yet9 X% l$ ~" l* O, ?) b# b: O
  set phase 0% s* y( w* J' L( o1 D2 c
  set num-cars-stopped 0
, ]# j, D. [( ?4 y; P/ L* q, `  set grid-x-inc world-width / grid-size-x
9 d* b% O5 {* T. w( J: l! }0 d4 l  o  set grid-y-inc world-height / grid-size-y& C9 \5 j& x5 _/ B* P" b$ M4 u

; f) E8 S# c# q1 K6 @  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ ?; D3 W" C- q4 i: n  set acceleration 0.099* u6 v5 E1 u3 d% k! G* {! ~+ G2 X
end, V3 F, v5 G3 n- l7 z3 h7 o2 f4 z

5 w' u% N1 U. p6 u8 o8 r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
/ t4 C0 k* a6 @0 s;; and initialize the traffic lights to one setting
$ L$ l4 I2 r3 E) r. V9 G+ z# rto setup-patches$ `5 \  b- J1 L/ Y
  ;; initialize the patch-owned variables and color the patches to a base-color
0 K" C0 U/ W  g9 S8 p. \  ask patches
" g( d& @7 t  `* ~" p  [$ A8 q  e% a) i4 y4 V  w3 J
    set intersection? false& m# o! M. V: h1 r" ?; D! l
    set auto? false; G8 v# h: O6 p- v1 V4 k( w
    set green-light-up? true  g  L; L2 z, A4 J* f; @
    set my-row -18 p' r, L( W  s+ j( ~+ A
    set my-column -18 ]. R( k) q- i9 A9 v7 Z6 u
    set my-phase -1' K+ m  m3 l1 g9 V8 u8 r
    set pcolor brown + 3
& q& R9 ?5 T0 _' u( D4 Q& t9 D- g  ]* R5 D7 b8 M/ V; O
8 E3 J" x" B$ G% P+ h* H5 S
  ;; initialize the global variables that hold patch agentsets6 W2 A! n3 P7 o5 @, ^
  set roads patches with
, A5 G: ?) Y# ^) T3 T/ R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) Y, h$ o  a8 c5 u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 P* @7 ~( R+ Q/ c' Y, L, p7 J
  set intersections roads with1 C) Z# I6 R& P$ X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and7 ~% e2 |4 Q/ M; k3 U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& W+ Z+ P- n# q$ F3 s

$ |7 x& [# k' h2 s* U  ask roads [ set pcolor white ]: z9 \/ \& u& g8 g- C; k1 T( g# |3 @
    setup-intersections# w) @2 V2 {9 H
end
( l: v" D1 W" t+ D, m  W! @8 P% Y/ \% z其中定义道路的句子,如下所示,是什么意思啊?) ]* @0 s  @# u, l5 s* L( S* M- ?
set roads patches with
' z/ u' d/ _/ A5 j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 ~7 j. u$ ]8 U- X1 ]; ~# f' M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, z3 \. m5 ?3 d% H& h6 w2 R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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