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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。1 y0 C! H& N. p% z+ M
netlogo自带的social science--traffic grid这一例子当中,
% h% y1 \- @/ r. I+ Iglobals
1 Q* Y3 D/ Y( t0 k1 U5 `6 Q) i[& m$ Z) j6 b4 G$ B0 J9 [% J3 l
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 e% @. y# A4 K3 y% O0 s7 @7 O% O  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 `0 B( H( P) w$ b' {/ v  C  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 |$ s! f" W8 a0 a( A& c1 J                           ;; it is to accelerate or decelerate& l) a7 L& S% |  c& u
  phase                    ;; keeps track of the phase
% I0 J5 R! Y. {; p/ J1 x* u; t  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" c+ C! ~8 {+ }+ l* Q  current-light            ;; the currently selected light; R5 X6 B  _( C/ x8 a* q4 R( X

9 b) Y' J7 Y! M# t" G, W8 c  ;; patch agentsets
& H/ h( [/ W4 ^, j, I# I  intersections ;; agentset containing the patches that are intersections( N0 S! [9 }$ S+ c. O* r
  roads         ;; agentset containing the patches that are roads
. e& G: D/ l/ j# b; []  V. J/ R9 W+ T. Q$ f2 H/ b
8 X& P$ S" U& [& \# a3 s) Z
turtles-own) I2 m6 G: C" L' R( F7 ~3 d- v
[
. S8 h. n6 R$ b: K* w- J  speed     ;; the speed of the turtle! `6 x1 F) S1 @  Y, M/ [$ ~$ F
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 f. Y# v1 |7 p2 v! }+ j3 Q
  wait-time ;; the amount of time since the last time a turtle has moved
. L/ ^5 t. r. o% y: z) u( ]]
2 h8 A* g! `' ?: D, O1 z/ {' q
; K) E4 t) K  ]  }patches-own8 H/ D) q, J# G3 j3 S
[0 G( L- X5 ^3 h. U5 B) @
  intersection?   ;; true if the patch is at the intersection of two roads
: ?1 k: n/ I4 E8 I3 N  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; H3 S1 A/ F3 b! A1 ?                  ;; false for a non-intersection patches.
3 s& K+ M7 ~6 x$ f7 y! [( o  my-row          ;; the row of the intersection counting from the upper left corner of the1 |# x  J) x4 v' [9 t$ k5 s# l: v, D
                  ;; world.  -1 for non-intersection patches.
1 e3 \4 d* M. m2 [  my-column       ;; the column of the intersection counting from the upper left corner of the
/ J# {' |. U( p" i/ _6 V% Z$ Q) V/ }9 V                  ;; world.  -1 for non-intersection patches.
8 z, L+ `0 T, Y7 E: N  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. V& j0 _* w1 B/ ?! n
  auto?           ;; whether or not this intersection will switch automatically.
* R( G0 |- e* [7 L$ j5 O                  ;; false for non-intersection patches.0 U3 @1 {* s) Q' l0 \# V
]
$ o9 x" g7 B: Y' O- L/ z3 s8 Y- R
/ D3 R0 h* m! R- \  d, v) ]- l, i7 C& F! \: y- F& P7 b! H* t; t
;;;;;;;;;;;;;;;;;;;;;;) {: q0 v! o! ^$ S
;; Setup Procedures ;;
; z# }# U" N3 w$ h& V;;;;;;;;;;;;;;;;;;;;;;, ~5 v# C0 Z+ w' {+ p
, p4 {& v, V7 p; N
;; Initialize the display by giving the global and patch variables initial values.( E; f  k' @8 M' B' d
;; Create num-cars of turtles if there are enough road patches for one turtle to
4 T, R( m' p7 g" T9 g( o4 H/ h;; be created per road patch. Set up the plots.
* P* h& B& Z# n* L' N3 fto setup
- I9 K& F- t! b+ U7 {; ~  ca2 S: i: P  U; _* k
  setup-globals, I* |! b. R: S

2 i" q0 d7 @: l0 z7 A" A& G. g( p  ;; First we ask the patches to draw themselves and set up a few variables% }4 }* M+ E/ r6 g( R
  setup-patches
$ ]1 u& \5 t/ e( f$ ]4 T. d  make-current one-of intersections3 r. G8 Y# y: }0 w& S/ L' |: a8 v, C
  label-current
8 I) e) G1 g7 C7 _3 O
1 l; ]% {5 C- y/ z  Q  set-default-shape turtles "car"
; [0 r' M8 H2 ]2 o  Y, \
3 b# d2 ]- `. i  if (num-cars > count roads)% l; x8 o" [2 A# h2 Y
  [
9 r; g* u9 f& O/ `+ S3 t    user-message (word "There are too many cars for the amount of "
* p8 }/ m6 |) `. F, [' L: Z                       "road.  Either increase the amount of roads "
" A* O) Z. l) Z, l4 s; ~                       "by increasing the GRID-SIZE-X or "
. o: O! w  Y6 B2 ]                       "GRID-SIZE-Y sliders, or decrease the "
' Y) }" D. O: K+ E! c, q! [7 ]                       "number of cars by lowering the NUMBER slider.\n"
3 M4 O* ?' h: V2 ]$ q5 f. V) S                       "The setup has stopped.")) B1 e: E* _9 ^
    stop' n3 s4 M. p# g% _1 V
  ]0 J5 n- M2 M) O/ M( j7 ^

5 z. C+ K  W! w1 m  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 l' ^8 A) n8 N& g; Y. i
  crt num-cars6 I) m! K. H6 r  G: K; f$ K
  [2 E+ C; d  y9 G/ R' w
    setup-cars. s, v2 d0 f  K2 e8 I# ^+ H
    set-car-color" K9 _1 {( n, m9 R# v3 |
    record-data- P  D8 V+ R$ u9 E$ O5 u
  ]
9 K8 c: V: K3 z) o. j5 Z/ [& W0 z
, P" z( F; m# Z( s: p/ @  ;; give the turtles an initial speed$ c7 L: r; [8 C2 G- S' v2 g! P
  ask turtles [ set-car-speed ]
8 D& s% P3 B$ D3 z( b  l( P# P$ T
* Y5 r- |/ R7 d( c  reset-ticks
1 n' B/ O8 q+ X/ P% ?end
5 b8 G/ t% f& h5 f0 K, \+ M9 I6 u# N5 p. P7 P' v
;; Initialize the global variables to appropriate values
7 \$ h. H! t+ g- V- kto setup-globals
( w  Z+ f! n3 B2 y6 d  set current-light nobody ;; just for now, since there are no lights yet' ~8 v) P; t. f8 r
  set phase 0
: A2 \5 O; F, X9 ~3 V  set num-cars-stopped 0
/ p' c0 ^4 C  k% r6 R: ?0 u  set grid-x-inc world-width / grid-size-x# b' D0 K2 {) [; r8 e
  set grid-y-inc world-height / grid-size-y3 a7 z  d/ }7 N6 Q- H

# p2 V: {( O- z8 w& E  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 ~: f' K8 \: z# O' c  set acceleration 0.099
- b1 k8 D" O2 z4 j; a1 h$ wend' w5 y% T2 H: J0 P9 H2 R# h

; M/ J) I! C( a) d0 @! a( j2 Y& E- I;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# c0 U& `' M' `' Y4 I
;; and initialize the traffic lights to one setting
2 \- i+ K+ H4 Lto setup-patches8 j" H! b. F1 A' [/ w! a$ L
  ;; initialize the patch-owned variables and color the patches to a base-color
  Q( F) ^3 P' j  ask patches
$ g3 N: b+ U' `% {8 ]6 h; q6 X  d: k  [" _1 f0 r' u+ F0 N9 `+ g
    set intersection? false# [6 J( u! Z1 K% x: z
    set auto? false: |( r- l" o% W6 j
    set green-light-up? true0 U% }8 r% P) ?! x( Z
    set my-row -18 E) Y, X1 l- C) f" T4 j
    set my-column -1& }2 S$ A- Q  y
    set my-phase -1
& J% r/ `. z+ ^8 b' t- ?% E7 k    set pcolor brown + 3% r' ?0 W% y3 l( h' b% {: Q0 k
  ]! K' Z6 M2 ?& z" N1 Y

1 V: X+ g3 x! b2 x  [" S0 X2 }# v  ;; initialize the global variables that hold patch agentsets2 I4 R- B% c; U
  set roads patches with
, k% r; j6 n+ g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: z3 x" |' T8 r) F- Z9 a4 n& d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# `5 C% b$ b$ _5 ~! y3 F8 V+ X, x
  set intersections roads with
8 U% e& K) M2 T' R7 m8 P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 z. g2 h  A( f0 h$ W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* I; Y6 b% i1 L1 }$ r6 F( y3 N$ X" W/ b; a0 }4 A
  ask roads [ set pcolor white ]
3 S1 Z8 k# P& V( i: [% A" W    setup-intersections
) G0 s7 u8 k/ b5 }end
& Z8 z  L8 g( {3 o& ^其中定义道路的句子,如下所示,是什么意思啊?2 s7 i  Q9 q* @2 R
set roads patches with% j, d& k# r6 t- d$ Y, F7 M/ ^0 L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ N* r, \( N6 W8 N8 a! K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' d7 g* f, q- Y8 I3 D! e7 Z9 I& M0 T. 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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