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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。( i# ~, P, b* \0 B
netlogo自带的social science--traffic grid这一例子当中,3 @/ V6 F' A6 N* E$ E
globals' A1 N& R, _' n
[
( M- h7 o. R2 @7 P: w4 N) I  grid-x-inc               ;; the amount of patches in between two roads in the x direction: w% \" ?/ d- n$ ^8 T
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. h$ H! Z3 E/ T# P" l5 n2 |  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) F3 ?2 R; r7 u4 T+ E
                           ;; it is to accelerate or decelerate9 Y6 y* n6 i. V( D. k1 E4 y' |
  phase                    ;; keeps track of the phase
/ E  ~1 Q+ ]5 `. N1 q  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- a  v2 Z# A1 }6 k0 F* }# T1 ^% O
  current-light            ;; the currently selected light# n9 q" ^# b, j# ]* n
$ I& L. R) U: V5 x4 G
  ;; patch agentsets6 F3 J3 q. }7 ?4 {' y! X
  intersections ;; agentset containing the patches that are intersections
' z- V/ Q7 a# l  roads         ;; agentset containing the patches that are roads1 m( m/ Z7 {; F7 p! a
]& l' R8 W8 n" Z" X

' q4 H. d0 d' ?% M& ~turtles-own
( C: B# F/ W; g1 ~; R5 b' A! r[! ^8 n+ P+ J3 }
  speed     ;; the speed of the turtle6 W; b  a# Q8 ^6 H# g4 _
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: U# _- u3 w; D3 `3 R1 p' t' b+ }  wait-time ;; the amount of time since the last time a turtle has moved7 ^3 o. V$ X* |* A  q- J/ x# B  ?
]
: n  n( T4 Q; i( _
- t4 G& u  Q( n/ F# w: wpatches-own
& z' T% s1 H" w[( M, y6 t7 r0 L' ]9 w4 W
  intersection?   ;; true if the patch is at the intersection of two roads
$ _0 g2 y8 O5 B  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- @6 H; c$ b% d9 a6 k" u: F
                  ;; false for a non-intersection patches.
1 [! p" P; j" P. p: j  my-row          ;; the row of the intersection counting from the upper left corner of the0 V$ z% I1 T# n9 V
                  ;; world.  -1 for non-intersection patches.0 V/ M8 q0 P. E+ B* K
  my-column       ;; the column of the intersection counting from the upper left corner of the
7 d! k" D9 Z- i# v                  ;; world.  -1 for non-intersection patches.
- y# l7 s! x' r2 C1 F# }% C  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- n1 I# b  q( L- |3 n( B2 Q! H& N6 |. r
  auto?           ;; whether or not this intersection will switch automatically.- b5 t3 p+ P# H% a3 Y" }2 A( m
                  ;; false for non-intersection patches.6 U7 x2 z: k% n" W3 t
]. K+ F9 p, C. R; K
) Q& M7 R; _& X, k( |$ m7 }$ j

% U# h1 |3 t9 t) v2 T, U5 r  u6 ?4 T;;;;;;;;;;;;;;;;;;;;;;; p# C0 Q& e6 y  u+ j3 @
;; Setup Procedures ;;$ y7 e3 g# h/ A$ m- a
;;;;;;;;;;;;;;;;;;;;;;8 i0 s) v3 s, Z# I
  D- V. M2 U" }9 P( B) ?
;; Initialize the display by giving the global and patch variables initial values.
; W; v7 A2 V: d  \;; Create num-cars of turtles if there are enough road patches for one turtle to
) ~" i2 M( n# e% o1 I# o;; be created per road patch. Set up the plots.% g2 s, R9 h+ D; Z; s: X
to setup
6 h. w2 p& e+ }8 y! Q  ca
6 L7 a( Q3 k, W: A' E/ g  setup-globals
: H! s9 e  G! X) n/ O3 k
- m1 K# P) q  N# H! {2 X  ;; First we ask the patches to draw themselves and set up a few variables
4 e) |# A( I; L  n/ k1 r7 s* i1 [  setup-patches  D7 W. P1 [1 L0 |0 [; u( s; w" p
  make-current one-of intersections
; q* }$ ]* m% S  label-current5 l) Y; c5 G8 m+ m( P; v/ L  P
: n1 }8 l8 }4 X" ]) `4 q
  set-default-shape turtles "car"* J% G& q8 W0 S" p# R

7 `- x- |% X' G6 a# _1 W  `& N  if (num-cars > count roads)
% k8 ]) l6 k; O  [- _' g- Q4 y* `; l: H) q0 K( \
    user-message (word "There are too many cars for the amount of "
9 Y8 m+ t6 R3 U" M                       "road.  Either increase the amount of roads "( a% f4 x( ^7 }
                       "by increasing the GRID-SIZE-X or "
% t, i- W! y% ~/ q: i0 q                       "GRID-SIZE-Y sliders, or decrease the "
- j) i9 r* i( V4 s4 s                       "number of cars by lowering the NUMBER slider.\n"
, c; G0 N: \. r: q7 V, e                       "The setup has stopped.")0 i$ W, w0 K" g- o( {
    stop
9 G2 B( Z$ ~. P. @0 q  ]) n2 p; I$ n6 f- l# A2 @

7 a4 U& v$ ?) P' C8 \/ l  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. J  h# q0 N$ ~. H! N
  crt num-cars
& P$ D8 H$ z+ y( s  [
0 Z7 K6 P. t4 w8 m0 t    setup-cars, j5 ?& O" P4 y4 v; v" r
    set-car-color
& _! B$ ^" `4 N. K    record-data' H9 L4 U7 h3 |2 n5 |* f" T. w
  ]- v5 ^' R1 x- O9 U. m* I7 C; f. t. Z

, l+ Y& I. V! F& A  ;; give the turtles an initial speed
; T) b! I- |) z- n+ `6 b! j  ask turtles [ set-car-speed ]9 f9 Z2 A" f5 e/ o# a0 I

$ c/ Y7 Z3 P# `! f; t* P# D* w" l  reset-ticks
1 ?) s7 a7 Q9 l1 \/ p! jend2 S# N9 g5 X( U$ c1 x0 _
5 ?' f# p4 v" b( |+ S. I
;; Initialize the global variables to appropriate values
% O" e4 G4 Y7 F' {! \to setup-globals, `% P9 u  T# t* q. Z3 F4 R
  set current-light nobody ;; just for now, since there are no lights yet/ Q' h; |: O4 @( ]3 P$ a
  set phase 0
' o8 \! Y0 f7 E( B$ m  set num-cars-stopped 0
7 u2 ?* c0 f/ U+ B9 d( e9 e# K  set grid-x-inc world-width / grid-size-x
% m4 `$ G3 _" h1 d) v  set grid-y-inc world-height / grid-size-y7 _& n6 t* b& Q8 O6 s. B

2 h8 w* t. A' W) I5 A/ w( W* v1 q# b  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
* S) ?5 ?6 ^* @9 o2 m  set acceleration 0.0998 Q3 [' J: Z0 c* o- s3 [& ?- m* p* c
end: m; {. W2 ?8 j2 R1 O
3 r% Z) C9 A- N$ v( P
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ `. n* H2 z7 P$ z9 }
;; and initialize the traffic lights to one setting4 d; m, r- ~9 y$ k4 i8 p
to setup-patches
8 t& @7 u0 _. U/ u0 g  ;; initialize the patch-owned variables and color the patches to a base-color$ U  I' g4 d% S3 Z! B. \+ l
  ask patches2 j+ V7 s. e$ x$ \  `6 [) U' i
  [& Z( m! d1 [+ E; H8 @7 D9 W' |
    set intersection? false( H* X  j( Z1 P" \# K! O
    set auto? false
+ D' |4 g; O" S5 E6 O1 h    set green-light-up? true
6 H# V4 Z+ a% o+ K5 I4 ~1 V    set my-row -12 ~$ x: @7 z! n7 i, G9 f/ H2 _
    set my-column -1  k) ^  B- b! G- k' U: i8 H
    set my-phase -1* y% S! m0 a1 w  a
    set pcolor brown + 3. J2 w, K' m2 I5 l( Y6 A
  ]3 \! h, t, Z$ R& A( F
, A4 I- L* y0 O* w4 d- q$ ~6 o8 W
  ;; initialize the global variables that hold patch agentsets
! p* x/ i2 [3 O4 P" S  set roads patches with
6 A6 J7 V' N- z/ B0 o/ ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( f: D/ v& F- d! I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 z3 I1 w) i2 {/ @: K9 p( l
  set intersections roads with; w7 l$ ]) `' p9 _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& g1 k* {: _, y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: {; R0 _5 {2 o: d* \; H
; I+ n* }/ b, k  ask roads [ set pcolor white ]' i1 O6 [( _- l4 q, [2 t; j. c* @
    setup-intersections
( `1 [+ n. O3 K# b* Lend
* v  k  g+ j! d! U* b  `8 o, ?其中定义道路的句子,如下所示,是什么意思啊?- M4 ?" t4 W2 \1 Z
set roads patches with) ^6 {+ O0 B2 _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* |! G6 g0 |! d7 O( h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% O, k  o1 Z' P6 @8 f! C" @" B7 w5 N
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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