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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。: l2 w5 g% ~1 t1 W8 R6 W8 K
netlogo自带的social science--traffic grid这一例子当中,$ w, d3 d2 M; j8 D  {; X8 e
globals1 X7 X9 z- O- Z
[+ S6 z1 O3 i4 Y/ Y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# J' [; B9 P& X$ t
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& a$ d; a) R) y; T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 w" E7 t+ T0 k& g2 `5 V+ e                           ;; it is to accelerate or decelerate! k5 y+ S3 ?  V0 l
  phase                    ;; keeps track of the phase: d5 H) |6 O3 F3 v- N* B% D
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 E! `! B  D0 E# h3 `1 @8 ?  current-light            ;; the currently selected light. H4 b0 D  s/ n
  u7 }: N7 X, g: c* O
  ;; patch agentsets2 R, q0 ]  V) x- p+ G/ h) M7 I+ @
  intersections ;; agentset containing the patches that are intersections
1 M* u! M$ R6 q, g7 D3 x  roads         ;; agentset containing the patches that are roads# B8 ^9 ^( L* f
]$ ]+ B  \* b# c! V8 a5 K
9 ^/ q' F7 E% A4 z# N0 C
turtles-own
' |8 o3 u! x8 m[
+ _2 p. ^$ B1 b6 e  speed     ;; the speed of the turtle; `' s# U6 w7 l0 d* d: }1 ]
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
' k1 R9 I" p" P# I, K# X2 ?  wait-time ;; the amount of time since the last time a turtle has moved: w" L: `9 d$ z9 n3 k/ u
]
  J$ U1 D' U4 j% X! M- y* n9 o7 z/ x- H  H% a/ b
patches-own2 b  E- ?8 z7 l1 v" b$ ], c1 O8 V* U0 e
[  F0 `, I, D* T, l9 p! s
  intersection?   ;; true if the patch is at the intersection of two roads' K- \! u/ X6 h+ l! j
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ C1 J: p6 J. [, F4 P
                  ;; false for a non-intersection patches.
6 ^, \$ h0 Z7 T3 R: Q3 O9 {  my-row          ;; the row of the intersection counting from the upper left corner of the! M9 M5 \9 z9 v
                  ;; world.  -1 for non-intersection patches.
$ C7 Q$ p+ k# z; H% j  M% E, w8 Q, H, U( m  my-column       ;; the column of the intersection counting from the upper left corner of the9 U3 S$ p8 L- f" f5 Q! J
                  ;; world.  -1 for non-intersection patches.' c6 e" \0 l6 Z
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- R( w7 Q+ U9 u; L4 a
  auto?           ;; whether or not this intersection will switch automatically.
8 [& k$ \0 ]; ^                  ;; false for non-intersection patches.* Z9 l% \% l" H5 O0 x. l; }
]
4 t6 f8 f: P9 Z$ g, I4 @7 J% T" ]) K2 f1 f; }5 n( c

7 M2 W5 ?" m) O;;;;;;;;;;;;;;;;;;;;;;; E. p1 B6 ?2 C* n0 @/ K$ p) ?
;; Setup Procedures ;;
( V: x) g$ i) ^- U! k  b7 ?;;;;;;;;;;;;;;;;;;;;;;
* _3 {! M7 H% ?2 \. i6 p  i: C0 [& w) ~1 n4 h: z
;; Initialize the display by giving the global and patch variables initial values.
! r& q( C# I9 s$ P0 S. P/ F+ U;; Create num-cars of turtles if there are enough road patches for one turtle to; R9 \, t5 Q# S* z
;; be created per road patch. Set up the plots.3 b+ w1 X5 u; C% d
to setup
, P# V* w, c2 a/ C, ~9 A* T  ca
0 y2 q- N7 J; v# Q! T  U  W  setup-globals
, G- R0 M/ s9 ]5 M2 ^8 P' Y1 [
  ;; First we ask the patches to draw themselves and set up a few variables: Y! r; W. k& K" v) E! ~
  setup-patches
$ }: d1 q! y5 R5 z0 j  make-current one-of intersections+ ?/ G# b3 M. q8 Q- K
  label-current
8 a& j3 Q9 S4 }. s& v* w( }
1 f- [( r5 h: A2 p6 q4 h  set-default-shape turtles "car"% k; }  q: U9 w" O- @

  w5 s9 I* l  {0 K0 L  if (num-cars > count roads)& e( `  L1 z& w! c
  [
4 S7 s9 M+ q& E1 _5 H    user-message (word "There are too many cars for the amount of "0 A" Y. _, A, s2 h" G. i$ b6 B
                       "road.  Either increase the amount of roads "
1 K% \% d& {' ~/ ^8 O5 D2 I                       "by increasing the GRID-SIZE-X or "
1 r" X8 F4 b  t; F& g+ @7 X! O                       "GRID-SIZE-Y sliders, or decrease the "
4 ~: F# e, Y+ W3 j1 D! R. {, Y                       "number of cars by lowering the NUMBER slider.\n"
# k4 j  |  ^7 V+ t" t                       "The setup has stopped.")% {9 P7 T0 X; d. l6 ]% Q1 k8 b, @/ W
    stop
: S5 r2 F+ o) z' |  ]
. c" p/ D- i4 J1 r* h
* P4 F! [' W# e+ ?0 T4 G: Y: ~  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
8 A6 A4 ?  s4 k. W) t7 f  crt num-cars  i6 g4 S3 t$ ~7 n+ X3 P. u) g/ {
  [9 }9 h' r: [* i4 b5 q0 ~% g9 _: M
    setup-cars$ o5 o+ A6 F  Q
    set-car-color" c) `+ H# O# _6 h3 }& O
    record-data( {+ S/ Y) m; m; Z  k& G
  ]
0 U- a1 l, B- H; x3 v# \* I
1 P* R: _: Y8 @) k  ;; give the turtles an initial speed
3 B0 C) Y. V' v4 [4 Z7 N* O: J2 N  ask turtles [ set-car-speed ]
  g' t  f* v7 f  L, Y( V
6 E% x2 _) ]/ M  reset-ticks
/ a5 o- x& }; O8 q( E/ K& M5 Lend
  J& j; K' o4 ]# `% e) ~' o
( W3 a; l5 e; C% ~8 l, d9 ];; Initialize the global variables to appropriate values  y4 }; l' o, i9 }
to setup-globals
$ m9 j; m  S6 d, k7 f  set current-light nobody ;; just for now, since there are no lights yet
& n! p8 j( k# @/ ]) y  set phase 03 a; m( K8 U6 Q/ K/ V8 Q) A  C
  set num-cars-stopped 0* l/ i+ D6 g$ ]
  set grid-x-inc world-width / grid-size-x
/ y8 w6 C. [. g  set grid-y-inc world-height / grid-size-y
. U$ j1 T! }/ l/ y$ A' O+ ]- k5 V( Y5 Z% P. Q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 e& F+ ]+ |2 X# o. h
  set acceleration 0.099
) A9 r% Y) @! \4 Send
% `( m8 {$ ^! `' z* t. ~6 O  e* k2 y4 E) W+ ]4 q# K; I2 j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 @4 T1 M, Y. a( L% L: _) {
;; and initialize the traffic lights to one setting
6 q6 W! P$ W& _, ]/ I% hto setup-patches
7 [$ G0 s7 ^2 ^5 F" J+ _  ;; initialize the patch-owned variables and color the patches to a base-color
3 i# e7 Q8 |% E( M0 k  ask patches
$ E; t* ]9 q; B* g! i  [3 M4 W1 Y7 [0 r2 C
    set intersection? false
: u; k) P9 W4 V" l, Z, P- O    set auto? false" _( D3 ~) s5 z& F: l  i0 E
    set green-light-up? true; f/ _! R$ v( b$ P
    set my-row -1  e1 r) j4 G1 W+ V. o9 z" x: g
    set my-column -1# i+ u1 b% a2 L. B( R
    set my-phase -1
. r' M$ @$ w2 Y: z, j+ L: d2 Z    set pcolor brown + 3
! a2 J( y$ K8 Y- B  P; ?/ a  ]
3 o5 h  Y( u6 e- J, N  A
# h7 ~6 U+ R' r- D. K$ X. a  ;; initialize the global variables that hold patch agentsets+ `2 k" G& u4 E( F
  set roads patches with
4 r# L/ E7 `/ l, s% J/ w0 c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. t3 G5 m- \- U; U: B% H0 x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* c# G9 w# {! ?/ ^4 H8 [
  set intersections roads with
7 s7 s, y/ R4 Y3 s8 t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- o( A9 K) T/ J: b" a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% F! H% L; N) P# {9 O3 }( p, ?/ S* G2 |0 L- u) h1 E5 t% \& _. j1 I
  ask roads [ set pcolor white ]
' O& Z$ u1 l; q0 y6 O$ e    setup-intersections
+ e4 T. W4 i; p6 ~, |0 wend& v; B/ Z+ N) i+ ?
其中定义道路的句子,如下所示,是什么意思啊?
8 s: f( m# x' m8 O* Q8 D set roads patches with4 J3 J: `# p$ L" h+ X8 p' g4 w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& ]( Y0 u" \" T/ p; F% }3 I( E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% i/ `' C1 C) _; @, `; J8 E; 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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