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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。$ ~4 `! s' W% ?3 U2 l& ~
netlogo自带的social science--traffic grid这一例子当中,
$ M# N' H; \- O" J9 @globals
/ l3 L, X+ E7 e+ @. m( m5 B[
1 \- @. K& v1 ]6 B! ^0 \( {  grid-x-inc               ;; the amount of patches in between two roads in the x direction
( c: Q" }- t# d0 ~$ j  grid-y-inc               ;; the amount of patches in between two roads in the y direction; u, q" I" Y& _
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& V' V# B6 Q$ m. i! s3 H
                           ;; it is to accelerate or decelerate3 c$ @4 _- ?1 Q5 g4 X
  phase                    ;; keeps track of the phase( s( p! x. |1 A9 }! i& l7 }; P
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure1 j1 C; Q: s( w% i/ r: F
  current-light            ;; the currently selected light8 I. F0 W1 J/ P2 `
" }3 c: @7 d" s7 i
  ;; patch agentsets. H1 o6 p0 ~3 H0 P9 P1 ^1 `, Z
  intersections ;; agentset containing the patches that are intersections0 s, n3 G) `# N" `4 m
  roads         ;; agentset containing the patches that are roads1 W5 H* h' o* f2 R* @+ A: o
]
  V9 I, `7 [% s
- n. G, v" u3 B0 {, d: ^turtles-own$ m2 Y  z8 H6 ?# V
[
" W3 }( m+ j- Z  T6 P" n: F  speed     ;; the speed of the turtle- P( l" o3 o/ P7 `$ n& d
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 u$ n: u" T; Z% _/ s. e  wait-time ;; the amount of time since the last time a turtle has moved7 G& K  @: [5 K; b
]4 f) f% }8 e. z+ _; z
: _9 O9 i$ Z, D! n5 L
patches-own
& s3 C+ G' X& W, d  }[5 p+ t8 D6 P3 m& s) ~
  intersection?   ;; true if the patch is at the intersection of two roads! J3 a/ i) b3 w/ Z. v/ E5 `
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, l- m0 I, L5 T                  ;; false for a non-intersection patches.0 Q: y6 o. X) L& s' O: R
  my-row          ;; the row of the intersection counting from the upper left corner of the1 S/ c* ~9 I0 u9 s8 k/ H
                  ;; world.  -1 for non-intersection patches.+ |# M* l+ u' D
  my-column       ;; the column of the intersection counting from the upper left corner of the: c/ _0 d$ X) ?. P9 i' u( U
                  ;; world.  -1 for non-intersection patches.2 I$ P( [) X7 E
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: g' C7 t& ^4 {+ X& q
  auto?           ;; whether or not this intersection will switch automatically.: v. f" z2 u4 k  f4 y+ H
                  ;; false for non-intersection patches.
- _$ Z6 i; F' W3 D2 t" w6 W]
5 D+ Y- p) H. J
/ l) p: T4 Q6 Q! l9 ^( c. u$ a. ]! [: V9 Q8 g* u( ^
;;;;;;;;;;;;;;;;;;;;;;
' ?: r% u1 d# ^. W. P;; Setup Procedures ;;
. K# k: @- A/ u) ];;;;;;;;;;;;;;;;;;;;;;
4 b  Y5 E% d' N1 {- C! ]1 `+ x5 Y4 V' ~3 h1 u# P1 @  Z- L! s
;; Initialize the display by giving the global and patch variables initial values.2 `. j8 j2 ?. b: C: d
;; Create num-cars of turtles if there are enough road patches for one turtle to: Z. [1 ^# t/ y6 Q4 q" J+ W) S
;; be created per road patch. Set up the plots.
4 x) m+ I$ `4 zto setup0 _6 y  T# N) f, c+ p: h' {+ ~
  ca7 {% l- Q$ L* w  O$ i: S& x
  setup-globals
! p3 e/ L0 u4 q; r, w4 _# M8 f$ l1 ^. `. |  o7 S$ f- j+ _# G
  ;; First we ask the patches to draw themselves and set up a few variables& z" ^6 o" y! u" H% b7 ]  y
  setup-patches) z( j! r: _! E0 s* A1 j# _; l
  make-current one-of intersections9 o; Y7 d$ {  Q* h
  label-current
- j# y" ]) I5 X4 s4 M: o1 a( C! A: M6 C0 ~, [' Q
  set-default-shape turtles "car"* ?& M( r" f8 k  }
* }2 q0 |+ x  a! g5 j  A! l9 l! p
  if (num-cars > count roads)6 Q, C9 t  q( q% h
  [
3 b+ u. }, b- V# p& p    user-message (word "There are too many cars for the amount of "4 `# n8 F- P, Y5 }5 t! N+ Z
                       "road.  Either increase the amount of roads "; u' x  e) F8 {  t
                       "by increasing the GRID-SIZE-X or "
3 E* w# Y' T0 q' V                       "GRID-SIZE-Y sliders, or decrease the "
- n! |) Q/ H: J! B& Y* \                       "number of cars by lowering the NUMBER slider.\n"7 U$ {. X3 g/ A" G' z  X
                       "The setup has stopped.")
) \- ]5 Y5 o2 D! P* q! u1 k% B6 [/ O5 }7 k    stop& f1 q( e' _9 @$ [
  ]
$ A5 U4 k) A; C9 V% `: C6 v3 [5 b( \- f! }/ }
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 b- S7 ]; ~+ T& `, |4 P' q
  crt num-cars: \( ]$ M- P' A! ?
  [
; D; [: J. _  T4 [: I; Q& ~    setup-cars" D$ c6 Y8 K% t( e# T0 }  x) U
    set-car-color# i3 x7 B6 h  Y
    record-data
* w5 K* \$ l( ~7 C  ]! q1 s" h. c: L

3 @$ w& d2 A8 |3 ~5 L- q7 A  ;; give the turtles an initial speed
" F: E* ?& R, J: b8 N( F- ~. I  ask turtles [ set-car-speed ]
0 j, b2 ^" E4 Y" H6 N0 g2 _3 g# I* D6 y
  reset-ticks4 O7 L% y/ c: O' c+ n% |/ K
end0 N3 l# [5 K% X" d) j
- G, W0 Z2 w8 \) e% s. p9 s
;; Initialize the global variables to appropriate values
8 Q6 Q2 w. z* e4 U! Z/ R7 S8 M( ^( {to setup-globals9 W- n# j# M2 N  n$ }( o
  set current-light nobody ;; just for now, since there are no lights yet
: B+ S! J2 ?$ h0 B  ]* W  set phase 0: U( n1 p/ K* C8 A. C7 c
  set num-cars-stopped 0& V5 Z7 x/ p+ Z# y( F
  set grid-x-inc world-width / grid-size-x
& y0 G9 i+ y, i# e8 V4 ^0 h  set grid-y-inc world-height / grid-size-y6 N1 k. l- }. a0 z, M1 D! {* t

) W  M2 y9 N& [5 C: \, v  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 z& v- @( q6 m3 T& v
  set acceleration 0.099
4 |4 c7 s  H- j" Oend
0 R; _4 J% D( ?
" o1 h/ C4 H5 X1 B;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
/ w9 n3 r8 Z) d;; and initialize the traffic lights to one setting
9 l' r& Q* {4 D8 _7 Wto setup-patches6 j# a8 Y$ ~9 r& w3 Q* J- h# s
  ;; initialize the patch-owned variables and color the patches to a base-color0 C* S1 G% w* i. Y* s7 G
  ask patches4 |0 C5 G; q- I* X/ Q+ ?# S; j
  [
+ O5 h/ j: |& ^1 f7 P8 x) {$ |    set intersection? false
& _& E1 B: r8 \2 K3 H    set auto? false- Q9 H6 m# i: Y8 {- |
    set green-light-up? true
: k: k' F8 P. g2 j2 d. i( G    set my-row -1
  a4 [7 U% F) Y+ i3 W    set my-column -1* I9 J. B! ^' J4 n0 I7 v- S
    set my-phase -1% S$ b; v0 r' o/ j3 j, _+ w
    set pcolor brown + 3
+ @! H+ Z+ A# r" F; U1 T& B  ]
) F5 S# _. C# X
( @& z7 d$ M) c2 ~% |( H! Q  ;; initialize the global variables that hold patch agentsets  Q1 |4 y7 \* ^" ^% b  P5 Z
  set roads patches with: U7 L$ d" w- A2 [. ^2 e$ U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ W$ `5 \5 O+ V3 V, z: j4 J8 o- h9 c8 {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ V* ^9 w% _+ @/ G% L  set intersections roads with' \/ I5 A! Z- E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 \. n) j( U$ L  B/ F! [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" h6 r$ v# A# s5 v  y, S( k8 v4 X( Y& v* y+ B+ m
  ask roads [ set pcolor white ]# a, V: j# F- \& w
    setup-intersections" `1 f$ A4 H& N: t, L1 q3 l* o
end0 U: i  N$ O: o  _" f
其中定义道路的句子,如下所示,是什么意思啊?+ |, _# Z  _: X& `# y- j- W) I. a( C
set roads patches with% U- |: W" U' e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! x$ `& l; \. P# \0 z0 e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], R9 L& @3 a6 o, x2 u  d
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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