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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。
- J1 R2 A6 U( ]- E1 ~  S: gnetlogo自带的social science--traffic grid这一例子当中,
) A2 C# a2 K$ U" ?9 n. rglobals
( I& A+ |4 `8 K% L  U[" ~+ b+ P4 F& i% U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 _( l6 W+ A4 i9 d4 ~, Z
  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 \( y# X! v+ ?0 g
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 J4 s! |4 I# t4 x* D+ y" h
                           ;; it is to accelerate or decelerate
* X3 M5 Y: L9 h; p  phase                    ;; keeps track of the phase
: T3 L- \7 O+ ~8 R  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  [5 p% n7 B# n, S) b% L& g
  current-light            ;; the currently selected light' a( B/ O9 E" j, B& h; f
  x4 {+ w0 W1 A# g: `
  ;; patch agentsets) c3 E" B( n" i" G( G7 E
  intersections ;; agentset containing the patches that are intersections
9 ^0 b( x+ |5 A; E+ ~" g, l  roads         ;; agentset containing the patches that are roads# R( b. T. ?& G1 X" C
]
( U, D- H1 l% ]: h. W9 a' K  z5 ~
4 a1 x! ]& G5 P% m  j3 M; zturtles-own
, S0 i; ^7 x. J$ E8 }$ j[
" P! ?- l% w* Z# S& k  speed     ;; the speed of the turtle
5 s3 k- k1 i+ M# @  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  V% |, ^9 z% b7 V" j% r; h6 n% L/ P  wait-time ;; the amount of time since the last time a turtle has moved1 L$ {% ^4 w0 F; d- T
]
- y2 [- _. q, ?
0 w0 W, C3 @1 R" vpatches-own1 n) a( ^8 d% A/ f9 H. Q: h" e! j
[
: i* w- Q/ w5 e0 z/ N/ _  intersection?   ;; true if the patch is at the intersection of two roads8 N4 v3 K) y+ b: i9 F/ p
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
1 i" \) r# w1 Z                  ;; false for a non-intersection patches.. J7 g: x" X4 p2 p* f
  my-row          ;; the row of the intersection counting from the upper left corner of the: J$ u2 q' O, }" x5 `# E0 d, O
                  ;; world.  -1 for non-intersection patches.3 F+ }2 p( C! l- B* o; A
  my-column       ;; the column of the intersection counting from the upper left corner of the9 b2 ?  V+ c6 \/ z# T( f/ T
                  ;; world.  -1 for non-intersection patches.( b5 g7 H9 I2 L- h3 U
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! ^; P2 N3 F, t& ^4 K5 p. Q! F
  auto?           ;; whether or not this intersection will switch automatically.: N, I9 j: A0 I
                  ;; false for non-intersection patches.) s0 l$ F7 ~. S% X+ H8 m
]0 Q! Q2 M  M+ W- m, o6 o
3 S+ n7 j: r/ Q: k  W1 s" W

* g" a- d( n1 G" u;;;;;;;;;;;;;;;;;;;;;;/ N& A. I- u# B" {: k1 x
;; Setup Procedures ;;$ N: A' K# a2 H6 U  L) a
;;;;;;;;;;;;;;;;;;;;;;
( e: o  }# r9 S: {% ^. q) P& R6 U1 Z
;; Initialize the display by giving the global and patch variables initial values.
$ V9 }, M; }8 v$ v;; Create num-cars of turtles if there are enough road patches for one turtle to
, n' E  j$ A6 f; c  a;; be created per road patch. Set up the plots.
  S, g5 H: C% c1 a+ bto setup2 ?, ~3 v* c* P
  ca+ t4 O: I8 C$ I8 x" R: Y9 o5 b
  setup-globals7 e; a/ j0 u7 d2 ?1 W7 U1 h! o

4 J+ ?) y5 [0 n5 E  ;; First we ask the patches to draw themselves and set up a few variables
" ~% p# @0 [& K/ f3 E. n  setup-patches
- l- P" l2 |$ U; d  make-current one-of intersections
: W' P1 T9 |( @& C3 F  label-current
" N( s4 R# l" X, R" V0 B+ r1 }
, X4 J$ g" I  L  set-default-shape turtles "car"
! G5 S8 R/ @) L3 V
1 O! U# k  q9 O& r  B% `& G  if (num-cars > count roads)
$ d& u- i4 r8 `- K! E! p& ^  [
. |# r+ s) N9 f3 F7 p9 s: _    user-message (word "There are too many cars for the amount of "
  Z1 Q. }( |" M& t, C. x/ w9 T                       "road.  Either increase the amount of roads "
) R+ ]% C( ?( B0 t: S% C+ }                       "by increasing the GRID-SIZE-X or "( l; j# e; n3 M9 w3 t
                       "GRID-SIZE-Y sliders, or decrease the "+ w% V( [7 ]( J! `
                       "number of cars by lowering the NUMBER slider.\n"
; i0 A. `1 H$ Y: f                       "The setup has stopped.")
9 V! [2 |$ \; J8 [  k    stop( v, |# h5 e: c' Q( O/ V5 J
  ]
+ C# ]; y5 ~, Z  d0 J" q4 M& b
$ t- D9 e& N' E% P- s  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 a, L( _; V, e2 w. |3 n) ]
  crt num-cars* G  F: v: b; Z9 D4 J
  [
! H4 r8 c0 J5 K  A# E    setup-cars+ c+ \7 }% R$ l, d5 M0 U
    set-car-color
& h/ ~& l  N: s9 b! L+ j2 `! W6 v, E    record-data0 c# d5 c% R6 m
  ]
) t# \. \: x/ V* {9 R/ Y, x. i0 `+ D$ r5 f4 z3 l$ w
  ;; give the turtles an initial speed% n+ l( v. V, L7 M& S
  ask turtles [ set-car-speed ]
$ q* u% ?6 l2 e
# y! r3 t4 Q4 l7 V  reset-ticks: k: }, Q7 V& \  ]) F. ^
end
5 d1 n/ `; C. |" |2 v3 }5 l5 d0 e( ^, ]+ T. i
;; Initialize the global variables to appropriate values) g1 p, @% u3 U! m
to setup-globals  h4 O6 z) E; e0 A7 m, `
  set current-light nobody ;; just for now, since there are no lights yet
  ^  c$ r- I- g" ~4 [$ l) a' _  set phase 01 h/ [$ g9 X# @; B5 Y2 j) X
  set num-cars-stopped 0
# ?! c! {  }6 u$ B% {  set grid-x-inc world-width / grid-size-x
% C# ]* [3 ^) |  W) u: l  set grid-y-inc world-height / grid-size-y
4 M- T" G' N6 [7 s) ^8 o+ F) i6 ]0 v% |
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; H+ i2 y3 T3 V/ `3 b  set acceleration 0.099
" M& ]; f2 I5 `% y& Send
7 x2 V! E/ T6 Z6 ?$ f7 R/ _3 y( ?9 @: E9 W
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! @  c% E8 k, L;; and initialize the traffic lights to one setting
+ W; c- Z/ I, G. F! h/ vto setup-patches8 Z, _- z! Q; r
  ;; initialize the patch-owned variables and color the patches to a base-color$ k& w+ V. ?" P
  ask patches
3 c/ p$ Y% w( _7 B. ^  [
+ h# R; Q$ Z+ c" a: W1 r    set intersection? false
5 A3 y  m" f. H8 b! z    set auto? false
* V! C7 @- C6 A2 j  W    set green-light-up? true
+ H- {  D9 M9 E$ _    set my-row -1
( e. K4 ~9 m0 U; v8 y" t    set my-column -1
7 ~0 ^& G* K, M) X& O3 Q" Y    set my-phase -1
; v7 c) G4 ]/ Y% w$ D1 x* u    set pcolor brown + 3
! `9 f7 z3 K& I  ]
9 y) m9 f0 u6 g7 ^8 |) _6 x# z% e
* ~1 W/ k: V: k0 c. I  M: H  ;; initialize the global variables that hold patch agentsets  L- ^/ j! L% G' W4 X9 x, O! r& I1 k
  set roads patches with
" Q% g" S, z! w! H4 M7 Y( b5 h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" W- }; t3 w+ x$ c4 j/ f7 g4 R( \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 S4 b; S: i! ^: K" H/ X% W5 o
  set intersections roads with
- Z: k# l" }9 e    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: k, c6 a+ t! I) a* i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) L) S7 b- T6 s. F4 @

8 U* ]' T+ N/ o% A  ask roads [ set pcolor white ]
, w$ H  O- X: M; M# m* g    setup-intersections" z1 g# u, T8 a8 }4 h- h! _5 ?
end
0 u. k2 p) c3 j. @8 F其中定义道路的句子,如下所示,是什么意思啊?
2 ~( X8 H" ^) R set roads patches with$ z1 |0 l: \, G! _. U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  T% U" \9 ?1 j3 X* C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 g# ?: b4 l3 \  o! @
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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