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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。) a& {" S: _; ~& u: A- b! G: g! y
netlogo自带的social science--traffic grid这一例子当中,
) ^' c) |0 g( y) I! N/ U4 t5 |0 zglobals
9 y  H- W8 ]4 V: x[
5 \; }2 H% B* a. `2 L. M  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 o: G9 f2 p. w9 e- o
  grid-y-inc               ;; the amount of patches in between two roads in the y direction; ]! ?1 P- m' s$ `- r6 H: M7 T* `2 P
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, r  k& l0 r8 Z
                           ;; it is to accelerate or decelerate0 ]0 S2 l7 {8 q  ^
  phase                    ;; keeps track of the phase8 I! v& Y" R( z; `( R3 j" N
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
! Y7 v4 k, d# X; i6 f; ?/ S$ A& l! C  current-light            ;; the currently selected light
1 \% V2 a/ X% U. p, \7 V  @: X9 ^) F1 K; W' M( \
  ;; patch agentsets
" K: m; b9 }1 H  intersections ;; agentset containing the patches that are intersections
6 l4 T9 X- E1 B: g/ P! {% }$ }3 b  roads         ;; agentset containing the patches that are roads
2 k& b0 b- @7 d]9 }# S% I  [% B0 n, A

- N0 v. k' Y7 v( E& @3 E' _turtles-own% n- f: `% g: \) B3 \
[
! \: N! v" V" d8 C  speed     ;; the speed of the turtle) H: v: P! ]0 S" J- p% g
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 P' Q1 B- x3 Y! y  t1 r9 M
  wait-time ;; the amount of time since the last time a turtle has moved
, r- l: w5 g0 q3 J  e( t]
: _- P+ L: f+ f& m3 I" {6 s) O. d0 E0 c! r2 }$ W3 ]+ |" P( N
patches-own3 X) F/ _0 E  j7 C1 x9 Z% Z
[
" ~4 g$ U. G- [: ~1 u5 c* B  intersection?   ;; true if the patch is at the intersection of two roads
# B3 q2 X( o% t0 j- Q  d6 p# C  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% C3 Q- W! G" V1 y5 v) V9 R* _. r                  ;; false for a non-intersection patches.
2 i% U5 a7 {0 M( q+ _$ j  my-row          ;; the row of the intersection counting from the upper left corner of the% V, o0 }& r/ ]& F
                  ;; world.  -1 for non-intersection patches.
8 {; S. Q/ k! K  }! _& i  my-column       ;; the column of the intersection counting from the upper left corner of the; B* ?, B8 P/ a! i5 p8 n" q9 g4 h4 R
                  ;; world.  -1 for non-intersection patches.
9 H0 \: H7 }+ n0 I& ?* A  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. H7 s7 ?& c- z# K3 a8 K
  auto?           ;; whether or not this intersection will switch automatically.7 a" f  W" T/ W- A' w  f
                  ;; false for non-intersection patches.
0 P9 U% o& W8 g5 ?0 f: A0 }]
( v6 ~9 d0 l0 n) p
! w% r( U% Q( f6 x3 p+ ?; b
* Z% W0 M7 e. q( u;;;;;;;;;;;;;;;;;;;;;;8 J- z  w) |3 c
;; Setup Procedures ;;2 d5 J4 E. x; U) x6 {
;;;;;;;;;;;;;;;;;;;;;;
, A  d2 @. i; P0 V
- y3 E4 c' |, f$ `( B% Z+ d$ u;; Initialize the display by giving the global and patch variables initial values.
$ e# i3 t. f" r3 w6 x;; Create num-cars of turtles if there are enough road patches for one turtle to
# u1 F0 g7 j2 O" ]7 H  v. c;; be created per road patch. Set up the plots.8 q1 W8 g7 j8 f% C! c  B
to setup
0 |( J1 Q, n$ @7 V" D1 {1 ~- B  ca
, e" Y5 p% K" I( H% }% \  setup-globals; K; J( p) e0 ~

3 `& L3 C9 q8 E) t  E  c( |  ;; First we ask the patches to draw themselves and set up a few variables
, i+ R3 C7 }# @) `. Y* o$ c  setup-patches4 F1 ^1 K5 I* l6 m5 J. X* _5 ]- v: d3 |0 `
  make-current one-of intersections
& J8 Q$ p0 Y7 }5 ^  label-current
5 {% ?: A; b: N, W* y4 {. C0 }( D4 w& s0 w- D
  set-default-shape turtles "car"
( ?2 {- `/ N8 G8 w5 `: g
8 R' E. p( ^* L# t$ f; q, o7 L( k; T  if (num-cars > count roads)1 v$ i% [" p. m0 Y2 w! w/ J) }
  [
, e4 z* a+ l- s1 L8 K2 T! Y6 R" i    user-message (word "There are too many cars for the amount of "  g! u  u1 |" F' ?
                       "road.  Either increase the amount of roads ": O0 G) c" v: b- q- R) ^
                       "by increasing the GRID-SIZE-X or "  |8 G3 c2 J; _1 X
                       "GRID-SIZE-Y sliders, or decrease the "
* g9 j- j0 r- t; c- V% O; O2 j& b# G                       "number of cars by lowering the NUMBER slider.\n"
9 k: X! ^) t. M                       "The setup has stopped.")
' A6 A9 m& n4 E4 X, q+ e5 Q( p    stop; ^7 J! u" \1 v( |* a9 P1 |
  ]/ e& `8 j# r3 I3 W- J3 l5 Q1 s+ r
3 X7 y! P" }2 F. ^
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% p9 d. _" W1 ?- h  crt num-cars
3 u/ L' C" E  v  [* f5 d; `7 m/ r0 M: H& J8 U: F+ Z
    setup-cars0 J& J1 w- L% A) [0 I( a# [8 K9 r5 }
    set-car-color
  Q% l+ Z# o1 X' o8 l    record-data
" E. j6 Q" R7 [( Y$ c  ]
5 j6 P8 v  y6 a, J3 K& O9 t- K* r
  ;; give the turtles an initial speed
; z. y9 F# S: z' K" E$ _$ A# c  ask turtles [ set-car-speed ]" e0 k2 E" u4 F8 l. g0 a0 D
( P( {% ~# f  m) S2 |' P
  reset-ticks- N& r* e6 P- P* O0 {$ s; n- j! e
end3 Y, h9 z2 N0 O$ A
/ N7 m, A* Z. l3 ^$ N* y# Y7 Z3 r
;; Initialize the global variables to appropriate values6 f: n3 h' ]+ r: f: Q% }
to setup-globals
" \1 q$ h& x( e; I  set current-light nobody ;; just for now, since there are no lights yet
* X" u1 y# v! R5 d  set phase 09 H' v- D4 y" j9 ^7 R" U0 \
  set num-cars-stopped 0# i) q& R' ^5 S
  set grid-x-inc world-width / grid-size-x
4 `8 S8 N8 E) T1 k. E  set grid-y-inc world-height / grid-size-y
) [, H& {! j. L* B# |- Z: U# V0 w8 |
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 X- s  l( p  |+ u. U* m
  set acceleration 0.099
: {+ k! C8 g9 \9 U9 m0 I( Bend
: q* v4 e. `: F( y) k+ z7 B6 A1 H) g0 M( H& R) \
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# C( ^( r# }/ s9 a' u1 L;; and initialize the traffic lights to one setting% }  r, Q4 ?' v7 |' o
to setup-patches$ R/ J4 ^; @% N8 i  Y4 C, a
  ;; initialize the patch-owned variables and color the patches to a base-color
0 V# `) B) m, h3 s! p9 |5 v  ask patches
& ?+ R) X: x. G  [9 Q) C9 V* }9 C. W
    set intersection? false, C2 l3 ]3 W3 e/ r( ^
    set auto? false5 w" W2 q" `0 M8 q
    set green-light-up? true& S  g! f' U4 N- g2 g" }
    set my-row -1
" B, I: q" `* X1 d$ o! l# u    set my-column -1. G( |5 }0 t& k9 U) ?. d$ a2 d; n
    set my-phase -1& l$ A4 I# J% p# Z7 G
    set pcolor brown + 39 v& L4 u+ j& j/ ?1 k8 I
  ]* g. ]$ B: R. u& W- A5 |) x8 t* G

& ~6 w5 O* L* m" D  ;; initialize the global variables that hold patch agentsets
, |+ Y1 }( S$ l% f5 q4 _  set roads patches with
( S% ]1 U( ^) i1 k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: X, Q' k3 V) _2 [! Y7 K! o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) ?8 D' g( P$ v# e' ?: i, l  set intersections roads with
: [; p4 w- X! T; B0 z' w! z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
# S. t/ [9 i3 S1 I" y6 B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 t7 w9 j6 u/ U. }+ L& h
, M: o, c6 v( D$ U# r
  ask roads [ set pcolor white ]
* g$ X* c$ ^1 F" U" n    setup-intersections! x& h& c1 s9 P; x! b: |3 u
end
: C, Q8 t/ k# Y" Q8 X. T其中定义道路的句子,如下所示,是什么意思啊?* H& ]% S2 j* a# a' t$ J2 X
set roads patches with
2 ]. p, B4 q2 q* ?/ y" A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 m; s4 |( ]8 g2 k+ e. Z% R$ W- _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 ?; u+ L& @9 G, ~$ W& E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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