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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。# f- u: R& z" R0 a6 J, G, G( q7 a. @# I
netlogo自带的social science--traffic grid这一例子当中,7 w0 e* i! @) P% c+ C" N1 }. e
globals
, Y/ p2 j6 b7 R9 }9 f4 }% b[
7 q9 O" h) A/ ]+ p  grid-x-inc               ;; the amount of patches in between two roads in the x direction# `& s- U9 |. T$ K3 g0 G1 O
  grid-y-inc               ;; the amount of patches in between two roads in the y direction) d+ q2 c' h$ x8 D8 N% _4 ?; ~/ R2 F
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ b2 ?8 b1 R7 H
                           ;; it is to accelerate or decelerate4 g# p- V. A$ O* @
  phase                    ;; keeps track of the phase
! G" ^4 y: @. W% o0 h# q1 x1 U. o  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" Q& O6 I6 c7 v3 j* c  current-light            ;; the currently selected light5 l% U8 n; I6 K' S/ j( c
7 W* R7 n, i! N6 ~4 k# n& N3 e
  ;; patch agentsets- V, U$ f/ z3 ?
  intersections ;; agentset containing the patches that are intersections
( g' b+ t3 i0 e; O  roads         ;; agentset containing the patches that are roads
& W. y' Z  m5 {]- N/ n0 O% J/ ~! T2 A. E! J  r
) U8 c* C4 S% D
turtles-own+ o" t  s1 Q# {+ G0 }3 s
[
( g4 a) ~+ {  L, {4 u' ^7 z; t, g  speed     ;; the speed of the turtle, \( j+ `  ]. U: t* R  x% J* v
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; d8 N' \1 F: N1 W# j9 z
  wait-time ;; the amount of time since the last time a turtle has moved; V; @8 s2 e; K0 k: _
]2 s; S+ K% j* s4 D) i& _
7 ?1 A3 \- U8 \* g4 {  A# @0 S
patches-own
( }3 N0 S, h* Y[0 e( `( J( f8 M6 L" w) \1 F
  intersection?   ;; true if the patch is at the intersection of two roads2 Z+ N9 X: e) {* ?- g- O9 b8 a( R
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& h3 S$ J$ Q1 B3 m" p( o1 s- q9 @                  ;; false for a non-intersection patches.7 q: R0 \, I& n0 r
  my-row          ;; the row of the intersection counting from the upper left corner of the0 [1 s; V/ V4 M& d3 y. d
                  ;; world.  -1 for non-intersection patches.
# n1 n+ M- [( m$ Y  my-column       ;; the column of the intersection counting from the upper left corner of the) @0 X& M/ p& B/ h! @
                  ;; world.  -1 for non-intersection patches.6 v; v7 I+ M6 w: U: [
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 j% [( M4 _4 f1 A# U8 I0 k+ n  auto?           ;; whether or not this intersection will switch automatically.) I. s1 g. p9 M. ~( B# w; c
                  ;; false for non-intersection patches.
7 o1 _0 ~. a9 d9 \- ?  e- ~! o]4 c1 d1 E" N" V3 u2 V3 ^, ?' U) v

4 W* A% c0 j7 [
) w& i+ F0 d! B4 ?+ N;;;;;;;;;;;;;;;;;;;;;;; f5 u4 T; s5 q! F5 G' G, \& M- o
;; Setup Procedures ;;
8 a/ }$ X( }- N+ x;;;;;;;;;;;;;;;;;;;;;;
/ N3 D# v7 Z  S: U+ Z- S0 K/ N
: O7 f4 Q* H+ m" };; Initialize the display by giving the global and patch variables initial values.
% F! r3 {$ ]- F! ]1 u;; Create num-cars of turtles if there are enough road patches for one turtle to  w0 c3 |7 ]# I& y1 |2 ]. y4 c( {; f
;; be created per road patch. Set up the plots.5 a* r1 K9 M! `4 _+ g: B* s, J
to setup2 ]) l" O0 n0 k6 y! Y0 k5 `: a
  ca
+ O  f- ^& V! B' s  setup-globals
5 E0 y; d/ g8 }- B/ }8 k/ O/ l# e  }, @# b) t9 Q) ^  c8 |- E
  ;; First we ask the patches to draw themselves and set up a few variables% e4 X8 B9 x2 {1 T" k) m/ ]
  setup-patches  f' u& O4 Q) m& X
  make-current one-of intersections
8 c/ m5 D5 ~2 @5 O) i$ d  label-current! C. p: i5 K2 @; b& _
, M3 o6 _8 O+ t/ T0 I
  set-default-shape turtles "car". g9 M9 A+ H  u  M+ l
$ x" w' Z* X' N) p
  if (num-cars > count roads)) {: q- ]6 D2 J" ?! J/ o* F6 r
  [
4 k3 q! l4 `1 U1 ?; u* U    user-message (word "There are too many cars for the amount of "
1 E" [$ W; s; E# V' B* |8 d                       "road.  Either increase the amount of roads ", w. Q! v& \8 L' A
                       "by increasing the GRID-SIZE-X or "
- i* c! s* U* U9 e: r$ e                       "GRID-SIZE-Y sliders, or decrease the "% R  Y: k* w" ~. R' [4 e+ w5 E
                       "number of cars by lowering the NUMBER slider.\n"
2 f7 Y( m0 H% [( N                       "The setup has stopped.")
- F$ A- B7 B) K. z! ~3 F    stop
. D9 c& M5 j/ d  c  ]3 y7 B- E; w9 b9 |3 \
, b3 P" G" w6 w( ~+ _6 j/ a& V
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 E' q( Q# X5 v1 Z2 D
  crt num-cars( P. ]( U1 ~. e: W% u& Z
  [& w/ u% x0 N0 x+ j' G4 T; }
    setup-cars
+ G6 ?0 ~( U% g7 k5 p8 b    set-car-color. m' A1 V. t) i# \0 ?( j3 O4 A
    record-data
. D1 f) A5 |& F% v' V  ]* C& M2 A  n# s% U

$ u, x: F) x1 i; W/ ^7 Z5 j  ;; give the turtles an initial speed
! v% ?2 n* M( @/ Z6 P+ F, {  ask turtles [ set-car-speed ]6 p, j1 N4 C4 D% o2 K/ l& e% N0 T9 ]

- z5 |, i% \0 Z  s9 e- n' a. i  reset-ticks
5 ]& y' P. ?) T3 \0 a. Dend
( d, X- `9 ?9 ]7 v, `* [' j  B
! t- U% J* R% O;; Initialize the global variables to appropriate values+ i- ]1 g- W0 [9 o8 N/ h
to setup-globals
6 Z2 g! D& C2 {: w2 U" p  set current-light nobody ;; just for now, since there are no lights yet
. D( ^/ P1 ]8 T8 [. r0 G  set phase 08 c" \9 Z5 E6 E5 U
  set num-cars-stopped 0
! ^5 W2 S4 c. j0 P  set grid-x-inc world-width / grid-size-x
1 H) _! V' L. A, P; `  set grid-y-inc world-height / grid-size-y6 l, Y. q2 M5 w. E6 o

0 C) @7 W& `: j+ k  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ p8 j  ?7 _, `; e. i9 M
  set acceleration 0.099
5 V5 z' R3 j, r* p1 @" x+ dend* A0 }' G* Y0 K
8 c1 {: I- l+ g5 O  ^
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 t- ?* Z% J8 g1 R2 H9 Z7 J% l! S;; and initialize the traffic lights to one setting) Z# a1 m) J8 q
to setup-patches. I3 F6 Y! a( o% k- L+ a. b& Z
  ;; initialize the patch-owned variables and color the patches to a base-color8 `* F2 a+ y' H8 E
  ask patches* E  l4 i: S% l2 f# L. u
  [
" K! i; G* W& C' V; G" l    set intersection? false* j2 H+ d: }; [5 h4 w. D
    set auto? false4 ?, w/ k9 v  G$ P% Q3 V  \- h
    set green-light-up? true
2 M" p: P3 k7 g    set my-row -1
. R/ ~6 B6 \# c) ~) A. a' a    set my-column -1
5 u) T6 I( r7 ~% y/ h  M$ o    set my-phase -1
+ u3 n  N, z0 o    set pcolor brown + 3
* R8 [7 t8 N- o# x7 R* {  ]6 A8 |: b4 j  H8 u1 u! c" n3 y4 g$ e# _

# R1 {$ ^) F, Q; ]  ;; initialize the global variables that hold patch agentsets7 H( Y4 i6 T# d  @
  set roads patches with9 i1 s! `6 G4 r/ l: R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 {+ l5 L+ J' W$ y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 H/ |0 {, p- z* h
  set intersections roads with  d3 G1 g" y* k: I, m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ v6 B( \% B8 p. a: s3 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* Z( _/ p& p( G+ T6 l3 C
$ S" A+ M- [2 {  ask roads [ set pcolor white ]/ ?( Y7 [9 Y! q' L, l# L) [6 Z
    setup-intersections' j/ g# m2 J  z4 Y' E) i* l: h
end: b: w/ q' H  F( t
其中定义道路的句子,如下所示,是什么意思啊?) P! Z  ~: n; s0 Z6 Y: Z
set roads patches with: |- f' S, J+ @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, d  j9 y, R) N& v* V$ C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 }1 C* {8 _, [/ @" w& c: k# v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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