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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。" ]' c+ @7 `& G
netlogo自带的social science--traffic grid这一例子当中,' a' `# t  \  i+ ?
globals8 O! f+ a) g. {2 J" z
[6 g, w* P& [, U3 Y& g
  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ w; \! m1 K( }* v0 U
  grid-y-inc               ;; the amount of patches in between two roads in the y direction# r  J' D3 U8 u+ d  k0 \. J
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if" {) W/ q$ u1 f# V2 y% B
                           ;; it is to accelerate or decelerate3 S1 s' a1 M# x! O- _
  phase                    ;; keeps track of the phase9 O9 _$ u! {- Y$ g, t- n
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 q! D. {) b+ a  N8 p1 x  current-light            ;; the currently selected light
) e! l/ v, M: N) e/ }# k) Y! T5 A- n3 ?
  ;; patch agentsets1 i. l7 s' r8 c5 T1 D" g; _
  intersections ;; agentset containing the patches that are intersections8 y0 D) W" z) o% E4 F3 s" a. M& M, x
  roads         ;; agentset containing the patches that are roads- B  s1 `# O0 Z' e% B
]
3 H* W  z# R; ^0 P0 {( I3 `
. R( M6 p5 p6 Bturtles-own7 W: h: B$ s- \1 V1 Q
[" R! B3 J$ L6 E
  speed     ;; the speed of the turtle  C- J. v  }4 L. e0 H/ h
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ M% S3 K+ z' p: ^" l
  wait-time ;; the amount of time since the last time a turtle has moved
4 w* g4 ]# w! o9 I8 w/ M8 I]
+ g8 U& ^; y2 I1 B9 A6 d1 z" ]- Y& l/ j' o/ I: |: u
patches-own
8 |4 c; T( P# H# w, I. |4 Z1 M' U[% Y% u) K% |2 H8 |2 h
  intersection?   ;; true if the patch is at the intersection of two roads
# P' l) L" }& k+ Y) E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
$ O, M% h& D) W7 j: f3 M% o0 p                  ;; false for a non-intersection patches.. l  O. ~2 w! X, j# D
  my-row          ;; the row of the intersection counting from the upper left corner of the
! J# H# W6 ]- T8 |                  ;; world.  -1 for non-intersection patches.) w0 |* ?5 F6 g+ N
  my-column       ;; the column of the intersection counting from the upper left corner of the
: t. K$ n+ k% ~" |$ z                  ;; world.  -1 for non-intersection patches.
; Q; W# p8 J5 r0 s$ _  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ ^+ F/ w) O0 D  auto?           ;; whether or not this intersection will switch automatically.
0 p. d6 z7 p/ d/ z* u$ Q- d                  ;; false for non-intersection patches.+ C  [5 C' W5 H2 m3 Y. {" c
]
! G) W9 y7 b9 F3 L4 x4 e' r" N) ]
0 g( s- d9 P' q! w# T! w
) ~7 l, u0 z! {& U;;;;;;;;;;;;;;;;;;;;;;' v- v! G2 @" J7 y2 O, x
;; Setup Procedures ;;  H$ ^8 b& L. H  R$ _
;;;;;;;;;;;;;;;;;;;;;;
1 a% l* R) A4 H$ ]' T, H
, @: p( c+ X  P8 P( O;; Initialize the display by giving the global and patch variables initial values.
& x  B4 Z9 {5 ~: r$ b9 A# |;; Create num-cars of turtles if there are enough road patches for one turtle to
; k, i, F4 I6 ?, x;; be created per road patch. Set up the plots.1 ~; V0 b7 _$ r! t! x2 |: d
to setup
: h$ r& [! X+ u( v. p) V0 O  ca
* C' L4 ?. t8 @/ E3 Z/ E- w  setup-globals
& s2 Q2 F& J& N. o0 x- l4 I& P. `" x# M# w/ C  Q) k
  ;; First we ask the patches to draw themselves and set up a few variables* F; Y3 n8 j; n
  setup-patches; ]0 j& q4 R9 @3 A
  make-current one-of intersections
0 j5 O( J! D0 v" Q3 |  n, y9 t0 S  label-current. Z7 _- i3 T" A% N

2 q9 O. z2 w6 N, K  set-default-shape turtles "car"" z) l, P  B* Y: C
6 _# Z4 U1 h0 h) f- X
  if (num-cars > count roads)
6 l! q. r0 ]! l7 `+ s  [1 m% L* [3 E7 l8 ?$ k9 [
    user-message (word "There are too many cars for the amount of "
/ T2 \- w3 p; l3 B3 S                       "road.  Either increase the amount of roads "0 f9 q/ T5 T1 X4 V/ p8 Y
                       "by increasing the GRID-SIZE-X or "
% J  t/ T- C3 Z  v! m/ ?6 O# b                       "GRID-SIZE-Y sliders, or decrease the "
4 u1 O# g% B: P  I+ o% r; W8 U3 u                       "number of cars by lowering the NUMBER slider.\n"3 c' y5 P  {. M$ x3 n
                       "The setup has stopped.")6 r* p8 _! f7 F2 Q8 r) }
    stop
" Q% W$ B# r9 C* A3 b  ]- Z1 Z* e! J, S3 F" {: y3 Q% l, p

3 x1 A0 x+ w1 Z6 W  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 u7 M6 m2 H; v0 b
  crt num-cars- s( ]+ i- ?, z4 Y
  [
2 h# d5 U) O2 z: C    setup-cars7 p% A* w6 j) G& \/ E# w; F
    set-car-color
7 y5 A- |1 n/ [0 |- y    record-data5 _0 v) \' G$ B1 i3 Q
  ]0 [, V# G! O  t( R1 ]2 B

/ o$ S4 {+ ^% G9 y/ @$ |5 [  ;; give the turtles an initial speed
7 @( J" @' t) ~+ X& q. R- l2 Y& ^  ask turtles [ set-car-speed ]
. a+ ?* O) E; b& h* q4 i) S2 k3 ?( ^. H( s" e
  reset-ticks- `: M5 R9 H; q# Y- T
end
3 N* h# n8 t" d8 I# J/ R+ h! N4 }% c# }! m  |+ h' N7 a
;; Initialize the global variables to appropriate values
; p5 ^( y: Y* ]to setup-globals
! E. K- N1 ]. u2 [, d+ w( C7 U  set current-light nobody ;; just for now, since there are no lights yet
; j& `6 R7 C+ V$ O3 _* [. [$ J) n  set phase 05 [6 K$ y" |$ i  u1 }! X) y$ y
  set num-cars-stopped 0/ k0 u4 A# N0 ?3 ~( S
  set grid-x-inc world-width / grid-size-x
6 K" o% ^' H- u. o! `1 S  set grid-y-inc world-height / grid-size-y
6 X5 z$ T+ P# R3 F, ]' q( d, a+ H: W) F6 n, c4 w/ {
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" \& L# U; c" ?: y% T& r6 P  set acceleration 0.0992 Q1 q* N, N  J/ x5 F4 t: {
end
" A9 A' |/ E$ P, ]" X' Z! L: Z6 f* Q' [3 N
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
/ i% M, M4 }  I;; and initialize the traffic lights to one setting* j$ W6 T) @$ a- u7 k
to setup-patches
3 v  H1 s+ k5 h& [  ;; initialize the patch-owned variables and color the patches to a base-color# d4 \5 O& b- E9 i; \
  ask patches
. I* {; }( o4 P8 g: F' \  [
5 a0 T. u8 u( \7 H5 }    set intersection? false
# q( U2 _" l5 H* W6 @& x    set auto? false
  q4 c( y3 y! {9 Q    set green-light-up? true* J- |' y7 f5 s  w4 q, K$ |9 s
    set my-row -1) @. V+ d  P! s5 E2 d2 \, Q/ D
    set my-column -1
9 g* f3 Z! x$ j    set my-phase -1
2 T. O/ M( g, G: k( ?5 |4 G" T    set pcolor brown + 3  ?8 \+ b" z! g1 \/ F
  ]
+ Q$ G6 m) z) f7 t
7 q) W* r, S' x( s: F) C7 b8 a  ;; initialize the global variables that hold patch agentsets0 y: S7 F6 y, H9 a& a8 L
  set roads patches with
! ^" E0 b& r% Y( N2 Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 D& W& W7 V6 t4 B- h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ i! Z4 @$ ^$ G
  set intersections roads with
2 {4 }- f/ y4 b6 u1 R4 n4 P, x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* F6 l: m, B1 n0 u) ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; g8 j/ \- D; s3 U; A' f8 e4 e0 Y7 H1 Q
  ask roads [ set pcolor white ]
# i9 r$ I+ Y9 t1 E8 A( {0 ~& f    setup-intersections/ }/ U! R7 g2 C0 X
end
9 H' V7 g% ^$ @) C# u+ M其中定义道路的句子,如下所示,是什么意思啊?. v5 Y, ?' v9 l. y
set roads patches with
5 g' \" U: f4 E. X1 \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- a4 W/ s, U/ @9 O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- D3 O$ F* l/ B) t
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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