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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。: h' q, H) P# Q" q: M
netlogo自带的social science--traffic grid这一例子当中,5 W' o. K0 @8 i" y3 e
globals& s: O( g1 n3 [: J5 W- Y1 \" }$ O
[; u  K, E; c" i) X# v6 h
  grid-x-inc               ;; the amount of patches in between two roads in the x direction; H! z5 c' k7 Q/ S' M. [
  grid-y-inc               ;; the amount of patches in between two roads in the y direction' k  b2 `) O  s
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if+ V8 m. G. S  n8 ?2 w9 Q6 S
                           ;; it is to accelerate or decelerate
9 q7 p2 e- Q4 N$ w  phase                    ;; keeps track of the phase6 F. T9 V  V7 B0 C. S
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, M" ~) C9 A/ z" C
  current-light            ;; the currently selected light7 s) J: Q0 _& y" S$ s
) e' l7 o& g) n' ?6 T
  ;; patch agentsets9 x6 C1 @( P8 E$ Z% ~
  intersections ;; agentset containing the patches that are intersections
2 z3 }* t, Q6 b  U7 ^9 G' t  roads         ;; agentset containing the patches that are roads
( Q% S& M/ E) E! Y% x& T4 W4 G* z! K]
9 U: n! Z- ~9 B) y
+ ~9 Y. o9 y; H0 X- h! F: J9 Zturtles-own9 D6 }( T' B5 X7 B9 U
[- K5 Y- z. ]1 o5 ]
  speed     ;; the speed of the turtle
5 a5 r, m6 a. F4 J4 K* X# H  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 |# U/ ~6 y- h- F2 H
  wait-time ;; the amount of time since the last time a turtle has moved: U6 s  Z* s9 I4 I! e$ Q4 m7 d
]
. j; N! X+ E4 h! j3 B  h* H" N, [5 n9 V
patches-own% f" S7 Y/ b  ]) T, I6 l
[' Y% x: a: H5 Y/ v7 ~* L
  intersection?   ;; true if the patch is at the intersection of two roads* {9 r: T) U. N& b
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. B5 o" Q; r8 K$ K9 u; Z; o
                  ;; false for a non-intersection patches.
6 R3 H  b: g' L1 T  h  my-row          ;; the row of the intersection counting from the upper left corner of the# V- E' N; c; r0 L+ h/ @
                  ;; world.  -1 for non-intersection patches.9 K3 n2 P, P! b/ r1 f4 ^2 J
  my-column       ;; the column of the intersection counting from the upper left corner of the
! R$ @2 N* f6 N: ]! r/ U                  ;; world.  -1 for non-intersection patches.
, {$ S; M8 ^- v5 S1 S9 s  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) d& a! D& n2 p0 D  auto?           ;; whether or not this intersection will switch automatically.
  u, R5 ?6 {- h' n7 F9 W                  ;; false for non-intersection patches." G6 i# `% o& p: F
]' ]/ S: q5 G, s3 |. s7 N
7 C" {9 Y* k; U2 L3 A% S4 `' t

5 I0 y6 a, W! ~2 C;;;;;;;;;;;;;;;;;;;;;;
, d% F9 e: K/ B% i1 Z$ _;; Setup Procedures ;;
8 h+ k) H7 ]0 V7 u- p;;;;;;;;;;;;;;;;;;;;;;
9 k- N6 W1 K  B7 ^; F6 W. t. K# O* p6 `; [
;; Initialize the display by giving the global and patch variables initial values.
1 v3 O$ x0 P4 M7 Z;; Create num-cars of turtles if there are enough road patches for one turtle to
1 I2 W  r+ o- |* Z2 O# h0 B2 K;; be created per road patch. Set up the plots.
" U, }( x+ {! S' o  q0 Pto setup
4 {' w% G+ D- l( }, i  u  ca, M) a$ V' N* V( F( h
  setup-globals2 y* {: m0 {+ j5 o2 z

: h7 m4 |* t0 c& z. t9 l  ;; First we ask the patches to draw themselves and set up a few variables
1 y6 w! M8 B2 y7 V  setup-patches, i: P& w5 X) F9 n& z4 ~% S
  make-current one-of intersections+ W0 D7 y" {1 X1 A# r5 L
  label-current
. K' [8 k6 V% t5 \' F' C, t
8 s" p4 ]( K6 _8 A( c- S1 T1 d% n: u  set-default-shape turtles "car"& D0 e6 y& B2 |& r7 ]+ X

4 \: J- E9 `- D/ u  if (num-cars > count roads)
' ^+ }1 i- h9 s+ `5 }5 Z  [) O1 F- j8 E' t3 d+ W5 ~$ u0 @
    user-message (word "There are too many cars for the amount of "
' l! `, H' J* q8 V( k3 `                       "road.  Either increase the amount of roads "
5 D: |# Z6 L, U, b- W: ^! t                       "by increasing the GRID-SIZE-X or "# _+ J5 o; z5 I2 j3 S4 x% }: w, a
                       "GRID-SIZE-Y sliders, or decrease the "
) R: v6 H1 ~, L+ v: \8 b% T                       "number of cars by lowering the NUMBER slider.\n"
. q0 d8 ?; W& w( p* e                       "The setup has stopped.")
8 {( g+ N. y  ^' I    stop
/ E  }6 N# e0 O4 z  ]8 R8 V) G) d$ R0 H8 z9 c

( D, [0 c8 U0 i0 r0 |; Q  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 w1 A) v' u0 m3 E
  crt num-cars+ F) D- @6 b" b7 @
  [
4 T  s% e) D/ c# T" f# I2 t% q    setup-cars
1 ~0 s+ \4 _4 v4 N7 D% ~3 a    set-car-color
2 o2 T1 u4 Q* d8 S/ A- c' K* j0 B    record-data4 ?. X6 y5 T/ `) o( ]6 ^1 P
  ]* ?% L7 e0 o( _* N3 @3 e

4 B, a' n- r' x- s8 s3 a  ;; give the turtles an initial speed
5 u2 K- K0 i5 M4 z& }, @: _  ask turtles [ set-car-speed ]
) N! b4 G9 n! }& g9 A- a! M$ m7 t$ G: `2 n0 q- }( k
  reset-ticks* V! b1 G3 F- c0 y% M
end# \; B+ E0 b5 D. X: e
7 B& s1 b. M3 X5 E
;; Initialize the global variables to appropriate values* b1 o) v, x" l- I; z& }
to setup-globals
" y3 K% \' m5 T5 u  set current-light nobody ;; just for now, since there are no lights yet) F. H; }8 V  @
  set phase 0
: X/ r/ q  m" ~: k( [3 \- @, h! T  set num-cars-stopped 0
/ F: t; d7 G- u( s7 w, U4 O  set grid-x-inc world-width / grid-size-x* \/ m; |5 F: \9 r$ x
  set grid-y-inc world-height / grid-size-y! W7 n. {/ g; b0 f0 {
& ^3 u6 p0 S* b+ h0 {
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; [5 {" o/ O/ N5 W  set acceleration 0.099; `, E4 c7 E8 t3 n* }6 b9 D
end" B4 n% o# f) P2 s+ {$ \

8 g. V, X7 S$ d& v/ ?$ F" g6 O;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: `( i) o6 F3 ?/ Y;; and initialize the traffic lights to one setting, P! Y& y3 F2 h/ d0 Z  e
to setup-patches
5 r6 {4 Y2 B6 K5 m1 f5 l! V0 N  ;; initialize the patch-owned variables and color the patches to a base-color
# b& c0 u, V8 I! p+ u& S6 [  ask patches
6 I$ o' @- h( S7 A. T  [
; O8 w; p( M4 W    set intersection? false$ a3 A! Q7 L0 Q: d4 B: Q
    set auto? false
! A( U% y1 R( D3 b    set green-light-up? true/ L5 l! v! w1 t) b
    set my-row -1
4 H+ I; L9 v6 e# D/ z    set my-column -1
- W" G5 V: O4 e- }& `$ f) \4 G& P. O; q    set my-phase -1: M( i8 I& \4 `
    set pcolor brown + 3
( p( S( i. M( `  Q4 b' U" _  ]# M8 P5 k8 a3 T3 }! r- R
* J2 _6 y0 Y$ N) L1 e
  ;; initialize the global variables that hold patch agentsets$ Z5 S7 V( h" I! r, a) ]5 M
  set roads patches with
, W9 _5 o: t! U2 h5 {, l7 m6 a, X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ V: |+ c6 s% `    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: x' i! `" i% K$ ~4 ^7 j" V9 q; d  set intersections roads with
0 W3 d; l) ^% T$ e  m- V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 z, y+ I4 ]# [3 M; j( G; a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ }( N5 P) B5 T( w) f* ?: R  @8 y  g1 g- G0 H$ q6 X
  ask roads [ set pcolor white ]
" x6 e$ K7 |9 {, t' U- O' s6 K& `* e    setup-intersections
1 f! Q( A2 b5 N4 k* j* r: d0 ^end
4 N* V0 \8 t" O: f1 C其中定义道路的句子,如下所示,是什么意思啊?# R7 `: G  r  c  w, l% P! T
set roads patches with* G0 i+ e$ ~7 n% E& ?+ O; W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 P& w0 z$ _1 g# a5 ^& ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: n, o0 A6 M, K7 O7 W1 z
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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