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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。
. O) }) X! @+ G5 [5 q; P1 enetlogo自带的social science--traffic grid这一例子当中,/ c. D$ A+ c2 V) i3 P0 t$ ?
globals6 I: i+ |6 x& S1 C, o; a
[1 F) F6 e2 E: U1 C" Q- {
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ M+ P% G' X+ [! g  grid-y-inc               ;; the amount of patches in between two roads in the y direction- @$ F; l* M  T
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 ]+ u9 K* c$ w; E; ]: v; X5 f
                           ;; it is to accelerate or decelerate
* o) \( J  w# r1 f7 H  phase                    ;; keeps track of the phase
2 T9 j  X/ M# U, U  y( X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ J/ ~& ?3 J0 m+ h  c' b; ^  current-light            ;; the currently selected light+ \$ \: X: U9 T  n5 w2 J3 F
7 T& P- e1 B  ~3 h7 G) @2 i
  ;; patch agentsets
, |: D+ O" {* Y% p) S3 [7 {/ K3 p  intersections ;; agentset containing the patches that are intersections
9 C" W- c) o2 V2 g  roads         ;; agentset containing the patches that are roads
+ Z8 [. E& G/ m3 e]
( a3 g3 ~& P% L, b8 k
4 A" f. t* @  F  y# S6 t/ `turtles-own
( u! M" G6 K: V+ R' G[' t) b& s/ q$ r/ ]; R. {% \+ b
  speed     ;; the speed of the turtle
' T4 f$ N; p+ H! a* D  up-car?   ;; true if the turtle moves downwards and false if it moves to the right/ ~% u+ g/ L  A
  wait-time ;; the amount of time since the last time a turtle has moved
: d/ q; J2 o% b/ {' \]
. P% q1 }5 b5 K% H. d( I& y% S+ T4 @( S4 P  \
patches-own, j3 J- s! e9 G0 ?6 n, R2 P
[1 p/ Z6 b0 m; c2 y
  intersection?   ;; true if the patch is at the intersection of two roads
2 f' b1 T  H3 z) ~. T2 X! v  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, Z8 @. E* R) p! a5 x" J                  ;; false for a non-intersection patches.: c/ Z9 i* ~4 M" v6 K' s, s
  my-row          ;; the row of the intersection counting from the upper left corner of the) J  M  A4 d7 a1 p6 _
                  ;; world.  -1 for non-intersection patches.! {" D& O6 I  ~
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 U/ q! T' e- {: ]                  ;; world.  -1 for non-intersection patches.  G# [) Z8 n: I( G. ~
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# r, N- p1 w& t( u1 I$ _6 W2 _
  auto?           ;; whether or not this intersection will switch automatically.
- M, s& _. R$ ?8 B# d6 h& n                  ;; false for non-intersection patches.
5 `, Q* r  P+ X% D- ]]
  W0 B) H7 h8 r, w
& c" g, }! m3 |" X7 c  o3 p* `9 s% S* N# A; m
;;;;;;;;;;;;;;;;;;;;;;
8 v! y! H. \5 t- _; ]! Y;; Setup Procedures ;;1 ?6 ~+ I7 s7 l, w9 M
;;;;;;;;;;;;;;;;;;;;;;
8 a/ g6 W6 M2 O
$ S. n6 f8 C8 R& G2 L/ r;; Initialize the display by giving the global and patch variables initial values.
: b# K$ n1 s2 d8 n9 V;; Create num-cars of turtles if there are enough road patches for one turtle to9 F0 q' B8 N4 B& R5 h! `4 [2 e
;; be created per road patch. Set up the plots.$ s7 \/ B. E. ~5 S( B5 C
to setup' t. T4 J4 U& Z0 V4 P/ m- S7 W9 j# ^
  ca
3 a8 E+ K& O. `. o: }: l3 z& r  setup-globals  l* y) }, _. m) l  [1 a) f

: m  J7 S! v# K8 A. ~5 T  ;; First we ask the patches to draw themselves and set up a few variables; t! W$ }, x: ?2 P/ J! a
  setup-patches* i! u, {/ |1 N) a7 {
  make-current one-of intersections
# y6 E  k4 B+ ]7 W- g5 X  label-current
& @0 A! L$ b  g9 M  Z! W# B* n- k# U  E/ p2 {( ?  R
  set-default-shape turtles "car"" Q! E6 e% h7 b9 g
) B! R2 h* r: U
  if (num-cars > count roads)! }  R1 K8 `2 _) N* ~- Z' g
  [5 h; i! E1 L& b& H
    user-message (word "There are too many cars for the amount of "7 E" W+ |$ _# O2 y# L! |) w9 T/ P
                       "road.  Either increase the amount of roads "
" ~6 Z7 @7 f' x0 K9 V5 w                       "by increasing the GRID-SIZE-X or "
- h$ r: t- n  k                       "GRID-SIZE-Y sliders, or decrease the ", f7 d! ~9 |4 O
                       "number of cars by lowering the NUMBER slider.\n"
2 N- b7 T! G% H                       "The setup has stopped.")
" u5 n% x$ B" g/ B7 l  J2 K3 m+ N    stop
6 A5 s8 V# v+ Y! v& P  ]7 a  J0 {  _$ T5 v5 g% t

. z) c" P* Z' q  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 v2 Q4 I1 P8 [
  crt num-cars
, l+ W. V8 A  z1 q3 I2 q! O8 ]) w  [& _# u' _, F" a
    setup-cars  o4 U9 L. Y; {! r& F
    set-car-color' B# n/ g/ @" [2 @
    record-data" c( o/ ]* T4 v- @
  ]% U+ }9 D$ N, t: t1 @# T

/ H1 y4 \; a- V6 P) {  ;; give the turtles an initial speed
% g% ~# J6 P6 k' o+ b: u  ask turtles [ set-car-speed ]) ]) D& p" i( _" b' S& u

9 T% H/ A( G* D9 W" k  reset-ticks' X2 \4 B7 `8 |% a
end' ]0 ]0 W; {! f0 r( c
) |( B2 R" y8 O, a) ^' C
;; Initialize the global variables to appropriate values$ O0 Q: X4 h1 `, A4 C& q% i
to setup-globals. f! L" j: g3 Q- b4 \
  set current-light nobody ;; just for now, since there are no lights yet
+ ?9 \3 h1 l; T7 d6 ]3 P7 j$ B, w  set phase 0
1 f* |9 ?, S9 b2 W/ ~$ X& N  set num-cars-stopped 0# Q, R2 v" L* b2 v3 q* v
  set grid-x-inc world-width / grid-size-x
  g& K5 v6 d) \2 J" p% }4 T  set grid-y-inc world-height / grid-size-y
' C* t6 u4 a* L$ q
( i- b# J# Y: x& r9 G% z: L, s8 s  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
* C; d: y2 T6 C7 {  set acceleration 0.099
4 E. S! k! k) ]! }7 L# h# rend
, J9 @/ U3 ^  l/ _7 f8 ]( U2 i2 H2 Q- [( ~) Q( G
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 i3 m6 Q& {2 |, h  a6 j; H- X7 m
;; and initialize the traffic lights to one setting
8 E8 [7 ]0 @! \& b1 H+ G; L; w5 f0 Qto setup-patches4 Q. z/ W0 r; x0 e$ t9 M
  ;; initialize the patch-owned variables and color the patches to a base-color
# {8 F: P6 H: O! y  ask patches
' Z4 O4 `4 ], D$ H  F, E  T  [
2 s/ l3 h4 w4 v& s) k    set intersection? false
% M" \8 l* l0 L) w8 v* y  C    set auto? false
  t4 `( l2 ~( d0 R  `    set green-light-up? true
4 m% _" m& X) F( \9 L- N    set my-row -1: P5 E7 n9 i' I$ U" w- q
    set my-column -1' A4 k! s, a  _/ p$ L
    set my-phase -1% [- z$ E* ^- S" i; T3 o5 Y$ h2 j
    set pcolor brown + 3: Y5 ]) `+ Q  [
  ]
. J/ P. k0 s0 `! `; y3 u, d
2 r: Z2 N) I: Z0 a  ;; initialize the global variables that hold patch agentsets) L2 I- P6 c$ X' ^
  set roads patches with
" S$ x! K9 t' {) n# g: L0 K7 S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 o0 F" k! U& R5 J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 R( x# r$ |) {+ P
  set intersections roads with
# R) m+ V0 H7 w& \/ N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 w$ d7 {3 C- R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; z1 ?  s2 N0 K; n6 o6 t% F# G

( w' |. a4 }) T8 f. [, f  ask roads [ set pcolor white ]
( l) x, Y, V4 S7 L/ [8 l1 [5 k  A    setup-intersections
; n/ q5 R6 y8 c# Bend( S' X% ^( o5 r2 Z/ ]9 h
其中定义道路的句子,如下所示,是什么意思啊?4 L- s5 ]* \1 W9 A: q
set roads patches with
& A) Z, `5 F0 h( {; n3 R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ ~6 S0 i2 @5 }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 n0 x- S& a$ G$ q8 ]9 l% I4 G
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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