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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。
. @7 T# Z( e/ q! A- j: Cnetlogo自带的social science--traffic grid这一例子当中,
/ M: H, d) m; w# Hglobals1 _/ L5 }. X- E/ t
[
! n1 |$ w+ @( @: y  grid-x-inc               ;; the amount of patches in between two roads in the x direction, T0 [& R/ u/ q0 e* a9 L
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 [: J8 W* u! I3 {* [  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ b( A! a3 e  r" ?                           ;; it is to accelerate or decelerate  |/ ?! B5 U* r6 B
  phase                    ;; keeps track of the phase
' X0 A, K1 G% ?2 }5 B  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* U2 f/ a/ r& ~$ B  K/ ?! c  current-light            ;; the currently selected light
6 `' G- N8 g; z( x6 h: n
' R# P& N& h1 n  ;; patch agentsets
- S% q' C' {6 }% B; L0 A# ]  intersections ;; agentset containing the patches that are intersections- E, @/ e) ^# k8 D1 S
  roads         ;; agentset containing the patches that are roads
; z' f' k" E# |. e]
$ U  _9 N8 e9 t1 z/ ]* x' t$ w  f% {# c
turtles-own
+ B0 X# v; {* O5 n, h[1 z8 A  ~  v  |2 v" i% Q
  speed     ;; the speed of the turtle
  Q: L( v+ @7 V1 ^3 m  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 U7 ~1 |# o8 G( k/ t
  wait-time ;; the amount of time since the last time a turtle has moved
& g. ~3 k) i' e% @0 c]- v8 E- P6 |5 G

; ~' e9 x% o. Bpatches-own
2 A1 |% P! a- v0 \[9 b6 W1 K' x* \" \
  intersection?   ;; true if the patch is at the intersection of two roads
" L$ G8 D/ h0 c* m  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 E0 N8 d( x; P# o; s! J1 i                  ;; false for a non-intersection patches.
9 F* `$ z* ^" U! `3 c! q  my-row          ;; the row of the intersection counting from the upper left corner of the
( D9 E& t  [8 K" u, f9 h, P                  ;; world.  -1 for non-intersection patches.3 L+ k+ W+ C' R/ W4 O- g
  my-column       ;; the column of the intersection counting from the upper left corner of the
: M) c  H) M* Z- G" U  x1 c% d                  ;; world.  -1 for non-intersection patches.# m) {  Z  Z4 U; D, }
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  n, d  ]( @8 b- I
  auto?           ;; whether or not this intersection will switch automatically.
. {: U" P, l* `; v/ A& d4 w1 s+ e* m! S                  ;; false for non-intersection patches.
5 k& \* t: e1 \7 X]3 D4 x6 F$ M3 }. V* j9 h% O
; N3 h7 F' i2 f

9 @! N& @  D1 \. q;;;;;;;;;;;;;;;;;;;;;;
% C) H5 ^0 ~# \. U( c1 P;; Setup Procedures ;;6 F% v$ U# E9 u1 X
;;;;;;;;;;;;;;;;;;;;;;
; ?) u' x% M9 H6 d: X) E/ f8 D' i! m: P3 {2 K$ S" R8 f
;; Initialize the display by giving the global and patch variables initial values.0 a8 |/ _  x9 p1 l9 Q1 `
;; Create num-cars of turtles if there are enough road patches for one turtle to. f9 V& T* ~6 a; D
;; be created per road patch. Set up the plots.
) a# m+ E5 Z. n8 ^- Gto setup
! C* Q  h2 `3 M$ F* n6 s! f  ca$ z- d) ]3 q1 n) [% N+ I$ C
  setup-globals
! p9 }8 ]9 }$ R  y
: D9 k: M4 Y( G2 h4 s- l( {6 o  ;; First we ask the patches to draw themselves and set up a few variables
; Q2 q& W- P/ W3 U  setup-patches
5 w! _+ l( F/ g: v1 e3 ]6 o& B' f: O  make-current one-of intersections7 p# l0 Y% ~2 O; m
  label-current
* ^/ @! {9 I# M# [
4 s0 O7 [3 k3 \% s' H/ M6 w  set-default-shape turtles "car"
' D7 H. @. ^3 L' {7 G  c5 p, |, l) ?7 W7 d# T& k
  if (num-cars > count roads)5 [) s+ ^1 b6 l& z
  [' b4 C1 d8 u& |- e, i
    user-message (word "There are too many cars for the amount of "- d/ p4 M3 _2 o" [! Q
                       "road.  Either increase the amount of roads "
% _) Z9 h9 s0 D1 W6 ~" \9 E; g- N                       "by increasing the GRID-SIZE-X or "4 b& t# K6 ~, R, T0 Z, ~' x/ ~
                       "GRID-SIZE-Y sliders, or decrease the "/ B9 W. S& C( {
                       "number of cars by lowering the NUMBER slider.\n"; Z% k, ?& m" U$ g) q/ T* y1 ]
                       "The setup has stopped.")0 [, O- }2 o9 I. R# z
    stop
; Z! W; M+ w, j1 a8 A0 `, d: d  ]3 O4 ]! \$ w& s/ q

8 N. N5 t& N8 V9 A3 j. a  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  j+ W1 X/ Y' d* x; y2 A6 @/ w0 B  crt num-cars% ~9 d1 p! Y' @" R/ v' P
  [+ N. I) ^$ X) v* ^0 f( [
    setup-cars; @' N1 f$ f" N6 \
    set-car-color7 P, ?5 [# F+ S4 k; _" L
    record-data
/ z& h' N: Y/ K% p2 {  ]( ~: ^5 U* z8 h; P8 P

4 I" p) I9 U/ @) \4 f  o2 \  ;; give the turtles an initial speed
. [2 w- c* |5 y. c. X- R* t' x  ask turtles [ set-car-speed ]
: }* s  Y- o2 p0 G( y5 S9 ^5 v$ R' C8 Q, p/ Q7 \
  reset-ticks
# ~# @3 Q4 ^3 u8 Tend' V0 p! t# J0 c# R! ?

6 x" r) f; r* o, m" Z) a( i% j;; Initialize the global variables to appropriate values$ L0 K. \2 [/ y( _6 N* K
to setup-globals1 H( m9 a: W, F+ `
  set current-light nobody ;; just for now, since there are no lights yet
4 S( m: E: {  R8 ]; Y4 R* K! H  set phase 0
  k, ~, n- y) X0 c- Q  set num-cars-stopped 0
# J' X# G8 z; U; g# _( y) ~* ?7 c# p  set grid-x-inc world-width / grid-size-x+ T/ H- ~: e5 @+ L8 o3 W9 l" H9 S
  set grid-y-inc world-height / grid-size-y
% \! g5 g7 m; p. T- G4 I0 h% `8 M6 u
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 h: Z7 m0 o& q0 R# M/ \# @  set acceleration 0.099, c5 n0 [, o' p8 O, G# B: D
end- `& N9 K5 ~2 C4 {  S2 w1 I
4 X, K. a1 g$ X6 k2 B: Q- o
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& E0 G1 R3 ]/ W& Q- O1 j1 g
;; and initialize the traffic lights to one setting9 o/ F; w' Q3 H; [! p, M
to setup-patches+ k& E; n; w: }/ w4 ^# h' C4 M
  ;; initialize the patch-owned variables and color the patches to a base-color: C+ C0 `( N  Q: k
  ask patches' d( k* }" ^7 c6 a4 N! S
  [0 U1 P! e5 g7 Z/ ?7 R( b  ~8 i2 v' p
    set intersection? false
" @' P3 z0 a4 J% h  k5 ], `7 C    set auto? false4 A% v- T. p- H! _5 [% o
    set green-light-up? true2 D5 {  ^' |, P& L+ n8 f# `
    set my-row -1
, I* ~+ ^- O( P/ A2 C    set my-column -1( l1 B. [% h& e6 t# Y3 j: F& V2 @
    set my-phase -1, v# w9 {* Q8 x1 Z
    set pcolor brown + 3, s( x. j  s" j# b2 J4 P$ V" m
  ]
/ q5 |& n3 Q; f  K. q* M
" u7 R4 k$ t3 V$ K+ f$ H  ;; initialize the global variables that hold patch agentsets
# |0 X) k3 x& L& g4 o9 N% M  a  set roads patches with' p5 m* X( z, s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% [! A$ w/ `9 F" p/ \- V) Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& S& B6 M" u# Y: S  set intersections roads with
: S0 V2 b' Y+ r5 S# @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) n. l  J) L( t% d' _- S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- _1 |+ l* V0 m  o4 S" c1 O& V
( J( x1 R9 }  k- c* X9 V3 {
  ask roads [ set pcolor white ]0 T7 X- A* j4 H* [9 e/ j" A1 A
    setup-intersections
$ }0 a$ I/ w9 {: Hend
0 M' C5 N2 c: |$ E& a. V) |其中定义道路的句子,如下所示,是什么意思啊?) V8 Z' O$ I; ?2 a! R/ \
set roads patches with$ M' U/ r% _" U, x* j* b- w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 x% B3 \; N  X# m) K6 @2 R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 k. k4 d6 w: M% }" u* |
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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