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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。( Y( S+ s! e! o+ q. o7 q! O
netlogo自带的social science--traffic grid这一例子当中,
' K# @. f; F' L) N5 sglobals0 d4 b4 x" k" t, G  ?  ~
[1 f2 {! K0 [0 p* \' K4 P, e
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 f+ {4 \' z6 T  W1 }6 ]* H+ L" U  grid-y-inc               ;; the amount of patches in between two roads in the y direction' c+ ]9 X, t$ Y) i6 M5 q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; ?- Q+ ?4 ^: r8 z- L
                           ;; it is to accelerate or decelerate$ r4 I, W1 b4 x. `
  phase                    ;; keeps track of the phase
8 _& Y, m* s1 F1 \* d! T! n! Y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ I- o6 `' J$ B1 F9 ]  current-light            ;; the currently selected light' L& }1 l  k8 O
: [* M5 m8 I/ R( ~% {
  ;; patch agentsets
# C; G5 n% A+ L9 |& w$ ~  intersections ;; agentset containing the patches that are intersections$ W% p# {) G: E) L" `% t
  roads         ;; agentset containing the patches that are roads
- J0 z0 F! K) o]/ W  B+ b7 v8 ?# N+ l/ U1 l5 N& N6 {

: U5 u; |' i& H& C* b/ Mturtles-own6 I" {/ u# q7 w5 _( U* z5 h9 W9 p
[
$ |8 y' Z' X% T! y% R# ?  speed     ;; the speed of the turtle5 b" F1 C5 {' b7 t7 k& u
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( n% L7 j- l# L6 o! Q& L  wait-time ;; the amount of time since the last time a turtle has moved
& |' c3 S) F9 }, r+ [8 ^]
6 U& h1 Y6 l3 a9 W/ |9 S! H  s* A6 N8 V! }# @2 V2 u
patches-own
+ r' P9 o& b1 W. P/ I* Q! z[
% C; j( o$ o) p) R. R: v9 T  intersection?   ;; true if the patch is at the intersection of two roads9 d2 m; O; [' c5 @7 g: r
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# d8 a; v' w) R                  ;; false for a non-intersection patches.
$ |4 J! r. A9 x, u* h  my-row          ;; the row of the intersection counting from the upper left corner of the
- o, c' D3 I- B8 ?" c! U$ m                  ;; world.  -1 for non-intersection patches.
, r2 N; s) A  t2 V  my-column       ;; the column of the intersection counting from the upper left corner of the
  U  d) ]& k( ^  W. W) n                  ;; world.  -1 for non-intersection patches.; k( C4 \2 m$ X# t' t/ ?6 N! i
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 f9 A  I' Y* u5 z9 d4 K% D* P  auto?           ;; whether or not this intersection will switch automatically.+ p4 S2 s0 Y. c. G% K0 r8 g
                  ;; false for non-intersection patches.
+ p: ^5 p- D7 @! r9 F]# _! h) @% p: \

/ E" v, D) \- S0 G/ ?
. w! m' \% u# ^;;;;;;;;;;;;;;;;;;;;;;
7 ^( a! y) @1 @2 O9 P8 g;; Setup Procedures ;;, g* B- u) \; w
;;;;;;;;;;;;;;;;;;;;;;! `" a8 p4 _1 r$ L. M) f, u7 R

* E! l: d$ y% }; a9 ?* n. [* o;; Initialize the display by giving the global and patch variables initial values.
" u9 c$ ]$ `0 d- ?" s+ ~1 h+ A% };; Create num-cars of turtles if there are enough road patches for one turtle to
6 C( U( C. d9 y;; be created per road patch. Set up the plots.
8 k$ @0 H$ |9 t7 Q! x* F4 T6 `to setup* E( b6 E8 o( u2 z' ^
  ca  @; c8 B* w. c5 [" T: _
  setup-globals( C0 p" b/ W+ B
  I+ L: Y& Y9 A' K* ?7 d
  ;; First we ask the patches to draw themselves and set up a few variables& x" [: C* X2 X5 i
  setup-patches6 `9 Y1 a$ H' f" z: h/ d) f
  make-current one-of intersections
' N( z9 }% _0 {  D! Z; n$ u  label-current
9 I- A( H4 U8 _/ ^1 G7 C
0 \7 W  e) a% X  set-default-shape turtles "car"  O: v& t$ b* n+ [, P

# i; b, S8 K7 `3 k$ u  if (num-cars > count roads)& c7 n( m. I! y1 `. [) F0 T
  [
: q. |" _! O/ }& U8 Z) `* U    user-message (word "There are too many cars for the amount of "
* _, s* ?) g( o; [                       "road.  Either increase the amount of roads ": U6 c, y, |  R1 G
                       "by increasing the GRID-SIZE-X or "0 l) g# ?3 M0 @  U- f
                       "GRID-SIZE-Y sliders, or decrease the "" P$ R, k, Z5 g7 o
                       "number of cars by lowering the NUMBER slider.\n"( |" g7 \3 I! K( n. l! p0 d
                       "The setup has stopped.")
2 {2 [: m& F* ^2 h, \6 P" N    stop
1 d$ k# g& X# ^7 H" B* ^  ]8 L0 A2 ~) r2 z, w- w0 F
# K% n: X5 c" H
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ D& U2 I  ]9 O- X# b* |- H/ B9 }
  crt num-cars- A7 Z1 j3 N3 u) U5 J! n) j
  [  C* d2 e6 |" B; N+ V7 O* D
    setup-cars
4 w& G! L& \) M! n. {( _, ~- _    set-car-color& R7 J5 I) }& p$ E% o
    record-data$ i0 J( e! Y/ O& f
  ]# s. [, Y, L* p* z

8 S: w1 }9 ?5 f& r1 y  ;; give the turtles an initial speed2 f5 M/ z* x# V7 X1 K% [
  ask turtles [ set-car-speed ]
( h4 b& e: `7 G! u" T2 j
3 ]3 a5 ?: c+ i$ c+ E) ?  reset-ticks
0 S& A. [* C0 q% Iend
# f8 O$ b7 k; L* p3 q# A9 I1 @. B5 n8 B
;; Initialize the global variables to appropriate values% ^- W7 z- Y0 j7 g
to setup-globals* w% Z5 h! d# P* w' T$ C9 H" c0 f( R' y
  set current-light nobody ;; just for now, since there are no lights yet  `& V$ ]" O. B: D
  set phase 0* V1 S5 I6 W( F+ b7 K: R' N) U5 B
  set num-cars-stopped 0
! I9 K" s2 P* X* P, \  set grid-x-inc world-width / grid-size-x4 ~7 f+ ~. u6 A5 u7 l  }
  set grid-y-inc world-height / grid-size-y6 |9 G( G$ A# P/ p' h: Y
! F. b# Z* A3 [3 ^; u- r/ q2 z, _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
2 c' o3 x7 e* B8 s7 E0 g  set acceleration 0.099
& F+ s* X0 @9 N( L- M! J# rend
- W5 `' H1 Z# ]. ]
, X" X% \. z8 l1 L* w. u5 Z/ g;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) F* E* z& N0 c
;; and initialize the traffic lights to one setting
3 F/ Y$ p0 ?' R; Wto setup-patches
+ v) c* F& W! X+ F8 S! S  ;; initialize the patch-owned variables and color the patches to a base-color
/ i( ~; k  Y! J  ask patches
' q2 Z9 ^! t. a8 c8 o7 T; K% P3 b  [5 f; u. ^5 U& l4 Q) q; f, A1 F, S
    set intersection? false* x) M! _, J) t
    set auto? false, o& D- o, Q: }4 v9 n
    set green-light-up? true9 B, f' o; H- e' ^
    set my-row -1
, h7 h& w: o* i- R. @# p    set my-column -1. i$ h4 t# n0 C5 c3 e/ j4 v
    set my-phase -1
/ Q6 Z. X0 F5 E4 r3 o! q    set pcolor brown + 30 _6 C6 u( r4 d* ~2 `: W
  ]
) t0 p0 K2 x: a2 o1 n6 G) q
1 h1 |6 d) i+ Y6 L' h( L7 o9 W( f# r  ;; initialize the global variables that hold patch agentsets
. M/ F% g3 n: x+ Z2 A- Y, P4 D6 x  set roads patches with1 g" k4 y+ ?8 Y0 Y# Q+ N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ }# |, v+ `: [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% ^- X. S8 d! u2 `  set intersections roads with
$ H# F8 f0 D7 w, z9 N9 R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* Z- S! t2 T5 r& Z  q9 x7 D: J) P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 _* @* x# }- G
8 V) i( w) K+ F+ \8 _4 w. k
  ask roads [ set pcolor white ]7 B3 L! G1 X- \  M# I5 M
    setup-intersections1 L/ U7 x, F' @
end
4 h3 S8 o, l$ l) \, Q其中定义道路的句子,如下所示,是什么意思啊?, L- x' l0 b6 D( [; n! P! T
set roads patches with
5 e$ ]' t5 O9 J1 J& [/ X4 q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 e+ z$ R3 e# l  X4 e$ w( v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], q9 Y; A7 _& O' s
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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