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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。* E& V! W. K6 i1 j/ n3 z
netlogo自带的social science--traffic grid这一例子当中,
4 t% X! o0 A7 U  m& Aglobals
7 X! X! {% S. [, K, x& @1 C3 t[- n0 j, x9 Q) g$ U$ M
  grid-x-inc               ;; the amount of patches in between two roads in the x direction7 b) p" B* b; [4 k
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 C9 w, Y+ g! R- [  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  r9 o$ z7 ^% i2 W- s' Y' p: ^5 R                           ;; it is to accelerate or decelerate) n% [2 z$ x8 I9 K
  phase                    ;; keeps track of the phase, |$ a# u6 n) `( T( h  b  D
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 z5 W! R$ t1 ]5 K5 C( n
  current-light            ;; the currently selected light6 y9 @  m# H" ?
; j  s+ ], p/ C8 T# Y+ {
  ;; patch agentsets
6 @6 l# m2 {, K/ S  intersections ;; agentset containing the patches that are intersections* y. V3 \2 I2 o) i3 K9 p
  roads         ;; agentset containing the patches that are roads
" N9 H! L+ B/ @, b; O+ [/ C( \/ C+ O$ o]/ w& d$ }1 f/ J/ K5 e' p
4 S/ i( j. K) Q6 b( `, [: J
turtles-own  v0 p: ^8 P0 I2 E8 _
[
$ Y, o! e4 V) A+ I# a  speed     ;; the speed of the turtle3 z& f$ {, m: p5 [5 G  f$ f
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* g8 X* O7 J( A! G: e8 X2 w$ c! ^  wait-time ;; the amount of time since the last time a turtle has moved* o" _: }* e* c7 n. y" ~1 o: e3 j
]+ }; A; Z$ M& k( Y3 r1 [

& c: m( [5 A% Y/ rpatches-own  e& e1 s# G- c
[4 O& f: R7 ^; V: t$ q9 v+ m  E3 R
  intersection?   ;; true if the patch is at the intersection of two roads0 v% k  g% C' b0 l
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) m$ w" B4 q! y& R' b                  ;; false for a non-intersection patches.
1 p0 O2 Y3 @% P' ~1 N  my-row          ;; the row of the intersection counting from the upper left corner of the( z" ~/ M2 Z0 M3 K# t7 m
                  ;; world.  -1 for non-intersection patches.
# u3 t$ Z& l# l2 h  my-column       ;; the column of the intersection counting from the upper left corner of the8 ?% S1 o! T9 e: l0 O( N1 r+ C+ h) ]8 O
                  ;; world.  -1 for non-intersection patches.
( D  ^3 s4 T0 ]2 \  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! c2 S% [  g1 k- `9 @  auto?           ;; whether or not this intersection will switch automatically.
' d( r: N% n  G8 U                  ;; false for non-intersection patches.: t1 H0 `) @& A2 P( S' w
]
, Z; G+ W& E3 ?" }; g6 e
9 N8 {0 D. z* r$ T% Z
- ?6 q7 b! E' Z, ]5 v;;;;;;;;;;;;;;;;;;;;;;
% ?6 J9 P% {! s' y  Z0 z) T  };; Setup Procedures ;;
! V& a+ k2 u. y0 H! [$ s; L;;;;;;;;;;;;;;;;;;;;;;8 m; l0 |! A7 D

0 O8 v# }6 G) E( I;; Initialize the display by giving the global and patch variables initial values." s6 `5 q, N9 }7 P
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 x! H4 S. W/ \3 ~4 P# {;; be created per road patch. Set up the plots.
" T0 F( E) W9 k$ Cto setup
+ F  r% r7 D* Y# M# P6 \9 `9 \  ca
/ x. ]( t9 B8 L  setup-globals
4 d1 n; {8 M$ x; J1 A. {# E  k3 T
  ;; First we ask the patches to draw themselves and set up a few variables5 X7 n: ~" h. n. E+ _4 O% z
  setup-patches
& N- ]; ^1 J3 [4 C+ Y  make-current one-of intersections
" ^2 B8 I  D3 |+ [9 }7 K  label-current0 ^) N; V- r7 _, N* C$ u
7 v. k1 X+ \/ {+ f: d
  set-default-shape turtles "car"/ u1 S! y# Q: W- j6 L4 @

% U4 C' J! D3 K3 h; y' e  if (num-cars > count roads)' x5 u; O, z" v8 O* k$ [( E( A3 u
  [
" D9 s7 M; N; X& O    user-message (word "There are too many cars for the amount of "8 W& @; o1 |/ Q- M
                       "road.  Either increase the amount of roads "$ T& M1 u; G5 N6 I9 [+ L
                       "by increasing the GRID-SIZE-X or "1 h* r- G% o7 _" g& B. g
                       "GRID-SIZE-Y sliders, or decrease the "
8 L4 L5 k) t) B                       "number of cars by lowering the NUMBER slider.\n"
: o) v0 |7 |/ B- J                       "The setup has stopped.")
* [8 r4 ]/ T9 U" ~6 S3 K    stop( }8 z6 A) V- i3 V3 b
  ]# I- @) U- X3 c: g) H2 f7 n

3 f# t9 }1 S" B; J: h7 G# ]) ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color- T0 F3 c( K: ~4 P( R7 Y+ P
  crt num-cars
( u& ~4 P$ ?' ~8 H; `$ g" |1 Z  [
0 T3 f0 F* ?4 ?6 w! ^    setup-cars
6 @. M. W% B. V* j    set-car-color
! F: q$ Q$ P; B& j6 C    record-data) F2 S# ?# o, f' H9 r- P4 K/ y
  ]' u( u/ W' x* a/ G

% A) s' I$ @) W1 Z7 e  ;; give the turtles an initial speed$ r" n6 x5 X6 l' N
  ask turtles [ set-car-speed ]5 E) v6 b8 O9 K8 A

2 R' K1 i5 y. z. K! H8 x- x6 {) b  reset-ticks+ z1 H1 j% Y1 H% d5 r6 j
end- ]& S6 g3 ?8 K6 k' [8 N7 p

' W& G: B# K4 M: s;; Initialize the global variables to appropriate values5 i. @; {! |' K1 I( V* B  S
to setup-globals
$ N0 m0 P: B8 h+ U$ |9 t  set current-light nobody ;; just for now, since there are no lights yet$ Y5 _; Z6 Z* o8 v1 x4 M! K
  set phase 0
0 }* g% t% |- G+ x1 _  I, l2 m  set num-cars-stopped 05 S# B4 j( W+ s) N2 q
  set grid-x-inc world-width / grid-size-x, _! Y) K9 W, p' l
  set grid-y-inc world-height / grid-size-y7 {3 M7 N% O$ a' U
" g( @% F' S: |( E& n# B+ |
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  K& D. I. X& E2 d' o2 \
  set acceleration 0.099* k: j) d; @; N- H9 }  w
end1 S, f. w" j  c

3 m/ W6 f6 v; [* g5 L;; Make the patches have appropriate colors, set up the roads and intersections agentsets,% t; t" I1 v* C; {3 [5 f
;; and initialize the traffic lights to one setting
6 ?& T4 j* m: L8 k; Rto setup-patches
0 d2 \) {. Q' n, |5 K. {  ;; initialize the patch-owned variables and color the patches to a base-color0 S5 _8 R" M) [; A5 f! X; f  n, Y
  ask patches
$ ~9 [! b' d; k  q' l  [
, O7 z7 c2 g; O5 D7 |5 X1 l    set intersection? false
7 U  ?  R6 g3 J+ q+ T/ Z+ L    set auto? false
4 N- V! K  ?$ V, m# V5 P$ ]) \    set green-light-up? true% W' a0 k8 \7 K& C; u
    set my-row -1  y  t2 ?$ s1 M9 ^- \
    set my-column -1$ |, E! \7 C4 V4 N1 V$ N. [# y9 z- `
    set my-phase -1
2 f( {4 k- r* E. }    set pcolor brown + 39 E3 z4 z1 s% O9 p
  ]
! M% M8 n* q" k4 `6 T* m8 F# W$ x& X3 [
  ;; initialize the global variables that hold patch agentsets6 `1 B: ?1 d1 ]7 ]8 Z6 ^
  set roads patches with
1 d1 N2 N4 h- R" _, J+ `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 o  Z/ G. A' S0 Q+ E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) v" d# z9 E7 p4 e7 x% y  set intersections roads with7 t; Y% r( |8 }# q- s+ v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 v) [1 w4 d7 l: j+ J7 ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 o6 }3 s! V7 ?4 U: s' R
  ~5 C* n( ~, s3 t8 g4 b( Y  ask roads [ set pcolor white ]9 T( B; K& s0 z8 E
    setup-intersections
) K/ N# c' O3 @9 eend
, J2 O( r3 H# ^# f( s( [其中定义道路的句子,如下所示,是什么意思啊?3 U# Z, ]/ E0 v
set roads patches with3 S# {) ^8 P% a# D  B. ~8 Z; {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 v" S2 e+ `0 B; L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ R+ {/ N! k+ n- F* D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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