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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。
$ p, w- \1 u1 Unetlogo自带的social science--traffic grid这一例子当中,! z3 m/ U( {, p. z1 z; I* T
globals( J% W& D: b& h
[
* G- J0 T) V+ V( b3 K  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* R4 z3 M0 r0 W$ |0 ]0 D6 c9 X  grid-y-inc               ;; the amount of patches in between two roads in the y direction
/ g- {7 k# i# e3 J# w  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- D5 ~+ {; \) r, \4 ]: W
                           ;; it is to accelerate or decelerate
3 j9 M2 W/ `: b1 ~) p2 p  phase                    ;; keeps track of the phase
6 C8 ^/ ]) S" b3 L' S% ^4 ^  ~' ?  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% x: ]" l% g. E  q
  current-light            ;; the currently selected light  c+ g; b' b1 t4 G8 N( }3 ~
. N2 e; s' U, ^9 \4 D/ O# `
  ;; patch agentsets
" ]9 F' n- |  x( T  intersections ;; agentset containing the patches that are intersections
7 ~5 R8 x# A. [, Z- u  roads         ;; agentset containing the patches that are roads% V6 F9 ~. d: \- E! A
]- d  P' r8 v; h- b

+ p/ k( ]8 R' C0 K1 u) }3 Q6 f% fturtles-own
8 f# J2 ?" S2 L/ N* u  z[, e" o  j* J; f8 ?" G2 o
  speed     ;; the speed of the turtle& l. Q' V$ Z& \5 ~0 ]' h
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  m+ O' Z4 W7 w. M. `! F  wait-time ;; the amount of time since the last time a turtle has moved# B7 ^) L. H8 n5 I. W  o; w& o
]
" l6 A; ~/ d+ w4 r
$ M: M7 k" r7 x1 n! E! }8 [: Upatches-own3 H4 O1 }- K5 Q+ j
[
6 \- b% M! o2 L- A6 R9 i/ N  intersection?   ;; true if the patch is at the intersection of two roads; G* g7 _; V8 ~/ b) P7 U; R9 Z
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
1 B3 g9 H# D, P. X/ F  U  v( `                  ;; false for a non-intersection patches.
. t& }) d& S% ^' {/ z: M; S. j  my-row          ;; the row of the intersection counting from the upper left corner of the
! A* X  e7 T; Z8 g8 f                  ;; world.  -1 for non-intersection patches.0 M/ Y' X- N: b4 q- i# U; X% d8 v
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 L& r6 g+ y3 P3 e; q8 r' ?2 k                  ;; world.  -1 for non-intersection patches.
1 n8 [; T3 y! x  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ Z# q: l# w& @# U
  auto?           ;; whether or not this intersection will switch automatically.
4 Q) h; [+ ~; X8 o                  ;; false for non-intersection patches.4 t! c$ {7 ]+ ?* C- ?" |# Q
]4 x0 E5 t% T6 Q& h3 _

3 J& V' @1 B+ O5 w* Y( q# f6 j# g% N) |7 I: l5 V
;;;;;;;;;;;;;;;;;;;;;;
% @& h5 m* D' J8 s, q: Q6 ];; Setup Procedures ;;, r% C. C2 o( b8 r
;;;;;;;;;;;;;;;;;;;;;;1 A+ F- p# z& E: R; C. ~
$ ?/ B& N1 m  r6 w
;; Initialize the display by giving the global and patch variables initial values.
8 `& P4 `; C$ o4 Z2 t& U;; Create num-cars of turtles if there are enough road patches for one turtle to
) Y5 q0 L. G3 D  ~# h7 R;; be created per road patch. Set up the plots.' S  r( C; H  s. A% U5 ?, e% C$ M
to setup
7 i* n+ l# P1 v+ F$ H! K& w  ca
8 [2 |1 o% d1 c' E2 p) U  setup-globals
# q/ I; k: b: }* B; c6 Q1 q" M  i& h$ j
% V. F& y% q6 y8 O  ;; First we ask the patches to draw themselves and set up a few variables
$ r, z! q# ~0 E0 i+ h: b  setup-patches/ u: S! C6 a+ @4 U' e, G
  make-current one-of intersections1 u- I5 I. V8 ?+ i: _
  label-current
8 ^6 _5 H- L6 K) N& x: q
( _0 L& F/ U+ Q% u- r3 N/ x1 h  set-default-shape turtles "car"
+ g9 w0 B/ `$ }6 H5 U
; {) O3 a% R0 \0 G; x. t  if (num-cars > count roads). O1 [- m4 ~, f; v
  [1 e$ J: d' p" E; k- z. f+ ^
    user-message (word "There are too many cars for the amount of "& l; w+ V' o( w, k! N2 ~- g% C
                       "road.  Either increase the amount of roads ". T* I2 w4 w7 G0 o
                       "by increasing the GRID-SIZE-X or "
; T3 M# ?# Y: `( p                       "GRID-SIZE-Y sliders, or decrease the "8 V; D6 G" Z$ e( o7 ]5 W! n4 {" Y
                       "number of cars by lowering the NUMBER slider.\n"/ v* P; c& n6 k& K& W
                       "The setup has stopped.")9 R8 B1 ?3 G" y0 a  [  c) R8 G) i  v
    stop8 a# ^( F6 h2 h, j4 w+ W+ q# i
  ]
$ M5 x& W; H& F- {8 H. ~$ k7 V3 \2 H
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- n" f1 M: I( M  crt num-cars
7 l9 T! |7 U+ q% D: G  h  [0 x7 d  u. G: L# [" t& u  e
    setup-cars3 m$ h7 x! u' @& W" d
    set-car-color
, b8 C7 d! _. w! L    record-data
0 B$ A5 L1 y$ q2 _+ u# B  ]- X. e! r  T2 d6 [3 W- ]3 q
& X; M$ E# m3 O* t
  ;; give the turtles an initial speed* ]$ P7 H! F) H5 W# s+ O7 {0 X* P; M
  ask turtles [ set-car-speed ]
3 t6 c4 |: z8 o$ \' }0 D6 y7 F: Y' o; O7 X+ |) I, [1 E
  reset-ticks" G$ c# E5 e6 p/ Z
end2 D1 G, t6 I) W. \

" d  T. R1 `0 O, T0 z0 J;; Initialize the global variables to appropriate values
7 ]2 e% B: V# `- n. Sto setup-globals
. e8 \$ R( m6 Y9 I  set current-light nobody ;; just for now, since there are no lights yet. P/ B7 Z: U9 d' b
  set phase 0+ t- ^  Y/ O: z7 n" {8 t1 R" w$ A
  set num-cars-stopped 0
" I" F7 u% u' }, R  J' q7 z1 k  set grid-x-inc world-width / grid-size-x) k9 N& O" S/ W, h% Q6 \
  set grid-y-inc world-height / grid-size-y
* Z) K* [$ q  A8 K* N+ W$ `3 J/ B. a: `- t7 {* L. q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 R$ v. t/ L4 X! K& m  set acceleration 0.0997 _* B# Y' o9 F2 a
end- z- O  W: \4 ]* Q. E7 T

7 @9 h. i; o$ @. z+ r. M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( m) K# q& N. X8 Q
;; and initialize the traffic lights to one setting
5 Z+ j  }! A: [% d4 zto setup-patches
2 [  z0 p# ?& h& r4 u7 T  ;; initialize the patch-owned variables and color the patches to a base-color( b( U0 ?6 @& ?. @  ^
  ask patches9 x; f3 C* Z' y
  [+ _7 D3 S. i7 X7 o+ V1 r, b  W* [- r
    set intersection? false# z$ G  e% `: ~& p" T0 G( B
    set auto? false  l8 |9 E( H+ j
    set green-light-up? true
4 Y% l6 f3 g2 O9 L6 p+ ?/ W    set my-row -1
. \4 c% H, Z2 R1 E. M    set my-column -1
9 ]9 A2 Y! i$ j- X* c    set my-phase -1
8 ^+ \* c; [+ y2 M' @! b    set pcolor brown + 3
& D3 ~" D/ _" g3 l6 |! l4 _- Z  ]8 E+ O& V/ g# C

2 ]5 i9 O2 i5 S# k  ;; initialize the global variables that hold patch agentsets
- u' y0 W  U2 p" q7 g  set roads patches with
7 i2 W& T. }; j) f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, _, F5 I- R# R' x) ]8 L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 ^. C+ z- Z* A; Z
  set intersections roads with
) [& L1 g" O/ f, N# ^$ e8 V- A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% n, s5 N3 b4 h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 R# i8 A6 J0 j' i
/ }: S% k% T0 z  ~# Z2 \) z
  ask roads [ set pcolor white ]" g, R. b9 b7 |7 V
    setup-intersections! Q2 [5 X: y% q  y8 b" R" z' h- h2 w
end' d: C& {- i7 ^- b* G3 D# m
其中定义道路的句子,如下所示,是什么意思啊?- f! D! ]" @- r) p- F8 i9 A
set roads patches with) u" R( f5 ^. m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ U- Z+ Q) B  s. X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 \5 p+ k. J& a* @8 J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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