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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。
: v( q2 Q& q% ?3 Anetlogo自带的social science--traffic grid这一例子当中,6 [( W, E2 n, Y: Y$ P$ |, D
globals5 u) y* g& T& \/ A7 y* v1 `+ s
[  {% b' Y; J) g/ i9 d# T
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% [' x& ]* X( ?  @; x  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  W# Z- M% x, m8 l  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 s* Y' N  J- ?7 n/ k& j
                           ;; it is to accelerate or decelerate1 {8 x: @) e' ?+ _
  phase                    ;; keeps track of the phase# j/ j8 ^4 N1 B# m$ F
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! z8 B# k5 c% C- n9 J- }: J
  current-light            ;; the currently selected light
" Z% f9 s7 u, Q" x' R2 J# Q3 J! m( ^& u3 ]# I
  ;; patch agentsets
& q) @3 G! _4 d! o; t7 L) P  intersections ;; agentset containing the patches that are intersections7 B* b! ~. `1 u- Q4 D
  roads         ;; agentset containing the patches that are roads" j, d. E/ B0 p8 p
]
4 h# ]9 S$ Y5 j( h
% u& V4 s' B, R. }turtles-own' l8 u! }% ^: q1 F% W8 b( G
[
7 _$ ^6 L0 u" d5 a! T- ~  J  speed     ;; the speed of the turtle
5 K4 ~* T0 ?( b* s* I1 {! }. \. }  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  u; Q- \4 b+ [0 D* G
  wait-time ;; the amount of time since the last time a turtle has moved% W) b# Z4 R  n5 I- T7 ^
]' P  \% O" O3 \# f

$ X2 `! n5 s& ^3 @patches-own
5 J8 ^5 t! q7 c8 G[
9 g7 Z# V( {6 W; P6 Y  intersection?   ;; true if the patch is at the intersection of two roads
9 g$ h4 M# H' ?  o- f) O4 A$ x' Y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 M* X- C0 Y+ r& F( W# y4 D' D
                  ;; false for a non-intersection patches.
) E: c* i. i. f) a  my-row          ;; the row of the intersection counting from the upper left corner of the
! r" O3 I; i3 X                  ;; world.  -1 for non-intersection patches.
' N( S: z, ^4 @  W3 c  D+ W  my-column       ;; the column of the intersection counting from the upper left corner of the0 _1 b  O; K4 v0 ?5 h* M% Q
                  ;; world.  -1 for non-intersection patches.8 q& @- @+ T& R* T! c7 x
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 J- O0 s2 F0 a* S* U; Y
  auto?           ;; whether or not this intersection will switch automatically.2 K/ ]  r9 q% ]5 D& W( }& `
                  ;; false for non-intersection patches.. S1 r% z, T3 A" [8 A' m6 W4 W
]
5 I  K: B2 `) {3 b) A% }
4 t3 c# {* \. P1 D, |0 D& r. h% M# y
;;;;;;;;;;;;;;;;;;;;;;( V' ^2 N8 \6 V8 ]/ Q8 _4 b- ?
;; Setup Procedures ;;( {8 A7 B$ \3 a+ A8 z, w; X. J8 l) Q% S
;;;;;;;;;;;;;;;;;;;;;;
  i% C; N% \% J, _% n% z1 R5 h  Z; l4 r) h
;; Initialize the display by giving the global and patch variables initial values.; h: p! E/ n$ C1 R& j+ z0 Q: L
;; Create num-cars of turtles if there are enough road patches for one turtle to
& M7 J6 i/ \( A4 K" W;; be created per road patch. Set up the plots.
8 O) a! T) K& Q# Qto setup
+ Q4 P0 k+ _, \( j1 u4 w  ca
& z( K" m! ?' }- O$ z$ j& p2 x  setup-globals" P/ J8 C6 X' o/ m" N/ l
5 w- z5 P1 U  x
  ;; First we ask the patches to draw themselves and set up a few variables
  ?+ F0 v; A# y; A# v" k0 U  setup-patches/ j4 _  T) o7 f& r
  make-current one-of intersections
8 p' p4 j* c, g/ {7 v* j! I  label-current
# q0 p# ~8 H5 |7 R; ~/ r' d0 P+ w2 y; a# W, j$ \/ e
  set-default-shape turtles "car"
7 L/ p) Z, M7 c! f, r# N% ^/ |5 M7 l" Z# U( ]
  if (num-cars > count roads)
3 L1 j4 H6 D, I7 h2 A; E  [+ h* o, C+ P: F) G) a
    user-message (word "There are too many cars for the amount of "
2 O( w8 q2 L( m8 o# Y! C8 Z                       "road.  Either increase the amount of roads "7 G9 {( f, H- ~  R
                       "by increasing the GRID-SIZE-X or "6 c. G# j4 C" W4 h1 d
                       "GRID-SIZE-Y sliders, or decrease the "" u: o" i; `: j0 T! Y+ k
                       "number of cars by lowering the NUMBER slider.\n"
$ l. j7 `5 }6 \* c  ~                       "The setup has stopped.")* o, {' R2 Y4 F" q
    stop* D0 ?! N- T5 U/ x& L" S* s
  ]' o' S; F& }; Q8 _1 j: ^" b
4 v1 n. a! F/ ~/ v3 I4 \
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 Z; U5 e* Y; x$ W5 l( [, E0 U) L# F  crt num-cars
& e, [9 O  P) z$ p" g4 B8 r  [! m2 X1 N$ T7 `, x0 Y* r$ K
    setup-cars; j& N# x# T& h* i2 c4 o0 C
    set-car-color
2 S0 y: d6 v% {% r6 ~    record-data
% c2 p' u) Q( T4 d' d3 x4 B  ]
4 r+ |# J2 K% p1 ?+ I3 j/ h1 m& y6 ]. C/ ~' V3 z
  ;; give the turtles an initial speed  W8 H: H; Q4 E7 t
  ask turtles [ set-car-speed ]
& s/ R5 A: W+ ^
5 k/ G+ N& u! v, ~+ D: |  reset-ticks2 i- R, [. t& r# k1 a* @) n
end
5 L  L1 k. E; k7 A6 B% i
3 N9 }, d: G+ l' S, |7 z;; Initialize the global variables to appropriate values
# n. J6 Z8 p8 Gto setup-globals
5 Z6 T) R8 g' h3 P# {0 ^$ a  set current-light nobody ;; just for now, since there are no lights yet' l! E- R3 K9 |, m6 k1 i
  set phase 0
) r% d  f  \* k0 t# ^  set num-cars-stopped 0) f0 o9 A- M3 `( d: n. }( L& x
  set grid-x-inc world-width / grid-size-x0 l4 C3 g* M5 V6 h$ r$ k1 J
  set grid-y-inc world-height / grid-size-y
: A9 [* n. X2 x6 z) Z- w3 h3 n
. A' [; F* e9 L8 X4 Q  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary* K* n' `3 `* O% v
  set acceleration 0.0997 i* |* e, \; Y& y! {0 k3 i
end- c  Y0 X3 [- k$ T
$ d* o1 {- g2 B; w" P' F
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 n( @: w) L1 S2 s$ [. A
;; and initialize the traffic lights to one setting
8 S; T0 e( G4 `) j7 I) [( Wto setup-patches
" Z. V+ y1 k9 ?# @1 P0 h  a  ;; initialize the patch-owned variables and color the patches to a base-color
* n3 E& {) s# C- e3 {3 F3 V  ask patches! ?) k  k* o2 |! B/ S- y4 Y
  [
" I; ?* e1 e3 c    set intersection? false/ B7 X; Z8 {7 j) x
    set auto? false
) y$ n2 [; ?* [, N' ^    set green-light-up? true* W. c8 J* g& i: S
    set my-row -18 a2 I4 r8 o" R5 O% w3 l/ t" u
    set my-column -1* a1 d: \- y. Y+ C
    set my-phase -1
/ K; m5 S/ e+ v# Y    set pcolor brown + 34 h9 [: }/ x3 c. I
  ]
! Y; g6 ^* _& k0 i' ^+ S9 `1 ^' r* P  o7 K0 ^
  ;; initialize the global variables that hold patch agentsets
. E& V6 i9 L& v/ D1 r' b  set roads patches with
! F7 @" _% r8 a) i- m1 z) d4 S$ ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& _3 N3 j+ D6 I$ l9 n9 [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 a+ b* Q: k. E5 d
  set intersections roads with* Q3 y$ U7 p1 F1 J9 S% d. j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( y1 ]# A9 r! T/ @% H! L$ H5 }( S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& X! J; F* K; j% H

; l+ j2 B$ k& x" r$ J  ask roads [ set pcolor white ]- A' Z# K/ {# R! s- Z! ?
    setup-intersections& `+ ~% K9 v! b
end
4 e9 O! |/ p# y' @/ f8 \其中定义道路的句子,如下所示,是什么意思啊?
9 k! W  N* F; R. q5 g set roads patches with% K1 s9 R. i3 D4 q" Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 R" W4 E+ Q  a1 Y# G( F0 A$ D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 S0 o" C8 o7 g* D3 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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