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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。
& G6 E3 [' f% e3 G8 `7 I2 a, Rnetlogo自带的social science--traffic grid这一例子当中,2 j  R2 ?: k( I
globals
6 Y5 f7 I" ?- O6 E[; F6 u8 n$ s; T$ l# _% ]% R
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 m% }# p6 \, d  O  G! Z% T5 O  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! l% m2 X+ M& o0 L/ j4 @3 V/ b3 b  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; d' @, {! S1 G, o                           ;; it is to accelerate or decelerate
/ V$ K! w7 X% h$ i* A; u  phase                    ;; keeps track of the phase
7 F8 m; t6 O' _  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# k" z$ `; }: T+ O, Z6 s
  current-light            ;; the currently selected light! \- L3 b4 i5 \
8 R" b4 y7 ^. k
  ;; patch agentsets) Z7 p" X* U/ G: B) m  J2 ]. Z) g
  intersections ;; agentset containing the patches that are intersections
& R/ B1 }1 [! v+ H( [- U; q( n$ b  roads         ;; agentset containing the patches that are roads% Y' n9 B$ U4 W! t! R
]
. _% ]8 X& h9 h  u  D  s" ^" c1 w- `% i3 e
turtles-own
+ x) P! R* g1 V( R/ j) b* M$ L[0 [: `+ y5 L! {
  speed     ;; the speed of the turtle3 D% K6 I' l, d" c6 C" [
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 b5 l% T! D) f2 m$ \$ w  H  wait-time ;; the amount of time since the last time a turtle has moved: s6 x+ Q4 ^' s) r/ b9 D
]2 ^! V' i' f0 k' X6 ?- B) C

+ N  H  R: @' r7 \) Opatches-own, L& L0 K  D# f0 \  @8 `1 \$ i
[
0 v; Y1 s* X( Q  intersection?   ;; true if the patch is at the intersection of two roads
: F7 C  @& U! b- M( `7 z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! v* r/ ^$ T3 V+ o' |
                  ;; false for a non-intersection patches.! A0 K. Z5 Z! f4 G# `$ w3 c9 G' d
  my-row          ;; the row of the intersection counting from the upper left corner of the
* m& e* R* [1 N* [; p3 H                  ;; world.  -1 for non-intersection patches.5 x" B7 m1 ?' ]0 H
  my-column       ;; the column of the intersection counting from the upper left corner of the
# \0 t3 e# D/ N+ b- o7 a8 `                  ;; world.  -1 for non-intersection patches.
) ^. y7 J) H2 c7 i1 s' ?1 e  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' w! @; d7 c/ z# C, j
  auto?           ;; whether or not this intersection will switch automatically.
* H4 a1 Q& T8 K  C4 A; u0 v                  ;; false for non-intersection patches.
- O# _5 T8 _# s' d. Z0 r- h7 U]' \! Z1 l. o8 R/ d1 L
8 R6 z# `* g2 g4 A8 b

2 V5 n% I) J* S9 s/ T  Z;;;;;;;;;;;;;;;;;;;;;;9 E6 j( l/ l. W
;; Setup Procedures ;;
; V  S0 k0 R8 B! K;;;;;;;;;;;;;;;;;;;;;;
: O1 u) d: k9 m9 |/ j! X. [" R4 J6 u( I
;; Initialize the display by giving the global and patch variables initial values.
8 z' s5 Q3 ?3 v, q5 L. v9 A* Z1 g;; Create num-cars of turtles if there are enough road patches for one turtle to
: m' F% f0 _& j% J+ g0 N;; be created per road patch. Set up the plots., R1 p5 ], u0 n9 _  i  G' T& R2 {
to setup; }; B' |2 _/ ^  }
  ca
: r2 `- a" q: O: A4 |* o8 e2 w0 |  setup-globals; U4 h7 g5 N4 ~

- Q) h5 F: z, N! t. ?. |2 K  ;; First we ask the patches to draw themselves and set up a few variables$ `- s$ f! X3 c+ U
  setup-patches
' A( o3 N6 ]1 \  make-current one-of intersections* R4 l2 t0 n/ X) G+ ?! N
  label-current
: M$ j9 m) c' c6 M: Z& W- u3 X& w8 M$ S* v+ V& D; @% ~, {
  set-default-shape turtles "car"! T8 r- D3 M! r& T% J

/ ?3 P$ a0 @' ~* h  if (num-cars > count roads)6 C" Y, ~0 R/ I3 k0 M
  [) v( E" p* W+ a7 T$ e
    user-message (word "There are too many cars for the amount of "2 d% I3 s# c; t
                       "road.  Either increase the amount of roads ". K3 K5 L; q  \3 J2 S+ p
                       "by increasing the GRID-SIZE-X or "
3 W( M% Q" c1 r9 R  U/ T                       "GRID-SIZE-Y sliders, or decrease the ": y; d( V" Y4 G1 r; W( Q3 v( b. @
                       "number of cars by lowering the NUMBER slider.\n"7 q) {" }& u8 L/ q' p* z
                       "The setup has stopped.")
( v$ \; f7 ^( D' c% I$ [# o    stop
5 r/ Y% ?6 {3 M/ E% u  ]
! p) G* Y8 h; b  R) P1 Q' T. [3 W8 {/ A1 y& N0 n) W8 B
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' [) _4 [7 a8 E8 c3 m  crt num-cars
$ C7 s( @! m* m+ T  [. L/ Q% P1 L; z5 C
    setup-cars
9 I% f) u9 ?( t% d    set-car-color& p+ U4 I: S4 Y
    record-data5 @. l$ A( ^+ [+ k
  ]
: m5 i8 c1 }& U% f6 F' J. v8 q2 j
  ;; give the turtles an initial speed
$ [) F, Z8 Q# M; ^- _7 c3 F  R  ask turtles [ set-car-speed ]& x& a! A( h( t% D! s

; d7 U0 O0 r3 v- ]  reset-ticks
5 l5 z" @% U- ]8 }end$ I& b+ b/ F2 I* X( F* X
$ S, S, O9 G) O8 P0 P2 ~
;; Initialize the global variables to appropriate values0 a& M8 b/ \  ^9 y: u: x
to setup-globals
, ^6 S* G9 u0 X0 w: s. w  set current-light nobody ;; just for now, since there are no lights yet/ m% k- \/ w$ T& r' K8 y2 T7 N. C
  set phase 0+ f9 U& [1 N& T, w
  set num-cars-stopped 0
9 j* O2 ]" f& R/ y4 N4 w9 I  set grid-x-inc world-width / grid-size-x
2 I3 w6 u$ Z$ ~  set grid-y-inc world-height / grid-size-y' c1 C: A9 f9 D' Z. k

8 s# o( K5 j/ w* Q+ G3 B  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- h4 B/ d. `' k$ w0 M1 B
  set acceleration 0.099
( v1 [7 N5 ?" J3 ]6 _! vend' u3 I. r0 n; H
# k9 T$ \0 _; A; Q4 D$ C5 S' `+ L
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# t0 T1 A0 P; x' D6 d0 Y
;; and initialize the traffic lights to one setting
0 ?" s! X# t1 P3 @; E" Yto setup-patches! A1 t' w  A; F* |8 E5 B
  ;; initialize the patch-owned variables and color the patches to a base-color
* ?8 L/ H* s1 ]& H1 _: g  ask patches1 U3 d( e) J4 H7 e- y" q# A' I& J6 {- G
  [
; E9 ]2 U  b. q& q. q( q$ d    set intersection? false: P! F  i" F' W! l
    set auto? false
1 L7 i/ W% b# j    set green-light-up? true
/ z* M. J' }* l4 d3 \1 J    set my-row -1( ^7 H+ k( c/ |5 C9 b% F
    set my-column -1$ |" f# s2 d. L2 j7 Q
    set my-phase -1, h& ~6 R1 B/ V$ M9 ]& d1 `8 ^" O
    set pcolor brown + 3
' \0 Z1 X0 B: D" {/ @# X/ w8 h+ }  ]& r& k, X8 T) N

. E& f. V5 y2 C$ K* R  ;; initialize the global variables that hold patch agentsets
2 V$ |* |1 [: S/ ]  set roads patches with
! X( y* R  U3 p; d3 e6 d) _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ r& a6 D. L' ~# O% K  u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ z2 u# J# M% T3 B/ [6 X8 H  set intersections roads with9 g0 o( E8 W' a/ y: B. H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' z7 D; O9 k3 {. ?3 h; Z* X5 s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) O6 x0 G8 q7 [' Y
$ v4 g; \* Q/ A+ k: G; C1 J7 T% `  ask roads [ set pcolor white ]
5 d; b3 ~! o; U& s* {! ]* \    setup-intersections
- N! @  e3 V% n) c: l! U4 R% |6 aend
2 Y5 k2 y0 M, D# s4 k$ N* w& D, S2 Z其中定义道路的句子,如下所示,是什么意思啊?; U3 W" m: ^- c/ X; i# @0 v
set roads patches with2 R4 n$ P: n$ v/ |. \/ h, @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: e9 W" Q& N( }" E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 A+ b$ M) d. r0 t  @/ q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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