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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。- ?, M9 a/ E- N8 E5 @' M
netlogo自带的social science--traffic grid这一例子当中,
. T" U8 y2 X+ ?globals" G3 Q* K! k( ?% A0 |3 d
[. l7 ]0 f5 B& u9 J9 H
  grid-x-inc               ;; the amount of patches in between two roads in the x direction2 M) Z! S. H& z/ v. N% y; e. X
  grid-y-inc               ;; the amount of patches in between two roads in the y direction. k* F5 K1 @% \0 @
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& n% U: x/ _) y* l                           ;; it is to accelerate or decelerate/ z* v9 I0 I& O/ v2 [5 v8 Q' }: p
  phase                    ;; keeps track of the phase7 R! t/ f2 B  B- C
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
! L+ t* e1 A- `/ \  current-light            ;; the currently selected light8 D' x# t4 [, Q, o7 i
) F, d/ i- u6 a3 U2 l
  ;; patch agentsets; [( K* }& A0 K9 l) n3 Y
  intersections ;; agentset containing the patches that are intersections
6 ~, K- r6 r2 f  W% c. Y  roads         ;; agentset containing the patches that are roads- p, _( V6 l. N* F) Q
]
+ Z- \7 \1 k  P( {/ W
& K2 g% A3 r- X7 U! k! |turtles-own
/ v+ v( ?, K7 N2 h( w[& f) P7 E9 @- O8 P
  speed     ;; the speed of the turtle! F- M2 c. z0 c
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# l- D: y. ~0 k7 y- U5 t; r% n; [
  wait-time ;; the amount of time since the last time a turtle has moved
0 s9 m  O. X- b1 L2 {) {1 r# G7 ^& T]: R5 ^; M0 d8 ~$ c9 }
3 C% y3 z# p+ a; |
patches-own, M( k3 C( ], ?* n6 G9 Z
[
2 P6 C! D) d. i5 v  intersection?   ;; true if the patch is at the intersection of two roads) g5 n7 E5 E4 [- _
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# w& K$ q4 N" ^0 p5 ?9 r2 W3 t8 j
                  ;; false for a non-intersection patches.
6 [2 {, _* y  Z$ S% `6 a) H  my-row          ;; the row of the intersection counting from the upper left corner of the9 s% X- {2 w) X
                  ;; world.  -1 for non-intersection patches.1 x8 a; v, W% U+ O9 `! ^3 [# v
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 ^; @) j( I8 T8 J3 P3 J                  ;; world.  -1 for non-intersection patches.4 M  \- |4 A  p# J6 H" \- @2 j
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- J! R# Q, \+ p# z3 w  auto?           ;; whether or not this intersection will switch automatically.
- U% {/ a* R) }                  ;; false for non-intersection patches.
4 \6 ^9 B+ J8 }( F$ D]
( O4 [# c. `; m8 m% H$ e- j7 b5 l+ S: g# G. K" I2 @
6 f9 J4 h0 j3 _6 O6 |+ K1 j
;;;;;;;;;;;;;;;;;;;;;;) h9 g1 s5 G; i. X) ^  z! U
;; Setup Procedures ;;
- Z7 G! E, {7 y;;;;;;;;;;;;;;;;;;;;;;
" \( x. ^  m* `4 X8 k) p4 H7 w6 E, [
;; Initialize the display by giving the global and patch variables initial values.; [+ I' W- k$ j; C7 a+ K
;; Create num-cars of turtles if there are enough road patches for one turtle to
% B' k/ R4 u5 b4 H;; be created per road patch. Set up the plots.# Q" t5 W8 T( w/ p  S# b# O4 F# g
to setup9 G4 P: A  G8 K( t5 Q) n
  ca$ A0 @" K5 A5 W5 e
  setup-globals
* x" X8 m1 H7 h  G6 u
$ z( ^; [# _8 k% d8 H: ~8 T  ;; First we ask the patches to draw themselves and set up a few variables
4 o0 X2 l) ]- E! Z: ?  setup-patches
6 j' \  z$ T$ m6 N% [  make-current one-of intersections7 n& C% r6 k* s* P- F
  label-current9 @5 M2 O5 d4 n2 O; |

# k- O( }$ Y& f  set-default-shape turtles "car"
5 _6 e: M7 w3 I! l2 i# S( l) z
, m0 E$ \. w# x  d6 `# O  if (num-cars > count roads)
3 W5 m# P, P, g6 r2 V9 M3 _" }  [1 N" K/ ]+ u) S9 I8 W, |4 t
    user-message (word "There are too many cars for the amount of "
% S; c  ?) K  Y1 j                       "road.  Either increase the amount of roads "
+ P+ x( O0 w1 k                       "by increasing the GRID-SIZE-X or "
7 j$ j* s% v% u, d( @2 b                       "GRID-SIZE-Y sliders, or decrease the "
; B8 G% p7 [. n                       "number of cars by lowering the NUMBER slider.\n"
& I$ [5 j' D4 q: k8 G& V8 q                       "The setup has stopped.")
8 T, X* e* \) Y: ^    stop
* x, s3 p2 Z3 O* X& V# F  ]. I4 P7 J* W: u! E& P6 l+ B- B" K
5 b) p- r/ }$ C7 L1 r* G; }7 ?, k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 ?6 C% [( g: ^: o6 S/ `. M( l+ i
  crt num-cars
" l# V4 q& p+ C  [
: x/ f$ {& K) V1 p, H: P    setup-cars; n3 ]2 G! _( A: H# i7 M, P
    set-car-color; m) V, a9 D: [4 w/ G* Y
    record-data$ x/ ?. K; n5 `! t0 I0 l# Q: P: O; t
  ]! H1 @6 t8 _: y* S* a
* Z: u4 W# T5 P) }% ]$ r
  ;; give the turtles an initial speed
1 W# S4 S1 Z/ Z* i  m2 @, c  ask turtles [ set-car-speed ]
  m3 X7 P: r) h# D
( K  W  S  W! x" o- Z. L+ r  reset-ticks
5 w0 m5 O" B5 qend
1 A, ^& t8 v5 D" T+ f* A) I
* I' o' P: E, \+ W" t* j* Q;; Initialize the global variables to appropriate values
1 ], H7 ^7 `. B9 dto setup-globals; n. ]' Z% S3 M; o
  set current-light nobody ;; just for now, since there are no lights yet
2 G6 F$ c$ A; v  set phase 0
: c& a' F, n( P  [1 e) `$ S5 u  set num-cars-stopped 04 T% e" D6 G1 u+ w, r' z5 O8 Q" [8 v
  set grid-x-inc world-width / grid-size-x
! {/ p$ P2 T0 y9 n/ q  set grid-y-inc world-height / grid-size-y# g% _) t, Z( [) F

' n) ?5 X" y" B, Q$ b( X. }  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 S) g; M% i6 @' E- V  set acceleration 0.099  t& h% ]2 q& h+ m# o% b$ B5 d8 X6 A
end
& t% m# C  a6 c1 ~; E# V4 M# m9 h" L) X% U
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& m8 b$ s: k9 V
;; and initialize the traffic lights to one setting; e2 ^, b' `. }( P; q6 @# f
to setup-patches
: a& e  Y8 K/ h1 Y, D+ e3 H& w  ;; initialize the patch-owned variables and color the patches to a base-color
; y3 B5 |( Y  ~2 L  ask patches( |" `2 V5 S: ~# f* h: R8 k
  [
. |  a$ H1 n5 {9 @    set intersection? false
. G9 ?7 O+ O0 G    set auto? false5 j: N( [( {0 m3 f3 \
    set green-light-up? true
" _% U* e+ ?8 ^! L3 g6 U    set my-row -1
4 |/ v/ E) K& H" r( A4 }! t    set my-column -1
# c( M1 I! U; C    set my-phase -1/ ?' s- u8 V3 E
    set pcolor brown + 36 d; ~5 P( K( u% U5 }
  ]
7 Z8 V6 _" }+ \: X2 B: R
. M& s( q% \: k+ m% R  ;; initialize the global variables that hold patch agentsets6 b# Q7 m/ O3 j
  set roads patches with  P" Q% i" n7 h' F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* t$ H& t3 ^( [) E! o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. N* W# D6 n" v% M( ]; j/ z
  set intersections roads with' d' ]/ X& R9 O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! l: a/ L, W  _& t4 m( k2 f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 B& v+ t% f! W. f4 b9 c

$ z7 R* a) H- J/ Y  ask roads [ set pcolor white ]
* Q" h* r1 v$ o* b8 }    setup-intersections, k& g! r& Y, O( e2 S
end
& [* {. l4 ~- h: E/ ]  C其中定义道路的句子,如下所示,是什么意思啊?
- B4 _2 h  M8 L4 f. Y& q set roads patches with
& p3 o8 F" ?  j9 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 E: @: X& ]$ v$ K% W1 Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" a& _, e& h% _8 A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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