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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。
9 h1 Z6 _3 r7 K  y+ W( m; fnetlogo自带的social science--traffic grid这一例子当中,- s7 q( M+ k: B4 e1 T0 K
globals
9 ~4 _% P# k- t[( n/ P3 F$ P4 l2 n( N+ E& w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction! q5 }- Z( z' a! P3 C* ~' e
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 }; a, _* B# l: E- v+ Q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; g9 p/ X5 e. n" {/ L/ Z5 Q
                           ;; it is to accelerate or decelerate/ |! F) G  b9 `
  phase                    ;; keeps track of the phase
" t4 p, h% V- _7 }  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ L1 Q$ c1 Y" [
  current-light            ;; the currently selected light
+ P" g3 c: s' @8 @8 Z( q* {+ [( o3 M4 T, `$ V. `; I5 S$ C
  ;; patch agentsets* B$ L/ j# U& Y# F; o
  intersections ;; agentset containing the patches that are intersections/ s* [) c& b3 g$ u
  roads         ;; agentset containing the patches that are roads# |7 j) i5 y- b$ f2 e
]; q! r) m( v( ~+ a; x: {

, {% |( e+ F1 r" Z" t" N; \' Tturtles-own
+ _' K! V# I/ M1 b9 }[% h. c# ?% w2 v* O) _) T0 f
  speed     ;; the speed of the turtle$ B6 h; W/ r! a# f( h
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* G; A0 S' o& B& T1 D  v* r  wait-time ;; the amount of time since the last time a turtle has moved
" R$ k! O2 y* b: O+ k]6 O, {9 W! B# ]/ d- l& D
0 Z- F$ ]: F- z& T5 }
patches-own
. p2 f( ?  o9 o& J2 D# R0 z0 K[: O$ h; ~) v% S+ i9 }
  intersection?   ;; true if the patch is at the intersection of two roads! M* x. Q( j( E) T1 Z
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, Y! O) j7 \0 f/ Z* G, b                  ;; false for a non-intersection patches.
4 n5 `5 i. N* a, u1 j, W- T  my-row          ;; the row of the intersection counting from the upper left corner of the; y1 ]. a$ a  c1 v! u& p
                  ;; world.  -1 for non-intersection patches., V5 s+ N3 I, ?, D$ @
  my-column       ;; the column of the intersection counting from the upper left corner of the" j4 d8 \5 d2 @' h. [+ r. L3 R
                  ;; world.  -1 for non-intersection patches.
/ W) a+ ~8 X7 H  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' s9 i" w0 k7 S
  auto?           ;; whether or not this intersection will switch automatically.0 v( ?7 s* e  ]  p- V
                  ;; false for non-intersection patches.5 w! u1 G9 C* U, Q2 x6 W
]9 \& t9 I4 S+ e0 ?; C* E9 t
/ [- @) @4 W4 E9 q; m  i

% u3 U7 R; V2 g7 r;;;;;;;;;;;;;;;;;;;;;;# Z0 \' Y1 N+ Z2 Q9 `; r
;; Setup Procedures ;;
8 V5 c2 ?* ^4 b! ]* Z;;;;;;;;;;;;;;;;;;;;;;
* R! U3 S* W$ s8 T  o0 V8 f0 S4 G' D1 \( a+ Z
;; Initialize the display by giving the global and patch variables initial values.
) ~, d: p, T' s7 f$ x;; Create num-cars of turtles if there are enough road patches for one turtle to
* Z4 v" `6 a  n;; be created per road patch. Set up the plots.
( T# J! R. H1 t: w, K2 t3 gto setup( U; ]0 N1 r2 E0 N: P: ?( D  e3 ?" ~  k
  ca. H) W8 P# }! d: H! t& i# z
  setup-globals' H! Y; Z" v. S9 J6 N4 j* N

3 G9 P: K  ?+ I" K3 a* {( G  ;; First we ask the patches to draw themselves and set up a few variables
  G5 o) J. G  w  setup-patches
' |2 t) c9 Z- o# V& C& w  make-current one-of intersections% y9 n- t0 Q+ @3 M/ O: I0 n
  label-current+ k; r# n- `: n5 v; I' q) L; G
0 G- r0 E5 k! t; u
  set-default-shape turtles "car"" ?0 |# q, e) _: C4 f. U# v0 l4 f, Z" H

0 B. w" L% M9 [# }# m/ F  if (num-cars > count roads)
+ `; ^( H4 T6 }  f' q  [6 f  @" K- }1 w' t' u! R3 i+ B" ~( F
    user-message (word "There are too many cars for the amount of "
% m. v9 [1 S3 ]/ w$ N6 F( I                       "road.  Either increase the amount of roads "
6 d# u8 I' f1 e; W/ J8 N; d                       "by increasing the GRID-SIZE-X or ", ^- X, E! m- A& y# |) q( e
                       "GRID-SIZE-Y sliders, or decrease the ". ~+ ]8 ~! p6 l
                       "number of cars by lowering the NUMBER slider.\n"4 _" o) v$ n+ z9 T: L6 Z3 L
                       "The setup has stopped.")
! h# `* U6 Y! x: G9 l- K    stop
- z) j/ G, {0 I+ e+ }$ U  ]; S( A2 P, Y' f% N
! }6 z1 B6 {+ m! D& U
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 R6 M( O4 E$ Z2 Z1 p) K5 R7 u( O7 a
  crt num-cars! a2 |* f7 A" ~: m9 A9 M
  [
) M- R2 }/ A+ k    setup-cars
8 |) D9 y( v5 d& C$ N- D* ^    set-car-color0 V0 K/ v2 U$ S6 m, N; I* C
    record-data1 m9 \# N* \- Y2 R; f
  ]
4 r: q" Q3 t' f0 b  w7 U, d2 u
* _7 \  J) U2 {. H4 a* u  ;; give the turtles an initial speed  o( P1 r! c, u' r( U0 e2 q7 k( o
  ask turtles [ set-car-speed ]0 N' J: u$ m3 _- U& X1 z7 I; `% G

+ c6 A: v' c- N8 }) a! h  Q  reset-ticks
; F6 p& B4 ]1 M9 F, C( C: nend
& O: v; F, H: q
! ?1 h( d  |9 Q. ~! {# ]" K;; Initialize the global variables to appropriate values
+ m7 o: D) X: f# d' Eto setup-globals4 c# i( _, {. E" V
  set current-light nobody ;; just for now, since there are no lights yet
* O' S4 h$ O! c1 _3 }" B$ C0 e  set phase 0, @6 n9 m8 @% Z% x
  set num-cars-stopped 0
$ o% w+ ^$ u% M( t- s) O1 F3 ]! U: N  set grid-x-inc world-width / grid-size-x
' S  d+ y/ `  m6 W1 _' o& }! y& ]  set grid-y-inc world-height / grid-size-y
2 x/ K) N/ a/ O, ~! }. u- M4 n9 [, U, p. \/ u, C5 X$ B  j* P* d
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 g2 J9 T* Q5 H7 D
  set acceleration 0.099$ T3 u/ E. K6 J0 i! C9 _8 ^0 D$ q
end
  }$ J1 V; ~* k$ c# M* H& ]
" r. J$ B2 I/ w3 U! K;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ j4 c# k9 s  g) ];; and initialize the traffic lights to one setting
9 }; ?! J$ a# D) m$ q/ ?to setup-patches
9 O  F- @8 h3 f' z( `* ~6 a$ c6 m  ;; initialize the patch-owned variables and color the patches to a base-color
' P, P9 H% }1 n4 o  e9 p$ u; z  ask patches
; i; G9 h* c6 ~* z! L0 @  [
+ |, K- k0 ]# T    set intersection? false
5 E! M5 }! l" M, U    set auto? false# Q- t* w, i4 l
    set green-light-up? true
! Z  v' n/ S& c& E! q& X: x    set my-row -16 L1 J, w7 m8 H, c! w# ~( u7 d4 w
    set my-column -1/ w8 Y9 z3 _; d( V
    set my-phase -1& Q3 F) U" ]0 t  F3 z/ n, D9 m8 S
    set pcolor brown + 3- Y7 W3 S" b" @4 z% ^# A
  ]1 `5 d8 D# w. M5 l# V
0 R7 h$ a& s) B
  ;; initialize the global variables that hold patch agentsets
# ~3 f) q. Y. a& |$ f  set roads patches with$ O0 C5 o- B! X' G( s  S0 {- r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( i0 X+ E& G% a5 M$ a- Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* F( Z! ]; z! m: Q$ W; G  set intersections roads with" \* Y* p: X% C% o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and6 M4 g6 h- P4 \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% Y& {, c9 S8 ]- e
( I: h) ]2 P2 j) ~: \6 b+ X
  ask roads [ set pcolor white ]1 s5 i4 c* Z" V) J
    setup-intersections5 {2 @. Z2 M! B. `& j$ u
end8 p- k  X- F. \' u" p% w
其中定义道路的句子,如下所示,是什么意思啊?
* d. F5 p9 S/ G5 }6 [0 | set roads patches with
! [7 J9 w4 y) d% J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: ~) Z8 _* c( u0 }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ X4 W3 R8 e9 L' k' j" t$ I! F$ t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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