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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。) e+ y4 E; i: N
netlogo自带的social science--traffic grid这一例子当中,
# j% Q4 U; @0 wglobals
& s* ?# C1 m) w  j4 S9 u+ l% G6 s[
, ?- {) G* ~' L1 ]  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 q8 _0 B# T( V$ P1 h; a  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 ~# }7 }6 L6 h2 b; {0 X
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ U2 {; ]) t: z- T
                           ;; it is to accelerate or decelerate
2 v7 G) @. ], n0 W& d5 N7 `  phase                    ;; keeps track of the phase
1 G" P: y! Z, x% d  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# @3 X+ R+ Y3 E+ x% Y' }' a
  current-light            ;; the currently selected light7 g4 _- \' H; o& y9 j' l

3 q# t0 U' ?& ], W- R. u2 M; W  ;; patch agentsets5 r, ~; e6 U! d+ p
  intersections ;; agentset containing the patches that are intersections. x! w8 q! {- K5 ?
  roads         ;; agentset containing the patches that are roads4 o" Y/ c5 V! j9 Q
]
7 y4 O! O# y3 K3 r9 x5 c1 V" X- V5 y6 y9 N5 H4 N! R- u+ S/ C, K
turtles-own
& E7 ^. a! P; }7 n[
/ C+ A1 a# O- d" ?6 ^8 t  speed     ;; the speed of the turtle
) @$ s  S8 d' b5 C+ ~( i6 c+ Y9 u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right/ e0 P. ~( e% c& \# S2 ^: V
  wait-time ;; the amount of time since the last time a turtle has moved
9 E* U4 g. {. J, {' L( @) ?]. s# u$ V. `# O4 c8 M
, P0 z  K- v( w% K6 Z) u' K) ?% S* x
patches-own$ J4 q; G% {' k& D
[6 t( N, T( F% `
  intersection?   ;; true if the patch is at the intersection of two roads
, B; A' b, |5 E7 M2 K' h/ A; Z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, Q- }9 c* V9 K                  ;; false for a non-intersection patches.
- s6 `3 S, J1 H  my-row          ;; the row of the intersection counting from the upper left corner of the
7 ^9 O3 ?* V# B! I+ ^1 N                  ;; world.  -1 for non-intersection patches.: B( x( R% N7 ^( U
  my-column       ;; the column of the intersection counting from the upper left corner of the6 ^8 d$ `/ m9 H& R/ W7 q, ?+ v
                  ;; world.  -1 for non-intersection patches.
# _+ z2 O% R( g2 h2 I, |  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
2 @$ f' X) X6 x. w% m" h  auto?           ;; whether or not this intersection will switch automatically.  i2 C! f" f4 `# ?6 o8 s! R/ G  r* J5 Y
                  ;; false for non-intersection patches.( q5 ^: C& a1 M; l) @) n
]" G" W( d1 w* \/ H7 N1 K

* _2 |% z; c; L+ i8 ^
+ K$ D( a; M8 n' {' @) p6 L;;;;;;;;;;;;;;;;;;;;;;. F1 X+ p8 B$ a9 M, C8 }
;; Setup Procedures ;;. R# E2 F" }+ _. O7 Q5 B% \
;;;;;;;;;;;;;;;;;;;;;;
, p$ y  ]5 q# W6 K( L* D. N% @5 L
, `- f; B' J/ `6 E7 |( s/ E) h;; Initialize the display by giving the global and patch variables initial values.
" j$ Q% k  O* j' o4 x- f;; Create num-cars of turtles if there are enough road patches for one turtle to- R# t0 w5 b1 s3 G( M: s! H
;; be created per road patch. Set up the plots.
. a% N8 k. f  S" Q- E; B! Y* Lto setup
8 u! j: K: B# n( y6 v7 Z' g$ `  ca
: x& n  |7 N' q  setup-globals
$ p7 D7 d2 U# }( n# u3 x, _# A8 `0 y! ]4 q3 D  G
  ;; First we ask the patches to draw themselves and set up a few variables" \# n6 u) ?9 `4 x
  setup-patches7 q2 t* K' ]/ h  Z
  make-current one-of intersections
- W- E0 H* A2 T, I% a+ s  label-current
( U7 r7 [: H4 W3 D1 P) S) L' K+ E& t( g& }( v, O7 q. `2 Y
  set-default-shape turtles "car"
9 |0 L# Z/ ~7 @( [& f7 q( V9 b* e/ I: T
  if (num-cars > count roads)# {' ^5 L) g, V3 E8 [
  [
8 a7 {; o0 y$ p0 d    user-message (word "There are too many cars for the amount of "; @) S: |1 x% r/ ^/ ~
                       "road.  Either increase the amount of roads "
; S9 s5 f' D6 D1 p- p- b: W                       "by increasing the GRID-SIZE-X or "
1 P% k+ A3 |. F, _                       "GRID-SIZE-Y sliders, or decrease the "* R' P7 h; V" @( u6 }
                       "number of cars by lowering the NUMBER slider.\n"
, t7 A; y8 j# n0 B                       "The setup has stopped.")
7 R) N* I2 K" |9 p  h    stop' }# ?2 L/ Z9 }) F  x$ d0 h
  ]( n1 f0 y: |8 c

5 Y% c6 z- b: }9 D  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; v0 h+ f3 d7 ]7 z. D- f3 j! k
  crt num-cars% W; D/ F- T; X
  [
, h: R) p, j; M% G+ g8 j" y9 U+ F    setup-cars  b5 b) @! b. Y5 n; D, O; Z) D
    set-car-color
: N, m* K7 c; \* B    record-data
2 r. K" N+ r! D! N+ J2 A  ]
; P$ Y* c) @0 o) F$ ?/ S# ~; Q
2 a6 t& ~* h0 D2 z& W  ;; give the turtles an initial speed
! _6 M( x  t0 L  ask turtles [ set-car-speed ]2 E2 Q! r( U/ A6 G: J9 t

' Z% V7 P# J* _: E9 ]( z8 y  reset-ticks2 G& f5 p3 B& R8 M; F) F# Y1 D/ ^
end( y8 _- O- {' Y. ?

, P4 q. b0 o1 X3 R8 _;; Initialize the global variables to appropriate values8 X  q! G- T! ^5 _" ^
to setup-globals- s; n1 V: M9 l2 x5 N3 ^' G
  set current-light nobody ;; just for now, since there are no lights yet
( Y, ]0 B. n2 \3 g% \2 E+ N7 s  set phase 0( K" J$ z- U; J1 h4 \+ E! }% X4 D
  set num-cars-stopped 0  ?# l+ J% L; e& t( b
  set grid-x-inc world-width / grid-size-x
* {2 [* F: c  W  set grid-y-inc world-height / grid-size-y
9 L% T! o3 o7 i( a, E6 c
% V4 n" }% X% K8 R% C- p: H* _" [  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 D* B* C' ^% Q/ G& R
  set acceleration 0.099
( i8 Z" G- S7 f! T# [( K4 rend2 Y1 m& e" e8 [% t

0 P" ], {8 W  n3 L/ [;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
& t# E" Y" F; P;; and initialize the traffic lights to one setting# E3 H  H, i! _, @, |/ ~
to setup-patches
6 l6 R# ?( G" ]3 t; A  ;; initialize the patch-owned variables and color the patches to a base-color
& V, F; T3 |. s% i) W  ask patches
0 |" {! \/ J" i! z& s  [
+ }( m4 Q) s4 g( C* a6 Z" v    set intersection? false
+ p: i  ^5 N/ b    set auto? false
: v2 g3 b1 C( I8 G7 Y7 p! d0 r    set green-light-up? true" J# u+ J8 f% Y* _, f: k
    set my-row -19 K, Y+ A; Q, X' D0 F8 A/ P0 W7 r
    set my-column -1
5 I% |/ B+ b. N4 d- ]3 `" S    set my-phase -1' j" F1 ?6 t* {" i, Y3 D# p4 @# ~
    set pcolor brown + 3
* V- t5 S& ~! E  ]
7 B/ j2 E+ h3 c' b, O: b" }
, e1 b% Z3 Q) D' [. E# m/ H) t/ C  ;; initialize the global variables that hold patch agentsets4 Q+ h8 Y- {& F2 P4 R+ J0 n
  set roads patches with
6 C3 O% o* c4 y/ d" h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  p5 q/ [& [; v6 c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( ?/ X5 q8 \- X. ?1 ]" O  set intersections roads with. L( @4 t4 @% i6 Y* C; ~: r  g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  j8 \3 i6 T9 q. l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 Z. r$ v+ ~0 `3 B: k0 ~

( G/ A! @$ k' Z! H% C+ W  ask roads [ set pcolor white ]
* F" j  Z  ]* t/ B- n9 g9 g, _    setup-intersections
" J: f  n: u+ L* R8 ~+ Tend# p- v/ |0 t$ e& p$ w" R. N- y
其中定义道路的句子,如下所示,是什么意思啊?
. B" @) Z$ G; a* a( }, X6 z* X set roads patches with2 P8 X& Z- m- C, J2 F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& d0 A/ B. J. _, P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 D% }  R" H+ P) D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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