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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。( C. [$ q! @" s* X  |5 j! y
netlogo自带的social science--traffic grid这一例子当中,) D, u- w6 M7 s! S7 }' D; l
globals
. H9 {, x( y+ F# [' M[: x2 M+ G' U4 e! D7 G
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
( E0 n- a& t! e% ]& f: _  grid-y-inc               ;; the amount of patches in between two roads in the y direction  k6 ^& K/ ~* ~& y" P
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 E# p9 n0 a; X9 q% U                           ;; it is to accelerate or decelerate1 u; c" R0 U# S0 l& x% E
  phase                    ;; keeps track of the phase
0 |0 ]9 ~, D' |$ C1 D  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* E; Y# n; d  |  current-light            ;; the currently selected light$ I6 E" K2 n# i% m' A
4 `- W, m( R. b: L3 o3 m
  ;; patch agentsets
& j& F6 G- y5 E( o9 t0 L) Z  intersections ;; agentset containing the patches that are intersections
2 A  b6 A3 M3 W$ a  roads         ;; agentset containing the patches that are roads3 A; n* [* ~2 ]
]
2 T* N6 o2 q& O) n1 l- ]& }
4 y& K6 g2 m: E: C+ d9 Pturtles-own
* n2 {5 B- O, C. D  n[, i  H# |: R/ H, t' c
  speed     ;; the speed of the turtle
$ {; N/ L2 l* |+ q  A# S- ?3 s; n  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ W( F; ~+ ?" I8 Y6 E
  wait-time ;; the amount of time since the last time a turtle has moved
2 D& [3 Z. `- K. H9 d" J]5 l1 O$ e! B$ W5 ]5 o* Q) M

" G, p7 o3 X6 Q6 U1 J7 m( opatches-own7 U$ g9 V) s  x/ w0 Y4 a
[( S! L' ?2 H- t$ G
  intersection?   ;; true if the patch is at the intersection of two roads1 @5 F2 x( h' `" ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" ~# n- h- w* o: q& K/ A/ S$ V                  ;; false for a non-intersection patches.
: U$ s- J3 j! l0 b  my-row          ;; the row of the intersection counting from the upper left corner of the
3 O$ t* f! T6 j& M. c0 Z                  ;; world.  -1 for non-intersection patches.) v0 e3 o. s1 b3 z. ]' p) M
  my-column       ;; the column of the intersection counting from the upper left corner of the9 V! v0 g- z; [$ n
                  ;; world.  -1 for non-intersection patches.) {" x7 E: Q3 v' T# K( L$ {" Y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- |& j7 E) t& o1 a: U0 t  auto?           ;; whether or not this intersection will switch automatically.4 |5 v2 E5 y6 B9 h
                  ;; false for non-intersection patches.1 m6 E' \: v! n3 E; U
]+ S% C# a$ p0 H' w

+ D  ?  J4 C5 h8 O" m6 M, n8 b) q. K( D
;;;;;;;;;;;;;;;;;;;;;;" j, U: T/ o/ m! H) [
;; Setup Procedures ;;$ Z+ s' W. r2 i
;;;;;;;;;;;;;;;;;;;;;;0 J4 Y& j8 M8 q

) w3 ?2 Y0 v5 u$ a% A4 g" E;; Initialize the display by giving the global and patch variables initial values.
5 g6 T% d) ]' T  Q;; Create num-cars of turtles if there are enough road patches for one turtle to
' G2 f) Z) P5 w;; be created per road patch. Set up the plots.
$ V! i- x% F0 U8 A, Uto setup2 h7 }7 z- U! P! r5 F. ^, V% `1 y" E
  ca# G5 w' M; g9 h7 b
  setup-globals) B6 a6 h/ B0 x& Q; I% K9 m
# w( n3 N* Y% b5 ?$ v
  ;; First we ask the patches to draw themselves and set up a few variables
2 _; R* v9 l  d4 P3 x; @/ x  setup-patches8 F9 z; [6 c0 g3 |
  make-current one-of intersections
  w. v+ g( }- l$ r; `1 ]( T  label-current
* W" G; @% A. k; g$ _9 \
4 i& m, D, C" c# P  set-default-shape turtles "car") E, K% @2 l6 ?0 h# J- x1 ~

9 ]- l) ^( B4 R, A  if (num-cars > count roads), z" G3 Y0 ~; {' s
  [1 ]: }! n+ D& S  S5 p
    user-message (word "There are too many cars for the amount of ", h2 ^4 I, k$ r6 k
                       "road.  Either increase the amount of roads "
( ?  {8 r8 [) P' I* n- G% l                       "by increasing the GRID-SIZE-X or "" K( I) R# ~) M$ S" x* {
                       "GRID-SIZE-Y sliders, or decrease the "* C2 h4 Y$ m  {  z- \  A
                       "number of cars by lowering the NUMBER slider.\n"
' G/ z; x/ L# g0 x/ m# j                       "The setup has stopped.")
2 i+ z7 y( V- r3 w2 e    stop9 a2 N2 y/ h+ O: T) c. [9 p
  ]
, r! D9 y) W5 o0 k8 r3 @/ E$ p6 }, {+ I$ B& Z0 H$ O
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 D( N, h4 M" ?, [
  crt num-cars5 o) _. u  K+ X0 i1 v: X: ?
  [
+ M7 j# r$ L- S# D" w    setup-cars
4 Q9 D; I- F3 v1 d! Q% r; O9 O1 V& W: z' `    set-car-color+ E' B: s% h8 R. o
    record-data! L4 p* Y8 @5 r& I( \
  ]
. X/ R, ]4 n% i) e  v7 Y2 z! u6 H% A+ P8 W' m) f) z3 o7 ~1 {: w* `
  ;; give the turtles an initial speed
; D( w7 w6 F7 f2 ]* Y  ask turtles [ set-car-speed ]9 C. D! K% k2 j3 g# i7 e/ c# w
0 P* n4 {0 }; k. c+ [4 J
  reset-ticks
5 m& }+ G; O0 _) c8 |+ `5 }( [end/ |0 X0 R3 p8 E# P$ }1 O# h2 o
( Y" [% h) |& c2 P
;; Initialize the global variables to appropriate values" a9 n* e0 S3 Y) A/ t3 ~
to setup-globals
9 h) ~, P& o2 w3 v9 r  set current-light nobody ;; just for now, since there are no lights yet
* q. M  X7 V1 A& Q% N) a  set phase 0
: R: b; D+ j. c  set num-cars-stopped 0
  J% P. }$ G8 z# n! b, ?  set grid-x-inc world-width / grid-size-x$ X8 a5 ^! x, z2 t8 B# I
  set grid-y-inc world-height / grid-size-y5 {2 y( }1 V& A$ g2 g7 `  y  A  F) ?
, [! V* I% J+ }" l% P3 F4 C2 K1 M
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 m9 ]2 a" Z8 A
  set acceleration 0.099; E% M7 O9 }7 Z
end
1 {5 A, ], ~  n
; G$ N! H9 |) ], ^; i;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% ^; S; r# n, W0 W+ Z;; and initialize the traffic lights to one setting( @2 g+ |) V# P' c5 y" m
to setup-patches  J* O/ x! \/ l8 {9 ~/ K2 _9 n# B
  ;; initialize the patch-owned variables and color the patches to a base-color$ S3 l8 T. t7 q# c* J$ T6 L; B
  ask patches! S( `1 h% H+ ]$ f3 f! c
  [1 F$ S: {  e7 D& E
    set intersection? false' {  @+ C5 S) ]
    set auto? false- S' c. p7 D# U1 e
    set green-light-up? true( H; H' e0 P3 z; U  s) }6 x
    set my-row -1. c7 N  C+ ~) s2 g- Q+ ]1 u
    set my-column -1! M! V8 \+ Y; L
    set my-phase -11 O2 g- s( f3 m8 q
    set pcolor brown + 34 F* @+ h: A4 m: T7 O6 H0 V* c; A# `
  ]! u: P& a- C' d) Z  \' b) i

) N/ a, }. m  @) ]* ^  ;; initialize the global variables that hold patch agentsets
; _. |  N; q. S0 O; w/ Y: |  set roads patches with, `( [, O( j3 y: ?8 W& N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- q$ {/ b3 }& s( J$ ]& ]9 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& S3 u9 k% [) t
  set intersections roads with
) I6 G0 g' P# d, D6 y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ d+ P$ y7 l2 O6 y" _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% B0 `9 t5 t$ s9 g) d. r6 v8 T3 J# ^& M) x3 \9 s0 v# `
  ask roads [ set pcolor white ]! k0 X+ ?! s5 r, T* Z
    setup-intersections3 A3 q3 s9 Z% g7 K9 n' b
end
) Q; H; C; E0 k/ h; f其中定义道路的句子,如下所示,是什么意思啊?
  k9 J; s* F; W8 `* o& c  O7 i# r set roads patches with
! Y( P9 }5 y! @  H" P3 M! k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 e5 r# L6 A) x! U& v- @8 t, I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 o, f4 j1 T5 {2 |. a' w% S7 |
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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