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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。
! X' ~. k2 u, t7 K- s9 @/ @netlogo自带的social science--traffic grid这一例子当中,
. O6 \7 }/ o0 u9 N) C4 G! Zglobals4 Y: g) T% s+ y4 e, V- a; q
[# s. v$ M3 B3 X/ i
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 |# Z) x" G% k) k6 Y  s
  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 E( v' c! ?! Z% A* y/ b' m) |
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: `5 R0 q* Y  g; X$ A$ z                           ;; it is to accelerate or decelerate
6 N2 M2 v: {7 H+ |& A2 E  phase                    ;; keeps track of the phase, Y$ V+ J1 o) E
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* y/ t  c" f, @' V- Y* k
  current-light            ;; the currently selected light: |; ~: ]$ M0 k3 b' V1 a
$ T" y. B, \0 ]4 M8 t' @1 o6 s
  ;; patch agentsets
# ]9 ~! P) U+ ]+ f  intersections ;; agentset containing the patches that are intersections
) S7 \' ]9 C, u8 O  |1 ]8 ]  roads         ;; agentset containing the patches that are roads
. O2 c- h  r* o# u) @]
/ W5 c1 B  ]& F+ U' y
1 r* ^2 V5 f& c; }% ]* H; {( o$ q" tturtles-own) {# _% }3 s% M1 w3 H+ L
[; h. o2 k! }7 N1 O$ a6 E$ w$ a
  speed     ;; the speed of the turtle
! ~5 d$ q9 F$ U& q3 v/ g* r  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 v+ M1 a7 z+ c  wait-time ;; the amount of time since the last time a turtle has moved
6 E# A8 I* i. @5 E]
& o7 s& f. Q. O
$ j/ U- r, ~; b) V  |patches-own  S* i6 N" i/ A5 O- C
[6 d4 G: {  z% W5 @
  intersection?   ;; true if the patch is at the intersection of two roads
  o! P% ~, t' _) K  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 r! T  S) [/ f# z                  ;; false for a non-intersection patches.- t* d4 ~: k( }  p0 L8 q6 o0 [7 N
  my-row          ;; the row of the intersection counting from the upper left corner of the2 s' h$ a2 h9 y- a! n
                  ;; world.  -1 for non-intersection patches.
5 L8 U8 q! N+ k* L9 Y+ {/ F$ j% \  my-column       ;; the column of the intersection counting from the upper left corner of the+ y0 [; R7 e! G4 s, @% T8 \
                  ;; world.  -1 for non-intersection patches.
' r1 ], `5 H4 |% z) B0 E  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( V5 a3 l9 M, q6 x# d! y
  auto?           ;; whether or not this intersection will switch automatically.
1 t' z3 K2 }& I) ^( x6 J                  ;; false for non-intersection patches.
; f( `; c* q4 P3 I, L* s+ B]- K. Y, ~. b4 E
. q( _3 i% h6 b2 V- n1 x1 W

! K2 f, [  i$ S# Y! H4 u1 P;;;;;;;;;;;;;;;;;;;;;;6 ~- @- y0 U$ a. V! f, j
;; Setup Procedures ;;9 ~$ K! J9 y/ V: o4 g5 q
;;;;;;;;;;;;;;;;;;;;;;
0 I8 T* J8 g% A( L( M% t0 l  l) j6 c: H' P. q
;; Initialize the display by giving the global and patch variables initial values.2 n: g9 X( d! [& S
;; Create num-cars of turtles if there are enough road patches for one turtle to
$ z$ S1 r9 X  B) \6 d;; be created per road patch. Set up the plots.* P; B) P: \) z  q$ i/ h; e
to setup
4 d, V& ?  v- ]4 ?  ca
' R& a1 v2 F. \6 i  setup-globals
# T) E) K6 [/ w1 U" I
1 O' M3 v+ K/ _. D) Q& x! e  ;; First we ask the patches to draw themselves and set up a few variables9 G: w3 N# q3 A% s& b
  setup-patches3 O  }0 n  q2 f" J: G
  make-current one-of intersections
# `4 }* m* [! O: U3 U6 Z  label-current
/ @2 z5 e1 R, `: @5 r9 `
0 f* ?7 i+ Q0 t6 l# X6 |: b5 Q  set-default-shape turtles "car"
9 X1 ^8 M/ ?2 G& J) B
/ J! v1 i4 i4 K. w9 B' W% m% m- w  if (num-cars > count roads)
& `9 a( K; P8 o: l- j  [
2 i# L: G. M( f* y' V6 f  U    user-message (word "There are too many cars for the amount of "8 k' h7 B! d% E1 i. m6 B4 L
                       "road.  Either increase the amount of roads "
/ v. v$ O6 s2 P! \9 ?; z                       "by increasing the GRID-SIZE-X or ": J/ Z  n6 u6 o0 f2 c( E
                       "GRID-SIZE-Y sliders, or decrease the "+ {5 I7 n3 t! `1 \0 u
                       "number of cars by lowering the NUMBER slider.\n"
  `8 g2 N/ e3 r+ a$ I* k                       "The setup has stopped.")
7 O$ J8 _) L3 A4 e* P+ ~    stop
. V9 B, Y. ]9 P6 z, M  ]# |! @& h# x. {5 O
7 V- \4 l: e7 }7 a5 U& l( D
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 P1 Y! }* F1 C! @9 q1 n% Y3 T
  crt num-cars
1 c- k4 W6 ?- v7 y7 V1 e$ t$ M( B  [' ~7 G8 u: |1 c0 M, L
    setup-cars+ E$ N5 t' F8 `* e, U9 k* z$ \
    set-car-color1 Q# W3 H* N5 Z( @/ {
    record-data
4 u2 [7 l# X" P* O# }& X) B  ]
' H5 k1 j# Q; }7 ^! }( {8 `2 ]! m! w2 d' V& g  q
  ;; give the turtles an initial speed
" e, M4 T9 G& g" r) l9 ~4 S  ask turtles [ set-car-speed ]
2 T: ^; Y( I; a" H) E4 h" d* R
8 \1 t8 u! X, I. S; z& G5 l1 A- {  reset-ticks8 y1 p" [3 I! s2 f7 T
end6 l" m; |/ C7 ~& c
. M1 h" N6 ^% C+ _. v- u5 I
;; Initialize the global variables to appropriate values
* k* r6 M3 E) Dto setup-globals
) I8 `* O7 U7 N3 {) k  set current-light nobody ;; just for now, since there are no lights yet/ q* s; m, J1 J& ~) A4 ?
  set phase 0
0 D$ W# A+ z0 o% K  set num-cars-stopped 0$ S2 o6 ]2 E7 X5 H9 P
  set grid-x-inc world-width / grid-size-x
* E( t# J. L, N4 m; K  set grid-y-inc world-height / grid-size-y
0 R- T7 b& f" H6 y8 B8 g0 Z7 Q
, m$ k( n, k- p# z' S1 d# A  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ [4 s1 P  [+ B4 v4 X$ @& Y9 T
  set acceleration 0.099  S) e8 x9 y! `/ y5 t- j- f1 b, C
end9 j) I1 g; [' a0 N6 z

  u/ w) D, K/ W1 O0 _7 r1 L# X8 D3 u;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 J* }; R) E, X6 T8 n
;; and initialize the traffic lights to one setting
( y: H3 k5 D6 B1 Z1 hto setup-patches
' l6 `( g1 A" w, y: D  ;; initialize the patch-owned variables and color the patches to a base-color
3 r! J' o) v& Y: e; e" L0 {# a  ask patches  ^  C" M/ H! Q& ?  |" W; C/ [' q* Z2 c
  [! O! A& P( {! r
    set intersection? false) g3 A/ P1 ?& N8 F2 n9 d
    set auto? false! a0 R$ M9 W% |! g, R/ A
    set green-light-up? true: o- e0 z' f$ Z% K* }6 p* ?& C
    set my-row -1
& y8 p* a- {4 M" x7 V0 N' D    set my-column -1# P( Y  r& N$ ^3 L
    set my-phase -1) j- a) t: K+ z0 p; I* b6 T
    set pcolor brown + 3
: d: z; b% W' t  Q  ]
7 n  b; U6 j& v# g% W6 o6 @
8 F. `! e5 S  L& L  ;; initialize the global variables that hold patch agentsets
& K, P2 q' b6 P. H, L: M  set roads patches with
1 J$ ~" D" J5 y9 @  O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ b+ a: e+ i; ~1 a$ `    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! V- W" m. z; D$ c1 o6 m  set intersections roads with/ Q# G4 d: T( t' ]& P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ K1 _2 O% ?' H6 k: ?! ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* m9 p/ o0 T7 G  W$ n% ^+ B$ u9 C; r
  ask roads [ set pcolor white ]
5 D3 M. u2 H( d, s( [+ V' j    setup-intersections
$ a; x/ {) h4 L6 {# C0 Rend( K& U8 l  p$ T; _1 {
其中定义道路的句子,如下所示,是什么意思啊?
) P9 ?3 p: l6 o2 J3 O set roads patches with
  t; }- R* o/ n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  T4 g2 N% ^$ [  j8 _2 A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' W# O7 g$ F7 v" k. F, G+ B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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