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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。
" w; y! Z8 g" X- l/ `1 Y" pnetlogo自带的social science--traffic grid这一例子当中,0 C/ v! |& A/ y
globals
6 P8 z# U* F& N3 H4 @[
. }+ ]$ `7 U1 |1 g  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 y& d- y7 |$ f( X! l" [' _
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' e" R7 D# q3 Z- n* f/ v  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 Y$ o, W2 {: ]' ~: X                           ;; it is to accelerate or decelerate! M, w" b0 i, p% _
  phase                    ;; keeps track of the phase/ F* }! N* q  Q# ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! I* D" W. o6 A$ n- z
  current-light            ;; the currently selected light" e8 |; ], v8 w. K1 O, V

, Y5 P0 J! V* ~5 F  ;; patch agentsets
" f' e% |/ n% E. Z$ R  intersections ;; agentset containing the patches that are intersections3 O* ]: y8 E1 X- E  g$ V5 Y
  roads         ;; agentset containing the patches that are roads
3 ~0 }# Y% @/ K, L; O4 G]) L! o' ^4 q8 r
. U% F" A" E& H% n
turtles-own
0 f; j8 g6 i3 k% M3 G[
$ y9 c0 k7 u% ]; r' l% z- v  speed     ;; the speed of the turtle
  _  z2 x$ v5 n( c+ q+ a& ^  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 ?' y- X2 @0 Z$ `) c4 {
  wait-time ;; the amount of time since the last time a turtle has moved* I. {3 J1 u8 I0 L
]) d4 C! x' b4 A! R
) B3 A. l1 R2 E7 o- c
patches-own
  F( B7 u' V: F' n1 }[1 y; r# H2 L+ `( G
  intersection?   ;; true if the patch is at the intersection of two roads# c- O# Y) S7 V$ s. i- }7 M3 `/ G
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.8 P7 y+ g) i3 O! ^5 m
                  ;; false for a non-intersection patches.
+ j* m4 O! T5 t: w- [  my-row          ;; the row of the intersection counting from the upper left corner of the4 l! ~. N7 z! J
                  ;; world.  -1 for non-intersection patches.
2 s+ j" R' n  ]1 b' Y7 u' ^$ E( k  my-column       ;; the column of the intersection counting from the upper left corner of the# ]1 l/ w4 `; ]1 {. @
                  ;; world.  -1 for non-intersection patches.
: s5 p1 x1 y" W  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) r' l/ i- k' A, [/ C% g7 \+ F2 ]0 |
  auto?           ;; whether or not this intersection will switch automatically.
  Q2 K8 T1 D  L8 x* e  n7 \                  ;; false for non-intersection patches.
, `& F8 N, B4 {1 ~3 f]
  J8 T5 z+ z' t9 w1 b1 R; e
) v# }! ]7 \+ {8 Q# {
- f) u4 Q; `( m3 u) T  R. q;;;;;;;;;;;;;;;;;;;;;;) D4 i6 F5 Y4 `4 I8 c2 b. h
;; Setup Procedures ;;0 j6 u" L' I% t! U7 |6 B
;;;;;;;;;;;;;;;;;;;;;;
$ t  L. E, ^) n1 x& L1 [& W" k3 N; [6 t5 `7 e9 y- V; }
;; Initialize the display by giving the global and patch variables initial values.
. ~9 S8 v; r( ]% ^( E;; Create num-cars of turtles if there are enough road patches for one turtle to; `9 D* j9 i4 ?4 Z1 ]6 G
;; be created per road patch. Set up the plots.5 J$ R) x4 `9 J% @
to setup. r* K3 ^9 H5 [! I9 Y
  ca
0 ?& b% k  I9 }' Q* f& c% v+ P- q  setup-globals
/ j9 g3 Y8 N2 C' F4 U/ R. \$ u7 D, t6 Y0 @0 y. r8 o( ?& W. }0 U
  ;; First we ask the patches to draw themselves and set up a few variables
$ R7 U( T$ ?! ^  setup-patches
, `- \- _: [1 C) S7 a: z9 J& o* H  make-current one-of intersections
2 [5 `, L% c+ t' E2 n4 c  m  label-current4 d2 z# T( Q+ [- |; N- V3 k/ H/ f

$ f! ]9 {5 Z6 [0 L; y5 A  set-default-shape turtles "car"
0 O& y$ s2 w6 r2 W
2 n1 u* v5 ]4 a* |  if (num-cars > count roads)
$ S8 X" m8 e2 G% n  [- N) Z- g" N- N8 U
    user-message (word "There are too many cars for the amount of "
( i( F( _5 S. O" W                       "road.  Either increase the amount of roads "
+ {+ d" J" ~. ^- \' a                       "by increasing the GRID-SIZE-X or "
# g8 s" [; S" s2 A  E, ?                       "GRID-SIZE-Y sliders, or decrease the "
: F9 f# z1 M1 Z" S5 f" ?$ L                       "number of cars by lowering the NUMBER slider.\n"
8 A8 C$ ]1 {6 l# w% G. m; v                       "The setup has stopped.")2 t  n) |: ^6 @
    stop
2 c* P$ |" p1 |1 G  ]
; ^  A0 x+ m' \( I7 M9 p3 t( |( b/ v+ h" ]% U
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" n6 z6 t& {3 |/ s/ G+ K1 X
  crt num-cars
4 w" ^3 V; |2 o3 {2 R' ~  [
) m* o+ H* P8 ]1 E7 a3 o$ W    setup-cars& K; G8 H3 r! G. N6 ~1 v
    set-car-color
1 Y9 e: k' S" O/ Q  H4 {    record-data2 L! ~8 I4 C  \  ]' C
  ]
$ g8 V8 W5 d' X4 i5 i" K
; X1 A& ?/ C0 o2 a( A  ;; give the turtles an initial speed
; O- `% B6 @4 ^# \  ask turtles [ set-car-speed ]
/ F3 }0 s& Z) i+ Q3 x
  }# [1 I" ?& m+ i  reset-ticks
3 M. @  C! `4 Z( P6 C8 `- qend. G7 n% ?' [- Y* v
% Y) k, r1 T& n2 \' l& L3 O. t
;; Initialize the global variables to appropriate values
  b9 x# P% d+ v$ E3 Mto setup-globals
# s8 _, B8 i3 z% G" T. O  set current-light nobody ;; just for now, since there are no lights yet" [6 p: ?+ A' W( J
  set phase 0
; H# K! C/ u; L! k: {  set num-cars-stopped 0
7 S" L! C# i# u( g  set grid-x-inc world-width / grid-size-x
- c: x* W- h3 ^8 V6 |# W  set grid-y-inc world-height / grid-size-y6 N9 {" f. ?) z

! @& l4 n* D3 b9 d" N  _$ J9 R  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  Z% [5 L- |6 N1 n8 q  set acceleration 0.099
) y4 f) m6 L  Q7 send
  J1 ?; P  _( z- q& P! u' a5 r
* G7 z. V. d8 z6 B1 u6 u;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& `' g! l! {- @! c- f" q2 P' v
;; and initialize the traffic lights to one setting
2 {" Z# K1 f1 u/ C5 k( o* M  p8 F) dto setup-patches3 P6 c9 j( F) T$ w
  ;; initialize the patch-owned variables and color the patches to a base-color
" @1 k+ R8 t* q0 f5 ]  ask patches# e% t8 p. V/ p( ]7 N8 [) ~
  [
" U6 W' k6 b( Y    set intersection? false1 y# P& P8 m0 d2 T2 e. V! F6 e
    set auto? false
0 L: U6 P0 z4 y3 [/ _    set green-light-up? true
8 ?2 k; ~+ l# Y& e7 ]8 w0 V    set my-row -11 j% \3 Z4 h0 x" J
    set my-column -1
. I3 J0 P( w, ^7 Q7 D" I5 p    set my-phase -1
% ?. q# B) t  v, [; }    set pcolor brown + 3' B+ g5 o+ }* m! g/ N2 W; j
  ]$ j& Z' V/ u' z2 K7 d

/ u. F+ f+ d: ]% A* }, D% K  ;; initialize the global variables that hold patch agentsets$ l6 f8 u2 |6 `; r; t/ b% ?7 R' b" L
  set roads patches with
: j# ^5 F; B% I/ p( p8 r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  P5 K- x. n: u$ G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  p- E: u8 i: a7 I# T
  set intersections roads with+ i" R  j3 {) p1 m, F7 Q) o$ ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& W; e4 u2 ^7 P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 G. @5 l) \* ]/ ~5 z8 \
0 k4 C  T2 ^- t. h: N2 {4 k
  ask roads [ set pcolor white ]9 O3 b; ^. r  ~8 |
    setup-intersections
, i# H( @* f' ], W. s: E& Hend
* B7 h* z8 O! Q$ }& r其中定义道路的句子,如下所示,是什么意思啊?
" O6 K7 ]6 p2 ^: r set roads patches with
5 |8 n5 a& s; u& W  V+ h9 b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% s: }# ~1 x0 Q; K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% e* I& O( \2 g- \7 W- p
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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