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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。2 Z4 B+ F9 i! f" F
netlogo自带的social science--traffic grid这一例子当中,$ p0 g* V% Q6 j& ]: x* M% r9 `- f
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction' D# E" }, j7 a# }) k
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! n4 O/ T+ `2 P/ x  I; |+ J  u  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
8 o2 |8 T" R: q: i* y% d                           ;; it is to accelerate or decelerate
4 k+ p. K0 X( |6 n8 ?/ j5 l$ z. p) s  u  phase                    ;; keeps track of the phase
9 _3 n2 y9 E, M$ b  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- t& q7 l' T2 q$ U
  current-light            ;; the currently selected light
; i3 A' [$ T$ }+ s8 y' p6 R4 ?: T/ x" N8 b0 i) H' i
  ;; patch agentsets
8 e9 F: N* a9 A5 X  intersections ;; agentset containing the patches that are intersections; a6 ], K: i8 a
  roads         ;; agentset containing the patches that are roads; W: `- J/ ?; `( j" I
]
9 X* V6 f- L$ Z
+ r3 ^; n. ~6 I0 O" t& K' ^turtles-own
7 z- i3 F0 d! F- Q2 v3 L[
- @  H* \, F5 @& R9 B8 P( K  speed     ;; the speed of the turtle5 ?6 q6 W3 V/ \4 r. r' |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* a% K( Y& u$ }% h
  wait-time ;; the amount of time since the last time a turtle has moved- N8 E/ A8 p; ~. A5 w/ T6 r
]8 S+ O8 J+ a0 Y5 c7 `+ k

) O# K. b% z& |' l* D5 O1 t* y/ Zpatches-own; X" }$ \' ~0 I, U  j' \
[# a) \' `4 |6 H0 R; I% X2 ~
  intersection?   ;; true if the patch is at the intersection of two roads
' S1 R3 m/ N9 M" {3 {7 b  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: l! M9 s- o: V8 B7 r! [0 r# @. \
                  ;; false for a non-intersection patches.7 i$ t+ C$ t' D9 g! H. Y
  my-row          ;; the row of the intersection counting from the upper left corner of the+ N7 l' A* s/ o
                  ;; world.  -1 for non-intersection patches.6 J/ k8 X4 h1 [
  my-column       ;; the column of the intersection counting from the upper left corner of the
" D+ G+ ]) _; {+ Z5 N                  ;; world.  -1 for non-intersection patches.3 `! c5 r2 H! i' M, y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: @9 U7 U8 W( c  `8 U
  auto?           ;; whether or not this intersection will switch automatically.3 t/ D1 i  o0 H" l
                  ;; false for non-intersection patches.
. _7 Y9 `; D0 }]
% z* l" R5 a9 U" C6 N& w: a4 V- w! o' ~/ A: Y" g/ h4 h# d9 u
% `+ x  V) E* S# v
;;;;;;;;;;;;;;;;;;;;;;( {- ?+ P" k  ?2 \& O8 z; f
;; Setup Procedures ;;/ o, x$ P+ {- ?6 _4 p3 ~8 [" u3 o6 {
;;;;;;;;;;;;;;;;;;;;;;
! R, J3 [2 f8 q# Z2 f4 o: A6 d3 P3 d8 S  H2 X
;; Initialize the display by giving the global and patch variables initial values.
+ @, N' Q$ d4 `: ~& |% h;; Create num-cars of turtles if there are enough road patches for one turtle to
1 Y0 _( Z, F0 a3 f* k/ @;; be created per road patch. Set up the plots.
; E0 N; Y) J8 f" |' t* z- m/ I7 yto setup
" I+ j: b) g# a( e5 }% P  ca
3 V% T  N  Z7 A5 N9 t# [# r# `  setup-globals
- u( J9 q5 Q) X0 Y3 N
' S6 J. u" w) b( S' ?  ;; First we ask the patches to draw themselves and set up a few variables
9 k' y8 T  V9 W# {' I; v  setup-patches
  j/ I1 V/ ^; g/ L; Y! W  make-current one-of intersections0 C- g, p+ U& l2 e) N
  label-current4 K+ v0 @; ], k3 p2 H/ _: a0 D

! b; G3 d4 B6 M  |8 v- [2 a; B  set-default-shape turtles "car"2 @" k, `' V/ n
- E3 X' m% X# M( v) m; p# G1 I
  if (num-cars > count roads)( S0 O" a0 N: c- V8 H
  [
6 v6 }2 v0 t9 {! h% F    user-message (word "There are too many cars for the amount of ", L2 r3 F2 k6 i4 n
                       "road.  Either increase the amount of roads "0 t$ y3 k! D1 c
                       "by increasing the GRID-SIZE-X or "9 D: Q& u6 X! a
                       "GRID-SIZE-Y sliders, or decrease the "
- P. W4 V% t! m9 b! J" M) C- g' p: g                       "number of cars by lowering the NUMBER slider.\n"
5 H  d& z* S/ ~1 }                       "The setup has stopped.")# P) ?. u# F; a
    stop; l  G1 Z( n; T6 ]7 r7 ?2 |
  ], {- |4 ?- ~7 i+ S; f' C( V
. o! `. q6 Z8 F9 H2 [& p
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 K8 V1 U6 j; t; B  crt num-cars) |1 X+ ]2 p4 p, B0 `
  [7 J- H+ Y# v& ?3 ?
    setup-cars
& g" H) x9 I/ q9 K9 [- l2 l+ D    set-car-color
4 k5 W" ]8 \' P8 K, ~    record-data
% Y" v. {4 Q" \  ]
( H6 J* `7 @1 g7 ?2 S/ V( d3 }$ N# y0 y; g+ V
  ;; give the turtles an initial speed
: x* L6 N6 J& b7 x  ask turtles [ set-car-speed ]
" B' D7 W3 b1 d4 ^/ M2 s+ S* \' m1 r/ N: V7 [, \6 S
  reset-ticks
$ K6 X2 A- k; K: ?( hend
1 Y0 w7 S$ B" u8 N$ r5 F7 T! \- W' M# f: W" ~" x9 T8 d* {
;; Initialize the global variables to appropriate values
7 a1 d  T4 `1 `/ c: C0 ?) F* gto setup-globals! ]2 A) i1 x' X8 Y: e- ^5 ?5 ]+ u
  set current-light nobody ;; just for now, since there are no lights yet# s* \6 @7 Q' z; r) `
  set phase 0
0 c" ?1 R2 Z: H' ]7 y- |  set num-cars-stopped 0
2 ^0 q+ \; m. L1 s. n  set grid-x-inc world-width / grid-size-x4 h! R) @% R3 R0 k2 p
  set grid-y-inc world-height / grid-size-y
; ], F' a2 s3 T2 }; ], T: g) W2 u! H5 D- N) i! N+ [/ u
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% F( n+ B% H* Q9 ]) E/ |
  set acceleration 0.099) F+ v; t) x7 H# d5 ?
end
, a( c  D; R. ~# ~, k# X/ w" k& ?* _. {( R8 [% U2 C" q/ _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 ^+ s4 E- d/ W  A;; and initialize the traffic lights to one setting
0 Q6 e; N  n- C( ?( a7 yto setup-patches
+ u8 K% E3 D) O" e9 Y  ;; initialize the patch-owned variables and color the patches to a base-color
: g0 I6 h* j# M  R' n  ask patches
5 z/ v7 b+ F$ a; `4 @  [% c4 [+ K$ h3 _; G; k) D9 c
    set intersection? false2 n. v/ _* l( v6 e
    set auto? false
, {9 R* ]8 A# f; r4 n' d    set green-light-up? true+ H2 V+ w3 l9 Q0 w
    set my-row -19 {# g, Y" v1 I( o
    set my-column -1* _$ n, f4 ], \- X( Z
    set my-phase -1$ O1 C- u- s) j9 l% E, D
    set pcolor brown + 3
* s) G- Y. r" `: r, a+ K  ]+ x# F1 R; i! \$ B  B0 q  w

! K9 ^, p4 Z2 b7 Q  ;; initialize the global variables that hold patch agentsets' Y. G2 F2 C9 f+ r
  set roads patches with
: }+ s: ^4 L% ]' C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; w' S, t0 S2 M0 _( x/ b- z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  t  C4 h( l' z9 q: x" ?; s5 y
  set intersections roads with
- q( j- H$ r- E1 p, e2 i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 }' ~0 K, Q; T" _3 S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 I1 P; Z2 k3 v* K; V
- r& x; O/ `& ?* ~
  ask roads [ set pcolor white ]
  _- G3 _5 A' a" G2 E    setup-intersections
, q3 X8 `+ K1 R" g/ u' f" K' dend
8 q8 p+ p% Z; I4 `; {- {其中定义道路的句子,如下所示,是什么意思啊?
, a4 b( y! v( r set roads patches with9 L) Z( e, t+ C2 d0 ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: B( c  V5 f2 [$ }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ A2 L; t: p" R6 [* p7 d& ^" V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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