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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。) V8 ~, p: {) S+ d
netlogo自带的social science--traffic grid这一例子当中,
1 {5 o( V+ ]7 tglobals+ F6 L3 ~/ J) i6 j2 z' }# s
[) h$ {2 @! o$ d' B' \/ {3 ^+ @8 v% `
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 w5 Q- ]# C5 x7 {# h  \, B& a  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# i' |; \0 O# N& e$ s/ c! X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* L$ l' v; J4 B' u' @: u                           ;; it is to accelerate or decelerate* l/ ~9 o4 S: k) [5 ?5 @4 ?+ e
  phase                    ;; keeps track of the phase
2 A7 O/ n2 N7 |2 h: _, L; K  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ D; [! j6 f: k6 u4 V
  current-light            ;; the currently selected light
; V  |8 l' ]; a, L
+ f4 @6 q$ x- b6 L8 n6 e" d! {  ;; patch agentsets& R, o& {: B% f# @% W
  intersections ;; agentset containing the patches that are intersections3 d7 x. r7 [2 ?, J6 x
  roads         ;; agentset containing the patches that are roads& [  {. `! ^: n
]/ p0 B! F) F! B; h5 ^8 a' q

8 S9 x' Q4 I- K7 u% [turtles-own
" ]- O" I, \- |, z7 }[
: g3 }- |: v7 t, C0 Q  speed     ;; the speed of the turtle8 p3 m: r. B2 W% V3 f9 i% v3 O( f$ a
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  |9 D) t0 W9 X8 s) k  wait-time ;; the amount of time since the last time a turtle has moved
+ t* B/ z2 S+ o' d) k]
$ @% c1 J& y- e5 o6 w
1 J3 J8 v1 w  i  ~( f0 ]patches-own# T- [+ W+ ^0 J% `1 v
[- K4 q% R( N3 N/ a6 z
  intersection?   ;; true if the patch is at the intersection of two roads! [% \4 b) e- S7 c# y/ C
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# n7 v. Z9 \! B3 x                  ;; false for a non-intersection patches.6 p! p) K3 g# z0 ?
  my-row          ;; the row of the intersection counting from the upper left corner of the# Y$ G# [7 \4 }3 P7 x( |
                  ;; world.  -1 for non-intersection patches.8 j2 v( c  m. B* E5 Z7 L/ g  d
  my-column       ;; the column of the intersection counting from the upper left corner of the
$ `. J! M- G0 l6 L% x                  ;; world.  -1 for non-intersection patches.
6 \1 d( m( T6 B! p" w  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." n0 O: E& E& }3 B/ x
  auto?           ;; whether or not this intersection will switch automatically.
1 u0 l$ {; h) T* z; B9 ~8 o0 Q                  ;; false for non-intersection patches.
( H7 p+ G. r* t6 a. D8 f0 R]
& o4 }; h$ l  [1 W4 v
2 B3 v1 C* Z& [, R
, k) j8 o3 ]( ^) D;;;;;;;;;;;;;;;;;;;;;;8 O/ M, K! {" h: w  }
;; Setup Procedures ;;9 e! r9 F2 }& B+ ^* d. O- b
;;;;;;;;;;;;;;;;;;;;;;* b) `, W& x! i. M, J1 a, e
& ~4 V3 ^/ A/ I6 K3 I' m3 K' Z
;; Initialize the display by giving the global and patch variables initial values.6 B1 \$ ^9 g$ g$ k* F
;; Create num-cars of turtles if there are enough road patches for one turtle to9 c  M' c+ E; g( @& q! J
;; be created per road patch. Set up the plots.. ?2 }' \: |) m1 u5 s
to setup
3 ~7 i- _. Z) v3 b  ca
9 V, b6 }8 E  z" {  setup-globals
7 ^  `5 F3 G' G5 X- a( T' _9 c
  ;; First we ask the patches to draw themselves and set up a few variables
3 x4 ^, O, V" D2 F* R  setup-patches
# P7 m, g+ r) ]& p& ^1 o$ N- U7 u& z) ~  make-current one-of intersections
* B* L2 H" {- |% K8 A* N* `$ G  label-current
; ^. X4 Q1 p9 [# D: `' Z& {, K" O$ j( o
  set-default-shape turtles "car"
5 S- ~/ }$ V1 ~: Q; `4 G
3 B' H( Z, j& m6 ?# w  if (num-cars > count roads). s0 _* H* C5 f' \' L/ n: |4 \
  [3 D" a% r' f: s# ~
    user-message (word "There are too many cars for the amount of "
# k7 G; r' V8 c, W. z* v; O                       "road.  Either increase the amount of roads "7 p) g2 U* t# ]
                       "by increasing the GRID-SIZE-X or "! s0 ~+ q+ K  F6 p7 l7 ]/ ]
                       "GRID-SIZE-Y sliders, or decrease the "
0 e. g5 b* M) s, C                       "number of cars by lowering the NUMBER slider.\n"6 I& X0 g* B/ J
                       "The setup has stopped.")
' {  k+ z* K" V% g    stop5 u2 q- X# N* F
  ]$ T% ?5 T! J) W* e0 R1 P

' x. [/ a" B* c& Q7 L( F- x  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! l7 @% M5 G& N+ `7 \$ z$ w5 c2 B
  crt num-cars
- b  ?& X; I8 a  [; o1 N& o* e3 V; M* W- o
    setup-cars9 N, t0 u/ c" }7 B
    set-car-color3 Q# e8 }% L1 h; `' Z0 V
    record-data
- Q5 c5 V. ~! D/ W3 L/ E9 |  ]
  D! ]& [) V- D- `" H0 c  F- [
, J7 r& _6 Z2 n' ?% ^; z7 w/ f  ;; give the turtles an initial speed
) e- M* O% h$ ^- n3 Q9 y2 }  ask turtles [ set-car-speed ]( I: f( [. o! Y8 W, U$ R1 ^# }
) A/ n0 {* V1 q, x/ ?
  reset-ticks
. _! I$ Z' E8 ?7 Iend4 A' f' f( T* c6 A# x; c9 @
8 u- Q! C0 P# i+ D& f: B( G% X' t
;; Initialize the global variables to appropriate values
$ H; v4 \3 G& \9 Tto setup-globals2 \. K! [. W- A
  set current-light nobody ;; just for now, since there are no lights yet% f* A2 B6 g% i1 A' I; Q( W( d
  set phase 0
) r# Z" S! S: b' ]  set num-cars-stopped 0
6 B! ]$ k6 _1 W' f* i4 A! n0 ?  set grid-x-inc world-width / grid-size-x  C% y* T7 l5 N
  set grid-y-inc world-height / grid-size-y
4 a& L4 a; E  j% m! _6 B6 x0 o6 q8 |& G, q( A2 w; n: i7 u% |
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) x; \( o6 R1 B8 F. y' Q
  set acceleration 0.099
" _; B# a1 C# _0 W% R5 y5 h% d2 ^end
2 _% N+ w. ^& r6 C" ?: e
9 R5 d% x" I6 T! l5 g5 };; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 V1 B0 t! n9 A/ i: R;; and initialize the traffic lights to one setting6 X* j2 W& P1 t* s1 `
to setup-patches9 ]; u8 M+ C8 ^! C
  ;; initialize the patch-owned variables and color the patches to a base-color" S" d4 S5 e) y+ n0 y2 n7 W4 l
  ask patches
* F% J3 h5 i# X4 \9 ^7 W/ I" M( o  [
+ _' f5 @0 i, v9 F' J- p0 _2 C    set intersection? false
; V/ g5 ?. ?/ [7 l    set auto? false0 k+ ~5 l4 j& O
    set green-light-up? true
- R$ C5 _( M5 J3 b/ n    set my-row -1& V; C9 f! U0 u/ u! ?' Q
    set my-column -1
  d' l1 S% e( E3 U9 B5 O    set my-phase -1" @; j6 o: j9 Q4 |  r. b
    set pcolor brown + 3
+ w$ Y' m' f1 ~. I  x  ]) ]4 J! Z; T  V; |4 y2 x

/ c) y8 X+ _3 c5 Z% T  ;; initialize the global variables that hold patch agentsets
" R( b( V$ F! H* O* _  set roads patches with: z) H; S  l" n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, z7 @5 q: A! a; W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* h& N7 }' M3 s9 Q% |1 v
  set intersections roads with  J' X! r& l& s- G- A4 i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. V% s% ~/ n1 u5 ?9 x! V
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ B1 h9 h- j1 ~" e* @4 p) Y: m
4 {" S# e7 A! y( `0 O1 j/ E+ @
  ask roads [ set pcolor white ]% e- J0 O  c. {! ]
    setup-intersections
$ W' o( J; z9 L, ^8 |+ \end
1 _( R4 o0 c% M其中定义道路的句子,如下所示,是什么意思啊?/ K7 R& B3 o; {: c7 o5 E
set roads patches with% r5 F# g8 {% w9 o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 J4 h7 {$ Q2 N" w6 D6 p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) f8 Z1 |5 d% n& R2 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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