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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。: Z2 L8 T: i. u. p! _* V
netlogo自带的social science--traffic grid这一例子当中,) \3 H% }4 s, E
globals' e( E7 h; ^; \9 Y2 q
[& ~- U/ s2 b" I
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% Q( X& M, X- ~7 Z  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 p0 q" o. C8 C; }  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. v2 S7 A8 q5 ]% g, ~9 W8 K. P8 L
                           ;; it is to accelerate or decelerate  ^$ _4 O8 g/ p% n$ v$ P/ D
  phase                    ;; keeps track of the phase  A1 O6 i$ ~& v. k  @- n
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 M' o6 `% M# n3 L. p& n- A- Q  current-light            ;; the currently selected light/ e1 P" ?6 U* m3 @
3 i: W' N( H2 a, n1 H- E. Z
  ;; patch agentsets& v9 `+ |; j& P& y% b' a
  intersections ;; agentset containing the patches that are intersections, V& L$ d7 Z, U; L. h7 A- ?; L
  roads         ;; agentset containing the patches that are roads8 C( C& {; y9 {+ g2 X& L% g
]
* T& ]! r2 u9 T& @4 |* k# A7 f5 x$ o7 o' g5 o( E# B
turtles-own
5 S; c2 ]% ^' p( F' Z[$ f: `2 J, h- B6 y
  speed     ;; the speed of the turtle8 q+ `: s8 O+ O6 ]1 K+ @, A
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 q+ |8 k3 _# E, [
  wait-time ;; the amount of time since the last time a turtle has moved) T1 W: [% ^: P3 d6 o3 E
]
. m8 Y7 s: f* q: f5 V, L- e# E
! N/ I# R+ V; C0 Kpatches-own+ B3 W" u1 ^& M$ O/ S" |: \
[
! \5 m( k; c0 B  intersection?   ;; true if the patch is at the intersection of two roads
$ X$ m2 p4 g& E% g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.) I% Y& l& a  G% x& @; ~) c9 W
                  ;; false for a non-intersection patches.
( e& j- X/ n8 w) K6 X  my-row          ;; the row of the intersection counting from the upper left corner of the: v6 A- a  E  j8 b
                  ;; world.  -1 for non-intersection patches.1 [- w/ }3 j7 k6 x1 e
  my-column       ;; the column of the intersection counting from the upper left corner of the
1 j$ S# C2 M: P* M5 F                  ;; world.  -1 for non-intersection patches.1 R/ V4 X6 [& }/ D6 o
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.; W( N& l$ @8 u3 y2 J' D
  auto?           ;; whether or not this intersection will switch automatically.: @* P% r! n( U3 ^% w
                  ;; false for non-intersection patches.
0 T0 T- a$ Q( x9 E/ D  ^* l]' L% g. X. z0 S. P9 t
% r/ y& [& ~  {! a5 V6 b

; l' }2 [( H* U2 ~+ Z; C6 n;;;;;;;;;;;;;;;;;;;;;;5 t# H' c  k: A
;; Setup Procedures ;;
6 n: ?6 L% F3 z( [) @: L0 B# g;;;;;;;;;;;;;;;;;;;;;;! Z4 s8 K5 }. @- o- M- D

  c* ~+ W7 @: d: }) _/ E;; Initialize the display by giving the global and patch variables initial values.* H# P( U: [! d. i- O
;; Create num-cars of turtles if there are enough road patches for one turtle to
; e! {9 u8 q$ C; ?3 d;; be created per road patch. Set up the plots.0 H' k1 X( d$ D0 q$ [2 r" t. X% h
to setup
1 V- C/ D0 u. i8 R) L% m  ca
; ?- _) G8 X5 g* c. J5 G# t  setup-globals' D; r8 m0 R9 a( i: m

/ N% y8 e1 ]% q( }2 z) |) N  ;; First we ask the patches to draw themselves and set up a few variables: ^5 x4 C, w3 I) O3 k; T
  setup-patches0 o5 j4 q. {, ~9 v4 x
  make-current one-of intersections
6 \% ^% }0 C9 }  label-current
2 f% O6 x. B. q/ `5 ?+ h( P% z& D3 n( i- E3 u! Z
  set-default-shape turtles "car"* y3 a0 ?% p1 @

+ [3 x: ~& d* J$ h* H( _; q: W  if (num-cars > count roads)7 @; j5 g+ Q/ E3 U
  [
  K+ \6 r. j3 D! \9 w    user-message (word "There are too many cars for the amount of "% v) U' P, v% J: E; G9 I# I
                       "road.  Either increase the amount of roads "
) W% y8 j; C$ P8 m0 S                       "by increasing the GRID-SIZE-X or "
0 S% r$ Z. l7 ?' q                       "GRID-SIZE-Y sliders, or decrease the "
- _$ u7 @- O) y# [7 v2 j                       "number of cars by lowering the NUMBER slider.\n"
$ O; ?7 T4 P1 Z* A6 H                       "The setup has stopped.")9 h/ m$ a4 A+ h1 p; i" d; @
    stop. S$ |9 y! B0 r. @, T+ X6 ^
  ]
% y) D' h( Q, u0 l8 N- J# p) x% o0 V; K8 x" R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 x9 s9 M# I  f. `
  crt num-cars# j: x6 J) z' T1 l$ ]0 Y
  [" a; L: u# r( `' {) ~. K
    setup-cars
7 ?$ o$ T9 ~$ V1 E% ^- C# ]) K: l+ l    set-car-color
4 \9 d3 ?) i6 {' _    record-data
. X: ~* |3 F/ p9 i2 t% m  ]
$ c2 W7 h+ q) d! O/ s+ u( e4 G) Y( @
  ;; give the turtles an initial speed+ K: r) U+ C+ M% c# K. w5 P
  ask turtles [ set-car-speed ]5 z. \# Y! f2 c: V

7 g0 H0 b' W9 I+ E- O8 c  T  reset-ticks
) v6 V! w) B2 _5 }9 v' Iend
* J: Q6 A8 o' i: p1 g3 i) o! K; p
: @9 `1 E3 }+ [1 P+ @' ^;; Initialize the global variables to appropriate values
' G) `7 T8 o$ b' w2 T8 Kto setup-globals% G( u$ @$ [- @, u9 N% C
  set current-light nobody ;; just for now, since there are no lights yet/ e$ R4 ^) T! E: C0 g! }+ b
  set phase 0
1 @, Z  `' D* Y, p' W( R  set num-cars-stopped 0
) C# i* {+ Y, N  set grid-x-inc world-width / grid-size-x
, _( n$ b" ~* w* `  set grid-y-inc world-height / grid-size-y- P9 Z: v. P7 O. J' J3 q% Z7 v
- J" r! O- y0 ]- B9 o
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' `" g" N) n3 C4 _2 r" O: g6 C9 `. w7 A  set acceleration 0.099
1 p. _' Z0 q" x* ^end& X1 a/ @/ U3 `2 e0 a) n, y: ]
% Y  p- V/ U, ^
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 G0 B# P: ]" |( `0 u( `;; and initialize the traffic lights to one setting0 i6 S0 ?7 d5 L$ H/ J1 |$ j
to setup-patches$ L1 e* h8 E$ Y; [" q2 S; r, L
  ;; initialize the patch-owned variables and color the patches to a base-color
; u7 B* s$ p1 Y9 n. m9 g' c/ Q/ `0 L  ask patches
$ v- Q% f4 S0 h) F5 ]  [
6 u* B% e6 z) d2 V    set intersection? false! x  w# b% a( N0 e; g
    set auto? false
9 X4 k. t* Y! g* v    set green-light-up? true8 y6 L8 I5 }! n/ P3 o* G
    set my-row -1
! O% E; A" B2 {8 \; v. ?+ Y    set my-column -1
3 W6 Y  h9 h' ]9 k    set my-phase -1% c! N/ z, F( Y/ s* V
    set pcolor brown + 3+ s9 q, K+ _- s1 M% R
  ]8 K/ n3 f' g3 Z) n1 B

; `7 s0 ~$ f$ V+ s  ;; initialize the global variables that hold patch agentsets0 o. c0 _& Z! g% T0 w
  set roads patches with7 y- K& \: P' ]/ z/ n6 g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" M% A9 d9 b  A0 {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ v: w' f% s; j/ V* ?3 k1 f  set intersections roads with
9 ]" P) I1 C4 C% @1 b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: @  U+ L# f5 H3 t8 E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 I" X- q. A6 H
1 z2 ~. T& `3 L/ `/ o. c& |
  ask roads [ set pcolor white ]
  s1 e3 P4 P5 w5 F7 a    setup-intersections
! g- G8 j$ r* x. [end
+ x7 |! N8 ~! y8 r- L9 N6 t' N4 T其中定义道路的句子,如下所示,是什么意思啊?& T- x; f0 x0 q
set roads patches with" M) I# v2 p' N7 ?1 a7 A  @5 l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& N7 U* d; D- C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 `! y5 z, l* K+ S1 Q+ Z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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