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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。, A! H; f$ ]- t
netlogo自带的social science--traffic grid这一例子当中,. i' S1 `% L" [5 I2 w' r, g7 |$ s
globals+ T, Q% m( C8 U! [/ s4 M0 ~1 F
[
, S1 B( x. x2 d# G% j  grid-x-inc               ;; the amount of patches in between two roads in the x direction. K* ^1 i3 @" x% S
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( ^- q; p5 ]7 Q) z, \' l  z# W  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 x3 J" M1 b& e! O! F, s
                           ;; it is to accelerate or decelerate& C9 \  e$ D, S9 d. O. A( g$ r
  phase                    ;; keeps track of the phase
  T9 N9 L, A& ^. `; F+ A, j  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# D' \5 y; T$ l  S: p" w7 b  ?
  current-light            ;; the currently selected light; v& I' I4 f" V& e* M

1 N% R% e2 A* P  ;; patch agentsets$ ?0 x1 _, Z$ _! [" \
  intersections ;; agentset containing the patches that are intersections* H: U% s4 Y4 n1 e% [: {8 l4 W: @
  roads         ;; agentset containing the patches that are roads
: x3 ]3 \/ W3 u' y; \]
8 g- O* q/ r# {4 C. U
) _, i/ Z% {2 x6 cturtles-own
1 b! f' k1 ~2 Z[
6 {# [8 C% k2 |" U  speed     ;; the speed of the turtle
- _% Y1 V+ \9 F: a8 M  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 Y$ b% H* w% W/ ?
  wait-time ;; the amount of time since the last time a turtle has moved
0 j  b5 s8 j' P2 O* S- L]8 d6 B0 [" y7 y6 M
, \" b$ x, s: F* i/ p4 }. M) _! R
patches-own! ^$ Y/ C6 X; s  T0 Q
[
% m6 i# [1 Q3 m+ }  intersection?   ;; true if the patch is at the intersection of two roads
: o' ?+ h7 U! y8 N; |! }$ ^! {  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ `/ I6 L0 V" Z# N  z                  ;; false for a non-intersection patches.
* s+ h$ X% X% R7 ?/ {  my-row          ;; the row of the intersection counting from the upper left corner of the3 B: h$ q7 n$ p# [7 J* L
                  ;; world.  -1 for non-intersection patches.1 v; t4 |* Z* V6 e3 {
  my-column       ;; the column of the intersection counting from the upper left corner of the2 R8 G5 {1 Z# r) x, `1 ?
                  ;; world.  -1 for non-intersection patches.
/ \* }7 p* |- l' }2 W  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 l% ~8 \7 A% |  _8 p; r, P
  auto?           ;; whether or not this intersection will switch automatically.
) v: m/ _0 [  Y% {7 D8 m& K                  ;; false for non-intersection patches.
$ u. D0 Q" Y) x/ q/ B: k]& }0 c- B+ d  g! g6 f/ Z. Y5 Y

9 U1 u8 p3 v5 m$ y8 [: u, S5 E" W( v8 j1 m1 @; b5 L3 w
;;;;;;;;;;;;;;;;;;;;;;
& I! |8 t* s8 n+ T& W2 R;; Setup Procedures ;;
9 n$ x/ ]2 j5 M; _( n* x1 |;;;;;;;;;;;;;;;;;;;;;;' Q/ Q5 }) n4 Z& T1 I- p3 T

* L$ |* X8 ?0 e;; Initialize the display by giving the global and patch variables initial values.' G( a4 {* C. k1 T- N
;; Create num-cars of turtles if there are enough road patches for one turtle to
/ ~+ }: }, G- ?' V- G;; be created per road patch. Set up the plots.; O9 M4 T% E5 h
to setup  M5 d6 X5 c7 Q
  ca, n0 U0 k. v% A! k9 G7 X! l4 s
  setup-globals4 S! U4 e7 E8 |3 ~, S- u' K2 U  o$ A

# k, b( f8 k1 ~1 ~9 \  ;; First we ask the patches to draw themselves and set up a few variables  o5 O: @' d& C0 k' a) b
  setup-patches" _) J- y% q) W1 G
  make-current one-of intersections' N) n. D9 f/ J( b2 J( U4 |0 z
  label-current5 N% M4 m( y* D+ s4 q; b4 X

, Q' ~7 r8 j( E% t  set-default-shape turtles "car"
1 j& x0 v7 G# T" E: K8 r0 F/ u5 L
( N9 Y* O: P% q1 m- M5 Q  if (num-cars > count roads), X$ g  Z, w  j. T9 S
  [
. O! v) s" A. ~/ m$ p' w& ?    user-message (word "There are too many cars for the amount of "9 v0 b" ]6 y$ ~; x. \0 a/ b
                       "road.  Either increase the amount of roads "  i2 Y0 }! y2 u" J7 w
                       "by increasing the GRID-SIZE-X or ", o0 W( E, |( }) }( x
                       "GRID-SIZE-Y sliders, or decrease the "  Q, M! j" n# Q; a* E
                       "number of cars by lowering the NUMBER slider.\n"& p' D4 d/ f) n" I7 |4 X
                       "The setup has stopped.")- M5 a# ~6 g( S' a
    stop6 l- C& `- Y3 Q  [
  ]
9 d/ m/ w% e) V- F! W$ l7 ^3 ^% Y
+ S$ `1 h1 |3 [. Y% e( U4 Y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 `6 z- Q& u3 s6 q/ ~2 J1 N
  crt num-cars5 g8 `- P5 X% d& p# }! D. d# e
  [3 t$ E3 H5 b: M6 h3 t3 r1 y- n$ ^
    setup-cars* |2 l0 y* E5 c& n. {
    set-car-color
/ M+ ~& a' C; H6 J9 x% Y    record-data/ g9 Y! ?; P/ l" ~2 `5 D2 Q
  ]
8 R9 B- {) K. n% g/ z- u
0 x2 y6 a  w1 L. c  ;; give the turtles an initial speed# e$ @) [5 M) j
  ask turtles [ set-car-speed ]
( x  R) a4 [! k7 W/ F* f
3 u4 `& l3 b: I* [3 R, u  e4 _  reset-ticks$ K6 L$ t& z" D8 W1 W. K
end( z0 F; c/ Y7 I( h) q* C  O7 b! c. s

* N- A& S" H5 {$ {' z;; Initialize the global variables to appropriate values" c+ `* ]/ \1 ~6 H% d
to setup-globals& d3 j8 T( P/ {- v- Z. s5 t
  set current-light nobody ;; just for now, since there are no lights yet
; P) j" R- v/ P3 _  set phase 0* k3 U7 [' S( ?& j1 E4 v3 i) u4 b
  set num-cars-stopped 05 E, X5 O0 z# `+ }0 D. ]
  set grid-x-inc world-width / grid-size-x
; q1 N. Q4 B" D/ L  set grid-y-inc world-height / grid-size-y! c% H0 P9 t5 Q8 Y% K/ S0 |" m; h
5 }7 h6 |- s9 a* A# [- ^  w1 N( O
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, [4 J7 y* O: G' q  set acceleration 0.099
8 x. I- V$ M5 j& h: t7 ^" m: mend; s& b' T& `2 u( p" W, _3 P+ V3 K
/ j4 I0 g% e4 o" J
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. W0 R$ y- d; Z+ h
;; and initialize the traffic lights to one setting. l0 v: a0 ~# f7 l% w
to setup-patches
. a" }/ b. }$ T6 @6 g  ;; initialize the patch-owned variables and color the patches to a base-color7 A  a- @# D  u% P7 H
  ask patches
6 f8 j* [- l6 _) _# y* K8 I  [
( K) e8 N! |: Q5 `3 F0 e8 E, }    set intersection? false. u) @3 s2 L5 H( i/ ~
    set auto? false" f# n+ {) k/ _3 ?1 |) {4 u' U, n
    set green-light-up? true4 v4 A5 ]( W3 M- u. A
    set my-row -1. @  I3 M7 [$ D# q
    set my-column -1
/ C3 o& m2 N! l5 W! [    set my-phase -1
7 x/ K: C, C1 j6 N9 }( h8 B$ G1 r    set pcolor brown + 3
  C9 W0 i& ~8 `: y  ]
4 r; z& O0 h4 I/ |) E6 Z6 X0 `+ n' n/ i, e0 M5 u: }+ V
  ;; initialize the global variables that hold patch agentsets
5 b  q+ A) s, r$ O' m- v  set roads patches with% s, \4 x; @' D6 d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" Y. u* H) @; W6 D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 S  m$ f( S) \* p: h! s
  set intersections roads with' s+ f0 Z! ?5 O: e& ~7 M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; f! ?4 [. ?8 n5 y3 s9 p( u7 Z$ E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! A+ c! Y& X2 [8 X% v' X9 `% Y$ e3 C/ ~1 E! K$ ~! z$ Y
  ask roads [ set pcolor white ]
8 \" M* }- x2 D" x    setup-intersections
8 l* l5 {% s4 s/ tend
5 s1 P! c5 i6 Z2 ?8 e其中定义道路的句子,如下所示,是什么意思啊?: ^" E( @' E8 p! ^: ]  @. Q( r
set roads patches with. c- w! O$ P; I! K( c$ m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  @. q% z3 p: U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% w6 {& Q/ R3 ^# z% f- c, |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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