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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 K" J: B$ k( O' Fnetlogo自带的social science--traffic grid这一例子当中,
9 k; U# h8 \% [8 ]* `globals
6 l* b: K4 }0 l; p[- [# o/ i+ ^1 A5 c" G
  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 Q9 b* p) d1 [$ n5 J4 c
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
+ u  c, t- D) I  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* T# o" O5 z" @8 \$ c
                           ;; it is to accelerate or decelerate
9 N, W/ x7 K8 a) Z! I  phase                    ;; keeps track of the phase
4 _3 o4 Y: C% \, F  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( M4 D0 d! R$ t6 W. u0 e
  current-light            ;; the currently selected light8 t$ |9 o' D# K# D# g( t& |

" t; I. L8 u, q  ;; patch agentsets
: p0 g0 q1 T& p; O  intersections ;; agentset containing the patches that are intersections- v9 g8 d* p% u" T
  roads         ;; agentset containing the patches that are roads' i  O9 }5 B) u1 K7 n+ r$ B
]
: d3 `4 D4 m# x) b4 K9 a- M$ h6 C( h
5 L4 g! f. |. j8 }0 o2 z# _turtles-own" e7 [& }- N  j2 D2 H
[
+ Z# M! {7 T: l* p; G* g% Z  speed     ;; the speed of the turtle
3 x5 Q9 ?3 R2 t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: E9 {) h2 l" D! {6 y  wait-time ;; the amount of time since the last time a turtle has moved$ h5 r$ N/ j* ~4 q
]
& H% G0 \- o5 ^9 d3 v
/ j0 X$ ?1 \9 ?patches-own1 H0 S) i/ p% W, V+ e- u. [
[& l& u- y4 }" X3 t7 C' z) \, `2 r
  intersection?   ;; true if the patch is at the intersection of two roads- D8 g2 h5 I, ?- H  M' Z- A
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  _2 h. O* a% j, |( y                  ;; false for a non-intersection patches.$ h8 H/ B7 |% ?$ ?
  my-row          ;; the row of the intersection counting from the upper left corner of the4 T7 @# _1 X) b6 M
                  ;; world.  -1 for non-intersection patches.) \# v8 k2 _2 e/ }3 U. C
  my-column       ;; the column of the intersection counting from the upper left corner of the$ m, [- M0 q. O# ^
                  ;; world.  -1 for non-intersection patches.
( @( J+ r3 I) S, b) O5 P1 X# p/ B  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- a) T0 w2 E+ b5 D7 c4 X# }
  auto?           ;; whether or not this intersection will switch automatically.  S3 c# G. K5 B
                  ;; false for non-intersection patches.
; ~$ K  i0 E9 ^  ]/ ]  F4 {, []
9 ]7 z4 @% U" L8 ]9 l( @0 `, F/ d0 h5 Z! v2 m6 }: a* T

$ [9 E9 E' c' L, X;;;;;;;;;;;;;;;;;;;;;;( }+ `4 o7 g2 t, K
;; Setup Procedures ;;
3 i3 g1 @, t4 @6 v;;;;;;;;;;;;;;;;;;;;;;0 ~9 V: Z' }( D" X+ n; ^6 a! ^

/ }0 ^9 Z9 @$ V" n' K" E* E;; Initialize the display by giving the global and patch variables initial values.' ?' V1 z! Q4 e% r2 E& ^0 N, |
;; Create num-cars of turtles if there are enough road patches for one turtle to
- b# M; z% X$ J3 c;; be created per road patch. Set up the plots.
9 }4 b6 g7 i& e5 l2 `7 Z3 p( `$ |+ eto setup
# b6 u# c; z' K9 @  ca
" v+ M$ ~) J" M. C  setup-globals
6 ~8 H- D% g6 s2 j- b' G; ~4 X2 N: w$ V
! N6 ]* i# e$ M# n  ;; First we ask the patches to draw themselves and set up a few variables
, K4 V4 q1 _/ W7 l% N9 V* f  setup-patches* @0 [0 L5 o0 k5 }
  make-current one-of intersections& F0 i; R  b% V  S
  label-current
+ Z/ o( \* p" U: x. C! [  M& P: a  H" ~) K$ p4 O
  set-default-shape turtles "car"
6 G" k* W5 X! {9 t9 x5 |: J) D: p9 a# G
  if (num-cars > count roads)
$ J* v( Y7 J6 b. N& @8 l  [
/ ~) C/ l) X8 B8 v    user-message (word "There are too many cars for the amount of ", w$ n% f4 {: j( y0 j1 @$ s
                       "road.  Either increase the amount of roads "
, u; g1 y: E, ^, u2 Z  Q3 F) F                       "by increasing the GRID-SIZE-X or "5 R5 c* c8 [% Y) v
                       "GRID-SIZE-Y sliders, or decrease the ", ]6 W' ]% ?* \) Q' v) e
                       "number of cars by lowering the NUMBER slider.\n"
8 a- L7 Q" W4 b                       "The setup has stopped.")
2 J9 U& `# u* [) C& s- ?6 j7 A0 \    stop8 S) K- n* o1 r5 }, y$ b% |/ }
  ]! ], A" \6 n% G: A6 F4 H$ r" B
0 X1 ^% U; `* G( i3 X
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ A6 b- Z8 K' r. H. _  crt num-cars
  M# }" F0 f0 @. R  k1 s  [0 M; @/ s  L: {7 G$ O
    setup-cars: f. {* Z6 ^3 t% H& w2 X& Y/ e  H
    set-car-color0 Z$ J. B3 `+ L) k6 X
    record-data+ [" o" I, Z, R' d% S" C
  ]
! z- q6 W. A) H7 r8 e+ u8 O6 p( s) j3 T
  ;; give the turtles an initial speed
2 f2 |# _) R2 Z3 }1 v  ask turtles [ set-car-speed ]
) i& L( l: R4 `. i/ @% V- J; A9 i! H4 \3 |
  reset-ticks( t8 K1 @6 W1 m- U, V
end
% ^9 H0 i+ l6 I  h$ X  h2 X  i  ?6 Z8 v- Z+ q8 ?! y) i' l
;; Initialize the global variables to appropriate values
; v' D3 p4 K- \  t5 I, Sto setup-globals
+ b4 M2 a" w3 F2 J& y  set current-light nobody ;; just for now, since there are no lights yet4 t: N4 I$ a$ v- D9 G/ j0 W, k
  set phase 0- E7 Z* J, K* o% s& e: S
  set num-cars-stopped 0
0 t0 J" V, y0 i6 {: L  set grid-x-inc world-width / grid-size-x" j9 S0 x: B7 q6 n6 e
  set grid-y-inc world-height / grid-size-y! Y! S: f0 {5 f( z" D4 r7 U- N. l

) v1 w6 C& s# y0 k+ ~& m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 o- k; v1 ]2 w- p( g0 B
  set acceleration 0.099
- k* c/ h/ y% b  I1 @  N. dend
8 f! W2 e3 T& C! @* s
6 |: ?' C5 d. d4 w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% ]3 O6 ^& h. C0 B6 h4 T6 m7 u/ };; and initialize the traffic lights to one setting: H  U/ B1 N9 |! V9 J; b
to setup-patches  U8 P+ V$ k9 B1 _
  ;; initialize the patch-owned variables and color the patches to a base-color( l4 M: Z, O' M5 v' t
  ask patches
' b; j2 o7 v* K2 }  [1 N) w, i8 S8 A4 a
    set intersection? false2 w: _9 v1 f& h, o3 b3 |
    set auto? false1 G# ^" p8 A7 [  |$ b+ E4 i/ i. b1 t( J
    set green-light-up? true
5 B: E" A, z" \4 F2 L; M6 n2 J    set my-row -11 m" N9 V9 a! ^/ ?
    set my-column -12 j& q6 f+ j: L5 P9 q/ P. G1 z5 i
    set my-phase -1
, j% _* R3 Q2 q    set pcolor brown + 3
$ s1 E; H1 ]$ p& X  P  ]. G' W6 }5 Z; f9 t4 n0 S

# \2 X2 Z  o0 m6 R  ;; initialize the global variables that hold patch agentsets  f, ]3 A* U. c6 m3 g9 p
  set roads patches with1 X5 o$ |2 h) ?( \4 L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- s5 I! O9 A( w6 ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; H* x4 \. ^% ^& W1 X  n1 E
  set intersections roads with/ I# j% ]4 A0 N6 Y  i- o( k7 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and6 O7 s+ M: P7 u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 L6 v3 l) J' h: k
4 h$ b0 x* d4 A$ Z0 l/ t+ I  ask roads [ set pcolor white ]( E& P" k* O$ i
    setup-intersections. @# K" a" T9 ~. Y: Z$ y& @
end7 i2 `, U8 N) s* t; m/ [; Y
其中定义道路的句子,如下所示,是什么意思啊?3 i( G6 z) \& ]8 U
set roads patches with8 C/ A6 B5 q0 R' W  T) E. f% u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, I5 v0 w1 C2 @" C/ D( S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" Q1 }7 q, \" Z( Y1 a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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