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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。! k. t  y+ e0 A" Q$ @* z% M
netlogo自带的social science--traffic grid这一例子当中,
6 a8 J0 O  q* Eglobals: O6 b* B3 A! L! [; S& t
[/ Y) A" T. r9 k4 f  b0 B- c. ~
  grid-x-inc               ;; the amount of patches in between two roads in the x direction& [7 p! q; \, ^
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 m& d5 v7 c8 v, R% Z  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. Z( D9 `2 Z  f  _+ Y                           ;; it is to accelerate or decelerate
/ U5 v* s) W' C" O; s  phase                    ;; keeps track of the phase
6 I, d1 h  o- H- E  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure1 e' a1 B9 ]9 B& n0 A8 i
  current-light            ;; the currently selected light
) j, p5 i$ c9 J4 S8 c5 F- f3 B( h3 |, S6 q
  ;; patch agentsets8 o3 }! H$ W* {  l
  intersections ;; agentset containing the patches that are intersections
8 D1 m; {% f7 X6 x* {, N% a) q9 W* m  roads         ;; agentset containing the patches that are roads
# U' l1 G+ J) |; T]1 \1 z+ L$ Y$ f9 t

$ V% e8 E' X! t* sturtles-own$ m9 r: c" m5 ?6 \) o* z- }
[! W2 m& I" X  J" j* y& Y' o; X
  speed     ;; the speed of the turtle4 F  W8 |+ w2 J% d1 @+ k0 m
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 K9 A& |$ E7 V3 G9 A
  wait-time ;; the amount of time since the last time a turtle has moved
7 I% U$ A; z+ r0 `6 `0 b9 y9 L]6 ^3 E: ~$ W& Z3 i( n6 \
; x, ]/ B! Y" D6 y
patches-own; g8 c* y" G# z% ]# y. U
[
1 I2 V- b2 P5 s  intersection?   ;; true if the patch is at the intersection of two roads+ \" o/ a) }0 h* M: w
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 p2 l8 c9 y) ~& }5 A
                  ;; false for a non-intersection patches.
5 k5 q/ F3 K4 }& q" ^$ |$ k& \; u  my-row          ;; the row of the intersection counting from the upper left corner of the2 [' S0 o+ |/ j  J
                  ;; world.  -1 for non-intersection patches.; N$ }9 H( D) k4 Z, a4 t" R5 `' b/ Z
  my-column       ;; the column of the intersection counting from the upper left corner of the9 m( f0 n0 z4 C/ O$ b9 W( {2 r
                  ;; world.  -1 for non-intersection patches.* Y( p& c- T( j! V8 N
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) ?% L' a* u; s2 Z2 R  auto?           ;; whether or not this intersection will switch automatically.0 h" d/ p+ K2 d. `
                  ;; false for non-intersection patches.
% S6 d$ X, V$ P' J: b: i: x# h5 g* \]
7 K9 J2 O  w1 X( e1 Q) n8 d3 c& h" M4 A% r. x# w+ Y  k7 G
4 L7 J/ O) C9 m. W1 g( ?  l
;;;;;;;;;;;;;;;;;;;;;;6 g( D, m1 a- W: l0 X: b
;; Setup Procedures ;;) p( h; b# x$ F% R) }& ?0 R
;;;;;;;;;;;;;;;;;;;;;;& e" m: E' R  q: Z, K

8 ~' T$ ^: ?- ~5 l0 @, |;; Initialize the display by giving the global and patch variables initial values.
% O7 N% t4 ~9 t3 |( k  R;; Create num-cars of turtles if there are enough road patches for one turtle to% m7 _) `5 y+ x2 \- T2 E
;; be created per road patch. Set up the plots.' H* `* ]( ]/ m
to setup- ^; v  S2 k" u
  ca- ^6 m4 J% C, J  |
  setup-globals
# x! K0 T) t3 {7 h
; R7 V% S) [" O. Y9 S  ;; First we ask the patches to draw themselves and set up a few variables
% q/ S5 _* w& I( a# L% N  setup-patches
# E2 p6 A( {& c* K) o  make-current one-of intersections1 f- C( N( j+ W1 U: U
  label-current+ m% I/ \: q+ P2 y0 y9 J- a" D, V

+ ^$ N6 h# F1 ]  set-default-shape turtles "car"
( |  k% N! a0 L; b0 M* w; K% M: s6 n+ G3 G" d+ c) ]
  if (num-cars > count roads)9 z+ H( i  r, m. Z
  [$ s' B( }2 s, B2 h: J6 e5 c
    user-message (word "There are too many cars for the amount of "
1 m) C) H1 I7 s: Y2 }+ I                       "road.  Either increase the amount of roads "6 j1 `# T% D: o! V
                       "by increasing the GRID-SIZE-X or "
6 @( b: k% i! R" u2 G2 }                       "GRID-SIZE-Y sliders, or decrease the "2 J* f' a8 P$ d3 I4 n
                       "number of cars by lowering the NUMBER slider.\n"% |/ ^  Z% V' y
                       "The setup has stopped.")
- F6 T# B" e$ u6 R4 }. X# h! D- R" f    stop4 h/ |7 r3 O& I* n( L$ I
  ]
9 b* k3 |1 `2 c# Y8 ~
, ^' x! X- e$ ^% b2 Q5 Z: t& D  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( ?; i' s# M. J
  crt num-cars
5 c' I8 b1 }3 ?5 O1 v  [, U. ~# [  g7 z0 `
    setup-cars
: O8 n! O  l) r3 t; E    set-car-color$ y! @! F( q$ g0 C& S: q: j
    record-data& s: I% D9 v5 X) k/ b3 O
  ]
6 X; J, e; ]3 q- I5 L9 r6 ]# b; t, [6 \& C. Z  |$ I
  ;; give the turtles an initial speed
, B* o) O$ ?/ w1 B# v( v: l  ask turtles [ set-car-speed ]/ ], T4 m0 z* `# I

, r1 u- v. @2 V$ n( w1 {: E  reset-ticks
1 o. C1 B0 Q7 X- z& T' aend
3 T* ?" d5 N0 D# R) q; x, \0 P
5 E- r: v$ P  |+ i2 \; J3 W;; Initialize the global variables to appropriate values
8 |( c; p/ y' A& xto setup-globals4 S& N% q3 t$ v- v: ^6 `, Y% Y9 p: O
  set current-light nobody ;; just for now, since there are no lights yet* r  Z  e2 _" P3 \/ x* J
  set phase 06 Z& P5 D# h+ ]1 m% h; H9 c
  set num-cars-stopped 0
* G% m0 _4 p" J  set grid-x-inc world-width / grid-size-x
: ?  d; \; M6 K) a1 D8 X  set grid-y-inc world-height / grid-size-y3 T  Q% W* |4 ^* I: }

1 {! i/ E) }' A6 V  J  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 ^. _3 T/ m8 Y4 s7 E( r" b' S3 n# M  i
  set acceleration 0.099
9 \3 A, E/ G" j* kend0 |* m- L6 {* {

& E8 o0 j4 _1 `" k" p; ]& l;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! H( u& w; X  g3 Y;; and initialize the traffic lights to one setting
9 k- u  Z2 I* o, l- v2 N0 G( Dto setup-patches2 G5 E# h$ R7 I
  ;; initialize the patch-owned variables and color the patches to a base-color  d% J1 E. w3 Q4 z+ W
  ask patches
; G! f) V% I0 |' ]6 q; C  [+ N, L* Z  H! e9 F# O% E8 \
    set intersection? false7 J' c' e4 m4 g! u/ E) d
    set auto? false0 C1 a& v$ U& `; Z. p
    set green-light-up? true& ?$ \' _/ h) p9 r" q
    set my-row -16 J) R/ p+ j! _* u% r- Z
    set my-column -1
  O8 w( }3 e$ S    set my-phase -1
" ?1 u9 T! M5 _5 H# G    set pcolor brown + 3# f5 [5 V' p( ^% j  `
  ]0 y. {) e! o) X2 p% y9 L
; D& i2 Z) H7 Y  i! Z. m! u
  ;; initialize the global variables that hold patch agentsets
6 v7 Z: j) c# T- x$ W- [  set roads patches with
# ]6 x* F) _1 j  v# Q1 [. e: R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, o' X. B* K, {+ W2 h* f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' |7 o/ O1 h/ B& [6 R
  set intersections roads with
$ z" X$ u5 U3 ]. o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 c7 F' @/ b. O0 M2 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 N7 p! A6 w! p, m1 y% m
" t; R( F* T- u3 D
  ask roads [ set pcolor white ]
7 C- f% p* w. [4 a    setup-intersections& L: J3 U5 ^6 f5 L6 u9 r
end
8 @4 l8 [* _+ u0 B) p其中定义道路的句子,如下所示,是什么意思啊?
, M5 f6 W/ @5 z6 x set roads patches with
: p7 n  r! z1 S8 V8 ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 G5 M! G6 U" }5 y5 N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 ^  ?  ?' ^! C5 [& ?3 Y
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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