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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。
# \  W" j& [1 y. X/ _3 T! ?* d. R7 A' Rnetlogo自带的social science--traffic grid这一例子当中,3 A% Q# i, [5 X0 M; ^' L- m
globals
: V# x+ _; a  J4 ?[
% O9 o6 r% p5 D" m, C, Q, I  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 ~  Z1 ]; Y5 Q( N' V  grid-y-inc               ;; the amount of patches in between two roads in the y direction" d8 r0 o1 t$ {  j4 A" C
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& `  Z0 p9 ^7 [6 x  G5 t5 d                           ;; it is to accelerate or decelerate
) _) [- k4 d5 i' y0 f  r, H  phase                    ;; keeps track of the phase
9 d: @% Q! i2 c4 @9 Q+ ?" v  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 b) Q! f+ G; c4 A) x
  current-light            ;; the currently selected light
; D, f0 {" _8 Q6 U
2 Y9 C$ ?9 _  s4 W( W& C% G, }  ;; patch agentsets* s2 H6 H, B. y/ @' n! V+ I, ]
  intersections ;; agentset containing the patches that are intersections8 n& I/ {6 l' N
  roads         ;; agentset containing the patches that are roads3 ]: [7 h, ]; P
]: o8 y2 v4 Q% \2 i0 R  x  p8 F

9 r  U2 M- X3 x9 F2 uturtles-own
/ u3 T/ T+ h- ?7 O[$ O& P$ s/ ^) h' p
  speed     ;; the speed of the turtle0 B' Z/ d$ ^2 L% x: W$ `
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 `- u6 \* `8 S  wait-time ;; the amount of time since the last time a turtle has moved1 n1 Z* _# M, j
]
7 Z! o" L" b0 C+ U4 G! {6 X% i, G7 N+ n6 a3 B% U& X( x6 h: V' L
patches-own
, B9 t: R9 E2 u( G8 B[2 W7 W& R7 F) p# g. T) M
  intersection?   ;; true if the patch is at the intersection of two roads
' Y+ |6 s5 x3 e% N9 Y, k  y0 N  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: l( F  V3 R& E) Z3 p3 X# L
                  ;; false for a non-intersection patches.# ^( p$ |( ^, |4 L* B% a5 y( N, t* n
  my-row          ;; the row of the intersection counting from the upper left corner of the
% t' `$ A- o0 G8 }8 j& _; R& p                  ;; world.  -1 for non-intersection patches.
) R. U3 n2 |  P% q8 x) T' U6 z  my-column       ;; the column of the intersection counting from the upper left corner of the1 E& s; T! A4 B: d
                  ;; world.  -1 for non-intersection patches.- N$ e  l% L9 d
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 n; N+ D8 d( \% x  ?: a7 G! D  auto?           ;; whether or not this intersection will switch automatically.  i1 S1 I- Q5 _& r3 L
                  ;; false for non-intersection patches.$ O+ ^4 z9 X1 q
]
) j$ e, V7 K6 A1 k. u) d! I4 r
5 k/ \" }( M$ [) o6 ^& \+ c' V4 U0 e3 b. }: E+ W
;;;;;;;;;;;;;;;;;;;;;;  c, g& \+ i% g0 S
;; Setup Procedures ;;
) `8 y/ [% c4 b;;;;;;;;;;;;;;;;;;;;;;/ x1 O& e6 g! h7 I# O5 @  F/ J

4 ~6 f* u* o  W* h7 U1 z;; Initialize the display by giving the global and patch variables initial values.; S% n: y2 _5 N! r  G$ @
;; Create num-cars of turtles if there are enough road patches for one turtle to
% k8 P9 m/ v( B  ]1 B;; be created per road patch. Set up the plots.0 o) I( A; {  e- f8 g8 K% j% H; z
to setup1 g+ p' ?( [& ~' w, j& R( [
  ca; J/ T( [4 S) _" \3 F5 U  ~
  setup-globals- \' e7 ]: i: T, _% v
  Z7 c! G. L1 ?' j3 [) i
  ;; First we ask the patches to draw themselves and set up a few variables
3 C, f9 l4 x5 \3 r; H' R) _+ t  setup-patches
/ T$ {% i- `* \  make-current one-of intersections  C7 {; V$ E, P4 M0 k2 e- B
  label-current
* c- B0 \$ a/ j) q, z
. _" v8 J# [- I* f. z0 S9 N  set-default-shape turtles "car"3 H' Z) q2 O. c1 D
) w/ t$ I& ?! M* V+ m
  if (num-cars > count roads): _% \  K2 v: x8 T0 c/ h. o. _
  [9 D# t1 ~2 w& g. P" H
    user-message (word "There are too many cars for the amount of "2 z; Q. K$ d+ _, L
                       "road.  Either increase the amount of roads ": s+ J3 t# w) ^- E
                       "by increasing the GRID-SIZE-X or "+ A6 ?0 o6 z1 Y1 j) K' G+ B
                       "GRID-SIZE-Y sliders, or decrease the ", N, U4 E8 q1 h4 ^, y  m* l/ c
                       "number of cars by lowering the NUMBER slider.\n"" Y1 E. ~$ S% B+ V% [1 H
                       "The setup has stopped.")
* q: N! ^3 h3 }) n+ B7 H* ~4 g    stop
  N  w6 Y* i' ~6 e  ]" Z4 g) @! M4 U* |' x

8 E; T( k8 Z. `: Q$ E; _  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. ^$ s1 @. p$ a9 Y  crt num-cars
+ n- M2 x8 t3 j5 d/ f  [; K/ ?3 E6 a1 y" l, H6 Y
    setup-cars
& v  |( e3 @, ^6 `$ n    set-car-color/ e0 D; x% n, x1 J5 c! V
    record-data
( e: W) D8 a. f% g2 i7 b! o* V) t  ]4 K6 J8 `: ^: g& d1 Z* s# Z+ S
+ K6 y) T1 @3 d
  ;; give the turtles an initial speed# b% i: H& \% b, u
  ask turtles [ set-car-speed ]
! K( ~3 a$ k2 \* z& g8 K. E2 f, |, ~4 x
  reset-ticks
2 H  I% d- O( J% N! r( _0 Nend
3 o; X3 T& }3 ~. t+ Z4 G' H; k+ {) t
;; Initialize the global variables to appropriate values
2 B8 L5 [& g+ K0 B. D$ Z8 D0 j) Dto setup-globals. h9 h1 _7 Z! g/ C) P  Z, E, H
  set current-light nobody ;; just for now, since there are no lights yet
. I2 U$ x: M1 D  set phase 0' x5 O, f- [$ n0 b, P* ]  o
  set num-cars-stopped 0
! m4 L( R+ d1 O" x* p. @: n, l6 h  set grid-x-inc world-width / grid-size-x
& y4 \2 x* n/ a$ J" d8 J5 N  set grid-y-inc world-height / grid-size-y& u! [% t- L9 j7 b/ J
# n) B+ Q( p  R% ~( M0 z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  ?+ q( J# M6 E1 p$ E
  set acceleration 0.099
# G' C( R0 ]$ ~" Dend
/ }. j4 D% S! z- [( L5 {* L7 j4 [6 c' W& Q6 f1 V' @
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: O" R. \3 d3 i( c; J
;; and initialize the traffic lights to one setting
! X9 u8 d# c1 p$ N: x2 eto setup-patches- k: U" J0 a& P9 a/ Z7 P' H7 R) Z
  ;; initialize the patch-owned variables and color the patches to a base-color
) Y; r; p+ r+ p  ask patches% o0 L. }9 t$ ?& k/ B
  [
4 {, s  Y* U( [1 [3 ~# P    set intersection? false
6 {. |3 G- r9 |7 A1 g) m1 S$ g7 Y8 n    set auto? false
, Q4 G' q6 l0 F    set green-light-up? true
4 x# ~+ P' @6 `    set my-row -1; {/ d9 L. t( y  G
    set my-column -1
/ a7 X6 r- a* F6 I, {5 M3 t    set my-phase -1
! S! o  T9 q& t0 l. ^6 G0 j2 Z+ N    set pcolor brown + 38 d' e$ \3 M: y, v
  ]
# X  K; E* n/ i5 O
9 Q/ p, c: L6 U" O0 I  ;; initialize the global variables that hold patch agentsets
5 i: w8 E  u3 f; z1 R  set roads patches with3 _' L" z- p1 O5 U2 F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 S1 ~5 I& ~$ ?5 B* B2 b, g8 c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* w( X( p' t/ b8 ]/ V4 V6 q  set intersections roads with% ~6 x, I$ A: L1 I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& s3 }  C3 I' U% e7 Z. Y- {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ G# b, F% u7 r0 e2 ]

$ l8 q- m, Y& m/ F$ B% |  ask roads [ set pcolor white ]
& _) {- \- n1 W0 l5 b" w    setup-intersections" @2 g" Q3 O5 l( A  L/ }) q- A
end
' ^: i2 i. e- M) c7 K1 D2 L其中定义道路的句子,如下所示,是什么意思啊?
; _* G, D  O" `) g2 N set roads patches with
/ {4 [/ X8 j& `1 F- V$ v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  P$ d7 z1 L2 }" B. A3 Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ K$ M; Y! u+ \+ r5 i
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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