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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。8 }8 G0 C1 r1 B! h  X
netlogo自带的social science--traffic grid这一例子当中,' p9 I! S! H2 C
globals
: ^4 _5 a6 o: R9 b3 J) @2 W[) O# V8 N9 ^) h; J- U  y  o( w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction) v6 F, D  }' y4 G4 S0 m
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; S, c* l" r0 R: P- H) [  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 }. j0 u& k0 K6 P
                           ;; it is to accelerate or decelerate
8 x2 K* w7 ~! Z) n* b  phase                    ;; keeps track of the phase
: k9 W5 x( Y! ?- [  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: G6 E- U( }! d5 M4 a3 u9 z9 G0 c0 w7 W  current-light            ;; the currently selected light
, U% U0 n( `6 k* _
# ?9 m' |( E9 X# C9 `2 F0 o  ;; patch agentsets( P( @- k1 b! P" ?) T+ T/ t8 J2 z/ q
  intersections ;; agentset containing the patches that are intersections6 [1 u) t4 P- J. D4 f
  roads         ;; agentset containing the patches that are roads: g8 W: ^+ L- X& L
]
. h; K% M) `1 n, r$ E' P: _. A3 G8 s8 t  d3 B8 ~
turtles-own$ c! a: a1 E: ?0 G
[- E- u8 J, y% Y- e
  speed     ;; the speed of the turtle
7 [5 _& K9 C. t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. ^. a4 `  O  `! B  E  wait-time ;; the amount of time since the last time a turtle has moved
5 d$ U0 J4 N7 E]  F$ \9 b8 m& g$ o

8 M8 p! |9 c( W' {) opatches-own6 Q; @- q6 s) G4 l# L  z
[
5 W, b! ^8 E, L' ~  intersection?   ;; true if the patch is at the intersection of two roads
1 I3 F, M1 d, P; o: N  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: z0 ~* K- i0 W                  ;; false for a non-intersection patches.
; C% e' a0 _/ @  my-row          ;; the row of the intersection counting from the upper left corner of the5 p5 D# d" g: ?# U' Y" k
                  ;; world.  -1 for non-intersection patches.& w9 h! y' l( ?: `# n
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 H/ W, O+ U1 }5 E- X* D1 Z, X8 _                  ;; world.  -1 for non-intersection patches.
/ X% z7 I  l. Y3 |: K$ `! ]  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 T' X, o5 s# Y" {, p/ r6 ^  auto?           ;; whether or not this intersection will switch automatically.. m$ e/ y5 [# b" j0 _4 n: o# g
                  ;; false for non-intersection patches.1 S( O( q) ]& x. U, e2 M2 N" E4 H
]" f" Z+ k3 o, O( J8 m. ]0 L0 ], ?: F# L
' s/ A* y4 a, t
5 I# h3 R; Q7 B6 Q; M& j
;;;;;;;;;;;;;;;;;;;;;;
# p: p, B  p$ V( I9 M;; Setup Procedures ;;
5 c9 j$ n/ u6 R* {' v7 Q) O( P  h;;;;;;;;;;;;;;;;;;;;;;3 I3 y% l3 y! h( \0 X* i" T& R

- G7 \6 h: M/ d! Q7 ^: _, E8 }0 t;; Initialize the display by giving the global and patch variables initial values.
# y3 y6 S0 D& ]* O  ^;; Create num-cars of turtles if there are enough road patches for one turtle to
+ g! |5 U( a, q) ~( H;; be created per road patch. Set up the plots.; i* K% X) U. [6 ~& C
to setup
1 c# U$ a( P( G% a2 p8 |! D  ca5 x% e$ [8 v( F/ f2 e/ }
  setup-globals' E% j! T* z6 \+ A" p' n

* \6 |+ F5 X2 {6 O- l8 h  ;; First we ask the patches to draw themselves and set up a few variables0 q( o  Z1 l( U4 L
  setup-patches
  k( ?+ n1 T2 p' b7 O3 I$ o, a7 }! T  make-current one-of intersections
& \4 h6 T% C5 i3 ]  label-current
' A& s3 x! ?7 U' K. t8 L/ b0 D
) _- M# ~; ~9 H* d  set-default-shape turtles "car"
  I+ w/ R7 @& c" ?' f' N9 @, j9 [) Y3 h& J7 [' o8 c" ^& u& Y
  if (num-cars > count roads); F- ?/ N1 o6 D% U
  [
& H- x2 e8 t) x, r# x    user-message (word "There are too many cars for the amount of "
, m" u0 o* c8 G( v                       "road.  Either increase the amount of roads "4 X3 ~/ W3 T: u8 `2 X
                       "by increasing the GRID-SIZE-X or "
. x$ c- C3 @+ O                       "GRID-SIZE-Y sliders, or decrease the "& M" N/ ~& G; |4 Y. @
                       "number of cars by lowering the NUMBER slider.\n"" }& e$ z( B1 [1 H+ E6 Y' |
                       "The setup has stopped.")8 l% l  L* j6 X" ?5 h
    stop
0 h( n2 L/ K7 A; Y8 @  ]" X3 K# X. @/ b( H

/ v: l3 y0 ?5 L- S  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( z3 [) C7 Z/ K- K7 f
  crt num-cars$ b2 [+ p# I) b2 J5 ]% n3 ~( y
  [6 V! p& g2 C' K6 p, d$ {% W/ @
    setup-cars6 w1 y# A% \& X) e$ \* P: ~$ L, K
    set-car-color- `! r# t  O8 `2 M
    record-data, |' C5 e2 X- @' ~
  ]
  i& Y0 j6 k. g/ F4 U
, U; G; v/ u8 X  ;; give the turtles an initial speed
3 v' z9 q) u5 ^$ t  ask turtles [ set-car-speed ]
1 c" c( {5 Z8 J- x7 \6 ?' U9 B. r& a8 ^9 P& x
  reset-ticks, L" H$ u. N2 f5 L) c: i
end
9 x9 l# r( f) s# Q! o& J8 J. h6 ]! ~' X; c) n8 G
;; Initialize the global variables to appropriate values
+ ?# m1 f1 V5 v9 i+ |, hto setup-globals; V$ p" m2 ?3 a' x8 \
  set current-light nobody ;; just for now, since there are no lights yet7 g7 O+ s7 a4 q: B- s6 ~! n- q
  set phase 0
6 Q0 b1 M" x6 k6 g$ X# ^  set num-cars-stopped 0- n1 O) d/ Z" e! t
  set grid-x-inc world-width / grid-size-x
  E* R; U' S: a! b  S9 c5 P  set grid-y-inc world-height / grid-size-y$ A0 ?) k" a5 [, `8 Q  E% D' d/ j
& [9 X( {% L0 c/ W+ E7 n
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
* {5 n# E( K% M: d" b( K: z. @  set acceleration 0.099
: \- i$ O, O7 [/ D" Zend
9 G1 r  y# U6 K8 r5 p
: @% ~2 z, E0 H0 B, D;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# M$ S. J; S6 G: ]/ F: B9 e
;; and initialize the traffic lights to one setting
  @- I9 K. |) s% r& G, ito setup-patches
- |4 ~- \3 M& g5 {$ y  Y  ;; initialize the patch-owned variables and color the patches to a base-color
& h7 M( s& d" s, B4 o# {  ask patches2 d3 I% H: |1 i& s; p6 A
  [
# u# s4 g/ ]( L$ s/ t3 l    set intersection? false1 m: m0 M& c, s  Y8 ?; v
    set auto? false
$ H' L& p: N1 V2 O& j9 w0 z    set green-light-up? true
' N# d& u1 ?, L& ^2 }) i( a    set my-row -1
: @, o: ]- U2 ?8 u0 u5 v    set my-column -1
. ~0 U+ m; A/ e3 |9 i    set my-phase -1
8 F% k4 s9 N0 z" I    set pcolor brown + 3
& W! O2 a$ v# }4 Y% i8 a  ]
3 e8 H# n# x$ v
4 F4 h7 ?7 Z6 \2 _5 r) j+ Q" R; a  ;; initialize the global variables that hold patch agentsets
; K, X2 l* Z, y! w% J! ?$ i8 O  set roads patches with2 W' I. t) N- `2 b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( j9 G- g$ I. ]! B3 y  y7 `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 C1 A: l5 O' T+ O. P5 u' @  set intersections roads with" _- A' B# V( w9 |4 j  x. l& {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; Q& J% D5 P: j( {" p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% P1 A) y3 l% F, C: ?6 @
3 `7 }9 Y% {! i8 P  ask roads [ set pcolor white ]' @% q9 b+ {% e
    setup-intersections" T0 R4 {6 Y  i  `! Q7 u& T9 z
end
4 ?% Q% r  v8 Z4 k' f其中定义道路的句子,如下所示,是什么意思啊?
3 m& Q6 `- \5 V6 }" H set roads patches with
. W) x6 c- V( \4 x0 u    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 y) T" l0 s; T3 \- T. P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" m: W6 V9 F6 {/ ]0 M
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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