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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 [( a$ X  Q: F" z
netlogo自带的social science--traffic grid这一例子当中,/ d+ _0 ~1 }$ k( v/ l
globals
4 d# u0 J( @6 Z& Y# v[; x7 j; v1 [2 A2 J4 J. d1 w) g
  grid-x-inc               ;; the amount of patches in between two roads in the x direction! s2 y- E7 S! x7 G* b
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 _% m) @$ Z/ x+ S  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
0 A- e" Q- x) b                           ;; it is to accelerate or decelerate
1 l1 Z8 i7 U( U+ p- L( _' t% A! u0 K  phase                    ;; keeps track of the phase
- k7 l( W+ l0 @, E- n  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* J; H) n5 p4 D' h  current-light            ;; the currently selected light
8 A8 X- m; x% n! d: [/ ~% q- ?! F7 f! N- _- d- u
  ;; patch agentsets' \: \3 ]1 Z9 i8 w6 |6 S6 o
  intersections ;; agentset containing the patches that are intersections: P* J. L' N- P0 k
  roads         ;; agentset containing the patches that are roads. V* N2 B5 d7 T& K. \+ b! E
]6 e* j+ j- y: K" G# @
  y# G. |: L, V
turtles-own" A9 n; _1 z) T7 F! Q& k: ^' U
[
2 D% \7 R, M5 Q! o  speed     ;; the speed of the turtle0 v2 ^7 z6 o) }5 g8 N7 C2 q
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 P  w7 U) F0 k4 P  c- F  wait-time ;; the amount of time since the last time a turtle has moved
/ z+ l. |- i# z4 L1 j2 J]
2 }6 {8 ~, b! D8 f2 ]- k& c
$ H" P" b9 q2 J% a% V4 e! bpatches-own
) q) ]7 ?8 m# G* _7 }1 T[: G" r6 b) w/ [. O5 w) x, T
  intersection?   ;; true if the patch is at the intersection of two roads
0 O8 {5 c2 o* W3 t, w7 h0 s9 n: ]/ M  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& m: M3 I7 X9 K! x; r3 z                  ;; false for a non-intersection patches.' R8 P1 }8 I9 P1 P+ s
  my-row          ;; the row of the intersection counting from the upper left corner of the
* R! I1 E# g- q" T                  ;; world.  -1 for non-intersection patches.% s( l3 m6 g& k2 M2 R1 M) e+ j! o
  my-column       ;; the column of the intersection counting from the upper left corner of the
  f2 u- P: c+ Y/ q2 Z3 u9 X                  ;; world.  -1 for non-intersection patches.
# Y& f* Y" O- G, ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ X  O& w9 B; y/ _5 g& {  auto?           ;; whether or not this intersection will switch automatically.
# n- l8 p: p9 G8 ^                  ;; false for non-intersection patches.
2 R0 O3 a! x% A3 l9 S0 X]
7 m& Z" f6 i0 N7 u; e% }' M& w) Z+ D% }, P- T

& A6 H# [1 u3 l  ]+ z;;;;;;;;;;;;;;;;;;;;;;
+ Q/ ?6 ]* t* E3 M$ \3 Z;; Setup Procedures ;;1 R( L3 L/ z" H1 }
;;;;;;;;;;;;;;;;;;;;;;9 w: D5 d4 Y; J0 x- d* Q7 V

9 q( E$ d, A8 w6 ^6 ?( n;; Initialize the display by giving the global and patch variables initial values.& L9 w+ o; s* b4 J
;; Create num-cars of turtles if there are enough road patches for one turtle to( a; I2 d6 u  G9 v& v8 T# r; P
;; be created per road patch. Set up the plots.
  d$ g  ^9 v3 O5 jto setup
& T( u5 Q0 s3 S8 q( j/ L0 t9 q: ?  ca
+ }1 D% m3 h. O  ?: A/ t& W9 Q  setup-globals
3 F, y  S7 O' Y- ?' D3 G. Y
9 K) Y3 C0 x& g  ^5 t2 F7 y  ;; First we ask the patches to draw themselves and set up a few variables& m+ q# T) p# Q; Y8 j
  setup-patches
( ]# P$ \! j4 d; O0 V. y- T) u  make-current one-of intersections4 o2 E3 d( T  B4 {* o
  label-current
. ], v, ^' Q9 ^( c4 ?- c. ?* {+ i3 I
3 q) p' L4 q' i* N; O  set-default-shape turtles "car"
' Z  W( o. E; ~# I$ L' q* L$ K
8 O6 |- ~- h/ ~& O$ e$ H/ |' _  if (num-cars > count roads)
% X/ ]5 S( G+ d  [0 K' x& k* y: k8 {6 k. U. @. m
    user-message (word "There are too many cars for the amount of "
+ C3 x. X; F3 O                       "road.  Either increase the amount of roads "" X$ x, }, ^( g7 c" ?  s
                       "by increasing the GRID-SIZE-X or "- c1 Z$ X  u& y% F* i
                       "GRID-SIZE-Y sliders, or decrease the "" s: S5 Q8 k& W. p: D
                       "number of cars by lowering the NUMBER slider.\n"5 y. K* _5 F1 N) `
                       "The setup has stopped.")
1 N- _; }$ V* L    stop8 [0 {& A: U6 ?9 O+ x' I6 @4 y2 Y
  ]' O( p7 U0 j1 `! U! V5 v

  z$ R1 s7 c+ w( A. c6 ^  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' `( K6 L9 `7 t
  crt num-cars+ u. r% G) w9 A) Z2 G# I) K  R) [& B
  [
2 C& ~+ D  v# l8 a- m& Y    setup-cars
6 l5 |' g% h: F% S: R1 B0 t    set-car-color! _$ ^. Q5 G' z) H% _; x
    record-data$ p3 s# U: [' G- H6 Z2 E: D4 k
  ]1 @6 F( M/ Z4 u2 C6 d
) C  s; Y) V! N* G2 F
  ;; give the turtles an initial speed
; G; I! @# Q% n' j( B" d( m  ask turtles [ set-car-speed ]: i4 n5 p- X2 x" w; I8 J
4 ]/ w+ U; S7 D: e, H6 U. o1 L: o
  reset-ticks; X0 O% ?2 A1 N5 u. p
end5 f9 g. A  W' Q
+ r1 v7 U/ ]3 Y6 J( z  j2 x' j& E  d
;; Initialize the global variables to appropriate values
1 n, K  ^( W4 A% t# p: I& Oto setup-globals$ ?3 k8 S  m# f
  set current-light nobody ;; just for now, since there are no lights yet
" O3 S8 w& I2 ?& g3 Y3 `  set phase 0
  Z# @! D# c7 G5 E# T  O  set num-cars-stopped 0- Z6 w+ T5 I- P
  set grid-x-inc world-width / grid-size-x
% {/ L1 S' s" U' U  set grid-y-inc world-height / grid-size-y0 H0 @) O* W4 q9 X

% ^9 u7 ~; I2 p; _2 }( m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- `% H; m7 ~4 m. Y
  set acceleration 0.099
6 a( E7 ~9 F$ o# Tend/ |/ h, P' c0 }$ `% o  }

( p! L% A' _  Y; G;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 T8 b3 ?  L. _: G& R, \
;; and initialize the traffic lights to one setting
* S: v4 r% Q5 u* R7 T1 E2 ?6 \to setup-patches
/ X  ?  q9 S9 n6 Y  ;; initialize the patch-owned variables and color the patches to a base-color' _. n% P; v& D4 I" q
  ask patches" ?' n9 t' }. H5 \
  [
3 T1 |- z' w1 B  @; J    set intersection? false7 o& p. j1 @8 [7 k
    set auto? false
" }% @. [  I( O+ ^    set green-light-up? true( H# A" ?2 F! u6 `3 E" U
    set my-row -1* J( D2 u! Y/ M3 d# W. ~8 T
    set my-column -1
/ ]/ s/ [7 v2 `: @    set my-phase -1  y, _' v, P! W8 {. w" ~
    set pcolor brown + 3+ B; I1 r  k) K
  ]$ ]# H' s' P$ Z- }- [
9 a6 ~! w* x: f4 t% ^
  ;; initialize the global variables that hold patch agentsets
3 K. _% ^! ^8 g( Q  set roads patches with( d5 F2 Q5 s: y; w+ S( r) f/ k' Q" `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) o$ v3 W$ b/ |4 i4 g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 S( O2 P- p1 w  set intersections roads with% w+ P* M; P. W& o9 ^" U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' d7 x$ v. D- m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# Z2 ]: O% c" p1 ]# u# O$ x9 n) i( h: j" @) s" F
  ask roads [ set pcolor white ]6 P; O0 x( F/ s) ~$ t$ x4 N8 W
    setup-intersections! Y+ G( |4 x3 s4 c" y7 A
end9 x- W3 a" z" _/ ^6 \* b
其中定义道路的句子,如下所示,是什么意思啊?; z! a. d0 e5 n+ u% H. v
set roads patches with! [6 x' {: B: K8 t4 i# V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ f# T, s* G" O* ^, q& M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( p0 [2 A; M  F+ ]/ h! p  M. d
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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