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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。
9 E& ?" \: v* C" A8 p9 G/ Rnetlogo自带的social science--traffic grid这一例子当中,9 G( d# O9 t, p5 E. }5 ?
globals
  n8 Y! K( U. C5 |& T6 T# a[% i( L3 Y5 {+ l9 d
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. `5 l$ Z% G4 v7 {7 y2 q/ w/ Q  grid-y-inc               ;; the amount of patches in between two roads in the y direction
/ L( c) {* m% U7 r8 @: d- M2 D  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( X3 d2 f" y1 b9 I  D
                           ;; it is to accelerate or decelerate
8 w8 r# W- I3 |4 S4 G  phase                    ;; keeps track of the phase
* j- Y; n9 @: A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 J% ^, \& Y9 u, \& J1 B
  current-light            ;; the currently selected light
  u! Q( r% {9 t* l3 H# z4 L0 N
" g! t/ _- I- Y* [  ;; patch agentsets
) ]+ ]( R9 c. h& O+ |  intersections ;; agentset containing the patches that are intersections. N/ x" j  [  {0 ]3 a' o
  roads         ;; agentset containing the patches that are roads4 X% m7 w. d- ?8 W0 M
]: d0 R9 t# u3 T8 r8 }% ?" |8 s

8 |  x1 X! C, X( ]2 j- f+ N: H8 eturtles-own: `# E) l" Q' C
[4 ?5 y! N0 @* B! A3 @) q
  speed     ;; the speed of the turtle- ]7 ]3 X0 R6 G; |" z# N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. O9 ^* q: W. e5 v. ?6 g" a  wait-time ;; the amount of time since the last time a turtle has moved. p; l* T7 i5 j9 x
]2 B. Z+ `" E5 e! |* r0 A

0 ^* Q4 ?' M/ B' L( ipatches-own" O& b$ e, @) K5 p4 C+ @
[! d1 h& Y! Y% F3 V/ }
  intersection?   ;; true if the patch is at the intersection of two roads
9 ~( c+ q( N7 x& I/ v  r& M$ `* n4 w0 e3 r  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' Z; k$ v* O, `- U' y4 k/ M+ B
                  ;; false for a non-intersection patches., h+ P$ g' O, e
  my-row          ;; the row of the intersection counting from the upper left corner of the& @, A& h- w7 g7 r4 C# m
                  ;; world.  -1 for non-intersection patches.
" t% R+ |. n7 t' b7 D$ u5 q  my-column       ;; the column of the intersection counting from the upper left corner of the- n7 D8 _/ E) H( Z( f0 J
                  ;; world.  -1 for non-intersection patches.$ X5 [0 `8 F% r, W5 a! w$ |( U
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 U7 e8 @" Y5 C7 }# ~6 I) |! Z( @  auto?           ;; whether or not this intersection will switch automatically.; t( K2 F7 U9 F/ X" T
                  ;; false for non-intersection patches.# y" ?8 i0 {+ [% P
]& Y% w/ P' i9 T/ Y

1 g3 q# }6 J/ A2 h$ V( I% S3 |
, l% ]% {! h, L6 X5 c& k9 s;;;;;;;;;;;;;;;;;;;;;;
3 Y! p! c5 I: |; t;; Setup Procedures ;;
5 n  O& `" N5 [3 ]: T1 |6 K+ c;;;;;;;;;;;;;;;;;;;;;;1 M" _) T, N# {

0 x9 R" v% t% V& j% r! K;; Initialize the display by giving the global and patch variables initial values.5 _( }% ^: H# W0 a
;; Create num-cars of turtles if there are enough road patches for one turtle to* ~  V4 W. w  {' X5 [
;; be created per road patch. Set up the plots.+ g: Q9 B: ^% ^5 e0 F
to setup
, f1 @  d7 E* K9 J3 p  ca: }) u& [; X/ r
  setup-globals
$ ?+ g3 H# M& W1 P! Z
2 E5 H4 u) ^9 |3 Z: |  ;; First we ask the patches to draw themselves and set up a few variables
2 ?+ `- O. k& s  setup-patches$ }& |; Y! p7 H. d5 {) \
  make-current one-of intersections
% k2 R9 t0 z' J  label-current
3 B7 I; @: U+ h- x* s9 V+ @
, P8 r9 l! t) _, T9 r+ @% B2 T  set-default-shape turtles "car"
/ U5 ]: C0 s" ^' I9 B1 |, Z4 t
  if (num-cars > count roads)( b( {; J7 m/ s* K7 h- W2 M
  [
, Y' r9 P+ [" a& f  d9 I/ }    user-message (word "There are too many cars for the amount of "( J5 H3 f: L( \. P/ d+ D
                       "road.  Either increase the amount of roads "2 P- q; \% F- T; t# h6 D0 T" ?
                       "by increasing the GRID-SIZE-X or "3 [' S5 C2 g5 a  p9 j
                       "GRID-SIZE-Y sliders, or decrease the ". N& W/ U. g' D/ H/ i  X
                       "number of cars by lowering the NUMBER slider.\n"3 n$ L& C8 a/ d/ ]& \: O3 h0 I% m
                       "The setup has stopped.")1 z9 e8 E' p, `' T2 B
    stop$ @: `. t* o) p. T/ A
  ]
7 M. j& J0 B) N5 I7 O5 k/ F" f2 w' J" {" g: E( Z+ \
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
4 `  t1 p" G, T8 p7 D3 {  crt num-cars% ?" Z7 G- m% J
  [
& u0 [. U% d1 a* b- ~    setup-cars2 o* l& L; d& Q1 M* J
    set-car-color, _2 }$ @4 P$ X2 r' m* E5 f/ a$ N
    record-data
1 y/ W3 D2 Z  d  ]
! _+ k& W- V9 G! t: z' _9 n. j+ T) a( T
  ;; give the turtles an initial speed, R' p1 P; u# C0 q: E: ?) I9 \
  ask turtles [ set-car-speed ]1 n$ V  Y, c! O6 }: L
4 A9 U9 S+ X# |' n8 g9 @& w
  reset-ticks# |, e" s/ h# {* M9 q
end0 W6 t0 n' W# |* t7 R

9 ]4 f( e9 v4 ~2 @& G7 {;; Initialize the global variables to appropriate values7 B, R) w4 l% f( g. X4 U9 a! X- O
to setup-globals0 o1 o. I$ Z! R. J4 H. G8 q' f
  set current-light nobody ;; just for now, since there are no lights yet
' {& V7 M! k1 ]  set phase 0; c7 z0 P+ P5 v* J
  set num-cars-stopped 02 [! @, B' b! {; X5 }2 }
  set grid-x-inc world-width / grid-size-x* S+ ^$ y) i* [- G8 g7 Z
  set grid-y-inc world-height / grid-size-y
4 f* L: Y! h& Y& C+ K
4 k* K8 @* Y/ V' ^  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 t) e5 p: z: M) Z* {6 }, U  set acceleration 0.099
! N1 j6 k* F  yend
& l: N& O& n2 k7 v
. [+ a( f3 Y( U. b! k;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. @9 M, {2 @1 F# ~9 U+ x2 C. w/ K2 O/ W
;; and initialize the traffic lights to one setting: y9 E, a: M: n1 j
to setup-patches
$ u8 S; v1 B' B0 q- @: A  ;; initialize the patch-owned variables and color the patches to a base-color' }+ Y9 o/ T# l  @% l6 f
  ask patches
* ?* {8 W$ b% B2 C% t+ |6 z  [
; R+ }; Z0 `2 M, j$ M% j* o    set intersection? false. A8 [* G, j# o8 B/ Q* _: K
    set auto? false" H, V* ]( D& x6 Q
    set green-light-up? true5 w! p$ Z# t, X6 L$ l
    set my-row -1
# q: d3 z; I3 L    set my-column -1$ J! L2 O2 r: |7 q3 P9 b* }# T
    set my-phase -1+ l8 o2 i# b& i8 @3 V- x* w6 @
    set pcolor brown + 33 W% `1 n" w9 B+ U( g/ G5 j( N& j
  ]' D; i4 G. ~2 F
9 i9 h$ c& X6 g
  ;; initialize the global variables that hold patch agentsets8 @" M: \' k' Z, j8 l4 h* e
  set roads patches with+ a% ], P- V3 q  i7 k8 v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 Q+ K* b2 |6 {6 Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 I' x" z2 B2 {; O  set intersections roads with$ G+ l3 e" t7 W* j+ r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 }- w, Z: l( I; c0 F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: \  Y9 R' c* v9 W3 p7 y
9 j# o; x& D7 S, p$ X- o3 m6 t: z
  ask roads [ set pcolor white ]/ y* q2 c! V2 r( G+ j
    setup-intersections
. Z- I7 S0 V, r) z4 l6 ~( n0 G* Hend
2 A' Z' \6 O9 x) R8 b; ~  |其中定义道路的句子,如下所示,是什么意思啊?
' z3 L$ S- D8 [% U0 b! Q set roads patches with, U5 @6 @3 A7 @3 H9 P6 n  I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% }& D+ L7 m6 b! v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 _6 i- r9 n- m) Q/ U7 W9 B$ T
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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