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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。
( D& G0 k, Y% {/ S$ N! c6 d! G1 d, Qnetlogo自带的social science--traffic grid这一例子当中,( j7 M; _7 ~; z$ n1 g$ h% r6 ?/ @
globals
% O2 D; F1 k0 b2 N+ m4 P[, Q2 F: q/ Z* W: X, e6 i4 [
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
( W7 V0 v# e+ t* F  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 v6 ]/ d* e# F7 D! l  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  }0 [0 \  F+ o9 F. p" s3 g! K/ Z
                           ;; it is to accelerate or decelerate
4 W% S  c* o9 v7 u4 q0 S  phase                    ;; keeps track of the phase- ~& R4 g0 k3 ]- h% }: h
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, h6 ]3 y9 j6 A% A* T, w; A) `; O$ C
  current-light            ;; the currently selected light
+ @2 P% P& p2 a' H' G1 E( C5 Q) k7 x) ~* `& ~% h
  ;; patch agentsets
% R; n3 Z9 c2 D$ [! ^  intersections ;; agentset containing the patches that are intersections0 z! m: X$ Y- R% W( F/ E. ~) \: c
  roads         ;; agentset containing the patches that are roads
' ?% a3 B. P" D( B, {8 j* []3 P- Z& n% |* ~' I. [7 l* E; @# ^7 L
( a) T: p8 B* n8 z
turtles-own
' K, ]" X1 m( ^5 e& Q9 l[
. q4 b9 n8 s3 z: @. N  speed     ;; the speed of the turtle, V3 O2 u' b2 ~! A% N% y# t
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- J" n* I  o/ I( \  {% s3 Z- ~
  wait-time ;; the amount of time since the last time a turtle has moved
; f. h, H# S; l) o) q: @]
6 {9 N2 Q: ]$ @, M' t8 k" w% I' `: b2 r; h2 Y! E
patches-own# Q7 n2 j/ `% F# j) G. Z: _7 x
[
4 g3 T) K, b% j: s1 r  intersection?   ;; true if the patch is at the intersection of two roads% m% X: B& `5 v) ~/ }
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 j3 y" k1 L! G& G8 {5 g9 a                  ;; false for a non-intersection patches.
% l8 w% l- N! U; V  a1 J  my-row          ;; the row of the intersection counting from the upper left corner of the& w, L9 i: y- f' x' G8 n
                  ;; world.  -1 for non-intersection patches.
0 @6 R7 A+ x: j7 n) `$ |8 S  my-column       ;; the column of the intersection counting from the upper left corner of the
. `0 {; r" {* P3 J* h                  ;; world.  -1 for non-intersection patches.
1 v. q1 D; }4 E$ }- _* K  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; \' }/ R9 q6 U  auto?           ;; whether or not this intersection will switch automatically.* z/ t9 ~- S$ P# w: b6 L
                  ;; false for non-intersection patches.
: X4 J/ p8 Q  E* L9 O0 I. A]
2 ]7 m6 O- [7 S! g& _  G; {
. u! z% ?9 V7 P0 p( m3 B4 K, @$ C
. ]- H: ~% W+ A! i;;;;;;;;;;;;;;;;;;;;;;
) P( _+ [) M) A. q;; Setup Procedures ;;7 q/ h+ @4 S* g/ e4 I/ C: `
;;;;;;;;;;;;;;;;;;;;;;# O( A' n3 t9 j' N0 U$ W

' v& C  P# w0 u4 {& L! _;; Initialize the display by giving the global and patch variables initial values.
) x6 f1 D% d& }- T) G;; Create num-cars of turtles if there are enough road patches for one turtle to
5 G8 c3 r% F7 g1 h9 D( b;; be created per road patch. Set up the plots.
1 R( I% S3 ~: [/ R6 Kto setup
; g+ F+ K. C+ V& B5 \  ca
0 f( ^, k) f7 o  setup-globals, W9 n' o- c7 C# Q: h4 v3 o* F
: d* t8 ]; N. K' K
  ;; First we ask the patches to draw themselves and set up a few variables( T: o4 }& ^2 ]4 ]
  setup-patches
' z! \9 R7 R% h  ^- ?  make-current one-of intersections; s; v8 m: U+ }; P
  label-current
- t7 _( m3 }" A/ ~1 `
* f' e8 h% E1 w" I* V) a  set-default-shape turtles "car"' o' O* V2 `% ~* m

, \, W5 `5 V8 R3 G3 J+ }% G/ ?( _  if (num-cars > count roads)
/ J0 g/ b4 g" U' a! l; u  [
* d! M/ n, O. Z) H" j0 A    user-message (word "There are too many cars for the amount of "* F9 v7 f; C& _, F- Y8 U0 e( A
                       "road.  Either increase the amount of roads "6 W3 f9 P5 N1 i! ~3 f+ w. u
                       "by increasing the GRID-SIZE-X or "# {9 z  c) M1 W' f% n  H( q' J. b; O
                       "GRID-SIZE-Y sliders, or decrease the "7 s* E! @5 H0 ~
                       "number of cars by lowering the NUMBER slider.\n"* w5 j2 T$ z; z+ c
                       "The setup has stopped.")- _' j5 S. t& _. @6 Q. B
    stop' D+ e9 V/ ^1 e2 M0 _- j
  ]
2 k% Q: n& x/ K% n
' k5 L6 b' A) e7 L/ [; D( R  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 {& o& Z# q, J! v9 j7 X  crt num-cars" t( [  m. P( U& S& i9 y
  [
: i% X' F$ f8 M. O# a    setup-cars3 w) x! q8 t5 E  Z
    set-car-color% w, e( M5 X( ]1 v4 g: O( ?- n; q
    record-data
& W4 M4 r4 r% f( S# R  ]9 W- ^% t* F4 Z$ n

. m; n; Y( t3 p8 @' ^+ `  ;; give the turtles an initial speed
8 w1 B3 \/ b- h; P  ask turtles [ set-car-speed ]
0 |) x$ L" K5 \$ f6 @+ {/ D8 a4 E# y5 y
  reset-ticks
8 G" ?5 S! Y8 {/ j8 G& T, @* b3 tend  A5 Q+ E1 R4 ]+ H+ L

8 ]- ], f& I5 e7 f* u% s  U$ S' B;; Initialize the global variables to appropriate values
9 q( X( ~+ H8 j/ E7 {2 E0 Oto setup-globals
6 ^0 g6 Z5 k0 H( g, I  set current-light nobody ;; just for now, since there are no lights yet
* {' o3 p) i$ j. M  set phase 0
" X6 h1 s3 F$ A1 x  set num-cars-stopped 0
6 a( M- E: K/ N2 u  set grid-x-inc world-width / grid-size-x
) J0 w1 ]2 L2 A  set grid-y-inc world-height / grid-size-y! f* s: W5 z! K0 J% R* P3 t9 p

2 w. q# @; n( Y3 i/ Z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- ~& ]3 s- ]. x$ F
  set acceleration 0.099
, x$ P) v9 W4 uend
) R0 V+ g, a# [9 G4 T+ X( _
" `7 s6 h, }& u& m" W;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 U; @* N& R" }( l;; and initialize the traffic lights to one setting
' _9 F' K% p6 }9 z; hto setup-patches' O, G( K- @) _: [! M/ M! n
  ;; initialize the patch-owned variables and color the patches to a base-color
, c& T9 d( ?; |) o4 }6 @  ask patches
4 H7 R/ K; v# Y  [
) K6 G7 V" |# U" e1 e3 V( _    set intersection? false
* W9 x0 ~  k( Z( E2 q    set auto? false( U1 ]# ~. [$ \
    set green-light-up? true
8 J7 C7 F4 s! {9 i0 ^    set my-row -1
' B7 h$ v) M2 \4 b0 @# P$ B    set my-column -1
& r" I" A9 J. h9 t    set my-phase -1
1 M: S. h( e  k' c) N- w' x6 s    set pcolor brown + 3
5 R& y7 O! \9 Q: m  ], F) @) ?( r2 t1 L6 _) G% z! L

9 i3 j$ Y7 j: ]2 O2 x$ R+ o8 H; V  ;; initialize the global variables that hold patch agentsets, \9 o. e3 K7 D, h) g
  set roads patches with
! ^; V0 Z. W2 A7 q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. B) G& y+ \/ n' S! |' e% Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 x/ J0 r/ i9 o6 {6 f8 ]( I5 U  set intersections roads with; n2 h) J* }! L! P0 X& _7 e# Q' ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" x+ ]2 s: u% c) L0 h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 T5 c/ g+ F" S( l6 a/ o
( P  ?1 \# {! z$ ?  ask roads [ set pcolor white ]' F3 X" U7 O; }/ A
    setup-intersections
* s8 `- x: V1 W- Dend
/ n( U' Q4 \, l' G  m其中定义道路的句子,如下所示,是什么意思啊?
+ E: S- X6 U( J, s; H1 _1 ]: D set roads patches with
8 H# g  B$ {7 u7 t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 J8 ]% h5 j2 W  l, s  o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 `( V; c9 h' ~- w, K" R
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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