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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。$ [, C9 q# D2 a  W- P, o. r/ C
netlogo自带的social science--traffic grid这一例子当中,  c8 ?- c, f& ~3 s
globals
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2 I6 s$ l* ~0 b/ |: }  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 G" W$ |4 x6 r0 c/ z  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ s% X* A! C0 k- _( }$ g
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 k! p5 b$ h" N- Q: f/ H/ I                           ;; it is to accelerate or decelerate
- T1 T* A. z( K0 u  phase                    ;; keeps track of the phase/ t( {  V- U1 h2 W9 s) y( y$ B
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 }" J5 ^) A1 ]3 v6 M8 I9 J7 {  current-light            ;; the currently selected light
- `- z' V# f5 u1 ^5 N8 I+ L9 a. v5 R: \- m: s" j# }
  ;; patch agentsets
0 i% l# H# r' q1 N) g  intersections ;; agentset containing the patches that are intersections
  I) P& c5 K7 W  K' J2 ~( X  roads         ;; agentset containing the patches that are roads9 l- X1 |; @6 w) ?7 R5 a
]% X6 t( d; f1 b  `: C  Z2 E; R
& n0 M, u! D4 o4 X% Q% ?) Z
turtles-own  s* `" ]/ J9 [% ]
[- Y5 x* G- ^+ P0 m0 ]8 H, q; ?+ _
  speed     ;; the speed of the turtle
6 A8 d0 Q3 @% w. J6 C3 a- A  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" Y4 }, [9 C, ~' R2 d* ^, K
  wait-time ;; the amount of time since the last time a turtle has moved9 g8 f% ^' X  E
]
- X3 z" L+ u$ {$ d# i4 Y" F$ M( v; w8 ]5 x% x
patches-own
1 ?* G- o# D8 f# N/ m/ L[, n9 E0 V% t7 |. I  n& R1 m- L
  intersection?   ;; true if the patch is at the intersection of two roads. M+ p- _* V+ a% r- H8 e
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' Z1 a  Q2 c2 O1 G( Q, ^( k2 }                  ;; false for a non-intersection patches.
2 Z2 O! w2 O/ x  my-row          ;; the row of the intersection counting from the upper left corner of the
$ Z8 G+ x1 z. Q/ \                  ;; world.  -1 for non-intersection patches.
! B6 o" J4 G; E( g% P1 _( p2 ^  my-column       ;; the column of the intersection counting from the upper left corner of the# V; I) q; Y6 w- }& k* s
                  ;; world.  -1 for non-intersection patches.# d% M# }0 M! l$ U' i4 `5 c
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
0 K# @& x7 ^- ]6 _  auto?           ;; whether or not this intersection will switch automatically.
. o8 D7 f# g. s% f5 J                  ;; false for non-intersection patches.
/ L: ^6 t4 p0 S% g! Z]
  o$ c; j, b$ h- x, _8 V0 ]% K7 s9 a4 B$ S2 j$ F
) _6 P5 H: J4 Q  N. X7 ?
;;;;;;;;;;;;;;;;;;;;;;
+ _3 A" n! ?5 g, x/ U;; Setup Procedures ;;6 i( P& E7 g9 m% T$ C2 x( z
;;;;;;;;;;;;;;;;;;;;;;
+ ]7 t2 r" K1 N8 ?+ o
2 r" ?4 m0 u8 ^3 l* l;; Initialize the display by giving the global and patch variables initial values.. r9 S& _$ Q" Q3 H5 O: }$ T
;; Create num-cars of turtles if there are enough road patches for one turtle to7 X: W, o6 O1 f! Z" Z+ P* G
;; be created per road patch. Set up the plots.: U4 N( k. W2 i/ c
to setup
1 `" S  n/ Y- {" @3 d% H# N5 g  ca0 `, l( C3 G' z* d
  setup-globals* Z) i! Y  N( E: C" Q5 W& Y

0 T' l- }- Q+ w3 k9 M( V3 t  ;; First we ask the patches to draw themselves and set up a few variables+ k- c' ~9 D2 s. {& G4 }; i$ j
  setup-patches
* V+ d& V# Q; @. [3 P  make-current one-of intersections4 Q$ u; d7 x3 l4 C
  label-current
% {& ~/ H( @- i: L( u" O
/ _3 |; C' \+ c+ D) h% d/ @  set-default-shape turtles "car"
7 N9 v; v5 y: |: o* D* t' N5 c3 K! `& \4 v9 f- S7 v! d& a
  if (num-cars > count roads)/ n1 i. m6 h7 S. Y
  [
7 t/ ~! u( o0 j' R    user-message (word "There are too many cars for the amount of ": H. E, V# c! D
                       "road.  Either increase the amount of roads "% k, W4 h: W4 i8 l. e
                       "by increasing the GRID-SIZE-X or "
* _+ r* }  y0 N% w! G1 L3 b  W" I( W8 @                       "GRID-SIZE-Y sliders, or decrease the "
) P, C) d- l+ D1 J                       "number of cars by lowering the NUMBER slider.\n"
4 t  r  j& p  A/ i' K) A0 ^                       "The setup has stopped.")- v" n7 h1 a' n* e/ M6 v
    stop
" d+ l% `5 U1 e& A! g9 e! b  ]' F' L* U, f7 D' ]; B

" Z* k$ }7 c5 v- s5 S0 S) @  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: V; f6 h, {5 a% i
  crt num-cars3 H( j4 B. T  K7 E2 F
  [
  ^$ P0 [% S3 R; L    setup-cars$ w$ h" C" ?& ]' D# M, a: w) O
    set-car-color
1 Q4 i- o9 P# o% X7 T) s    record-data# w, X- Z: }  M  A4 u6 W
  ]. W! ?7 [' B% m) H2 D) n" v  S
3 }9 Q8 {6 d7 m' P4 E
  ;; give the turtles an initial speed4 M- K9 \; w2 w
  ask turtles [ set-car-speed ]
  H2 d4 j! G0 K* u/ D& W" Y) W: q7 V# z* L
  reset-ticks5 V4 F; j7 k! ]4 [; z
end
) c, y5 j1 P. u" Q$ d. Q
1 g& r0 O5 \$ x;; Initialize the global variables to appropriate values8 x7 {0 r7 r9 ^& V
to setup-globals  I- n5 z; S$ x8 ?' w
  set current-light nobody ;; just for now, since there are no lights yet
4 B% Y! @4 C- v0 N/ H& A- W  set phase 00 Y3 V: J/ G2 Z& d9 f( A4 V/ o$ ]- M
  set num-cars-stopped 0
2 _9 Q# u3 j* O2 ~  set grid-x-inc world-width / grid-size-x
5 W3 @' Y5 u- P8 y  set grid-y-inc world-height / grid-size-y
/ A0 x" W( O% K4 P2 i
% j) q4 n1 e1 W) u  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( S9 F  f. X+ n0 e' ~
  set acceleration 0.099# [% Z% K. ]) x9 V9 k& G3 `
end
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, |% H7 P2 A$ w- A* J;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 t( U+ d5 }- x% l# r3 _
;; and initialize the traffic lights to one setting" x  X+ M  j6 K! Y
to setup-patches% P7 N! i  H( D# m
  ;; initialize the patch-owned variables and color the patches to a base-color
$ Q8 m7 U# H- e3 G  ask patches, H% o5 X) j0 c
  [
: s- L9 b- f' u% S5 n0 t    set intersection? false
* ]+ U4 |6 g- B! N& x  ?" P& r9 ~' r    set auto? false! u$ h. R( F4 v; q# B9 o( ^
    set green-light-up? true0 z, d  h+ ~- ?& F
    set my-row -1
  M% ^0 E$ D- c; ^; K    set my-column -1& I/ Y$ U: B4 _% g% ]0 {
    set my-phase -1
1 O7 U3 T& f. Y* N    set pcolor brown + 3. a/ b' S1 @5 x$ @# `. q9 X! @/ x8 p
  ]( y+ t- \7 B2 k

/ m: y  V% ^0 E$ k  ;; initialize the global variables that hold patch agentsets
1 p" S: F8 Q  |! r( u, s" T- r& d  set roads patches with, \7 P( m: H* G0 A6 B* S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& X+ m' w1 S, w( s# f! |! C9 `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- i+ y$ K: a0 h. |+ L
  set intersections roads with7 P0 E1 f6 u& y$ }6 `: h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and# C# ^) c. X' ~( T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' v3 s( I" q5 r+ m8 h5 b3 _  A3 Q; p% o7 x$ @5 N0 M/ v0 e/ t
  ask roads [ set pcolor white ]
) g& a* X" Q3 E, {, `3 g9 W; J! |    setup-intersections
+ p3 x8 S9 @- v' K! send; h1 G, l8 W1 H. K8 G
其中定义道路的句子,如下所示,是什么意思啊?) j4 r; ]5 K! Z
set roads patches with
, B2 F0 P% E$ I; l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; U7 M# U& W; i# O4 L! p' ^; Z- |3 K2 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' E( i. X4 i% {+ e/ G* C1 ]
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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