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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 U1 @% |2 Q. u5 |
netlogo自带的social science--traffic grid这一例子当中,
; A2 ?" i+ i6 {5 I* dglobals3 @7 A* P2 m! M
[% G- Q# _: C2 K: j1 Y9 `; m
  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ P* R7 X5 L" Y4 a2 k
  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 [5 V' D! a, t6 v" N
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' C8 W0 H6 s# I' ~  d& V% z; O                           ;; it is to accelerate or decelerate, s9 r5 |( [/ Q" F0 d" H
  phase                    ;; keeps track of the phase; |2 S0 n, B8 T  P% p# U
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 u3 h6 b' R! I/ h$ X% r8 k1 m
  current-light            ;; the currently selected light5 n2 y- G  Z- @( }9 q
/ H! U- N9 M+ R3 s$ f6 F! _8 x4 }
  ;; patch agentsets; `" [. `( Z+ h. |1 M+ @' P& _$ U
  intersections ;; agentset containing the patches that are intersections( U2 V) m4 n9 H
  roads         ;; agentset containing the patches that are roads; a# B4 ]. l$ ]9 J
]
) u$ v2 x% G3 K" E+ G9 D: R' V" a8 w% S; d6 y! S! V
turtles-own
1 s3 c% [+ z5 R' |. _  x+ M) P[, S( M- w2 M+ F8 _0 u
  speed     ;; the speed of the turtle
/ o+ e# b, r* N* ~, t# N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 Z  E) Y; |" K$ [1 G  wait-time ;; the amount of time since the last time a turtle has moved/ q' ]" x4 |3 m' \( A- m
]
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patches-own0 R2 y+ T0 r. r( n9 O
[/ p* a( k  e8 @: f/ T
  intersection?   ;; true if the patch is at the intersection of two roads
: s; }6 L6 P; k  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ Z$ P) i* D  O9 d3 f2 S* C3 w! n2 [
                  ;; false for a non-intersection patches./ x+ h, B' ?4 S0 I
  my-row          ;; the row of the intersection counting from the upper left corner of the
3 R) w; I/ F' Y) Z                  ;; world.  -1 for non-intersection patches.; U0 f8 Y4 H7 F" E
  my-column       ;; the column of the intersection counting from the upper left corner of the3 l3 T; E- ^" G" s
                  ;; world.  -1 for non-intersection patches.3 A, ~2 n& Y. N8 e. V9 m- D
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! L" `% r  s  n3 f* W. V7 z  auto?           ;; whether or not this intersection will switch automatically.
; H$ y) o4 A( M0 ~4 a                  ;; false for non-intersection patches.
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8 p1 X% V! ?7 a0 E2 L7 {
6 A7 R9 h. M+ i2 V+ q" b
;;;;;;;;;;;;;;;;;;;;;;7 e$ {" o# j/ M+ h; P! U
;; Setup Procedures ;;
% v# W2 S& Z5 _6 d5 p;;;;;;;;;;;;;;;;;;;;;;
2 b' r, z% g& p2 \4 D  @) M7 l2 o& o, r3 |
;; Initialize the display by giving the global and patch variables initial values.
- V7 `' t/ w* V  R3 J1 \;; Create num-cars of turtles if there are enough road patches for one turtle to5 O7 H( C2 F! x: ]
;; be created per road patch. Set up the plots.
6 I$ [# X( `7 A+ _# N6 Gto setup: u$ P$ k, J$ T, c
  ca: R! Z4 o1 B# t# C9 ]
  setup-globals
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  ;; First we ask the patches to draw themselves and set up a few variables
4 V# F  w/ h5 R7 y- N: x6 v  setup-patches
; l" \' |" e' T: i) l  make-current one-of intersections+ _& r, t: ^- E9 k
  label-current4 U" x/ v: Y( k" X" Z. f
0 ~# O3 ^. x# T1 X
  set-default-shape turtles "car"
4 A# L4 _# C& y2 G
; Y" b" ~8 H3 o7 T9 r  if (num-cars > count roads)9 A$ [7 @7 C# n0 o( f
  [
8 {5 N# x2 Y7 V    user-message (word "There are too many cars for the amount of "
% O2 m1 a8 e' |% }/ f% t8 z5 x4 V                       "road.  Either increase the amount of roads "
% l9 n6 W& l  Z! V3 d' c                       "by increasing the GRID-SIZE-X or "  p* W1 u4 r  Y2 Z# x
                       "GRID-SIZE-Y sliders, or decrease the "' T1 h0 L# t6 F$ z
                       "number of cars by lowering the NUMBER slider.\n"- j3 Q1 \2 n# j& v( Y9 k: _% n
                       "The setup has stopped.")
; F- ]. ]* F) h* T8 ~    stop6 i1 C' G" _& @+ W2 R$ B
  ]
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  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
8 u# `0 \+ Y4 L" c: A' [2 h2 Q% b, q! p  crt num-cars% n9 V7 }0 a1 h- L; L5 T
  [/ H7 o4 g# ?4 [( S
    setup-cars1 S" X. Q3 Y: E6 Q0 Q% b
    set-car-color6 ~1 o6 Y4 j$ f9 \7 V2 U* o
    record-data2 i  ~! a8 k, b- _
  ], ~: n9 H% y: b; Q5 Z- P: Y
# ?% x2 Y# H1 k) i
  ;; give the turtles an initial speed
$ r+ W3 e1 ?; |, `- k  ask turtles [ set-car-speed ]: w6 t" d. `; D, W

5 A7 V; ]$ P: I0 T; y. i( `' R: p1 U  reset-ticks
$ j; p  l4 x4 Iend
, O; S, l1 ~& U& t7 I* F" Y
$ I6 \) G6 {. N6 j1 G;; Initialize the global variables to appropriate values
0 ?& `' e" O& L9 Ato setup-globals
) J( v$ O$ O" S8 V) j% f9 a8 z* @  set current-light nobody ;; just for now, since there are no lights yet
: T0 Q" ~9 F: a; J% s. ^- v% i% o) \  set phase 0
5 S& U, e* d/ q5 ~  set num-cars-stopped 0; p$ m+ ?3 G  w; o" ^: t
  set grid-x-inc world-width / grid-size-x2 b/ ?5 w+ n& Q. o* A! t
  set grid-y-inc world-height / grid-size-y
% f! l9 d% I; z% Y
: k7 j3 a4 Q/ H7 s. ^  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 r8 ?3 t# q# L( i3 n
  set acceleration 0.099
4 R! o! g" m# J* m; Rend
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;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  j6 i" x3 [2 [$ J: u;; and initialize the traffic lights to one setting
  B; s$ i2 _2 z0 T2 W1 k9 h2 f+ [to setup-patches
( A( B. E4 v' j  V2 h  ;; initialize the patch-owned variables and color the patches to a base-color% F6 A3 n6 D5 m2 A8 e
  ask patches
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    set intersection? false
5 x. `8 |7 J: Y7 r% {    set auto? false8 r% |1 [) t: f
    set green-light-up? true8 }" N" E" v) V! Y  T& D1 S
    set my-row -1
- U" x1 I8 m0 F    set my-column -1
% h. \8 G" E5 t" }* S+ K    set my-phase -1. d3 P/ C/ w$ Z+ k8 `5 F. S
    set pcolor brown + 3" z' t3 n7 i6 J! Z) C
  ]1 ?. B+ e' w! n" A1 ?
( R, p) T/ M9 I' g7 n. |
  ;; initialize the global variables that hold patch agentsets
3 {, T0 q9 W' H$ }9 l- @( E  set roads patches with
" \' g& _4 N+ M9 C! x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* D8 W; s4 ]: D* G$ ~( `* g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 s7 x2 o1 L3 P  a( r1 o
  set intersections roads with9 s: n4 U- o3 n6 t! z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 |7 c5 j6 K' y  p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ T9 M  Y3 i6 B! k, c, o8 r
% s4 ^/ ]% ~$ w" @6 G# D# a  ask roads [ set pcolor white ]
: ?4 u" O- K+ _7 c% h4 {    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?
6 [. ]' ^! @( f. A0 s set roads patches with
: z! N8 |$ \7 v2 a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 k* l9 x' B4 r2 u: E6 o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 e6 k$ p7 t. K# n2 y  y) H4 v' 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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