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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。# b3 M8 M" t9 b' U9 e
netlogo自带的social science--traffic grid这一例子当中,
0 P9 Z# I) D) z; C1 `% Lglobals
; x  U, Z9 u! z8 ]( R8 h[
+ w& h& ^4 ?6 o) E( W# e$ n  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 C5 A2 ~3 ]2 k* g2 U$ f7 E6 {  grid-y-inc               ;; the amount of patches in between two roads in the y direction
- _* N& J- z: [* q+ y: u, ~  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% ?" U, T/ @& m                           ;; it is to accelerate or decelerate
$ ^0 b* ?) V( Z! M: {3 ~5 y  phase                    ;; keeps track of the phase
" o/ q* T4 Q- ?6 w5 g  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- ^2 Z3 k4 j& X# `2 n
  current-light            ;; the currently selected light6 N/ f/ s' R% `+ k- i4 M

# f6 L6 m: t8 K% y9 N" ^. }1 s  ;; patch agentsets
2 g) s! @/ B* Y( R' z  intersections ;; agentset containing the patches that are intersections- c- q- S4 E9 w+ |: Z
  roads         ;; agentset containing the patches that are roads
) f+ o8 S) Y6 l2 X  t* g. q]1 W+ o3 u0 i4 b8 w' P

' Z' J: [5 X: N. a) V5 }, gturtles-own
1 P6 g, Q0 B" ~; O# a& G' H[/ u7 P; Q1 |( Q5 @
  speed     ;; the speed of the turtle
" r1 `. ]9 R2 O- Z, u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 ]2 A# _/ v! B: p8 Z. l7 \* _  wait-time ;; the amount of time since the last time a turtle has moved6 B, P  @& x! m6 E9 M) p( X0 }
]6 ^  Q$ y0 o+ e' W
- J! o* v. ^3 V! a$ n& E1 n
patches-own- d9 D6 C% ~6 F: n8 R# [0 o
[# ~2 B3 S( V* k+ l! u5 Z0 y
  intersection?   ;; true if the patch is at the intersection of two roads& p7 f! s4 y# r6 o% g) C
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; @3 J* u& `* J! d0 n& S( e( X
                  ;; false for a non-intersection patches.5 Q0 |% M8 ]% V0 a+ \3 @. Q$ ?& Z
  my-row          ;; the row of the intersection counting from the upper left corner of the
) |) Q4 o7 o3 d- C- E& D                  ;; world.  -1 for non-intersection patches./ b4 E  N' _9 A# M  K) U
  my-column       ;; the column of the intersection counting from the upper left corner of the& F: l- X/ w# Q2 l
                  ;; world.  -1 for non-intersection patches.
. E9 r* L: Y- w  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
. A! ?; T0 A& N; O0 e4 Y  auto?           ;; whether or not this intersection will switch automatically.
- Z/ f# Z  `# m) q' M6 B                  ;; false for non-intersection patches.
, k  n2 K1 m) p. i" M  Q]
  q) S- [$ u: U. F# i- R5 o( @4 R/ b9 J# h$ P# w, C
  f# b/ f: S5 q2 o1 l9 B
;;;;;;;;;;;;;;;;;;;;;;8 }. Q8 f$ ^, m. g
;; Setup Procedures ;;7 z7 F6 x# ?8 p8 p) @
;;;;;;;;;;;;;;;;;;;;;;
* V6 L7 i, S0 {5 B$ F8 `
5 V% R% o! u7 l: V* G;; Initialize the display by giving the global and patch variables initial values.
# v$ o: m. M7 o7 k;; Create num-cars of turtles if there are enough road patches for one turtle to
8 z$ i) c3 O( V0 @: C5 V3 B;; be created per road patch. Set up the plots.
5 s5 {9 V# N! Q, {* H/ x2 _" b6 Jto setup- T: l% x4 ]; o5 D7 ]1 `- N
  ca
9 o3 \2 S6 w2 B. Z: x  setup-globals
& o6 P% F, w; ~$ q7 u% t* P" l: P7 Z0 J6 @: |
  ;; First we ask the patches to draw themselves and set up a few variables* q/ i4 C) e% \9 V; `* E/ {' R
  setup-patches4 Q+ ^$ F7 }- B: M# Q
  make-current one-of intersections
1 v7 e  f& s. T$ }  label-current
; N6 H* Q% k7 e, w9 Z) S( z4 @
$ }+ a6 k! A; |; X  set-default-shape turtles "car"# V) `3 |. g7 i: B( u
2 L/ y( T& W2 ]' r6 j' A
  if (num-cars > count roads)
! ^! i6 C5 g( L% \* G* Z+ p) i7 V  [, d$ n  F7 }" ^+ `7 A
    user-message (word "There are too many cars for the amount of "5 B) C% F* l' [6 |: ]7 {
                       "road.  Either increase the amount of roads "4 R( C( @9 _$ \" c3 `9 A1 L( d
                       "by increasing the GRID-SIZE-X or "
+ F* C/ u8 D5 {                       "GRID-SIZE-Y sliders, or decrease the "3 ]" [" L3 q* F- v  F' G; q
                       "number of cars by lowering the NUMBER slider.\n"
; Z+ T6 U3 c  {8 @5 w* @' P                       "The setup has stopped.")- _# _+ D$ k/ r
    stop
1 `, m! N, m) ?. N( c  ]4 A* L8 U6 R6 I1 B4 {  _

) [; S: t  T. C' Y$ ^- o, R  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' n. h4 R! h. v5 m# B: K/ l& I  crt num-cars
* ]; s# N, ?; Y9 ?' K/ A+ Q# ^  [
& L: l" m; \( T$ K) h- T% v    setup-cars* _8 `! U7 P+ y/ U5 o
    set-car-color
$ Z: p. \% s* O5 r+ ]    record-data- F& Y/ r/ b* O6 P. R# P6 w
  ]( I, d/ x1 _/ j

1 X+ m/ R- F3 A3 x( [- g1 b3 x  ;; give the turtles an initial speed0 s" v! P' J1 w
  ask turtles [ set-car-speed ]- g4 M1 r' R/ l0 C0 N2 C: D
+ i  A) b; J: _3 c* y
  reset-ticks& D; Q) g+ D8 S8 J8 ]" ~
end( m, @; X: W: n# U- g" Z
- u: _$ [8 j( h4 c3 _3 H
;; Initialize the global variables to appropriate values
( q( U" Z( a- b4 H# e$ oto setup-globals
9 I" U* N$ M" k% t3 J$ D: h: _  set current-light nobody ;; just for now, since there are no lights yet
% H, |" P- ~. U* p4 b3 h  set phase 0
) K: o' L6 [& X7 R  S0 B' P  set num-cars-stopped 0' q$ u. S" r" L# z
  set grid-x-inc world-width / grid-size-x
: Q! }4 l/ U* d+ H. t. ?2 E4 ]  set grid-y-inc world-height / grid-size-y/ T9 n: m' t3 [" k* J9 z
$ J+ H7 p6 t0 c/ S: W2 X2 q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 V& v0 K% Z; T" f/ f
  set acceleration 0.099
% a6 m0 V, L6 h8 h" |end
4 W4 S% e  J: E$ v2 u' ^$ m
' X5 x3 i: j. ~/ }3 q; r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 j0 b% K$ q7 B# s7 b0 W" J# ~;; and initialize the traffic lights to one setting; E% w7 ?/ }5 f0 \& t- K
to setup-patches$ Y2 a- P' w3 f( D# R
  ;; initialize the patch-owned variables and color the patches to a base-color
  b- V' b  c$ l7 M  ask patches" r0 ?. m/ {) c7 M  L
  [
7 E# d6 s. f5 u& p4 o( A    set intersection? false+ }2 {0 K  t# C2 p5 z; @
    set auto? false
# X' P: ?2 D, w) e& f! n5 ]' l* e* n    set green-light-up? true
8 s0 a" Q: |" z    set my-row -1$ j0 p% I2 V) |0 Y- Q6 w( A
    set my-column -19 h+ H9 c6 d2 [6 H- W! D# i% P
    set my-phase -15 A; z6 J! G2 ]" }  @
    set pcolor brown + 31 q! b; i& F5 p
  ]$ A' p* h9 D/ k- n
3 x7 k3 z& W( E7 ]# Y. G1 R/ p2 V
  ;; initialize the global variables that hold patch agentsets  O, b: I7 U6 H& f2 K3 p
  set roads patches with- N( _/ m1 |8 [' l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. k- p: \, A2 ~# ]* S# S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( n* e5 I- x  i6 T  set intersections roads with
7 v4 U: S; s% ~3 h( W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ v" d' P% V2 E7 s6 l0 V! l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- B* v; c6 T' H
3 J8 _  R* k6 b/ F/ A5 K
  ask roads [ set pcolor white ]9 Z/ h) C0 {) Q4 @, ]6 [8 h* V1 i
    setup-intersections9 ^* g! n. X9 f8 L& p: u5 @8 f
end' z: s0 M9 n& R; W3 N
其中定义道路的句子,如下所示,是什么意思啊?
$ Z8 a6 B/ s6 d; V' ? set roads patches with
& j1 x4 r5 O$ |; u8 M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, ^6 V7 w) w- N" m- O6 a( z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: ~1 B5 L/ B8 Q, d$ o
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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