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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。
# i+ ?, |! i- ~% wnetlogo自带的social science--traffic grid这一例子当中,
$ O% _# T4 w: x- E7 U4 g$ mglobals
' V. u. C9 k, G/ S# l0 V) \0 |1 L1 V[# ?, v9 u, p* @. e# N4 F3 [* @2 E
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# U3 K! z5 X, H8 w& t3 W6 t
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* _/ I; h! M2 C) q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( D+ C; C; o5 x! e4 u9 [/ O, {1 l                           ;; it is to accelerate or decelerate, t& i  H" d' p6 X& D
  phase                    ;; keeps track of the phase4 q2 P% O! N; `5 k- V
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' _+ H8 }; E+ m! B. a/ `
  current-light            ;; the currently selected light
+ h* h8 z7 H: Z+ E6 Y& ~6 `0 K) }$ f- r7 k/ l  j
  ;; patch agentsets
3 [4 O+ [+ H/ U  n- _# U  u  O  intersections ;; agentset containing the patches that are intersections
2 T: e  k. |8 E2 r  i2 t3 E+ n  roads         ;; agentset containing the patches that are roads* l4 ]) a$ R' k/ P' |! X; Q
]
1 h9 ?) T! m, f. v! T/ H4 s
6 ~- z" C( _2 e. H; E3 ~$ b! G+ ]2 y- Rturtles-own% I7 D8 q# C* m  G" o+ R
[
* c' ^& t& a/ ^  J0 D  speed     ;; the speed of the turtle
1 S" ^5 l5 z$ V8 I9 F. q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 l- Q8 `- [- L* V. ^" L  wait-time ;; the amount of time since the last time a turtle has moved: t* _0 `8 z$ s1 t" q5 F/ D0 V" h
]
/ s8 l; l# n- L& M, u1 e( ^4 ]% `
patches-own9 n& H: N2 j' w: g
[
5 ]1 {. O- ~4 x  intersection?   ;; true if the patch is at the intersection of two roads- `0 D5 g/ `# L/ S
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; y4 O, L) e0 P0 e2 m0 J
                  ;; false for a non-intersection patches.
, }! p4 |; i6 W0 U3 ~  my-row          ;; the row of the intersection counting from the upper left corner of the
( l7 g  y- e5 ?1 o                  ;; world.  -1 for non-intersection patches.
$ a3 m- L' {" X" W  my-column       ;; the column of the intersection counting from the upper left corner of the
' z# Q2 Q1 j* n5 g$ b                  ;; world.  -1 for non-intersection patches.
* `. O3 x- A/ `  g. C- f  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% k8 i$ I! N$ s8 M- u1 `  r) c/ ~  auto?           ;; whether or not this intersection will switch automatically.- }* e: X1 A' H- M, @
                  ;; false for non-intersection patches.4 f$ v2 A# ?1 z6 y( O1 N2 }, N
]3 ~/ |$ R2 L* A! E, q

$ Q/ ?7 M3 W- T* ^  s  a( j/ ]6 @& W& I! @- Q. w
;;;;;;;;;;;;;;;;;;;;;;
# ]6 E7 t; }& z0 b;; Setup Procedures ;;: v% v3 W2 G  |- |  x4 y
;;;;;;;;;;;;;;;;;;;;;;" K& E; Q- o6 M& a6 p: u/ n+ \$ w

* L# l) a/ z6 x& e. X3 _! B;; Initialize the display by giving the global and patch variables initial values.( P) `  w2 ?0 ^
;; Create num-cars of turtles if there are enough road patches for one turtle to
# V0 b' E! \& i* R;; be created per road patch. Set up the plots.
5 U3 V$ S5 l5 J, Y+ \5 Xto setup% i* r0 g8 W# J' }
  ca6 ]9 P) T6 b8 o/ k
  setup-globals; X1 H1 r; a% R; _9 p& e2 J" T/ T7 X

' r" l3 h9 i- e! V1 E% z  ;; First we ask the patches to draw themselves and set up a few variables; R  H& i) D: Z2 g
  setup-patches* s. U- Z/ J& y2 i% W( k
  make-current one-of intersections) P7 ?9 f4 X3 |6 p+ x
  label-current
0 E& \& w) C& L% V# C: r
* C/ s, U; U, ^6 ]" n0 \5 N8 s  set-default-shape turtles "car"
: @- F0 X$ F' s; k, x/ a
( o- x( [7 j$ h& V$ }5 [6 W  if (num-cars > count roads)
& C9 k- t0 J5 O! [9 p& U! y  [
( P3 O; G+ l1 @* n# m    user-message (word "There are too many cars for the amount of "
; f; C! _9 f: [8 b3 e( \- U                       "road.  Either increase the amount of roads "
+ @, ^3 C0 R/ Q/ x                       "by increasing the GRID-SIZE-X or "1 {" }0 h  S% Y; c+ l1 `
                       "GRID-SIZE-Y sliders, or decrease the "
1 e2 J9 I3 E4 ]1 p                       "number of cars by lowering the NUMBER slider.\n"/ J; E5 L4 k  N1 Z& n
                       "The setup has stopped.")$ b9 l9 K  K; }$ `: O1 W) K
    stop0 a% m) Z8 U; k/ a6 L
  ]( H4 Y  M# X+ q6 G
1 [. p& D5 j( T8 n. s; o
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! [) V* l9 ~1 c) Y
  crt num-cars
8 C2 |7 q2 v" t% B. F2 S  [
) e# e" E* a3 G    setup-cars: u# d- }3 E- X) L* `
    set-car-color
. u+ @: W2 ^! s7 j$ I6 e/ ?8 \    record-data1 ~) z% T- s' r# b
  ]7 f( v( i4 u9 m5 o* o7 [- E0 ]
* V, V4 c7 [5 `" T/ f! J; W8 Q
  ;; give the turtles an initial speed
7 R, J( P  y! V2 R0 i" a0 E  ask turtles [ set-car-speed ]9 T3 @( }0 A6 z$ V& U

. c; X  S1 `; n  reset-ticks
4 p; r6 q! A, W9 ^; o, [end* M/ }7 E. W" B* n* |- u9 t
$ P! E# v9 X$ p3 F2 O# ]  K
;; Initialize the global variables to appropriate values
2 a, S& W4 [% b7 R$ Tto setup-globals' G: x/ `+ c0 z: T
  set current-light nobody ;; just for now, since there are no lights yet
/ H9 a1 K% ~1 K% z* W  set phase 0
8 H# \# U  n0 G( E6 S6 Q  set num-cars-stopped 0, d9 s! E! q; `% F; _$ j0 W
  set grid-x-inc world-width / grid-size-x
4 ~2 I! {6 ^( h) J8 I$ d1 L  set grid-y-inc world-height / grid-size-y
: ^2 U. V3 o. b: g2 B) |+ _# `- P0 S7 Y  F( A
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 C, U$ ~& D% [, I" d# O2 w  set acceleration 0.0994 @3 T. t5 ]; b5 O
end( q: m$ E8 H! e' i  O

3 r9 H$ X. {6 x;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ w+ ]4 Q( k& I+ Y/ e;; and initialize the traffic lights to one setting
$ g1 N) u) h2 R+ H0 S2 cto setup-patches
/ o7 X8 B2 K/ S. z( _  ;; initialize the patch-owned variables and color the patches to a base-color
& i- `3 a8 J( ], g  v  ask patches
# R$ l& @9 y2 P  [
  |3 E4 [. G/ H3 g, y% ?& x    set intersection? false$ W( a8 k" Z. I1 _. k. x8 F$ C
    set auto? false$ b1 K: ]% U6 ]8 w5 T+ K# T8 ?8 ~/ G
    set green-light-up? true
2 T4 l) k8 w1 K* H7 m3 D0 t    set my-row -1
( F" B$ p7 b# S7 A8 Q% t    set my-column -1
- G9 g4 X" i9 Q8 o) R5 ]2 g) e    set my-phase -1
* r$ s) v3 t: V4 c5 D2 ]/ J; X* r    set pcolor brown + 3( Q) y( L: f1 y
  ]
3 B) c9 b; u/ w0 |. v, e! Q0 _: W/ E: l2 r: p; F/ g. z) a
  ;; initialize the global variables that hold patch agentsets
* u6 A% K! H! I$ s' t$ u1 n9 ]0 a  set roads patches with  M! Q4 F5 y1 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. e7 E& U7 K+ o5 X1 _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: s. ^; q. e% \! }0 P  set intersections roads with5 ~; D: `6 n2 K( J+ t+ r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 {! d1 z' {0 r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 A. w# O- r. d8 b9 `

4 i( W9 z/ o" d6 d  ask roads [ set pcolor white ]
6 B* H' C9 L! A8 w5 b" Y2 l+ G    setup-intersections% z% p) y8 x. I% z# ~- `# m9 ^* H
end; w+ J9 C+ K' {6 t- T. N
其中定义道路的句子,如下所示,是什么意思啊?) l- w  U/ F% D5 v
set roads patches with
% N& Q4 u- b) u* f1 U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& f( |5 K, R9 P3 B, f$ v, T2 y/ h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ z$ y2 P. |$ n7 @2 z( }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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