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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 S# d% q4 s1 d" u( C
netlogo自带的social science--traffic grid这一例子当中,
6 R" F5 F6 A. G7 bglobals
: u3 b7 {  u' m3 T7 b[. f& X* m) f+ h$ S
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, m" E" ?7 k1 W2 r  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; Q# `: \( {6 P6 N2 D5 h  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  t' p, L8 {. P. \( Z: ?
                           ;; it is to accelerate or decelerate
2 Y0 Y7 L, Q5 E1 d3 a& e% T2 ^  phase                    ;; keeps track of the phase, y  w% t4 M8 v& M. Q' l  C+ c
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 B" t' M9 w* N  I
  current-light            ;; the currently selected light2 J4 X# z- x% M$ h. {% }7 v

) R; U! ~/ N4 R8 i& D1 c  ;; patch agentsets
4 H9 y' N1 q4 t6 `8 |$ X  intersections ;; agentset containing the patches that are intersections: w  {# k2 a& m$ z9 M$ o* C
  roads         ;; agentset containing the patches that are roads
7 e& L# `( r; m$ @8 C! A]6 t, {) [1 a' u8 A

( ]7 i, g8 z& f8 ?& uturtles-own. W) i6 `. R& }+ W4 ~
[
+ e5 H* N: Q% }) b  m1 _  speed     ;; the speed of the turtle+ U& o: k! R: \% S: y; ?8 m
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- N" J- E5 M2 W  S- m$ H
  wait-time ;; the amount of time since the last time a turtle has moved5 x& q' Z& A4 U3 t# Y
]
- a, F/ ~4 x, f2 E' A) ?7 ?+ u: c$ P+ I
patches-own
" Y2 U) ?4 Z; h1 Y[
* I( G" R0 [/ A3 D$ J4 N( @% _2 m" M  intersection?   ;; true if the patch is at the intersection of two roads
" v& `* c1 E5 ^5 }0 o  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 \- ?) X  K  B7 d" {  W: H                  ;; false for a non-intersection patches.
7 `; j4 C7 {. V$ N; u; |+ h6 W: B  my-row          ;; the row of the intersection counting from the upper left corner of the
; o& H; |  X( r# q                  ;; world.  -1 for non-intersection patches.1 j1 B3 ]* R1 c. }0 A4 T
  my-column       ;; the column of the intersection counting from the upper left corner of the& y- u# k( ]5 e6 G6 Q  Q1 T4 S
                  ;; world.  -1 for non-intersection patches.
; t! X) A3 z8 U! f' U  T* o  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 `5 y; q9 [9 q, \. H  auto?           ;; whether or not this intersection will switch automatically.8 f: Q' F) ~. _$ w1 U6 q  Y
                  ;; false for non-intersection patches.
' Y4 K6 T+ w4 r0 O]3 m4 a1 H* O+ N4 W

4 V% d( H0 H% w
/ f; Y0 y0 f" ]5 m: _! o9 Y;;;;;;;;;;;;;;;;;;;;;;
) ]- p: J+ g9 o+ e( f;; Setup Procedures ;;: G' J  s3 Y) q! c0 I/ \4 w
;;;;;;;;;;;;;;;;;;;;;;8 {) g, C3 z* x0 w+ M, k8 W8 z7 D$ I5 ^
3 B. I* s, B& g
;; Initialize the display by giving the global and patch variables initial values.
' }; T6 J9 U: e9 e% o3 W$ b;; Create num-cars of turtles if there are enough road patches for one turtle to
# a$ L' X9 k. J3 t;; be created per road patch. Set up the plots.
5 [1 z( H) q5 z9 g) u6 E$ x9 |to setup: Y# w( U* X3 t
  ca
8 F; r7 H% V9 J% Z; h  setup-globals, S1 [$ O& o) J1 `2 Z" P

2 N6 z( s) I4 z! p" u  ;; First we ask the patches to draw themselves and set up a few variables2 e8 w' C+ S% H3 ?8 h) ]
  setup-patches
  i! o1 P& m; @7 w" a8 J) z) p% z/ j  make-current one-of intersections
6 J4 N& P- M0 E  r. h  label-current' S1 |; d  d0 q
6 l5 x7 m' q  R# G! }& n& K
  set-default-shape turtles "car"
! F3 V6 P* @% J( Y: g* u- B$ V+ X" P, E4 W# R
  if (num-cars > count roads)
1 d' N! R6 P9 r$ v3 \* J" `' L  [2 t: n1 R' {" q4 x6 S/ f/ d
    user-message (word "There are too many cars for the amount of ") w' t+ n' }8 t( Y9 s' Q
                       "road.  Either increase the amount of roads "
" H* p+ z- r$ I8 X                       "by increasing the GRID-SIZE-X or "
2 \, d  z, d) V% ?3 a' B                       "GRID-SIZE-Y sliders, or decrease the "1 I+ a' k1 Q( w  ^# F
                       "number of cars by lowering the NUMBER slider.\n"0 v6 Q! |5 q5 J3 d% y/ S! E
                       "The setup has stopped.")
4 G6 t, `6 x9 F& F6 D* m+ l0 K9 H+ s    stop
9 g! B! H& Q" h: {  ]
/ a# S( D% Q1 @4 i  W" o9 p' |! {6 I- H% @4 W
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" F/ B' E) [2 A0 r* ]* J  crt num-cars
5 c# W$ C" u. V* y5 E  [
1 v2 u0 `$ n; V2 `* Y7 m$ t  \    setup-cars; @- M% b0 J& @
    set-car-color
/ l2 d. L' o3 F    record-data% P& U3 f5 A( ^4 B
  ]
- K; R7 b; p2 Z2 ^" f  B
/ m/ V, E3 k' l' E  ;; give the turtles an initial speed, u! d. g( k1 Y! v$ e8 G6 j6 C
  ask turtles [ set-car-speed ]
7 w( \8 S# K. a  K. M  K+ i4 a( w
) ~2 U3 E' M/ T+ P+ i( u  reset-ticks) E/ x4 }/ ]0 x7 X- `
end
4 r! C: T2 B! ^+ _9 f2 C
, A9 N3 k5 i& c+ X; M" d! ^;; Initialize the global variables to appropriate values" F; \; ]0 ]/ V# d# Y% y9 Q1 ~9 P
to setup-globals8 T$ t+ c8 r7 X7 {$ J/ y# a) V) ^
  set current-light nobody ;; just for now, since there are no lights yet
1 c( ]7 m7 J0 p, S$ C  set phase 0: n. G1 m* k) k: d$ P- W2 y4 @
  set num-cars-stopped 0
/ `4 }0 `0 d$ R% d5 f- W) H2 a+ s  set grid-x-inc world-width / grid-size-x3 t4 V& q; j& k5 q& ?
  set grid-y-inc world-height / grid-size-y
) |. Q% A. {9 \- H5 a$ O# g4 ]0 {$ _" o
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 [  F" A& ]& {! u
  set acceleration 0.099
+ N! \4 f6 V' i. G# ?9 pend8 u5 B  o8 S/ y

# g, x7 f" k8 J: \, c; U0 x;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
6 z/ x2 n, I) l' f9 _+ V. V;; and initialize the traffic lights to one setting3 w* b. k. l. n7 o1 w4 R9 D
to setup-patches% q2 B; K9 {* j" e- d  g
  ;; initialize the patch-owned variables and color the patches to a base-color# P, b# g0 c' L; s8 D* @4 m7 \
  ask patches
& Q* n' M* |4 d1 _# ^- d6 t& w  [! p" ?1 V# O) F
    set intersection? false
( F/ ~6 `# \' v- O* Y& [" N1 ^/ {    set auto? false: H, W9 e; y9 ^$ P9 @! ^8 m
    set green-light-up? true9 I5 Y' ^7 l' U$ Q
    set my-row -1
2 d! @  E% Z6 D    set my-column -1
/ x' }7 b2 _) _' Q9 ?9 h% b% w    set my-phase -12 h3 s; L+ u: I3 P
    set pcolor brown + 3
+ |0 B7 Y' P% B% z  ]
' J8 [2 y7 ~  J, H! `$ z2 e: n( K# ^! a; C6 \3 _' w3 `& P3 L
  ;; initialize the global variables that hold patch agentsets
* l2 }3 ?. e7 v( s7 P# E, Y  set roads patches with
9 v" n) N: {5 a5 O3 R6 ^9 [( r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: h# p6 c5 |  w3 S0 c5 K7 o* T: l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% w- K3 @5 u+ P4 N5 C
  set intersections roads with
4 x) X# B/ z2 g. R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! C7 N# B' U" J$ Y2 O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- _" g) P! e; K! S* \; D

6 m4 x* n& W& a" n+ H' {0 W  n  ask roads [ set pcolor white ]
) x4 z# m' M. c: t    setup-intersections2 t' t+ F- I3 k
end7 `* p* S! ^/ h& F
其中定义道路的句子,如下所示,是什么意思啊?
% n2 E8 ^% M( |. S* X% Y set roads patches with3 w, Z/ l; ^; C! l6 X. ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 ?  A7 D5 J1 h# s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; I8 N6 w* y8 l: Z8 G3 E, x* _4 u
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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