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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。
7 q' J- b* r+ nnetlogo自带的social science--traffic grid这一例子当中,
$ g# i" S3 u, G& g/ X9 o# `, _7 l+ T) lglobals/ ]! D9 @. q: Y0 y# r! w8 M
[
  m' g1 O; C" a( Q  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& ?4 t! V! A0 D6 m! P; P  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, L: v- \! B" L* }  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 }. c+ q+ ]! p2 A& K$ Q
                           ;; it is to accelerate or decelerate2 K3 `  d: z$ a* ^9 }! P. M7 z7 {
  phase                    ;; keeps track of the phase( E4 L: I. L5 }# O7 G1 O* w+ W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 C! s; L" y+ L: ^: V  current-light            ;; the currently selected light
3 T( c* p% y5 Z4 c4 q8 T& s! \$ D/ {& L' z
  ;; patch agentsets
8 F% ]5 a+ c1 }( Y. d  intersections ;; agentset containing the patches that are intersections6 e& j/ X7 c6 K
  roads         ;; agentset containing the patches that are roads" Q9 b3 C- N) O, g/ `( j/ T/ c6 |
]
: X: i  u8 m  ]! @  ~  J7 ?" m% `
" i& M5 R+ J/ r* pturtles-own7 b6 I1 b5 k" H
[0 M5 f2 d  |. O4 I/ Y1 C! L% i
  speed     ;; the speed of the turtle
" P( W0 g4 [2 m4 c* W1 u" `. q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right% v( B+ c+ t7 h4 W2 z6 e  H
  wait-time ;; the amount of time since the last time a turtle has moved0 O* B9 G3 G$ o0 g& Z
]! n- V3 H$ j. B& L' Y4 l1 x
  [2 z8 b2 a+ j2 Z' v
patches-own
# B" b% w7 B9 F$ D[  Y) J- l/ c5 w# p/ h6 t5 _6 ?# M
  intersection?   ;; true if the patch is at the intersection of two roads
9 k/ M3 ?1 C  x; w- a1 a6 B  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; Q. V/ i5 F) {" r6 n; R
                  ;; false for a non-intersection patches.
3 Y5 K2 z1 v# {% y  my-row          ;; the row of the intersection counting from the upper left corner of the
- M+ L2 O* Y8 m% x) f, G$ O                  ;; world.  -1 for non-intersection patches.; _# K" E' m* }: I6 X4 w' `! t
  my-column       ;; the column of the intersection counting from the upper left corner of the) k, D6 K+ K7 r  E8 ~
                  ;; world.  -1 for non-intersection patches.
* S1 \: F$ S7 r0 D+ m5 A0 A  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) @5 X8 D. f3 J. z9 y7 u3 J2 R  auto?           ;; whether or not this intersection will switch automatically.& P& {6 p. k+ j( L
                  ;; false for non-intersection patches.9 P, X2 R# [& ~" ]. d. h& D
]6 s; \8 J  ?8 O" i9 ~' [8 d: d  m
: \8 K8 M5 r  j

, s$ N: }# k! ~$ S  B- Y4 n9 t) l1 z;;;;;;;;;;;;;;;;;;;;;;4 G: R  x  R# T1 S. \2 ?; K3 S
;; Setup Procedures ;;1 r6 x3 M2 z! r) s5 {6 r
;;;;;;;;;;;;;;;;;;;;;;
  l( b( `. e' k! U, A; I
+ u1 d$ F! r; V; S; q;; Initialize the display by giving the global and patch variables initial values.
; a- H4 @+ W& k, o) Y;; Create num-cars of turtles if there are enough road patches for one turtle to' S$ c& j2 w* L- l' ~
;; be created per road patch. Set up the plots.
5 d# _$ j  @$ C2 Y! Ito setup
% X! u) U0 P2 l; T2 ]+ [$ s  ca4 O$ N* B, c0 U& A6 ]8 @
  setup-globals
% i+ f0 P$ s  Q4 }/ [8 H/ A
) _6 X9 ]2 J% V& {% ?- g- y  ;; First we ask the patches to draw themselves and set up a few variables
/ K9 E. v$ u) N) `" \, K8 _+ U  setup-patches
8 ~6 y- A! ^) P  make-current one-of intersections
  o4 N* w" j4 i2 X# j+ j; C  label-current3 @. Y' r; w2 g. M; ~* t, _

6 ?# q1 o) H3 F7 ?2 e9 v( k  set-default-shape turtles "car"" M3 B, R) A. n7 v8 D! D

: P/ ^- t+ [7 h( W- n  if (num-cars > count roads)
* F+ d) m' ?) y$ ~5 Q0 p  [
- c' U/ |/ j3 i    user-message (word "There are too many cars for the amount of "
8 P* V5 p" {1 S6 ]& }6 w5 A                       "road.  Either increase the amount of roads "2 m( ?4 q- b' o" ^+ ]1 \! N& ~
                       "by increasing the GRID-SIZE-X or "7 E6 m4 P! R; L  y9 D; ?. a; w
                       "GRID-SIZE-Y sliders, or decrease the "% _5 N+ H5 Y+ g# I( _
                       "number of cars by lowering the NUMBER slider.\n"3 e) k$ p8 }+ Q" ^6 g' n
                       "The setup has stopped.")) b  n& J( p3 a9 k2 K
    stop) T4 O) P; u/ _2 `$ L
  ]
+ [/ i. j3 J+ o3 x& D  {8 |+ d$ F6 }4 R/ }$ f6 k  o# |, P' `
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" {. i0 r$ }0 {  crt num-cars: v! L$ |! ?' ^- I
  [8 A( h) }5 ~! S" k9 U: d
    setup-cars
$ X2 ]) S, P+ R4 h, V7 m    set-car-color$ N" x' \" [8 C9 n0 n- I1 K6 b
    record-data$ h4 y* ~5 O3 W, r  v3 o6 E
  ]
; H3 C( z% q( [8 i. A4 @/ x' y; F" Q+ t( A4 j) ^/ {3 ^- t0 l
  ;; give the turtles an initial speed
8 T2 N0 ?; N& N* s; L$ o  ask turtles [ set-car-speed ]
1 o: r% z4 S: y0 M0 _) _
' V0 v' P3 j6 f" ^  reset-ticks6 Y+ @/ o& e! S0 S
end
7 |4 [8 [6 p3 X- r0 t# ^, q6 b9 M/ w' R& B+ @9 J
;; Initialize the global variables to appropriate values3 k! H. y+ X) e7 E
to setup-globals
) r0 ?1 P' m- L2 y  set current-light nobody ;; just for now, since there are no lights yet' f/ z5 M* l/ Y1 l1 s
  set phase 02 A. L- `) @3 H7 }5 o6 f8 C6 V
  set num-cars-stopped 0) ?6 G' @; K1 `" T! G3 [
  set grid-x-inc world-width / grid-size-x
& x' f% s6 C1 y3 C6 ~: J  set grid-y-inc world-height / grid-size-y
: H! B; A1 ?% Y
: e* A5 T, c, @8 K  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ P* f* A# e! B7 N' M( O
  set acceleration 0.099
4 d5 A2 P! j3 @* ?9 y' h5 Kend+ j5 M! K* p7 T: y. c
" t% ^% I- j' `6 {6 c# }- o$ z
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 n% g0 w  z7 M;; and initialize the traffic lights to one setting( d; u2 H! M) L# i: g* v# Q
to setup-patches
' e0 T4 {0 `/ l, k  ;; initialize the patch-owned variables and color the patches to a base-color
1 k. ?! Y5 F7 H! Z. |, W. h; Q  ask patches8 ]( i6 g: W0 T- R. P& G; J
  [
; B  I- m" M0 @4 N. L( ~' b    set intersection? false
0 G* h2 a) R0 K0 u+ {+ A- O: L* e    set auto? false7 h4 [: j9 @1 e% H% ]
    set green-light-up? true
* C8 X+ d: Z" I. _+ u    set my-row -1* w9 o! `5 U$ U; h0 f
    set my-column -1
+ \5 L# A: o( C    set my-phase -12 ^& ^& e* ?  M! B- K
    set pcolor brown + 3
  E$ ^6 B* T& l! H% ]  ]) L' H2 ^2 e, H' ~7 [6 M0 Z
7 _+ x+ r! i; s$ O
  ;; initialize the global variables that hold patch agentsets, ]: h, }! ^6 J5 N; G+ L& y: l
  set roads patches with$ B5 l8 S6 d, Y" t: y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ p6 Q% c2 \; K7 Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) C3 V, _9 U8 |! _" Q5 o, g. e
  set intersections roads with6 \8 e7 _" b8 C* H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: K1 a$ `. n4 X* R, `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 ?* o  M9 M+ O* }
1 G7 I8 N) L7 p8 A# w3 i  ask roads [ set pcolor white ]0 p0 w( u4 t: S
    setup-intersections+ X- n$ J- ~4 ~) \/ e- H! c. @: e1 J
end" M) _4 j, Z& P- U: F* S! s( C
其中定义道路的句子,如下所示,是什么意思啊?
5 ~  u5 K+ ?, @$ u set roads patches with2 n3 s. E* ]& ]+ p( J& ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 b! ~  c* L# q/ ~" D! X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 ]$ q! j# `% L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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