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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。
0 ]! W- X- v. S& e& k( E4 rnetlogo自带的social science--traffic grid这一例子当中,2 G" o6 Q' g. E" E1 u
globals  G( C& v+ s$ H# h8 }
[
! p+ Z0 k: w: r3 @  grid-x-inc               ;; the amount of patches in between two roads in the x direction7 r) a! t& r; ~* I8 H
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, t" s2 ^9 w( P2 w$ N  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( e/ Y) a" I4 e3 r
                           ;; it is to accelerate or decelerate  Y- H, m: _1 X) j5 P
  phase                    ;; keeps track of the phase
" z- M8 q2 r5 u. _& ]) j( ^  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
! Z$ [* X( ^9 q: D' F  current-light            ;; the currently selected light9 x$ z, l+ O0 O7 ]1 o: L5 F; L8 t& o
  C8 G( _7 P* Y! G. q7 K
  ;; patch agentsets5 }! B5 V- f7 t* H, S- X
  intersections ;; agentset containing the patches that are intersections
9 Z- |: u5 [' Z" ]! V  roads         ;; agentset containing the patches that are roads
, Z, `3 {8 _5 z% s6 M9 l]
6 ]5 l+ ?2 h( z& v
1 g" a$ n% q' Z2 e" w; |0 {turtles-own
) q" `, l, ?) N5 e[
+ o" v  W8 T  O0 W1 [  speed     ;; the speed of the turtle
8 ^2 J+ F/ D" p  w8 X$ w  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, s2 e0 T# f' O) I* `  wait-time ;; the amount of time since the last time a turtle has moved
+ m* J9 G1 y8 b# v: r]
, D. @3 g% N- r/ N. x% X/ E( d
! b( i6 N3 e' Tpatches-own
/ l/ ~9 O, l# I3 H[
( O0 O( b9 N) N2 ?5 B  intersection?   ;; true if the patch is at the intersection of two roads, \0 K6 r3 {. d4 f4 Y0 V( [
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.8 D/ X+ }  q" `  I* c
                  ;; false for a non-intersection patches.
8 I& s# t/ P, Z( a7 u  my-row          ;; the row of the intersection counting from the upper left corner of the
# ~1 |+ R! Q" q! x                  ;; world.  -1 for non-intersection patches." F9 I2 l0 v+ r) W) K
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 F% e1 g% c( Z& n% G                  ;; world.  -1 for non-intersection patches.6 X( v; X4 X$ \3 x5 Y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 |; H5 k1 N1 Z& D* q" G4 \
  auto?           ;; whether or not this intersection will switch automatically.
. B7 x8 c: |8 l! ?+ I' M                  ;; false for non-intersection patches.
  o. {: r, \% \. S" X- p]
% Y) P5 x2 j4 I: h* ^6 R- r2 |3 `6 q- A

$ K2 N' P( ~% |7 R+ F;;;;;;;;;;;;;;;;;;;;;;
8 h$ ~) r% a2 h) T- J7 ?7 D0 |0 \;; Setup Procedures ;;# q/ G* `. _1 Q6 S
;;;;;;;;;;;;;;;;;;;;;;; u- m' O: B' d& m

5 U8 ~3 b) }: J;; Initialize the display by giving the global and patch variables initial values.& f+ S5 ]# e- D) D6 i& u
;; Create num-cars of turtles if there are enough road patches for one turtle to% U8 E& @7 \4 t$ q# {1 R3 n
;; be created per road patch. Set up the plots.
- S6 Z7 q  W4 f3 H  f1 Ato setup9 a8 M( K/ X( M. D, z
  ca
9 t1 g& `+ ~+ D% f# ~  setup-globals
  ?$ x/ |; v2 `5 {0 v" K7 V. i4 Z0 v) |8 K$ h
  ;; First we ask the patches to draw themselves and set up a few variables
& a- |$ S9 q( i/ }* a  setup-patches* M: n+ ]& ?' d& [& Z
  make-current one-of intersections
( N  f3 w  x; M2 J  label-current
2 K9 M! r, k% E" p# i- C- k( Y" M4 t, n% a7 p
  set-default-shape turtles "car"
0 J) a' S9 ?1 y& l
% G# K- {' X- V: L  if (num-cars > count roads)
/ `+ C! ~; ?0 i! o4 r  [
' K- \, M" Q/ K8 c, a3 n  n    user-message (word "There are too many cars for the amount of "
7 x4 I4 C1 Y* h1 Q* y                       "road.  Either increase the amount of roads "
4 ?/ e* v* q" J7 i1 V( u! g                       "by increasing the GRID-SIZE-X or "
; \8 N4 O9 P3 ?* ?                       "GRID-SIZE-Y sliders, or decrease the "7 E, r$ w# p$ P" ^8 r- X
                       "number of cars by lowering the NUMBER slider.\n"( U2 t2 N3 ^* B+ ~  E9 K. ]
                       "The setup has stopped.")( T3 H% v! g' g
    stop
% f1 z9 y! ]5 V0 B; U  ]( u6 W9 \1 M  ]6 V6 J5 O# ^, r
7 Q# t9 Z" y0 a4 w0 [
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: }& T% r+ U6 U  crt num-cars0 H6 V  t0 {3 n1 @1 A" l
  [; X! {$ }9 o! d4 S2 d, }5 Y
    setup-cars& ]. {. S+ Z/ H6 s. a0 e
    set-car-color
: }2 I2 l: q' ?" t    record-data
9 P) f/ `/ D9 S3 @1 b: e  ]
$ L9 L! ^% Q7 |' I0 Z% V2 U! ~3 K' j0 t% V* f+ W/ h
  ;; give the turtles an initial speed. E' e" b- V# d$ r. D: g
  ask turtles [ set-car-speed ]
6 p* F' F  c/ r- j
, H- n6 @# C( n6 l. t  {) i. X  reset-ticks. H  g/ H" Y6 r, i8 t
end
# y+ w$ E  f$ N
" |  L8 {7 Z0 y6 J7 C1 H- \" j;; Initialize the global variables to appropriate values$ R9 I( U* a) ~; O! q( U8 H8 m
to setup-globals9 O8 f2 |3 B( b+ c' I: W% M  z
  set current-light nobody ;; just for now, since there are no lights yet
% [/ T+ J4 c/ y; K! M+ C  set phase 0, [, I) i; U: L! y3 y* g) B: ?
  set num-cars-stopped 06 I% a0 e5 C( M) U
  set grid-x-inc world-width / grid-size-x
1 P# b+ |. o3 `; |  set grid-y-inc world-height / grid-size-y- G9 e- G# J  t- @! ]$ T

( r# C8 l$ b$ J$ k7 P; s  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  P& r6 e; k& u" O! _, a
  set acceleration 0.0997 M- m3 s+ i7 T3 k! q5 A
end
* ?" V4 }; P" K7 V1 U: @; V
4 Y! _& D) x  U+ ~; @;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
6 v/ \1 a6 T5 @;; and initialize the traffic lights to one setting* h* v$ B  B  w8 }" O9 W$ Q3 b# e4 |
to setup-patches
3 I8 _( J/ p, j: S/ J( s  ;; initialize the patch-owned variables and color the patches to a base-color
% H! m' ^4 V$ F! B& ?) F  ask patches: y7 Q& `7 c7 ^) ^$ }5 l. T/ E
  [7 N7 j0 W* H9 @$ k1 G* L3 r" g
    set intersection? false$ r6 ^* y0 t6 K# e9 A- ^
    set auto? false
7 t* L( C, m* S9 M# [& p/ I    set green-light-up? true
9 ]7 O4 b# |$ t2 n5 x    set my-row -1
- M2 N3 k1 m7 s    set my-column -14 m- [6 Z) D$ J) C
    set my-phase -1
2 x! z" X$ B5 R/ G+ N$ Z' D    set pcolor brown + 3
, q; B$ e7 S2 V( {  ]/ ~, i- p+ V! n

" e  ~: {# R4 w7 F6 K7 B  ;; initialize the global variables that hold patch agentsets
  j2 m/ W/ L3 g0 e' }% @9 E  set roads patches with
2 q3 M/ b3 F+ M+ G% o0 p; }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# U, c" G& N& e2 x0 ]3 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; O& S: o* J; \& Z( @9 }& L7 L  set intersections roads with
% [; w. B6 ?. g9 F& ^6 ]* B9 C% b/ p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 Y& {2 K* V1 V" |5 T1 `! j  i" M8 H5 H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 c6 ^6 W% c+ J2 M. A# B! e8 C
. g* P, }" |* H& Z0 `5 D
  ask roads [ set pcolor white ]# e( O; T6 c: D5 }; ^, k  X: S
    setup-intersections
% t1 ?3 r! e1 K2 D, D$ ]8 Pend
1 n0 Q6 I1 }# ~- E6 f其中定义道路的句子,如下所示,是什么意思啊?& X( @7 i/ Y5 {. Z4 I
set roads patches with
6 G. L& n- a! Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" a% w: t7 T( k: [8 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: g  W2 }& m0 x+ M* |: y" q6 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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