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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。! s0 `/ t2 R" Z; Z7 `
netlogo自带的social science--traffic grid这一例子当中,
( ~' ]3 e& l8 _7 c, y' u- w! S, j) vglobals
! d% X% @. R1 q) E[
" w( G* N2 u% z6 u4 J$ v  grid-x-inc               ;; the amount of patches in between two roads in the x direction
; E6 a& `) u; S+ X9 W  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( \+ \+ V% g% q, X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* M. ^3 ?0 r; K" H2 ]
                           ;; it is to accelerate or decelerate
. b' P7 ?4 A, `8 W/ M  phase                    ;; keeps track of the phase
; {9 \: p; C+ e5 [2 J  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& l" J# R# b4 ?
  current-light            ;; the currently selected light
. k6 Y! Z0 L2 z$ r
( M6 r' q5 s, B& \4 y  ;; patch agentsets% W) R0 j0 _5 g$ V1 r
  intersections ;; agentset containing the patches that are intersections/ e& G, \4 d+ o( N% x) ^+ k6 d
  roads         ;; agentset containing the patches that are roads: h% U. H+ y3 y0 q9 X' e9 E
]
# B/ a- a  c6 {3 L; d, k$ ~( ^7 y9 v5 Z9 B% K( Y
turtles-own& R: k" O0 t- q3 N8 s
[4 z& S( C4 k$ U  r# `* r& X
  speed     ;; the speed of the turtle' Z' ~; s  @4 x' k5 z- O. I
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 c" h$ `" v9 F8 x9 u( M/ T
  wait-time ;; the amount of time since the last time a turtle has moved
# a% r# |* a6 I8 @7 E8 I]7 _/ \* B- t) @2 s

, D4 Z0 |% S' ~% Dpatches-own! T4 p! ^6 P# ]! R. m5 B- g
[% L6 Z: _$ U4 n) F$ J" \
  intersection?   ;; true if the patch is at the intersection of two roads$ E" e6 P0 V2 e
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 {: S. F5 p' x                  ;; false for a non-intersection patches.1 m4 ]) n  t) _! ^2 q
  my-row          ;; the row of the intersection counting from the upper left corner of the
- p' F5 F+ j, X; c! q# M" R                  ;; world.  -1 for non-intersection patches.0 g2 ]/ W- ]8 n* D  M7 k8 P. q
  my-column       ;; the column of the intersection counting from the upper left corner of the
$ }" v: u7 I0 l5 W; q. u                  ;; world.  -1 for non-intersection patches.
. q; V9 `; s. n0 e: A1 u2 k! f  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 F1 z7 I  |: D- I- x  auto?           ;; whether or not this intersection will switch automatically., }) C& z6 L6 V: O
                  ;; false for non-intersection patches.6 t% ?% b2 A: I3 H, B. n) |
]
/ x  E) L& H$ n* a0 I) D* A! O3 B9 E) }( x3 c
0 L9 Z4 x8 }. y
;;;;;;;;;;;;;;;;;;;;;;
; m: `5 V6 K* D' h- c* F' ^; H3 u! c;; Setup Procedures ;;3 t/ [8 ~4 c7 C; l; G
;;;;;;;;;;;;;;;;;;;;;;6 z& t- e  B" w7 X& j8 y

' t% n5 \. [5 T( a/ ]! \;; Initialize the display by giving the global and patch variables initial values.' E1 i% E8 t' \$ i8 @
;; Create num-cars of turtles if there are enough road patches for one turtle to: N8 i6 [4 |4 O; @) B' ~
;; be created per road patch. Set up the plots.
% U1 S5 L3 \2 C5 ]to setup  n) G, I& Q& M, E$ S8 x2 H' v9 `$ _
  ca8 s' l- m7 g. W5 }* y8 ^
  setup-globals
( v5 o1 }! B) B; ]8 t, J
0 K6 w3 K& D" @5 U  ;; First we ask the patches to draw themselves and set up a few variables
  z) A7 X* r4 |$ Y. S, i/ p' L  setup-patches
' l' U" V5 e2 ?' K  ^4 V9 I7 U8 H  make-current one-of intersections$ \/ d8 M7 {& s; }' c3 S8 e
  label-current% S9 C2 g# y. ~3 F& g5 w
2 ]. @+ o; K. J. a* e
  set-default-shape turtles "car"3 `  m. B% C7 V- X

0 F  ~2 B  m* A( @" w3 x3 E3 N  if (num-cars > count roads)
2 {1 e. |; z6 u+ F% e  [
% z# s( s3 P8 N/ N% w/ l9 G$ R    user-message (word "There are too many cars for the amount of "
2 m+ l1 o+ j$ l2 @5 g' `5 N                       "road.  Either increase the amount of roads "
7 N3 z- R8 \8 R' U0 |2 F% U2 P                       "by increasing the GRID-SIZE-X or "$ L# F' m2 L, }1 Q. h  F
                       "GRID-SIZE-Y sliders, or decrease the "
9 q1 f: `# J& z" I                       "number of cars by lowering the NUMBER slider.\n"
, n* }: h3 E5 ?/ I  o6 D                       "The setup has stopped.")+ x2 m0 A/ K8 Y7 V3 n! }$ s
    stop5 [: P5 J. k3 `& |( I5 P# N* d
  ]
) H$ [3 l9 W9 V! m+ B/ f) I3 r4 _8 z+ I! \% a% M
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! T6 |& U6 Y  w! _$ i( d/ J2 P7 z
  crt num-cars
& P( `0 I# \" s- m. G; B  [  j- {. b8 X: U5 I) o
    setup-cars
1 Y  Z* G, z. z* V' t5 K2 z' V    set-car-color
2 s0 p# n* c) s  g" y3 h7 L    record-data' n. W) c/ i! y
  ]
) E+ J1 d- n5 p( Z8 M: F2 K
6 y0 @  H0 K) M- D& o# ^2 H  ;; give the turtles an initial speed
1 v0 X4 X. K% [  Y, m8 K. }2 _5 e  ask turtles [ set-car-speed ]$ o3 M8 E, G: s

1 M7 s( U( [  b3 B) ^  reset-ticks
! M2 A8 ~3 {1 k& J5 ]$ uend  u. Q$ X, I  m6 e6 I6 h8 M( O
; I- ~+ c+ F/ u/ h
;; Initialize the global variables to appropriate values+ t% \+ k* z- K$ C
to setup-globals
$ i0 i: b$ ^" d! h% [  set current-light nobody ;; just for now, since there are no lights yet0 {5 n" k; u% k
  set phase 0
! ^# Q8 S8 s( Q( @; K  set num-cars-stopped 0
- k  ?# c. p$ u4 p& Q2 i6 r  set grid-x-inc world-width / grid-size-x5 Q1 D  b3 ?" p3 K- t
  set grid-y-inc world-height / grid-size-y7 j  |* E) |( {+ V; z: B) d

; h6 J% ^7 S( X# J) F: n  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( L) |: |/ y) V" c( e
  set acceleration 0.099% Y6 e1 c, k% W0 `) {
end
( z  u" @* ]1 u. ^  G3 L: ~) Q; V( J9 b/ E5 _/ o$ x
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 }& f- e6 \1 @
;; and initialize the traffic lights to one setting
$ w  k( @, V7 h1 V' {8 B- qto setup-patches
5 c! f. W4 m& l% u5 h- D$ @% e' W& \  ;; initialize the patch-owned variables and color the patches to a base-color8 P$ G' S) p' j- T; \, R# e
  ask patches' _) b$ c9 `# U& j) }! }# R
  [8 b5 j3 c! B4 S; A% `
    set intersection? false# J* [& v: y1 B* h% S6 g
    set auto? false
/ w) V9 C0 ~+ G! M    set green-light-up? true
4 m  y- G3 O' T  W; z/ E: I. o    set my-row -1
+ W$ M2 ]/ _3 Z; i( U3 j    set my-column -1
* E9 Z' C" x- M* m3 N1 B    set my-phase -1# c9 m% d# E. Z- U3 F& Q
    set pcolor brown + 3
* Z0 ^6 V$ _, H+ e  ]
6 J' E2 S9 o, f9 p
5 U0 [; K0 Q9 E8 L3 X9 S  ;; initialize the global variables that hold patch agentsets, I' n/ d% P5 A5 ]
  set roads patches with: W2 f' q1 ]. @( F" k- c0 e( k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% T/ `( E- Q$ u; y* Z0 y9 ?! p. Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 i- P- _( f5 ]* @: s& u) d
  set intersections roads with8 O' |& M' U0 ]9 k5 y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; Z. _2 F/ P6 @- s  _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 e* ~3 J8 K6 c$ O, c  T$ I( [9 B; U5 J
  ask roads [ set pcolor white ]/ V) Y0 Q2 Q# k7 e- B3 o
    setup-intersections! ]* _7 S: Y/ _5 p- b3 a
end
# _4 x7 ]* v& i; [9 ^7 T其中定义道路的句子,如下所示,是什么意思啊?
& |7 Q( U! ^/ E' W& S8 I! R set roads patches with
, u+ y( |7 U# h* K9 {3 n+ t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& D, [6 z/ l; n/ p$ _( n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" D3 _6 J, p: n) G" I# 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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