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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。% _& \! }9 I3 g- M2 p4 S9 n4 L  U
netlogo自带的social science--traffic grid这一例子当中,  z' j6 \1 M. ^1 c; V
globals
- j8 x' G0 N- N. z3 i[6 z9 ]$ }8 o/ I9 ^  C( D. Y/ w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction) Q; T) L* f4 o6 J( r# p
  grid-y-inc               ;; the amount of patches in between two roads in the y direction* a) S1 \1 K4 i/ |& A
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 f; c* `1 W& o$ q0 H9 F2 v
                           ;; it is to accelerate or decelerate+ C& f7 M, o3 ~: c# {
  phase                    ;; keeps track of the phase
2 Q. W4 N0 U3 Z7 q  _; G5 m2 t+ ~  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 h. J. A3 Z; K' [6 ^  current-light            ;; the currently selected light% m; }+ _, A1 w

  O. {7 Y8 H4 J9 Z/ |7 Z2 f% b  ;; patch agentsets! {9 V- ^: p1 U% _" u5 y; b
  intersections ;; agentset containing the patches that are intersections: I* C! V1 S# y
  roads         ;; agentset containing the patches that are roads) X* n& b) @5 N8 V
]
' L3 b# ]' f% Z- b3 X3 G/ F& ~1 O- y; u  f$ X; Z
turtles-own% d' o5 ?4 Y& c. a3 z
[. Z: Q- s6 I# {7 \% b, |8 r# E  w
  speed     ;; the speed of the turtle7 G4 s; J& t, B) x4 q' l; G5 [3 S
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# |; H: G' G+ s3 X  k  wait-time ;; the amount of time since the last time a turtle has moved
7 ^9 ^7 P4 J$ }+ q! T], |* w. l' e! w" @

# x) ]6 C0 R3 R6 Y+ L4 p+ kpatches-own
( \! I) G" E8 T, U[- \8 P! }7 y1 o
  intersection?   ;; true if the patch is at the intersection of two roads
: b& E1 q# r" [3 {+ _- j. \  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 N% N( _3 H* b# i  P3 B8 g5 r                  ;; false for a non-intersection patches.5 i# W& f: F3 E) h! m" u
  my-row          ;; the row of the intersection counting from the upper left corner of the
, _' Y* A" ?* C. A: ~                  ;; world.  -1 for non-intersection patches./ R5 ^5 D! b# o8 H5 x% C
  my-column       ;; the column of the intersection counting from the upper left corner of the8 o& [+ h4 g# q# L% j5 c+ W8 r
                  ;; world.  -1 for non-intersection patches.
0 c. u- G: q- t. [% @8 p  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 o# C- ^1 ]& V( {/ U  auto?           ;; whether or not this intersection will switch automatically.1 |0 i( E' I! z# u. @
                  ;; false for non-intersection patches./ Q! ~" M" {1 q/ k9 C) W
]' U4 @: L8 i1 {! T- D0 J: r, X
; q5 Y* ?* Y7 t" I
- G+ z# V& Q; e$ R$ W; V8 A* E
;;;;;;;;;;;;;;;;;;;;;;$ Q9 a, Y# A: q8 q5 r7 a0 A. [
;; Setup Procedures ;;
. X5 n; W5 ~$ d* _6 }5 K" L6 a;;;;;;;;;;;;;;;;;;;;;;& y/ o* P3 o8 f

0 U! v$ ^) W2 n* b$ F1 {; ];; Initialize the display by giving the global and patch variables initial values.- k1 ^- G* a' ?  y* e; d
;; Create num-cars of turtles if there are enough road patches for one turtle to( M# Z3 t5 l  _; D! J  k6 ~! B
;; be created per road patch. Set up the plots.9 p: X/ c, O" j& _$ g3 g) r
to setup
$ {3 b0 [, h. F9 ]+ X% _2 z# |9 {  ca: w9 z  P7 g# H+ n' b3 s- T  q
  setup-globals
: _, W7 R3 T: k" r5 N5 Y$ R" m% W' Q: ~: y. M/ v
  ;; First we ask the patches to draw themselves and set up a few variables
2 }3 i3 p& ?9 c6 [: }8 V  setup-patches& g9 F4 h5 M" v# S
  make-current one-of intersections, F. O2 D2 }; L
  label-current7 {% B- e8 K9 {: u+ Q7 ^* e

* k1 R5 I5 B0 E% Q: ^  set-default-shape turtles "car"9 `3 D) ^6 N2 n1 {4 ]
* i: F( U' u6 o' T) A0 g6 k8 g
  if (num-cars > count roads)
# y( n+ Y# ]% O  [
  J% {2 p0 j! f$ [3 ]    user-message (word "There are too many cars for the amount of "* T1 P# P" }3 U: R0 D- Y8 B+ m
                       "road.  Either increase the amount of roads "4 ?; F1 k# H# ^% X" A3 z. D( z0 P- t
                       "by increasing the GRID-SIZE-X or "
) x0 Z+ a' K" ?                       "GRID-SIZE-Y sliders, or decrease the "
1 i- p. Q8 J6 Z( m2 R: Z1 g                       "number of cars by lowering the NUMBER slider.\n"
1 H/ u; p' I9 \. {                       "The setup has stopped.")# x# _( }6 D6 W! A
    stop" I4 B4 H+ Q. o
  ]9 N  z) C4 X+ x/ R
& Y' B. I1 k' Q% ~$ F4 U! O
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, q8 [$ t6 G6 q" {3 e
  crt num-cars7 e' ]! f7 T, r7 ^& _, g8 A. G
  [
% N# C: p; a- o$ U, k    setup-cars
* ^+ O1 u/ y, W9 g8 F7 a2 f7 H    set-car-color
6 h- g7 r- t0 L5 I1 b    record-data" I! ^; K+ u4 w. ^# p. _
  ]+ E5 a8 _5 ?' Z, ^& \+ I# @, h# ~

# |! U* s9 f- G  ;; give the turtles an initial speed
* ~1 [7 l- R' j8 |  ask turtles [ set-car-speed ]
, L$ e/ Y* O3 R2 p- `- F6 `7 X7 V9 f8 w; i: n: v
  reset-ticks
/ d' R( |8 s# ~) G* Dend4 C; f# K) D, C5 h' y
- g3 `3 h; [8 f+ c" h9 l
;; Initialize the global variables to appropriate values5 V7 r" d- S, o% m& E5 |: s
to setup-globals
/ s& w: S8 H8 M  set current-light nobody ;; just for now, since there are no lights yet
8 C* ^* N8 k' G# r" V' C  set phase 0: e# [9 B' `9 x1 s- z
  set num-cars-stopped 0. Y* S* Q2 s1 T5 B& D. L/ c! R
  set grid-x-inc world-width / grid-size-x& D! n5 t; E9 m; c3 ~$ ~
  set grid-y-inc world-height / grid-size-y
* Q" d( O" S9 z: M+ \6 B( J) z" u! k' l+ f( N; E' a- X' V
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
2 e$ |" N% f, a  z4 i- P  set acceleration 0.099
2 i, }4 V# j  n* n) L5 ~  qend2 D: H2 q/ M' L% O) I0 a7 {: O

$ J# F, }7 h8 q) Z1 f  P;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ o. S- d- d# u/ i$ T;; and initialize the traffic lights to one setting
0 k* R* J) E* f7 Q+ J1 H3 B) D4 Hto setup-patches
4 W, W  L2 v) n) a4 ~: h& C+ ?  ;; initialize the patch-owned variables and color the patches to a base-color
  X$ V. ]8 r6 u  ask patches
2 w' ^' ^, Q; x4 C. l2 P7 L9 q  [' |+ m9 c$ ^! N1 `  Z& ^: t
    set intersection? false2 _1 c  l; ]" i7 L1 u) b
    set auto? false% j( W0 w3 m, q6 ]6 g( i2 ]
    set green-light-up? true
" Y3 @* B  w  E, A    set my-row -1
! O: a" H) D% R0 w    set my-column -1
$ ?% D: B6 S% b! v    set my-phase -1
  o8 m- j1 @) n- l# Z3 D' s' Z5 {. Q    set pcolor brown + 3
. F9 T7 P: m2 j: f7 J# U# m  ]
3 i0 f, `3 K3 y# W6 Y
# X0 S( ?! y1 R! [" i  ;; initialize the global variables that hold patch agentsets9 h2 D2 Z% e% U8 g0 m
  set roads patches with, {% N/ r4 m. h% ^9 r* f. _6 R- f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; |* h  m5 T6 V# D- W- ]2 s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 R+ X; _3 g$ Q) T4 u+ m  set intersections roads with- {( I' S# C* m5 p/ R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
# i2 L/ ~2 A0 K8 Z% r! ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& [  M* }( u4 ^
- J* ]( e3 \, D+ |6 K  ask roads [ set pcolor white ]4 h7 Q% K4 p8 K4 |2 d8 [' `
    setup-intersections3 _3 Z- s& k  H1 C; s
end
0 f5 ?  s4 F8 L, [/ l/ t其中定义道路的句子,如下所示,是什么意思啊?6 e+ a. q" C' [' n! E
set roads patches with; J: y9 @; Y& Y' v% ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# y( ?3 }/ D0 m& u" @& I0 j, Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], M6 ^1 N# v, P1 u! e$ y  ?& Q, |
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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