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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' F' v1 i, e1 O: {( ~
netlogo自带的social science--traffic grid这一例子当中,
5 N; _  i/ f5 E% c; a& Gglobals) j1 D; ~* F- D" c) E
[
4 i& W$ U! l  }0 t" E  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ u# U) F0 ^; I4 f" H1 t; g
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. X7 K! h1 [& Q* Z! ~! u/ [1 J; v  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. Z3 ~7 @* \# h6 a$ r* u' D% O
                           ;; it is to accelerate or decelerate
5 \, _2 [; k3 |" D$ L; e2 J9 D  phase                    ;; keeps track of the phase
! H$ f" ~7 o  Z& P  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 V* A) V- {* n  v  current-light            ;; the currently selected light
2 E, e' X3 P  H4 U4 `4 k2 w7 e1 G" p0 L% g+ ^5 d
  ;; patch agentsets
- @9 e  A% X% C2 H  G# X: S  intersections ;; agentset containing the patches that are intersections5 T1 r2 q9 \1 B% {
  roads         ;; agentset containing the patches that are roads
9 X* [6 i7 ]6 u; H* x- q]
: R$ k/ T- i8 M
$ B, A/ L. @: u. c! ?turtles-own
5 p! d" _6 q, ^% j( g% e! u% U[
7 G  q' |1 m4 }% i" F7 t, `  speed     ;; the speed of the turtle$ P# j& e3 Q5 G( n  x# |2 {
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 n, v; D* p$ D/ ~3 o! X6 f
  wait-time ;; the amount of time since the last time a turtle has moved8 V- n, r% p/ P
]# B1 t+ w( P+ b1 ~+ s0 X
: b) Z% ~' i/ A( F5 \- f
patches-own3 N3 q  e3 ?. u! [
[
2 ^  ~: V0 c. }+ \, C  intersection?   ;; true if the patch is at the intersection of two roads
" {/ d" U& h* i+ I8 v  G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
7 d+ D' J, }( L, P  w" f                  ;; false for a non-intersection patches.2 b6 @2 X& R( Q+ s2 B
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 K4 U3 G7 m5 Z( B. {: o+ j- S  y3 ]                  ;; world.  -1 for non-intersection patches.) Q* q( |$ C7 }4 ]
  my-column       ;; the column of the intersection counting from the upper left corner of the  [- |, @! U: b5 U+ h
                  ;; world.  -1 for non-intersection patches.
& d8 {. X7 ~4 v) X, I  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
, d% d. }3 A! r$ `* w+ l1 c  auto?           ;; whether or not this intersection will switch automatically.# C. ]2 |! F% s, V1 Z" Z; c  i
                  ;; false for non-intersection patches.0 |5 x+ A; L+ P# P$ }/ U0 M" c) R
]
5 ~  F$ n7 i3 @/ f. L! ^+ h9 N+ B3 B8 n: F$ `2 |3 H

6 v# ?! }: N2 W; q* ]) l) a* s;;;;;;;;;;;;;;;;;;;;;;
1 |1 K4 E* K% B' ]3 g6 h;; Setup Procedures ;;- \$ J) e* {; e# P/ y8 ~* h/ U
;;;;;;;;;;;;;;;;;;;;;;# d6 d9 {5 b2 f! W+ b; l; @
1 {% N: F3 P* G4 W" |, Q
;; Initialize the display by giving the global and patch variables initial values.# C' C% h" T- K
;; Create num-cars of turtles if there are enough road patches for one turtle to' _& i5 C) f3 i2 \( v; n
;; be created per road patch. Set up the plots.
$ L1 m$ g3 a) T5 m6 R* d* P5 ~to setup
6 q, i2 I7 F& Q  ca+ t: N/ F! q8 T% u) Z
  setup-globals; V+ P7 p8 u# N

, B* c4 {' u0 D* S  ;; First we ask the patches to draw themselves and set up a few variables
2 W9 v3 k  O) Q7 Q: i* J- J  setup-patches" I) f  p; F% m* b, {2 U
  make-current one-of intersections. e' ~* X2 C7 K
  label-current, N7 s3 |+ S7 X9 F1 c6 ?6 ]5 f3 _

, _( y9 t, K" U. w  set-default-shape turtles "car"3 n0 _. _1 ]: Q6 \; J9 j- U# i
2 C2 d* L2 ]/ |7 a* V1 ]
  if (num-cars > count roads)
. F9 q( E: U; U( C7 A5 M  [" a. k- j/ \, [; c& ?2 Q
    user-message (word "There are too many cars for the amount of "
$ E& u# Q- A/ E4 P+ n                       "road.  Either increase the amount of roads "1 Y& [( _: W0 b2 d9 F) w- D
                       "by increasing the GRID-SIZE-X or "
8 z. j+ q6 c0 q+ E( N: K0 W                       "GRID-SIZE-Y sliders, or decrease the "
3 v) Z, @9 C2 [$ w$ i                       "number of cars by lowering the NUMBER slider.\n"4 r" u" `1 c; p% b' ?
                       "The setup has stopped.")( m! I* _" \7 ~& X# ^. \3 S" Q
    stop
' p: o  a9 G# [7 J  ]
7 B; V$ t7 c# M8 e
8 W/ V" O; l; z) y* N" [! F  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
+ K3 p2 l) e$ b# ?: ]( U  crt num-cars8 J5 r3 \) [" D1 x7 @  c
  [
, Z2 Y- f7 a& y$ J7 ?  M    setup-cars
8 O" \" g  l7 ?* _2 o    set-car-color. k6 @  N+ w9 m! V
    record-data
# X: ^/ M( z& S3 {8 j) j0 B. e  ]$ \) w3 s! e" V  g$ q
$ H; Q% X  c' s" X# A' P
  ;; give the turtles an initial speed
0 A+ p- `' Q& w. r. b4 j" L  ask turtles [ set-car-speed ]
( \! a  j0 k4 U* O2 P3 a$ k5 W$ x* ], d. x% V2 I; K/ `- {
  reset-ticks
$ R4 Z( ]; S& S) f# M9 F  M2 Oend
* ~* l% k9 O2 o2 T* _/ T6 a& o8 l0 v" o; r% ~; y
;; Initialize the global variables to appropriate values4 X  m$ y6 n) @' z1 w9 N
to setup-globals
8 W) {) H7 `5 R" Y* v; F  set current-light nobody ;; just for now, since there are no lights yet
* Y/ O+ B- g' c  set phase 06 N1 E; o: g4 V3 T
  set num-cars-stopped 0
. Q& f" x# B; }+ X& D2 c0 w  set grid-x-inc world-width / grid-size-x
; G& p/ ]- U& f3 N, N' Z( e  set grid-y-inc world-height / grid-size-y# L) G9 A! _6 j, W$ ?

1 Q7 v/ S0 I; p, ~9 M' j$ U  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- r" p. ~# a: r& P
  set acceleration 0.099
/ H" H3 u+ r% G  |1 gend: ]2 d5 R5 @( k9 t$ `9 V- w

& A) R( L6 E2 t. v. I' ], N;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ Q( H  b0 S  M( Q3 `" K
;; and initialize the traffic lights to one setting5 V: e* Q) s- T8 N9 ~- N! A" z
to setup-patches
4 H' ]% p* v' N0 t  ;; initialize the patch-owned variables and color the patches to a base-color/ E3 E# O5 r2 U- U4 T3 W% _; |, S* w
  ask patches: {) {) D/ f) Y5 L* a6 S+ j$ d
  [
9 ?1 k3 J) a3 p% |  s$ W. d    set intersection? false
. T( K& s! i* a) ~) j0 _    set auto? false: G! w$ s& S. h
    set green-light-up? true
3 }. p* M6 i; W+ j9 ^7 C    set my-row -1
# e( f2 C8 D+ P' b1 r$ s    set my-column -1
3 l' z" ]* I6 r7 N. C% Z, G    set my-phase -1( ~! d$ e! ~# F. p/ [% d
    set pcolor brown + 35 M+ i3 B' o* c0 b' s4 V
  ]
$ f% [$ Z0 j' C3 Z3 j2 t
" W2 ]+ @+ `% z  ;; initialize the global variables that hold patch agentsets
% y  W5 U. U4 A) w7 R  set roads patches with7 c7 P$ R8 s! ^; a0 E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& ~$ u5 L( B& t' W6 o9 n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* o: Z5 g0 ^6 B' m! j/ B7 n
  set intersections roads with
! G' l, ]4 c2 r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 Z: P; Q6 h2 N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; E  L" {  }$ z% r- y4 m5 b7 }
* g+ f" [% d5 @$ y
  ask roads [ set pcolor white ]
4 n$ V: I0 a* d    setup-intersections
( v5 A( d: e) ^# I5 ^3 V* [7 I, f0 _end
. R0 ~, j2 K& ?* A" |其中定义道路的句子,如下所示,是什么意思啊?, \3 Z0 e! l% M
set roads patches with" @; ]' C0 D+ O4 x( Q$ O% ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 J; f1 O, N' i' _" g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) I" m3 t! q3 r8 X( B: [2 I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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