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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 q  L3 W6 _* a: s% k3 q
netlogo自带的social science--traffic grid这一例子当中,+ U! ^% T  L( Q! O( M" {
globals5 U( m! Z# R  {6 F# s
[1 f  b9 J# x: F+ {+ W& q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 }1 M0 U. N' K, K0 N  g8 U
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* p# L, B3 d; ]  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
# h4 o0 u4 K! b                           ;; it is to accelerate or decelerate- y  p8 C- `, T6 s% {
  phase                    ;; keeps track of the phase; b3 E3 u& j$ Z5 ?# h; {
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( z6 P9 \  w8 K4 [, P
  current-light            ;; the currently selected light
! R9 s& G) y; i. ?. ]
9 s3 U0 m) L# x3 c) O  ;; patch agentsets4 v/ R3 j) W+ z4 k. b4 W- w$ W+ J
  intersections ;; agentset containing the patches that are intersections* L' O; o5 I- X# T- w: E1 n
  roads         ;; agentset containing the patches that are roads
$ Q; o" Y' y2 R/ j0 O]4 F$ g) ^# n* h$ X
; Y% @& s0 N& J" a. g- r2 \- b
turtles-own
  l7 X5 V, Q3 N5 a! \[
8 K0 ]8 Z& R9 l) u  speed     ;; the speed of the turtle
7 q7 E& I" y6 T5 P  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, P' w! b  ~4 z# C! O! J  ~
  wait-time ;; the amount of time since the last time a turtle has moved
/ {  S! J" m5 j/ v]# W: e$ ~! C: `4 h* i

2 z7 O7 ~3 G% e1 r2 _; K2 \patches-own1 y7 a" k. e8 @. i. A
[3 G: O# M: ?" |% {. d" d
  intersection?   ;; true if the patch is at the intersection of two roads  g( V2 d8 {4 _0 ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( y, }2 b+ y& g: g                  ;; false for a non-intersection patches.
( |- B5 M2 L3 P- K% L- Q1 g  my-row          ;; the row of the intersection counting from the upper left corner of the
* U: p9 }) q$ x- P# Y" A                  ;; world.  -1 for non-intersection patches.# z; k6 q; X* G9 m1 N
  my-column       ;; the column of the intersection counting from the upper left corner of the
# m- b3 _. I, x/ W) ?. c+ V                  ;; world.  -1 for non-intersection patches.* U1 E+ ^+ s; w7 k3 P
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% G) p5 M# ^+ r. S% O( [( e  auto?           ;; whether or not this intersection will switch automatically.& V* y3 K' |+ T% ^$ O
                  ;; false for non-intersection patches.
7 n$ J9 n/ G2 N3 Y]
0 v: D. B" a" d# Q" ~
9 W7 x9 d2 }) z, X& |8 n# L4 }" T1 k
;;;;;;;;;;;;;;;;;;;;;;7 g& ^) P$ U$ v
;; Setup Procedures ;;  t) j9 R% a, }% W- B/ ]2 [
;;;;;;;;;;;;;;;;;;;;;;% b0 J9 h7 B7 N) {% q' B

! n0 G! \/ x% Q. y' R4 {;; Initialize the display by giving the global and patch variables initial values.
, a& H, u  N9 Y. q6 D8 Y" b; U4 u;; Create num-cars of turtles if there are enough road patches for one turtle to" m2 |/ U- v* ?& n: k" P
;; be created per road patch. Set up the plots.# ]. m0 ~$ D# q! u7 P" V
to setup/ T* Y6 f# Y" V- R0 L/ {: Q3 F
  ca
# @7 }- O/ Y+ a6 k6 V  setup-globals
- G  Q7 F) |  [6 f+ j, T4 I, W4 L$ g6 Z, k  A0 Z
  ;; First we ask the patches to draw themselves and set up a few variables9 x9 ]% d" x% v9 h
  setup-patches
% D" e, L) c! ~# F% v  make-current one-of intersections3 {: J: q: L, q/ x) Z
  label-current
; o3 Y! |4 |; w9 _5 y6 J1 K7 l1 T" j: v* J% I# h) m
  set-default-shape turtles "car"" A" M% Q6 A0 r8 Q4 X
1 B( D+ H& t) y# K4 I$ `0 j# ^
  if (num-cars > count roads)
8 W8 D/ ~/ J8 z5 }! i! z3 _  [
5 j  r) r8 P% d- b" b; P2 c8 B- Y    user-message (word "There are too many cars for the amount of "
! M# h) p% D- ~; f1 {                       "road.  Either increase the amount of roads "- B" [4 h& \5 `  U6 o0 O! k
                       "by increasing the GRID-SIZE-X or "
1 I% y, _+ u* U                       "GRID-SIZE-Y sliders, or decrease the "
9 E5 s; x4 N1 w                       "number of cars by lowering the NUMBER slider.\n"5 C# v  t% ~; A# [! }; q) f3 H: m
                       "The setup has stopped.")
6 D7 s+ j9 ]" ?! ?- K    stop/ s7 J$ H* S  Y7 z/ X
  ]  E' R  i8 M: D8 q& O  w: l1 \* N/ M
# Z! ]/ b* U4 f0 s2 o5 a5 S
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: I, `# D8 C# c4 S. N5 H* P  crt num-cars' }  M$ ]5 D9 x/ ]8 ?
  [
; w$ Q2 U' r8 C/ c2 R" T' H& }5 ?    setup-cars8 j: q- X( f7 a0 _% |2 N
    set-car-color
" L5 f( ]" d0 `' K, h$ {    record-data
, `: M8 Y7 D' ~  ]
& n& Z# m& e' ]1 z
9 a' D) c7 m7 a" D2 S- Y- ]  ;; give the turtles an initial speed
8 _6 T4 p% i! ]& x  ask turtles [ set-car-speed ]4 ?# m: l+ l$ Z! C3 J* L
2 b$ x0 V8 W/ J% {+ f
  reset-ticks
5 A: s& v- s( J$ ~( B/ Y; v" W8 R  Lend! y- o) d8 f, {/ k# c/ W

+ F. r2 `+ r2 T! l/ V;; Initialize the global variables to appropriate values
3 [. }! b, |+ _* Q; q, I) V( d. Oto setup-globals+ b1 Z5 x7 S7 Y4 ]  ]+ V
  set current-light nobody ;; just for now, since there are no lights yet
- t" B* X1 |- ]1 ^7 z  set phase 0
! ?" j  u4 C2 E9 }! W6 U  set num-cars-stopped 08 W% H3 k% N/ g4 @6 F
  set grid-x-inc world-width / grid-size-x$ @/ i0 H! q, z, }( `
  set grid-y-inc world-height / grid-size-y
  w; B$ f8 P' ]3 }
) Z$ ^. I8 l$ b  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 d! o% G/ c9 G/ k  set acceleration 0.099- [. r* y' z$ |) J: q. g; s$ n8 H
end5 I. U# d/ y' R1 Z) c. K5 p0 V$ z

, z3 H4 h) ?) N  q# X5 U;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" S- j3 v7 F8 n" L& |' B;; and initialize the traffic lights to one setting, r5 O# I! ^- m1 k8 @2 S& e
to setup-patches
7 Q, S5 c2 g3 Q1 `0 e/ U6 @  ;; initialize the patch-owned variables and color the patches to a base-color
) c% N. j5 }( |5 O( T4 c' u. |# W: X  ask patches! |7 {) {  ~8 |1 x3 O
  [
! u' N4 ?3 N. d4 i2 E. y: Q    set intersection? false
' Z# l- n9 w, x2 x7 H( d    set auto? false# N6 z" \& I0 L! L1 D# B  m8 K
    set green-light-up? true# `$ t  T0 e( Z9 R+ G) E3 _
    set my-row -1
6 I: ~- Y9 k8 E+ H; ?& o    set my-column -1
( o9 L* c; k0 i) u. k6 x8 K" |" b$ @    set my-phase -18 s$ B* o: E8 V) s
    set pcolor brown + 3
# D% J7 s7 S5 A  ]) @; x8 x! S* }# J9 M9 T) h/ S

' A9 G. w" `, P  ;; initialize the global variables that hold patch agentsets
0 F7 i* w" `- N, N% {/ f  set roads patches with8 w) W5 t6 O2 z  u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) z( r! M. l1 V# @  e6 V! d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& q/ e8 I( Y  X- Q9 }2 {
  set intersections roads with
" s- G3 t. }( P# h: Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and# O0 S' M9 M: D- A9 ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ L: x. _! r- g. P
; k' w8 O  c! S6 l% g$ d  ask roads [ set pcolor white ]( r2 A8 \& `/ Q4 z: i
    setup-intersections
% s5 T* L6 ^4 y' {& _% `3 Nend
: a& h; n" [2 Z1 ?9 p& _# B4 n  y其中定义道路的句子,如下所示,是什么意思啊?5 G3 X$ F/ T8 s* q# k
set roads patches with3 D0 C: P2 R6 \6 K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- o5 R% @$ I) F; _) ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 m9 h5 O$ b5 K" 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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