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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。
; d! V4 A  a2 _) }* ]netlogo自带的social science--traffic grid这一例子当中,
1 I; z9 D5 K1 ?' N: m6 a# J, }3 xglobals
3 t# L( H, J) T2 v" I[: I: `/ k/ I/ \7 }% v) O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 g' T/ N! Z& f8 k6 w
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ Y; h7 y, Z9 S
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' x& ?4 K0 N4 n! Q- K5 o                           ;; it is to accelerate or decelerate2 x2 c+ J3 G" y
  phase                    ;; keeps track of the phase
0 X+ a& g: q2 C9 G2 I* k  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 o' e; N' R& g6 j% m. @  current-light            ;; the currently selected light
& w6 F' T8 \7 T2 y2 J5 S% y8 c3 C' B4 b
  ;; patch agentsets' V, |) g  D6 T" e2 d
  intersections ;; agentset containing the patches that are intersections0 @* l/ J, x7 r7 ]4 @! s
  roads         ;; agentset containing the patches that are roads
" Y9 n0 V  c/ I- p]- H% U5 X/ _  [5 Z8 x+ I2 @7 N& x, `
  K) X1 n2 q5 u1 F
turtles-own! P* ~1 p. o, U  Z9 p
[
- i7 a: g. c* r' ?& H: f6 ^  speed     ;; the speed of the turtle( u1 v7 j+ p8 n; [- H2 M
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: T, r7 `$ f9 }; w0 b  wait-time ;; the amount of time since the last time a turtle has moved
* j( i6 V" \6 ?]
' T& w1 X, I2 u2 A
& v4 p- u, R$ I; z8 P7 N; E; T- zpatches-own$ D& n2 T4 g0 L; O8 L5 g
[1 i) [7 b; G5 T  g7 ^
  intersection?   ;; true if the patch is at the intersection of two roads3 u# I: `# N) |7 H8 B2 g- C6 [
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 X- `: U4 k8 V+ l) p                  ;; false for a non-intersection patches.
; a; m3 h  P' ?' |" `  my-row          ;; the row of the intersection counting from the upper left corner of the
/ Y6 G2 E- c1 R6 F& C6 W( R/ w' j                  ;; world.  -1 for non-intersection patches.+ X; Y* ?' V8 F  g4 m0 p6 a
  my-column       ;; the column of the intersection counting from the upper left corner of the
: V, O* s9 M! [1 E5 R3 b                  ;; world.  -1 for non-intersection patches.0 `2 I+ e* w9 l8 s! ]* h1 q
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 I% ?+ R2 j9 s- f
  auto?           ;; whether or not this intersection will switch automatically." P3 X' ~% z7 V
                  ;; false for non-intersection patches.
9 x5 R5 M- E$ Q& s0 h7 [) N]
' R9 d; ?. w2 h4 F, }% Z- a# c" [6 v& k4 |& u+ i
  e8 P. _1 v: k6 @; v% f
;;;;;;;;;;;;;;;;;;;;;;
; b- Q# |3 a) i6 Q4 X;; Setup Procedures ;;
& E& R! a9 `4 K+ R  T% Z;;;;;;;;;;;;;;;;;;;;;;
; i$ l( S, Q" s( F7 Q1 i) V$ o
, b: E; R4 h' n! E/ D* T/ d;; Initialize the display by giving the global and patch variables initial values.
; B8 `3 ^' S- L0 k% t;; Create num-cars of turtles if there are enough road patches for one turtle to, A1 d8 E" Q7 b8 K; `
;; be created per road patch. Set up the plots.
) T8 P7 j/ y* Tto setup
; ?/ U/ v4 X+ A  ca
# k6 ?- c6 @0 e' F  ?4 @( p' X7 x  setup-globals: X6 U4 |( B3 w# c# E3 @% O
. _6 B. ?8 Z9 y$ s. ^0 O
  ;; First we ask the patches to draw themselves and set up a few variables& M# ~5 G# O! t% _2 W, N
  setup-patches6 k4 |# @2 s' m2 P9 H
  make-current one-of intersections, F5 L+ e) u" v1 c8 b/ C3 B
  label-current1 S% d) E8 Z$ v5 x
( N  z/ R- P' L! \; ?
  set-default-shape turtles "car"
, u, s7 x* B: i+ e4 [( w
, F6 I7 q% S  v) V) b  if (num-cars > count roads)! x, j! _0 F* ^5 l
  [
& }7 {' M& D: B& e8 R    user-message (word "There are too many cars for the amount of "
/ c0 F3 z2 k, m4 ~2 t% q! @                       "road.  Either increase the amount of roads "& {- s* y) P0 y2 y4 X
                       "by increasing the GRID-SIZE-X or "& l, B; o: E! Z
                       "GRID-SIZE-Y sliders, or decrease the "" }# }; [  @% Y4 k; p% p
                       "number of cars by lowering the NUMBER slider.\n"
/ Y& @9 ?  y- G7 M+ F4 P8 C                       "The setup has stopped.")
) j8 P1 W; U& H2 k    stop0 G. j9 r( o9 |$ p+ W
  ]' d% T' b" e% `0 y  `

  c, w9 s" L8 q' [  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 }9 u& N$ j9 x: s3 z- I+ ?  crt num-cars; w5 k/ V9 H# n3 n0 m" J+ m
  [
: B7 C* T: W4 \  q    setup-cars
. Z. c: o8 C' j( e/ I6 i" [    set-car-color% \! u! }. a3 [3 I2 O1 R5 \
    record-data& D( c& n2 V6 Q% H% W" N
  ]' U& j0 [; l, X/ A% P) W. n

. N) h; E( E; o: E  ;; give the turtles an initial speed7 Q0 Q* d1 I9 t) R
  ask turtles [ set-car-speed ]
5 G$ Q" K1 c4 d; ]- T! b9 X- A( P* L, Z3 o
  reset-ticks
* o* |5 W% [8 n0 v) f- nend1 q2 |% c0 l8 x1 f7 H1 r* {/ W

6 e7 {! e2 L7 B6 r0 a;; Initialize the global variables to appropriate values
; g( m8 b- T( c% C  P0 N2 dto setup-globals$ y7 z# J4 s7 ]* `% x
  set current-light nobody ;; just for now, since there are no lights yet  I( d' h: [* ~7 p- y
  set phase 0/ t) A: O$ }) A
  set num-cars-stopped 0
! n, |( ]! r4 ~, d5 F. C( [3 j  set grid-x-inc world-width / grid-size-x4 Q& q4 L2 A6 `* w! f
  set grid-y-inc world-height / grid-size-y# A' b2 O3 N4 d; e8 r, O* Z

. i; R. r. ^- L) I# U  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 w' F( s, ]3 n5 E* R$ Q  set acceleration 0.099# a" s8 d, o; u5 P' C
end3 l. y+ ~* C, n* F2 `

% q, M( a, E7 H" l1 d( `( ];; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( V1 F' y( V; c- h4 `0 H;; and initialize the traffic lights to one setting
, s# l0 C2 t, ?  K! v# q8 xto setup-patches! B& S/ `' H  S7 K* ?: k
  ;; initialize the patch-owned variables and color the patches to a base-color$ t0 u9 z2 L7 w  Y- Y
  ask patches
1 s; `" g4 k; G$ A: W  [
$ A, Y, f6 n) r* [& o! P    set intersection? false, u5 @9 m/ R1 u+ O) \: j
    set auto? false
8 Z7 e- Y/ U# m  r1 C    set green-light-up? true: p, Q) Q1 k) b! l
    set my-row -1
4 ~% l4 U  [' `5 p1 m% d* T! u    set my-column -1
3 e2 x: \1 |5 l- l) M, Y! H    set my-phase -14 u1 P) p' k* O1 y' C* `7 h
    set pcolor brown + 3
, F5 \, \  d0 Q, y  ]% e7 ^9 U+ u, k* n3 g1 S
  W( u8 ^) P" k& a. }
  ;; initialize the global variables that hold patch agentsets2 `6 Q/ E0 L1 n/ [- r- ]- Q
  set roads patches with6 x' F1 |, o" h7 g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% g8 P5 ^6 ]. S1 J; `" E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& g; H, c' e/ g& A  set intersections roads with
( Q3 ~$ `* N" _6 P, B7 V0 e+ |    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 [' z+ K8 A( S0 z* b2 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 K; a- I! v6 {. i2 _* f
& }+ R9 v: m1 B3 D  ask roads [ set pcolor white ]
: G4 A. j& e+ K8 D+ |0 B    setup-intersections
& W9 c, [5 i8 Q  |6 m7 J8 A3 Aend0 O( n" q4 r$ Q# z( ]
其中定义道路的句子,如下所示,是什么意思啊?
/ Y8 B1 @3 n' c$ a set roads patches with
* u: g" \* [1 O& D    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# U6 V$ Z: I' z0 T9 z: P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; M$ G* ?" g0 z. }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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