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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。
( I; C, F5 |2 [netlogo自带的social science--traffic grid这一例子当中,* f9 c3 M# b3 w, ^( }6 w6 P& G
globals0 \: \1 W# k: P7 J) o( `. L
[
+ v* L+ o% u9 P0 u; G: I9 r  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ w# W8 u. d- j% Y( Q( K# v" Z  i
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: C1 k% F( b! c/ C% ]2 ~  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& `% E% D! b' G& F) [
                           ;; it is to accelerate or decelerate
( S1 h9 v* @2 E0 a. B5 z+ l& |8 u  phase                    ;; keeps track of the phase0 M- r6 i, I; C# [* E* Y* A- H
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 u# j& L6 S$ Y; N! F/ m
  current-light            ;; the currently selected light/ Q- ^% ]+ v; {+ F: z  U7 e5 t
' M  [% i5 `- m
  ;; patch agentsets- c+ z( T$ ]0 ?/ u: v" i
  intersections ;; agentset containing the patches that are intersections
/ P7 Y5 x! C+ G0 l  roads         ;; agentset containing the patches that are roads4 N! e7 ~# ~  T- S
]
  L8 W1 a, |0 H6 q% f% C
( Y, q. H9 r2 G3 a5 T; Xturtles-own
, l* m5 e) g1 r" i8 F[
0 ^3 N# `" O3 D; k; n1 |8 C  speed     ;; the speed of the turtle
1 }  a4 r' s) U% f  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! b5 e; X  V- z
  wait-time ;; the amount of time since the last time a turtle has moved
1 D0 ~' }5 j7 M  k9 L/ C]
  j( {6 Z0 Y( e( ], F8 n4 h% k
  O8 d, G# ^5 `9 n* S' Qpatches-own
1 s& x7 r4 I" d2 F4 \0 |[
# p9 N( |7 N' L9 T, z  intersection?   ;; true if the patch is at the intersection of two roads
9 o, ^/ m0 u5 x  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
* c$ i9 w4 X' a) ^* b& T: O                  ;; false for a non-intersection patches.  F: S' y5 F) T& e
  my-row          ;; the row of the intersection counting from the upper left corner of the! U' ?  U* [" r  G% G/ |
                  ;; world.  -1 for non-intersection patches.
; [( X6 B' S  R, G9 I  my-column       ;; the column of the intersection counting from the upper left corner of the
8 t# F8 ~' H: o6 w" {. G& r                  ;; world.  -1 for non-intersection patches.
/ j; O9 \5 K0 O  x  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 L' G% N4 b, s  auto?           ;; whether or not this intersection will switch automatically.
5 a* z. y! \9 }  V3 c9 I                  ;; false for non-intersection patches.6 d1 M6 Z: U2 Z$ b; P* g
]+ X, O2 W0 s( u0 O
# ?9 a2 a2 N& \0 {' l  V
1 s$ h7 K0 _! E1 X; k
;;;;;;;;;;;;;;;;;;;;;;0 F7 \9 j7 e8 K9 N7 t& {
;; Setup Procedures ;;; j  w, K% D7 o+ F6 R3 |- ^6 Q
;;;;;;;;;;;;;;;;;;;;;;' I- b+ ~. u0 C  R% I  v

; h3 Z0 r1 ]. L# B4 t3 v6 V;; Initialize the display by giving the global and patch variables initial values.1 Z7 T& S) I' P" S( }
;; Create num-cars of turtles if there are enough road patches for one turtle to: \3 L5 S8 \5 s: h$ O# j0 y
;; be created per road patch. Set up the plots.
1 q8 q7 P: G6 z1 Dto setup7 c  r! e  R/ V% L3 W6 C" G( K' ~
  ca. w: P: b. Z; d$ d" L* f
  setup-globals
  f& c, i9 o# a0 R) w) J. T3 V* M( h
  ;; First we ask the patches to draw themselves and set up a few variables
! ~8 ?0 o! z! @& c2 G+ d) W: M$ y  setup-patches
" T3 g& d: I0 j. z( z' d( r( d( @  make-current one-of intersections
% m+ ~1 Q5 N9 Q0 ^+ m( a. ^  label-current; u2 D5 c$ `4 a: ]! ~* ?, c2 j

7 f5 d+ K4 s) H# K; ?5 J! ~6 @" c# i  set-default-shape turtles "car"8 a; ?) q1 a' S
% T, K+ E3 C) x, x- [  g0 I! v6 z
  if (num-cars > count roads)
- M+ X! c# K. k3 Z) }  [/ i# a! _6 a2 E6 v' h1 ?; Z# W5 z/ Z  A2 ]" d
    user-message (word "There are too many cars for the amount of "! N( B9 L& Z# c& s7 e# y% |/ `
                       "road.  Either increase the amount of roads "
4 e1 m7 r9 R5 j- G4 O" E# s% W1 [                       "by increasing the GRID-SIZE-X or ") t1 y: h- m( G1 l, c" `. `- q4 c
                       "GRID-SIZE-Y sliders, or decrease the ") H7 E4 k1 n7 K9 Y
                       "number of cars by lowering the NUMBER slider.\n"
7 ^+ N! i4 n- Q                       "The setup has stopped.")
, v- {. g0 w5 b6 V2 I4 M' U    stop3 X; h0 [" _6 \
  ]. a8 R8 X" g0 d. e9 F2 T. E
# m  i7 w' J2 e4 P- f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- @0 F( t: n, g& Q( Z* P) A  crt num-cars  M2 I6 J5 y; \! J  t  A
  [
! c  Z& Y9 u6 e3 p5 ~$ |    setup-cars0 ?: g$ M) E% p
    set-car-color8 q( w* A$ U+ v( Q) I: ?
    record-data
) [8 C$ \  D* Q. w. w, `  ]
1 B# J" _8 @4 V1 T& E$ C2 w. |* B. `' f1 P
  ;; give the turtles an initial speed. o  p8 z. ]: p  d
  ask turtles [ set-car-speed ]6 z- N5 z3 |; p. s" ]/ K

; c2 k' K" q$ A" e1 j% h  reset-ticks1 Q0 W) U; t( x4 @
end
0 {0 M1 {; R0 U/ r
( H  A, f) A/ ?3 ~/ L;; Initialize the global variables to appropriate values
; {) q2 i" V1 \! V5 C4 u& ato setup-globals( |1 p: i+ m; z2 j2 s
  set current-light nobody ;; just for now, since there are no lights yet
2 B2 k3 Z/ B4 [3 N7 d+ j  set phase 0& H1 h" o% v4 s$ x
  set num-cars-stopped 0
$ e; u& |" g* L% y: m* l  set grid-x-inc world-width / grid-size-x
3 ^. {+ j$ r8 s3 o  set grid-y-inc world-height / grid-size-y# b2 Z1 L) ^0 [+ ^, ?5 X( q

% {4 M* j* k3 V: x" s. u+ [3 E  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 r) R' d2 g7 Z+ L/ n! ?" N  set acceleration 0.0994 P, u9 h: N1 [- Z* U5 x) R; h4 t
end7 K; f% g& D" R/ A1 o

+ ^% d; R9 D" I9 {2 \; _0 i: I;; Make the patches have appropriate colors, set up the roads and intersections agentsets,3 t' V) m# p/ d! c* B" _
;; and initialize the traffic lights to one setting9 p2 \& W, t9 ~# {' L: U
to setup-patches% P8 F: k# d/ f& e
  ;; initialize the patch-owned variables and color the patches to a base-color# \6 L9 ~! ^% B+ e5 T
  ask patches; _0 z, H; g/ f6 t- R
  [
% a; K9 ~7 h. u* i0 G    set intersection? false2 c3 u3 a& A) Y7 [3 V8 u+ ~
    set auto? false
8 s, O3 Y1 ~& n1 C3 s    set green-light-up? true
/ Z! `3 Z3 J. M; q: h    set my-row -1$ [$ p1 J2 W# \# G9 v  M
    set my-column -1
' u2 i! h# s6 l% }, M    set my-phase -1
& D  Y$ q, s, H& l    set pcolor brown + 3) x$ |4 ^: T+ P: c
  ]
( y4 s: q+ U% ?# Y6 a, K: z: V6 Z9 n% o, |" O8 g3 q2 U. N
  ;; initialize the global variables that hold patch agentsets, m  q8 t. q6 d
  set roads patches with( ^8 [* X3 w( p: u) n0 u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 N7 h9 Z$ P) I) |# c/ D( h9 z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 l# h' W, Q9 h* Q( q# x
  set intersections roads with
% P6 O% @4 q( g5 c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ @( Z1 R9 U7 K: R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: C4 n9 p  n( ]" |% F
1 U9 H4 N9 `1 ]8 }9 f
  ask roads [ set pcolor white ]% w8 G# q7 [1 `) l3 \% P. }
    setup-intersections
- g: R1 e, k; Z1 O5 `$ f/ ]6 d2 Z# e; iend5 o3 Z, K3 {. n" x: D8 c
其中定义道路的句子,如下所示,是什么意思啊?7 M7 x9 |% p5 D+ ]# e7 K
set roads patches with
- i) A4 ~" ?& Y6 [9 Q% R/ ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; f4 ?& m" l: M) \( S1 _! _  y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ q, `, X6 L% e2 P
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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