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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。
" E; g5 P( f1 `2 N7 V& Ynetlogo自带的social science--traffic grid这一例子当中,
- m/ H# N( U! q5 ^/ Q) X1 rglobals  n6 s( A0 L+ w7 d5 s1 Z
[9 f- |: ?+ ~' L; N' T: g
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
; e# w( ~6 w2 ]2 |  grid-y-inc               ;; the amount of patches in between two roads in the y direction. e$ G& R( Z* R
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; I' J1 s/ ~% U0 X, I# c                           ;; it is to accelerate or decelerate
% z) J; Q4 {. P2 ]  m1 ?* |  phase                    ;; keeps track of the phase* D% m, {* v4 m# ]1 A
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 g- b9 P; x7 J4 c- P4 D; r. t
  current-light            ;; the currently selected light* x" v1 b. v! g7 x/ [
% ~( b" E% Z" w) D
  ;; patch agentsets
( q# O: B5 D1 P  intersections ;; agentset containing the patches that are intersections
' X0 W( s& B# B% u. t' G" R  roads         ;; agentset containing the patches that are roads
& `: ~9 G( f& _8 {7 N& S]
( a5 n/ _* ]2 p4 p0 F0 d' M# [# X
turtles-own0 m$ M6 F( ?0 ]. l$ A+ n/ z5 E
[' W& A0 c0 M( `+ g& N! V6 ^
  speed     ;; the speed of the turtle
: _6 E; ~- i* q* P. r8 @# G  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 ~  k" D3 x1 Z
  wait-time ;; the amount of time since the last time a turtle has moved! e- e' W" D$ w9 \
]
( n# p) Z  v+ y, u
6 s6 u2 T# _- Z/ L' M7 B2 xpatches-own- s, A$ N4 g! q/ a  k
[
7 H/ K4 N$ B( ~* l  intersection?   ;; true if the patch is at the intersection of two roads
9 I2 c- Z6 U+ L1 i& d, s4 ~& p  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ x% f8 f& M- x' p: j" C" T                  ;; false for a non-intersection patches.
: q% T& J2 w& E: s+ e  my-row          ;; the row of the intersection counting from the upper left corner of the
! T7 k% V4 Y9 P; F5 i7 @+ d                  ;; world.  -1 for non-intersection patches.6 d8 Q, m2 C5 {  L2 a) H# M0 W
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 i! X2 D% M' K8 y8 T( r                  ;; world.  -1 for non-intersection patches.
; M" U7 |; P& R( ^- ?: ?- `  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.5 q9 q. N$ G4 o5 p* {
  auto?           ;; whether or not this intersection will switch automatically.
' B! ^# G6 u' o4 N& s4 |                  ;; false for non-intersection patches.4 e) k; q3 T8 }) U" y
]
3 g, c+ f4 a3 J% X3 b' |: p  [- ?/ _6 @* c
& T7 m4 Q, z, |' `% C' ?
;;;;;;;;;;;;;;;;;;;;;;" @- l! {! k3 a4 j8 B, Z0 E
;; Setup Procedures ;;
9 m, {& r1 G0 x2 r;;;;;;;;;;;;;;;;;;;;;;
2 M1 |1 f6 `/ h
  Y/ }: p  X- d( m4 C;; Initialize the display by giving the global and patch variables initial values.4 c5 h) i- i5 \; K
;; Create num-cars of turtles if there are enough road patches for one turtle to" z! V6 N9 v3 U: V' b
;; be created per road patch. Set up the plots.
' V. m+ f/ K- y# L( X7 N" Lto setup3 l' w2 }9 o  N& E3 L7 T
  ca3 v" H2 e% H3 L# |3 w; h
  setup-globals( o& r. P3 i7 E) i, V2 Y

% ?6 U/ d& [0 X2 m: h  ;; First we ask the patches to draw themselves and set up a few variables' T+ z: W3 u3 F" D2 B, B
  setup-patches9 J1 Y8 J1 V0 Z7 g# j& i
  make-current one-of intersections/ |8 b: e& X% w2 {
  label-current
! w& Y, [" c% a& K) V5 J$ H6 x4 `
+ v, s5 J% S1 s  X  set-default-shape turtles "car"
) M, U' [& l* l& Q: d6 |) U2 i& y% U3 |: u1 B
  if (num-cars > count roads)
% f6 E2 }/ Q3 j5 C8 }  [
. T3 S) m1 _9 q* `    user-message (word "There are too many cars for the amount of "
# C% q6 \  D( @$ G2 q  y8 r4 U2 C                       "road.  Either increase the amount of roads "/ C/ t( G, I. }. s/ Y
                       "by increasing the GRID-SIZE-X or "
, j1 R9 E! Z& K                       "GRID-SIZE-Y sliders, or decrease the "
$ h3 v* I: l9 Z8 P8 a                       "number of cars by lowering the NUMBER slider.\n"! Q3 K+ g2 _) \' ~$ ~
                       "The setup has stopped.")7 `( Z. L5 ?& v  F% V
    stop% Y) C, a, R0 n
  ]- x5 R( M. F; n2 M* z* V

7 k: A: X7 R! W1 S8 Q  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
! `6 f4 O, s, i6 w% y9 E  crt num-cars
; C' C& S1 C4 \0 I) k5 X( M  [# o2 h$ `! c' m
    setup-cars
6 z3 D# v/ k0 k8 p3 \    set-car-color
$ e$ ]- C! o4 @4 w# s    record-data( C3 P% @' N( j: I! j
  ]6 ^' p- U7 F  F. A

8 p3 [8 W- n1 h+ z1 R/ C* W" ]1 u  ;; give the turtles an initial speed
1 w1 Q- h$ o1 j# Z  ask turtles [ set-car-speed ]6 G+ a& o5 V# a* f/ |
$ B* W+ B. Y, t, p
  reset-ticks
/ U7 K6 e- x4 y& a6 eend
  i  S% r: X, B* Z9 _  u- R& v! @" d- U; T) D7 ~/ x5 n$ F
;; Initialize the global variables to appropriate values* Q, ]5 h8 \) D) x! ^
to setup-globals
0 i% T: I$ }1 N( L/ R  set current-light nobody ;; just for now, since there are no lights yet( z4 t3 f, X  H* u& V
  set phase 0
6 @2 e8 S3 [' \, i4 l" N! l  set num-cars-stopped 0  ]* I, S3 l) i' L/ y
  set grid-x-inc world-width / grid-size-x
0 i, |- s  G1 R  j  set grid-y-inc world-height / grid-size-y
" h0 |0 v3 ^. Z+ p& L* x3 k9 b4 S7 d& M) C2 x
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- \* K5 P* I4 C$ a' t
  set acceleration 0.099% G$ Q( [" B3 n0 n- ?2 [  z
end$ t% f( ~; z- G5 J
# g% a5 P2 i1 V7 G) u5 M
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 M0 N( d0 g& U( Z;; and initialize the traffic lights to one setting% s9 b% x7 R$ L. ^; e
to setup-patches
* T/ H3 ~) |, D) V1 c8 w4 [' k9 X  ;; initialize the patch-owned variables and color the patches to a base-color
/ X  m# E9 F! h8 u  ask patches
4 j- W) Z+ z0 `. Y: W2 N  [
3 }- e3 e. t) ?6 {! H3 h# e    set intersection? false
9 v8 x' c9 o/ c$ ~    set auto? false
! q+ `# J7 ^& ]3 x# b/ D) p& F    set green-light-up? true  ?; O  K' b9 X5 P1 R! I9 a
    set my-row -1
3 j' b3 X! n& f. t0 D    set my-column -1/ i# A+ Q0 g9 ?' [5 {
    set my-phase -14 T( W$ R1 P; {8 W* e  h2 J9 q6 B
    set pcolor brown + 3
2 K8 {! G- C# b: Q  ]
" b0 K2 V* A# p# P
* D' U6 z! H# P- G6 w  ;; initialize the global variables that hold patch agentsets  g1 G& i6 _4 r$ e
  set roads patches with
4 Y7 [. @% E1 f. m. I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 P/ T3 ]7 s" _' A$ ]6 k, E+ P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* K0 o8 ?: }, C) p  set intersections roads with
" @. W+ F; ?5 g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ O. s/ j2 x& t% j) c; B5 t) y5 J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& H8 ]: Y7 }$ A& L( n) O  N1 m

  Y1 ?) z2 ^# o+ I  y. n0 f  ask roads [ set pcolor white ]3 M. {7 C5 x( [- H- o5 e8 X8 M
    setup-intersections5 j7 k5 H4 d' o! U
end" ^4 d; J' g# @- M. X# k0 T
其中定义道路的句子,如下所示,是什么意思啊?
/ F& ?8 O: O( x" r$ T set roads patches with
6 J) b/ g+ N, p% J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- X1 R7 M4 K6 I8 Z$ a# r; L1 E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 Z' |+ a: S# f! Z& O9 O3 x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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