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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。8 V* `& E& \  d: j- ]
netlogo自带的social science--traffic grid这一例子当中,
' R1 f, S4 P$ K5 b7 D& F/ }globals) Q$ l$ `/ ~# k- `$ J6 W; M% D( x
[5 x5 y6 ]8 b& e
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 i% t3 `, r' r/ h: ^6 H  grid-y-inc               ;; the amount of patches in between two roads in the y direction( n; r% X8 `9 w  o) B1 Q" I$ v
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 ~! h: L" O: e; l3 f; ^                           ;; it is to accelerate or decelerate
+ g- h: S( x& b* R  phase                    ;; keeps track of the phase
0 a. h) _$ m8 _6 n; _6 B  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. _- d) h6 q% q: e9 L
  current-light            ;; the currently selected light
& ?  Q' p/ V, ]. u; d
3 d; K' ~/ e3 G" M  p  ;; patch agentsets. [& q* P' f, b; q. ?5 Z$ Y
  intersections ;; agentset containing the patches that are intersections
( K5 H! I+ H! ~  roads         ;; agentset containing the patches that are roads  a7 L0 |9 `( b
]# X- \# ~8 g% M2 k( G2 [
7 T- A: x# i% x, c
turtles-own
; g3 @) @6 p1 b" {/ w/ d[
5 l  L  R# L! ^7 b  speed     ;; the speed of the turtle0 N2 S2 {! n3 g/ e4 W  |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# k/ E2 W5 U+ t* |# c; Z6 X
  wait-time ;; the amount of time since the last time a turtle has moved
& Q% }6 R( M" h, q6 p' F]+ Z: |* R. R3 t, I

4 ?- _  W4 f5 t8 npatches-own
; c! r4 T# D: ~[; S$ ^6 U9 R3 N6 D
  intersection?   ;; true if the patch is at the intersection of two roads
+ i. U2 r7 }; \4 n9 g% l  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 p# b+ I0 g4 p  }  d; W6 v3 q                  ;; false for a non-intersection patches./ p7 D0 H$ [( Q- J/ u6 C+ ^
  my-row          ;; the row of the intersection counting from the upper left corner of the$ i2 Z8 x) e# x& d! t& J
                  ;; world.  -1 for non-intersection patches.7 K; l# k; t. g+ c2 _: i1 A
  my-column       ;; the column of the intersection counting from the upper left corner of the
7 Z  \/ }/ X8 B9 n4 q                  ;; world.  -1 for non-intersection patches.8 a& j# I' o/ E  i1 x
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 \7 }5 }4 ~" f6 ]% S
  auto?           ;; whether or not this intersection will switch automatically., R: ^$ N5 v4 t! ~
                  ;; false for non-intersection patches.
+ O  K# E# E3 `2 q]$ J" a2 A. n; [4 @9 W

% S6 u" _' x  c% q# ?; ~6 O8 p
* F& F! A8 ~+ a, @;;;;;;;;;;;;;;;;;;;;;;; t1 u9 {) \0 R+ j/ V" F" r$ e+ j
;; Setup Procedures ;;
4 |/ a! w7 m$ V9 H: l. Y;;;;;;;;;;;;;;;;;;;;;;
" I! N* }" F* s! l; w1 d8 _' e* w, @1 b! W) ~# s
;; Initialize the display by giving the global and patch variables initial values.
/ @( t* i: |. I& b  d2 Q% W9 U0 ?;; Create num-cars of turtles if there are enough road patches for one turtle to
: H* l, z3 ^+ B! K  C;; be created per road patch. Set up the plots.
$ z0 n' U1 @( t# x2 W: h$ Zto setup
% R5 n+ \- X  }  ca
! z7 f/ D, y9 D8 C% X" D  setup-globals
1 O& T9 X$ E0 Q
; W2 F  {3 n/ x- r: v7 w- n/ F  ;; First we ask the patches to draw themselves and set up a few variables# [3 s3 u0 L$ D
  setup-patches# ?. {, e0 B% b0 c6 v' E6 d% U5 W
  make-current one-of intersections7 F/ M& j5 I0 V9 f) B/ g7 I5 h
  label-current' N9 I& J6 J7 ]: z9 S+ ~

3 {6 n& V' {0 U3 g, G/ j  set-default-shape turtles "car") R' B$ [" V2 _$ J5 v& m% p
, [, y& |" E$ j* s8 D. S
  if (num-cars > count roads)
4 }3 Y1 ?7 m( R* G3 z  [
2 \6 h$ Q- j% f5 P& A! _6 X    user-message (word "There are too many cars for the amount of "
9 P! J& n" t3 n3 j                       "road.  Either increase the amount of roads "! H+ L. g  Y$ q9 D! Z
                       "by increasing the GRID-SIZE-X or "- n+ h! h6 l2 X' e- o- n! q& L
                       "GRID-SIZE-Y sliders, or decrease the "
2 X7 o1 K0 }- \% t$ w$ Y* G8 A2 ?                       "number of cars by lowering the NUMBER slider.\n"
! o' j4 D4 {3 ]% C* ~                       "The setup has stopped.")% T4 p1 i; v. l+ J+ f2 M
    stop
$ Y7 ^( p& c. x, D% [. v4 F  ]& h- [' ^0 k5 J

$ ?5 {" e2 w, V  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" ~3 H- K0 d7 q! [
  crt num-cars
- }) A# r& X+ x, ?) ^  [
1 P: r" v2 [: }0 z6 R5 J- V    setup-cars/ W4 h2 J: Y$ [2 ~5 V2 o! }
    set-car-color. o- G/ e* W' w( r- ^/ C+ C
    record-data
- _. |4 ?* K8 @  ]
' v- U9 Z1 O8 a% D2 u% ~$ s  n) Q; J; N5 i% I8 z* k  J  V1 w! u
  ;; give the turtles an initial speed/ T1 q# w9 M' n. K2 M( p3 `
  ask turtles [ set-car-speed ]( M1 v7 q/ r6 }% t0 I: ]8 t
: Y% H% S; [; V
  reset-ticks
3 }6 n1 m5 i% ], b. Z. D- yend4 e5 x( A: p% y- b

! \3 ~9 c, O3 j1 M* S& d7 x' i;; Initialize the global variables to appropriate values" A. Q! F% e9 v2 |  r: \# Q
to setup-globals
* m- d' `( m1 I& q0 \( E- E  X; S  set current-light nobody ;; just for now, since there are no lights yet
8 i) F2 g8 ]2 u; H  set phase 07 O3 S. g/ U5 X" j1 [5 f! d; O. e: ^
  set num-cars-stopped 0/ @% ~: b% Y+ ]- P3 X9 b( ~
  set grid-x-inc world-width / grid-size-x/ @! L$ r4 X. Z( f: g$ t) H4 m* b
  set grid-y-inc world-height / grid-size-y; C2 C# K0 c3 H  ?/ m+ o

, r' [. S* l  C! g( s5 q& p  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; Q0 `: F# B1 d
  set acceleration 0.0992 |( c" H' ?' L) N! Q7 m7 m  p
end) E3 m1 n: z# n$ @

0 G- E8 P  K" c5 I* a7 d( S: P;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 I7 p! v4 w- E% Z; ~5 v4 w;; and initialize the traffic lights to one setting: a: r% T+ F9 t6 O# {1 v
to setup-patches
( K. z1 q1 d  D' n  ;; initialize the patch-owned variables and color the patches to a base-color- K8 G# t" z4 R
  ask patches
$ W/ }. @: }9 G! Z+ }2 @  [
0 y8 q# u# G( f0 {2 a/ O" k    set intersection? false
- D, T% k; ?7 c4 W: q    set auto? false
! `! L; V% {, f8 d4 f0 e# N    set green-light-up? true
  ]& g- l, _, C0 v+ w7 n& Q9 z    set my-row -1/ p& M4 R/ K" r0 ?1 h: w
    set my-column -1
/ W" K% S0 s' d, K  ^2 e4 H    set my-phase -1
7 D6 |1 X4 G1 H" u9 c3 O6 X, i& g    set pcolor brown + 3
3 e" X) {7 s2 H( v; z8 |  ]0 e2 ?' }9 n& |6 u8 x. z, D- o5 Q

: d7 \' e# `% }& L3 ^$ X  ;; initialize the global variables that hold patch agentsets4 C) h4 ^4 N' ^8 W0 n/ m- c; y
  set roads patches with7 d2 c; E; \% |* R# ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 y* p6 @5 \6 s8 a; Q4 E. w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], L) V& Z, J, t5 ]* I
  set intersections roads with1 ?5 D  P* x% v  F7 @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 e$ r# [* F8 n/ G! e- t' b& |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 t3 I: G3 U7 @' h
$ ~0 L7 ~( ?. L; f
  ask roads [ set pcolor white ]
3 i; v' A+ ?8 K3 ^    setup-intersections
* T3 u/ Y1 E, t" D0 O) |$ lend
$ Q7 A9 B, e$ P* X* v其中定义道路的句子,如下所示,是什么意思啊?5 N0 K. {  A  r0 N
set roads patches with
# n" a4 b, x4 q; E. h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" |) C2 w5 z' z6 G# [; J0 D6 h" s! H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. z5 {+ D7 s7 f& a8 Z7 d' o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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