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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。( p- u+ `8 V# ^0 w& b
netlogo自带的social science--traffic grid这一例子当中,
% [8 W5 S- |& B8 t9 ?globals
* C1 n& J4 E; q6 ^# W[
6 o+ \" J* Q" p0 h' ?  grid-x-inc               ;; the amount of patches in between two roads in the x direction! _& B7 [6 I# d- s6 `
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 O7 Y9 ]+ d2 c; [& u5 B
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 f, Z! Y- i; N- g2 r" |
                           ;; it is to accelerate or decelerate
% P% e3 J# B( e+ [  phase                    ;; keeps track of the phase
7 k: ?4 U! Y. w( B0 q0 k6 Z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" `8 t6 `3 A8 Z1 @
  current-light            ;; the currently selected light
, l& X9 n. v  y( N
3 p2 T9 H! y/ R7 S) H  ;; patch agentsets8 o: K# N$ b: x8 p
  intersections ;; agentset containing the patches that are intersections
+ o, U# I7 q" d( [: `( i+ `  roads         ;; agentset containing the patches that are roads
, D4 U. ^9 m& w$ B]
8 }0 {8 r5 L" f7 p
/ L; G  D% N% T" A. G5 ~8 dturtles-own
7 \$ p- p/ {5 D  v, k8 y8 `[
2 y1 D0 y" L& W" `/ e7 r+ k4 h/ D  speed     ;; the speed of the turtle
& m7 U  Z8 _4 j  s) q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  F2 g9 B) N: k& A2 Q9 d* B
  wait-time ;; the amount of time since the last time a turtle has moved
! g0 B% N7 A7 X' r]
4 i8 g2 O( _7 u) [, d9 g+ A
+ b; i* d$ b  @7 ]% v5 D; m+ Opatches-own
, P% ], u- p, w* }5 S% t[
; a0 n$ Q0 Z: }* Z# [7 m  intersection?   ;; true if the patch is at the intersection of two roads
" k- ?0 K2 d) |* w7 W3 ]  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 b+ A3 e8 U% ^
                  ;; false for a non-intersection patches.+ U& K, [& @) V7 b7 N4 v7 Q
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 `  u( q' a7 g# D                  ;; world.  -1 for non-intersection patches.: n9 N( B( w) S- ?
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 e- k$ \: s! @1 ^7 W                  ;; world.  -1 for non-intersection patches.3 S0 q9 Q, L8 A2 ~
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
4 G$ w! d8 E0 V, g  auto?           ;; whether or not this intersection will switch automatically.1 p( D# s  V+ L1 K7 o% a: n$ i' r
                  ;; false for non-intersection patches.
: p2 I( q5 b) j! e8 ^' j2 j]
9 E1 j+ V0 q5 ?0 }& O3 t% b- ~8 @7 {* q
- u( h0 Y! Q0 A1 a( [2 }: `$ h
;;;;;;;;;;;;;;;;;;;;;;! b7 C1 h0 R/ Z- Q
;; Setup Procedures ;;& w1 J8 o  b7 \) }' J( G( Z  p" }
;;;;;;;;;;;;;;;;;;;;;;
/ d) |+ v- B6 I5 g+ C
* Z& ?3 b- J7 G( z  i8 n& ^;; Initialize the display by giving the global and patch variables initial values.
4 D- \7 c" L* ~# n2 f;; Create num-cars of turtles if there are enough road patches for one turtle to
& f. Y  I- p! q* E$ E7 r5 E;; be created per road patch. Set up the plots." ]- v' C. s5 I+ v4 j4 L  s
to setup7 i& Q1 z4 f2 @7 F+ \
  ca; f- x9 @) ?- k  M  \. T- k
  setup-globals$ e) S2 |5 }! R2 F: L5 i  ^

* i8 e+ ~& i: \4 J9 A7 M  ;; First we ask the patches to draw themselves and set up a few variables
0 r! r( N4 X0 z) I% e% G6 M6 o  setup-patches
/ a9 @; t" L- ]% P( m( m" S, ]" c  make-current one-of intersections: k* G$ [# I0 H, J3 s
  label-current
- [% E! k) D8 B0 f! n: K- e9 ~# z- E: [* ]
  set-default-shape turtles "car"
% L4 a: y: w% w% s9 A: i* a( r8 K; x' p. C$ v6 L$ n9 m* o
  if (num-cars > count roads)5 ^9 s6 o! r; S! b
  [
$ I4 w6 p2 L* }( P( H4 h7 ~    user-message (word "There are too many cars for the amount of "
1 [% [% y- J  }7 X- V( }+ Y1 J                       "road.  Either increase the amount of roads "' m4 e6 |& E8 o' r8 A1 R$ j
                       "by increasing the GRID-SIZE-X or "' m0 |; _9 F: U1 Q: F/ X
                       "GRID-SIZE-Y sliders, or decrease the "- q0 w: Q9 y/ x# l8 W. {' v
                       "number of cars by lowering the NUMBER slider.\n"6 W0 o$ a/ k& u; O3 h
                       "The setup has stopped.")7 F3 ^" P8 q* y; z  J
    stop
8 A% `/ S& [8 N) G3 e" c& I  ]
( o& K! g; t% D- B1 P6 _& h/ c" U# Y( V* |+ Q( y/ a( I
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' E- c! C* {1 U& S' c  crt num-cars
' c! ]! L8 C5 I9 e9 `3 s  [
1 A' i- A0 @0 c8 s7 x    setup-cars
4 Q2 A4 g* R2 V# k5 b: m    set-car-color. T: F" \5 j9 p/ H6 c
    record-data) {5 m) u0 G6 B# k7 N0 U
  ]: y7 C; Y2 O# r$ M0 I7 I; z8 G

7 {6 v7 |% D  Q  v. H4 \' G' D  ;; give the turtles an initial speed
- Z! X" d( l1 N* {! W* g0 ~5 C  ask turtles [ set-car-speed ]9 h7 ]; r* C) i7 e) u

) a! t+ n  m+ g1 M. b& O  reset-ticks- d4 \% X0 C2 z+ E5 L
end0 @. _3 D# I" m' f- U* P

1 ^7 X1 K/ O+ @;; Initialize the global variables to appropriate values
& z7 v0 i. P/ N- Kto setup-globals9 h8 y2 E- t. ^, r" n6 l
  set current-light nobody ;; just for now, since there are no lights yet5 B& H7 Z+ G" Z9 e8 |
  set phase 01 W0 X2 c9 j; b% Q$ v" I
  set num-cars-stopped 0/ P  ^$ E5 C. P. j  H; a
  set grid-x-inc world-width / grid-size-x
) A* l1 x! s2 a. \2 p  set grid-y-inc world-height / grid-size-y
5 D5 c# H, P) Q# u- U+ e, r0 V
% p4 V" ]' r0 n- D  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ q% s6 n8 D( D, C
  set acceleration 0.099" e1 x, u+ d$ {# ^9 r# w/ Q: p; f
end
4 A6 d* R2 A& ]: o+ B3 g7 t' w! }% M$ b7 l6 p8 W/ R. m# W, T( W
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  U+ F* k: s4 r* ^. R( g
;; and initialize the traffic lights to one setting
3 x2 l6 H: L1 fto setup-patches
& X- E( B+ I0 Q) i) D, |' s  ;; initialize the patch-owned variables and color the patches to a base-color3 X# R# Z) y0 [$ \5 u" ~7 h7 U  Q! ]& ^
  ask patches
" }' ^3 N; Z& Z: R  [9 ^% f: r8 h; i7 Q2 X
    set intersection? false/ c$ g$ w& B) s' s( }, K! v
    set auto? false
& |$ y0 e+ Z8 \* p$ b, f' @, h: g    set green-light-up? true' W0 p8 D% v! s2 k0 T
    set my-row -1
( _2 d9 g8 j0 E" C4 }    set my-column -1
5 A; ^1 e$ J! o4 `9 N    set my-phase -1
( ?5 L5 e* v7 N- _# P: F    set pcolor brown + 37 @7 c4 |- C" [  c5 C( q7 v8 J  b
  ]) O( D9 A% E- }

7 \% P6 d0 C/ M: [; n+ m( u0 n  ;; initialize the global variables that hold patch agentsets( R' J; [2 q2 M* f) R$ {
  set roads patches with: v0 L5 w# a, ~: |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; h, y/ h) w2 w  [5 K# B6 V4 ?) P" A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 u2 ^& \9 Q9 V; S! K, U; U% F
  set intersections roads with
/ Y9 S& Y6 A7 @  W1 t: \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& u/ u; N" `) h  m4 j. V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 O" r# H) k0 u; w" ~  ]$ _1 f3 J* Y. }+ o
  ask roads [ set pcolor white ]
: o$ g# L( J, j8 M9 L9 T* t( S' [    setup-intersections
, e) ~" c% }) D$ X( q3 Oend
; m. Y" r- W) i其中定义道路的句子,如下所示,是什么意思啊?9 g4 s& a! ?5 x% E0 }6 I' K
set roads patches with
& F( ~7 W2 y9 m2 B) m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) F! _2 ~, u( D3 `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; B) Y" B4 c% v/ U7 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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