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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。
5 C( J) ^* G  N* D0 Z" A" _netlogo自带的social science--traffic grid这一例子当中,+ v0 W# A$ L& m$ y9 k: ]
globals
  `  q6 X1 P; b6 B+ v[( L4 H$ x* @* c* o
  grid-x-inc               ;; the amount of patches in between two roads in the x direction, ]2 F& O' d0 ?$ v, q- }8 X  o
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
- H; }; C' O. k# k  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- }. q. {* z0 L" |+ c, l
                           ;; it is to accelerate or decelerate$ k( i( M  C0 B4 S' y
  phase                    ;; keeps track of the phase: v& |* |) J" ^- m  w% a+ ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ L5 x/ t' _. }  current-light            ;; the currently selected light4 T  M" p! w5 P
7 a. S! C! _! n3 |) J
  ;; patch agentsets
0 [' E. Y( i6 _) f# R7 ~  intersections ;; agentset containing the patches that are intersections
3 x1 `( a- B, U+ X+ ]: a  roads         ;; agentset containing the patches that are roads
$ ^# C. b4 M4 L' m! H: `]( F8 H, Y, ^$ Y) z. G6 `+ m
# R) h* [9 F7 N5 k( ?" Q4 P- h
turtles-own
+ ^6 f# g( L4 Q7 J[
5 v3 h; g" t* r! m  speed     ;; the speed of the turtle
  Q; [# R! i/ i5 g' w8 ], S  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, m: n, T% N- k; {+ f* M, h  wait-time ;; the amount of time since the last time a turtle has moved
4 W# P& S' C( c: [! Z- A]  U" E+ q! \5 y. A0 n& X- A
4 L7 s5 p; v/ M& D8 T2 v
patches-own
% a- [% U% j3 w3 h# j[+ G. d  y+ `3 b
  intersection?   ;; true if the patch is at the intersection of two roads
, Q  ^( R. p: e; c1 D( }  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 t( n6 o* r9 x& M3 `4 n
                  ;; false for a non-intersection patches.
4 `% A2 d3 q8 o9 {) w  my-row          ;; the row of the intersection counting from the upper left corner of the- o1 g7 g2 A- o# T' u  N; l% d
                  ;; world.  -1 for non-intersection patches.6 M; u" e- T6 [6 O/ r
  my-column       ;; the column of the intersection counting from the upper left corner of the: i: \( f) r7 d. n
                  ;; world.  -1 for non-intersection patches.
& r$ ~# z+ q- v( _; \  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ ]' a- U# o# x  auto?           ;; whether or not this intersection will switch automatically.9 h; \) {3 a' u2 q) [
                  ;; false for non-intersection patches.9 F2 i8 [5 D; o! ]) y
], w6 m( n; ~0 e2 H- W

$ i0 c4 b( W0 d9 Y
/ q. r  v7 j/ v( n. f- M9 G4 f  |7 w8 v;;;;;;;;;;;;;;;;;;;;;;
0 f8 l) C& U9 n* D9 L;; Setup Procedures ;;9 F1 S0 ?" ]+ e! {- U$ o7 ~
;;;;;;;;;;;;;;;;;;;;;;
; ?  @. K* j9 [7 F% y/ p. c
8 |5 J5 _" [- }2 j;; Initialize the display by giving the global and patch variables initial values.
/ z, q1 }4 ^" [: D& Y$ o;; Create num-cars of turtles if there are enough road patches for one turtle to
1 `, u2 c9 \" D8 ]8 o! w;; be created per road patch. Set up the plots.
1 T4 B5 U* u3 v6 B" W/ N  Cto setup
7 t  s; A' U& ]: W1 S9 _  ca
, [  t  y. |: s" \4 @  setup-globals
+ c8 H, c! V+ ?3 V* w2 `3 }$ c8 _3 E' V3 X7 E/ X1 n
  ;; First we ask the patches to draw themselves and set up a few variables
  k5 ]; R7 D) z% A# z9 o  setup-patches9 y. }! p5 ?" C1 P
  make-current one-of intersections" H2 F* J6 X) f5 m" ^6 @' Q, A
  label-current! F# I2 d  U. o1 p9 V

3 W/ d9 ^9 }6 n) U  set-default-shape turtles "car"
3 Q; G" z8 Q! R7 e9 w" b( S2 i/ R7 s4 J+ D* o9 y, {- @
  if (num-cars > count roads)/ J. y6 N7 H# @6 b
  [
2 }4 }) @6 \$ V" z# m9 e& W; G    user-message (word "There are too many cars for the amount of "( }1 p( \1 o# j6 g8 i( T, x
                       "road.  Either increase the amount of roads "  p, K9 S8 h! D- p/ s* i+ N; m
                       "by increasing the GRID-SIZE-X or "( ~1 K4 E) ]/ q' T# k
                       "GRID-SIZE-Y sliders, or decrease the "+ {- X- t1 c# h" n( l1 V$ F" t
                       "number of cars by lowering the NUMBER slider.\n"
  B/ y. B0 `' B$ f: R* m% J: G) d9 \                       "The setup has stopped.")5 ~6 ~# D- U  X8 {! H" V- U8 l! W4 N
    stop9 `; [. {) R; O! V6 T
  ]) p5 b* b/ L& v
& f) Y( O1 W  u# {8 ~" b
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 k* H% ?# H/ z9 m& U2 r+ J  crt num-cars
- v, w$ H9 E3 }. G  [4 i9 e' V/ f& I
    setup-cars
/ }- n! H1 T+ \: G+ M- R8 [0 ^    set-car-color( r4 P( P. k# k9 T: C- y( Q$ E
    record-data
& [( r9 J3 g% f: I. U" c  ]$ b' \% R2 T! t& H

: a2 t" K. v; V% Y! \  ;; give the turtles an initial speed9 g7 H' {! R& s
  ask turtles [ set-car-speed ]/ t. U  b( s8 c! @$ R4 h

. B7 ~' T, W& a6 V/ a" w9 J  reset-ticks
3 Q0 N3 K, X8 }, L" s1 ?: }+ Jend; p6 f* K1 Q! _" R# v# Z8 i; O
/ D! u! ]+ d: r# Z6 [
;; Initialize the global variables to appropriate values
! [% A6 ]8 A: l( G" {+ tto setup-globals
: ^0 l, l7 q9 e% T; R: b: b0 n$ c  set current-light nobody ;; just for now, since there are no lights yet7 E1 d& g. Z. u- d9 z
  set phase 0, J: y3 x3 c. |& s) Y; p; C! b
  set num-cars-stopped 0
0 h% ]6 x: q. ^; _  set grid-x-inc world-width / grid-size-x
0 ]& ?' w( B' z9 _2 B. C+ d' x  set grid-y-inc world-height / grid-size-y
8 }- l+ S! ?; C: V
* z! G/ a7 J. ^9 v- V- q$ g9 `* _  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& p, E, M3 P/ f; n  set acceleration 0.099
/ g& @* i8 R6 T, b" Jend
8 H/ c1 k; @0 R6 p
, I" A- w# O) F6 g& G5 H( s8 g;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 @$ J7 B+ l" p$ N
;; and initialize the traffic lights to one setting% g: h& X! ]0 l$ x
to setup-patches
' @1 _8 D/ l; T; B; r0 C4 g  s  ;; initialize the patch-owned variables and color the patches to a base-color5 q3 J  q* N* G" N# S
  ask patches
$ O/ c7 |6 s- J8 M: W  [1 Y3 U% d1 G" q& z
    set intersection? false3 t, a6 s1 X$ X
    set auto? false
! R- u5 z' L$ U0 D* U; K; k* m7 t    set green-light-up? true  r/ s4 Z! K- ?3 k6 W, [
    set my-row -1
3 J( s+ m, i( o6 b8 N- {' p    set my-column -1
4 g3 I$ U, z+ h* N0 o: }    set my-phase -1
! H8 j% C! S. k4 z8 T    set pcolor brown + 32 D9 ]- T7 U9 n0 m7 |' N) B
  ]
8 G& C  P1 A( ^; @; {
% |5 Q; x8 a7 s0 n  ;; initialize the global variables that hold patch agentsets' A  d4 u3 A: e9 J- ?, P) C' t
  set roads patches with4 I! Q/ b* g& z$ R# n9 O  B& o' M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 c  s% q, G! y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* J8 L9 Z0 v8 ?  N, B2 a1 H4 V9 Z: p
  set intersections roads with4 \4 ?* ]/ x4 \0 ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
$ Y4 i) `  _. w4 Y5 N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 V' t. R0 e# }" |; |0 Q& F% W5 X: h9 v" r& b
  ask roads [ set pcolor white ]6 [& y, z7 ]5 Z' j! \
    setup-intersections
; H' f# I8 D* n9 m* v2 u* _) e  H4 v# Wend/ ^% {7 @8 ?% J0 e2 n, M
其中定义道路的句子,如下所示,是什么意思啊?
7 Y/ `. K0 C. P set roads patches with
1 M! r# |% t4 R' G$ ~; u    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ h8 g) B0 ~4 ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; @2 G+ g2 \7 G, P" ?# ]2 T& }2 M+ r
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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