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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。) n/ A* M8 K4 v+ S8 k6 v
netlogo自带的social science--traffic grid这一例子当中,
, F, j0 b# U+ s  d6 a; P# lglobals
0 P) o; d2 h" N1 r7 X5 s[
/ D4 {6 [% K7 j# O6 k  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 X# F3 L+ \0 \/ T8 {1 I! f
  grid-y-inc               ;; the amount of patches in between two roads in the y direction' D  X5 }# L7 a; l) Q5 d
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 n" r" Q: R1 n; _
                           ;; it is to accelerate or decelerate5 a" {& s# d  L
  phase                    ;; keeps track of the phase9 Y; R8 k/ E# T% c. l  x
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% m( b+ q( q- y$ Z- a  current-light            ;; the currently selected light
$ k& Q9 z( f, b! a- J8 {
5 E5 f: w) P8 v: T3 A1 c: I! j0 ^  ;; patch agentsets& N9 E" ^6 B2 H  v+ W
  intersections ;; agentset containing the patches that are intersections6 @3 v" g& {9 ?( i' U  b$ I
  roads         ;; agentset containing the patches that are roads7 N% K1 x( C6 o" s. `" o
]
. M- Q( Z7 p7 O7 K. I* S- C6 Y, b
" q8 U/ h0 f) \+ Hturtles-own  U' O8 ?( _/ F+ n0 X
[( G% O/ E. \) E) }" C
  speed     ;; the speed of the turtle" y6 C( q" N% n6 _3 @8 q. c; b
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; F3 ^6 K8 d$ z- x, v) f6 b* K1 o1 G
  wait-time ;; the amount of time since the last time a turtle has moved
! ?3 J; p2 E/ d4 y. T" h5 g+ j]
8 w7 y1 L  ~, I% v7 Z5 m6 J- I
! \; f) t% y1 K  q3 {patches-own
+ {1 {" e2 y2 Y2 l* R5 t6 g4 i[
" I. W# O( J2 f  intersection?   ;; true if the patch is at the intersection of two roads
! m2 ^) u$ l! E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 j5 g# E+ F" c0 Q' B                  ;; false for a non-intersection patches.8 y7 j3 h" o8 H1 k) k7 D, z
  my-row          ;; the row of the intersection counting from the upper left corner of the0 c" r% L+ ?3 Z
                  ;; world.  -1 for non-intersection patches./ `3 X- H( T% z$ h
  my-column       ;; the column of the intersection counting from the upper left corner of the% V$ j  o8 n+ Z+ ?* ~. S5 q
                  ;; world.  -1 for non-intersection patches.! w; ~% @  R; V/ D' s4 u8 \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
2 v  f0 v. g! ^% i6 w  auto?           ;; whether or not this intersection will switch automatically.
" V4 \) P8 m3 T* o6 |                  ;; false for non-intersection patches.
* T) i* j7 I1 D]# A) W& w! x% d

% ^- q2 \9 l3 x( M3 U9 A
1 @- p) e+ u) r. z;;;;;;;;;;;;;;;;;;;;;;0 x' |6 z6 m$ ]
;; Setup Procedures ;;6 V2 P! ]8 F  O
;;;;;;;;;;;;;;;;;;;;;;
- u( Z. ?3 @+ E- I- x4 C6 `* M9 S  t
;; Initialize the display by giving the global and patch variables initial values.2 o6 L. x7 i. y/ `' x7 L- I0 F" q3 e
;; Create num-cars of turtles if there are enough road patches for one turtle to
3 W" ^' g5 L0 V4 K( N4 j8 I;; be created per road patch. Set up the plots.
  P0 B, Q3 [: A- F3 Z% M7 q% gto setup
0 l5 A( l* `9 m3 ^* R+ `' G  ca
( E. ^2 s$ X/ {$ }. H" ^  setup-globals) ?2 y% ]& z+ l* \4 O
0 K% [7 D1 u' w. u7 b  Z( @
  ;; First we ask the patches to draw themselves and set up a few variables# g% {; Z# G. \9 i- L, n/ X
  setup-patches: [7 }! ~7 k$ v/ d+ ?
  make-current one-of intersections+ Y8 \4 S6 p) p$ @
  label-current; Z7 h$ M7 o! @# U; {. [0 }! r, O4 ~
! Z6 y! @% z. K0 Z1 W1 X
  set-default-shape turtles "car"
. _( k9 J: M# x6 U5 V* D" `3 c% E# Z( J, [
  if (num-cars > count roads)
: l/ U! j. G: S3 e3 M  [
1 D) j3 b9 Q/ }" \" W    user-message (word "There are too many cars for the amount of "3 }+ Y! \/ n/ _! O6 s, \
                       "road.  Either increase the amount of roads "2 q' X3 D+ B$ L
                       "by increasing the GRID-SIZE-X or "3 z* m* V2 s$ p- I) q$ Q  N8 E
                       "GRID-SIZE-Y sliders, or decrease the "4 V# W. R% Z+ K& D0 b. [+ B% m% }
                       "number of cars by lowering the NUMBER slider.\n"6 n& V; n2 X- _* n; q: r
                       "The setup has stopped."): {1 W+ z2 G" j* t+ D4 M' B& j! `+ \
    stop8 ^6 F2 ^) w* p. r! K% g
  ]% q1 m3 a9 a& ?% D3 `

0 q! K8 E/ m7 v" v  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 q3 V! I% g0 f6 m$ l  crt num-cars" ?" {0 d: ?$ B( a5 Z) @1 U' `
  [
5 O$ Y6 W4 s$ \' K6 x5 @: z    setup-cars/ q- w, ]8 K5 o$ F) p8 A  v0 w1 }
    set-car-color
" |% J3 j, Q: l5 }: p! E9 C( {    record-data
( n5 k) ^7 S# {" t  ]
( B" W: c+ f9 e
2 E0 P' a6 H1 G3 F: s6 k  ;; give the turtles an initial speed3 v- K& b4 l  R; }3 r5 v* P0 z0 g( a
  ask turtles [ set-car-speed ]
6 E! M# p0 a( x* G6 s5 B+ Z; p8 V8 V) ?% y( @' a( W' b# r# Q
  reset-ticks
# _9 v0 j3 r, D  A! nend
! U* w( }+ S! m9 K2 W0 F
, v) X3 o6 Q9 t# `( o. t1 A8 @;; Initialize the global variables to appropriate values
3 e! }6 F5 O3 `to setup-globals
' l$ K9 I$ d8 ?  set current-light nobody ;; just for now, since there are no lights yet
3 N6 H, K' y0 n, P  set phase 0
$ q5 u+ o5 A: h4 I# ^* C3 q  set num-cars-stopped 0
$ a' c. k8 \# d9 c  set grid-x-inc world-width / grid-size-x
5 ^' g0 `/ |/ @7 u  set grid-y-inc world-height / grid-size-y* Q% G2 P& u/ K1 ]- D1 O
2 i- z: h3 G  i. J8 Q4 x3 s  X( ]
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; O. Q7 [6 E; t1 P" n, z2 C
  set acceleration 0.099
! N; r' d* F# ?  K* uend
  E  v: O* @) j4 ^, R% Q9 f& s+ C4 j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 `2 O! h" B6 m, S
;; and initialize the traffic lights to one setting
' V5 W/ _( J; H2 gto setup-patches
# q; ^6 ~' V3 o, H  ;; initialize the patch-owned variables and color the patches to a base-color: @& q9 ?* y( D9 K# {( V
  ask patches* |5 H6 q' x. \3 {9 H6 w5 l. t* W
  [0 f1 R4 n3 @0 Q% |
    set intersection? false* W/ l, \8 J: T3 H9 [
    set auto? false
) j1 y) |: }! s) K# b    set green-light-up? true
% _* Z) `) V* {    set my-row -1
! b3 r' V7 b" `) P$ c. G    set my-column -1
1 M, ~, s4 d: U8 B! n. q# B) D    set my-phase -1  O: s  g, h' F9 r: y* I3 }
    set pcolor brown + 3
$ {& Z9 X7 T& A  ]
- B3 h, ], O; m/ c( h3 t- R$ S0 ]& y7 U$ [
  ;; initialize the global variables that hold patch agentsets5 ]' y& o* P6 ]3 f
  set roads patches with" K$ b0 G$ I$ d1 ]/ v7 y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ O. @& }. v9 G% I  M$ ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 C) V3 n' n$ B- Q7 m& q  set intersections roads with1 D+ Q' l1 a8 ?$ O/ C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. D+ x) ]' V6 c2 m! g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 E  W# l5 W; Z  K5 T2 W. E, U+ _) Y' n) x9 C% A* j: f9 P0 n8 g
  ask roads [ set pcolor white ]
$ n7 o' W* W9 }$ D1 D8 [' ?! e    setup-intersections) }; }, ?( ]: X/ D1 N' W
end
: N+ A# q" C% [其中定义道路的句子,如下所示,是什么意思啊?
: [( Y( b9 F8 f. r4 \ set roads patches with
5 O% g# [. n7 D) i8 ?# q" @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 K+ ]" Y) @# I' U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% l5 ?  K) |6 _, K. X+ U. F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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