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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。
- F. W7 Z8 ~# X8 g/ Q' v# Xnetlogo自带的social science--traffic grid这一例子当中,
. M; W- Q1 B$ Bglobals+ a4 w+ d; Z- Z4 O
[6 H6 `# E& l& d7 X2 z$ \1 a1 F
  grid-x-inc               ;; the amount of patches in between two roads in the x direction' K3 f# I& M) u: V, Y4 l/ d# @8 K  h% @1 V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction3 d6 n, e7 b" h/ R
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if4 D% f7 }! o, q7 \
                           ;; it is to accelerate or decelerate
4 n2 C# O1 Z3 f( E3 L8 j8 K, N  phase                    ;; keeps track of the phase
5 }9 t* m8 Z: E. J: c! N  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure; h3 f* b% ?, o  E, S
  current-light            ;; the currently selected light
2 o* n: S7 _) q
! y4 {0 Y5 V! Q- h/ K. Q+ x  ;; patch agentsets$ Q9 q5 }  E) r# u% c" }6 ?
  intersections ;; agentset containing the patches that are intersections" \( p$ L9 d2 F% e6 a" a% ?% u
  roads         ;; agentset containing the patches that are roads
* ^4 V1 y% [$ t3 j! U: s1 E]
* v( k* k* w. @9 ^- Z) w4 `8 e+ S' C- ^5 C
turtles-own9 u! i! h" l: `. v- f# q- k* s4 o
[
. m& j0 u4 P2 }  speed     ;; the speed of the turtle
" s2 G. u& o' {  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, \0 T1 r, ]4 M
  wait-time ;; the amount of time since the last time a turtle has moved1 ]  W' X6 R5 N; R5 ~
]5 [: u/ Y8 \# m; w
2 B1 ]! ^: ]' V6 F
patches-own
4 T) F* G- Z. B, E1 A4 m* k[, g) d3 y4 D4 @  ^2 X; ~7 K
  intersection?   ;; true if the patch is at the intersection of two roads
% C' t7 v& U5 E/ c+ @- R7 p  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ A$ K0 V1 l; u. I: `& F2 H8 ?
                  ;; false for a non-intersection patches.  i, `* G% L; H: S4 g
  my-row          ;; the row of the intersection counting from the upper left corner of the6 U: F7 {! n/ r! `- |, r8 _
                  ;; world.  -1 for non-intersection patches.
$ ~% l1 X" y3 E  my-column       ;; the column of the intersection counting from the upper left corner of the
' B0 O* Z) w9 \" v0 o( V. _                  ;; world.  -1 for non-intersection patches.
  d' T" @2 q# j; N6 \7 X9 C) L  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 h4 b) ^: x; M/ q- `' C2 z- J
  auto?           ;; whether or not this intersection will switch automatically.2 Y6 F* l" A4 _: z
                  ;; false for non-intersection patches.
5 N5 A* g' C. B9 J]0 C8 q1 c1 z; ?7 ~
' z2 [" D, ~7 m& p' L) q$ J
/ V& _/ z3 @# Q8 @
;;;;;;;;;;;;;;;;;;;;;;
- |6 r3 _. L& D7 L;; Setup Procedures ;;
- ]( [0 U6 v5 L* }! N5 S6 a;;;;;;;;;;;;;;;;;;;;;;. Q  A( C7 b* Q  f  n

* I2 d$ g" P* G" V' V' @" };; Initialize the display by giving the global and patch variables initial values.
  Y: Z7 v1 h2 K;; Create num-cars of turtles if there are enough road patches for one turtle to. i/ G3 j4 z3 b1 R
;; be created per road patch. Set up the plots.
! M6 Y. x8 R$ G# z4 y; [" F7 Wto setup) R' t8 o. B4 [' x9 v1 ]
  ca4 E- t4 q$ v4 J
  setup-globals
; [# U: W6 \( a) ^+ ]5 d% w. h4 x1 V) v5 O6 @: o
  ;; First we ask the patches to draw themselves and set up a few variables
% X1 F1 n" P5 a  setup-patches8 T1 R5 D; B) X# U+ o. S
  make-current one-of intersections
9 e4 x. P8 M' D) H1 `  label-current
! q0 K9 C& b' r- k: k2 R* A7 ]# Y# p4 J- f" z) r
  set-default-shape turtles "car"
! W3 _' I; A2 _5 M! O9 n# u: x8 j' M5 F5 }' o; M
  if (num-cars > count roads)5 w8 r! r6 I# N3 L6 f" {
  [4 `  [" s2 V) [
    user-message (word "There are too many cars for the amount of "
9 q% a+ i, I  ~+ x% @6 f                       "road.  Either increase the amount of roads "; X7 _0 h8 H1 |, f) f$ q" J" s
                       "by increasing the GRID-SIZE-X or "
, @( m6 k8 Y6 f0 {6 l1 t/ `                       "GRID-SIZE-Y sliders, or decrease the "
' X: J1 A6 W4 }9 O) v& ]" p                       "number of cars by lowering the NUMBER slider.\n"
9 O& x! W" z8 m+ J' `$ k' f                       "The setup has stopped.")
: Q, D$ S' ?0 T! y    stop/ Q8 |- t* g! n* h; `1 O. }
  ]
- X3 `9 Z0 Y- [0 N0 K
9 K$ H4 Y6 U* P2 X# ^, ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) n; Z" Z2 I) p# e, \  crt num-cars
; c# z5 k8 W' e' t4 D  [
" [4 @: s& E; F; G( o9 `0 N! Z0 `    setup-cars' [$ |: @; B8 ]  r: H
    set-car-color
$ x) a# B* H* a8 ^' }    record-data
0 `# T# O2 K  L  ]" b9 t- S! u2 K: K7 y! s3 W0 [5 m
  M; z; L2 J$ T. H1 Z* M' l0 t
  ;; give the turtles an initial speed( d% Z7 D- m6 }; a
  ask turtles [ set-car-speed ], \! a: e6 C0 X/ |2 n

; M. B, b$ D3 R3 j5 a: h6 ]" w1 s6 b  reset-ticks8 S, j  D2 G: D; X
end1 S! U& S9 f( j& v

! P) n& r: q! k5 d4 L6 s# A;; Initialize the global variables to appropriate values# x! h, @+ o. ]' e  n2 K
to setup-globals; v6 {! H' s2 q/ m; q7 i( |
  set current-light nobody ;; just for now, since there are no lights yet1 E% U7 z( [5 v/ T
  set phase 0
' U; j5 @  X% W' `! C$ T  set num-cars-stopped 0
0 y8 u( R( B* }/ b! ^  set grid-x-inc world-width / grid-size-x/ x' t/ D2 \, w. u8 i; \! m3 A' X
  set grid-y-inc world-height / grid-size-y3 x! E+ ]8 v8 f1 N0 x

3 V9 q5 X7 Y8 h8 w0 o$ B+ i5 Y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 [; ^$ s! Z- O6 o/ O/ h" W' c1 Y  set acceleration 0.0998 k2 W# s3 X( J! e0 f
end: c. j/ Z& U0 u" D6 v) M% K5 W

2 M- M9 g; V0 B9 ~4 e;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 S+ w7 Z1 h8 v5 p2 p
;; and initialize the traffic lights to one setting7 H7 Q" |: F; s! r
to setup-patches" w5 G, M; q: y# N9 ?
  ;; initialize the patch-owned variables and color the patches to a base-color
) f1 j  a9 Y% g5 S: P0 O5 |3 U  ask patches
& u) B& e* x  [+ J' R  [
: F) g( v; q$ V' E& C# }8 U5 g    set intersection? false
( e3 Z4 L$ \! H; Q% ]    set auto? false- T+ ]& G) b# q$ C
    set green-light-up? true# a/ B  G2 ?6 ^
    set my-row -1  m: A. w3 i. ~' f7 c4 K
    set my-column -1
$ W# s9 _) E1 x% V+ m; ]* h    set my-phase -1
1 i3 u# [( V1 a- \2 ^6 _0 J    set pcolor brown + 3
! ]% t. r/ s3 Q5 K" g* {) z  ]. n6 A' s6 ^2 x! E+ P

$ B) _$ [' d: ?) Z9 s. m9 ?  ;; initialize the global variables that hold patch agentsets
% D) k6 w$ j1 u; H2 P: W" @  set roads patches with0 l1 `- a' U& V+ s1 Q0 u& y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- [  r7 k! q; K# Q2 T# E6 Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% m# t. N6 c1 x5 B* g6 F  set intersections roads with
: X4 }( Z# o% Y& P# O8 E+ d: P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( ^) W, O7 ]1 R# L  {' B2 e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 |5 K7 ~6 ^) O# I  ?- H) H
7 [8 F) ?( ^1 ]# t* Q1 }/ T0 \  ask roads [ set pcolor white ]
4 I; L5 v7 g. }7 [/ @4 J+ L    setup-intersections: [2 r( X  e& b+ I* ]: S: `. c
end5 J. b3 G6 L8 J. I% O/ m7 _
其中定义道路的句子,如下所示,是什么意思啊?3 P5 o6 [2 r+ Z9 J& ~
set roads patches with4 X! d# H/ T; u* m7 K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( U0 y& F- @  R1 y- z0 `  q! {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 @) g5 I; G: Q5 \/ ^. w: 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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