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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。2 }7 s% k  O7 G4 w* Q
netlogo自带的social science--traffic grid这一例子当中,
! \, K* e5 l: A1 m& g# E2 D( P. Q0 zglobals
* w! @3 b4 _7 `7 k; A, h4 x7 T[. n" m4 l* Z3 f# k
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 {/ s* {( t" L/ a$ N" k2 e  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 p) X/ R7 S/ U- S# \0 c
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, M% p- L- c  x- v7 ^, `
                           ;; it is to accelerate or decelerate4 D' K3 m' z2 f
  phase                    ;; keeps track of the phase
+ b. G% Z% A. P9 _# ]  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ b3 M! U) x" w$ I6 P' n) b- f  current-light            ;; the currently selected light  j$ d' }  g9 e! B! g

3 k5 Q  A4 s2 R" ^  ;; patch agentsets) G# w$ d2 Z# I6 n/ B5 g) t# c6 M+ t
  intersections ;; agentset containing the patches that are intersections) C3 r( G! A0 g# L- j" G% x; u
  roads         ;; agentset containing the patches that are roads; c7 M8 h! _0 M! r/ i5 O
]
4 t3 u4 M5 ]2 H6 A+ ~# S
/ e' E* U1 t( ?turtles-own& F3 I9 P7 L6 D8 K
[
9 u! K' p. }6 t8 k4 f  H' |  speed     ;; the speed of the turtle* |0 I9 }& S8 D! ?
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ @+ r  X  w4 @
  wait-time ;; the amount of time since the last time a turtle has moved0 U) M+ l# C2 R0 D7 U6 n; I
]4 o0 G5 X/ L) [  b: K; o

1 M: U9 }5 \  y! Upatches-own
3 |, }; m$ @. g5 J# N; i8 }[
# v% X3 Z* `- h4 ]2 m  intersection?   ;; true if the patch is at the intersection of two roads
( E- f. U# X) }  r  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 N% ?  @; r9 T+ i1 _' j# f4 W% C
                  ;; false for a non-intersection patches.0 k# F% C8 J: p$ e5 T, Q- z. N# b2 |! r
  my-row          ;; the row of the intersection counting from the upper left corner of the& X2 j/ z& x! }" [$ a  P, ?$ ?
                  ;; world.  -1 for non-intersection patches.8 ]+ d& ~  i0 u- c) X
  my-column       ;; the column of the intersection counting from the upper left corner of the8 \! S3 j/ y; N& t" m/ n% H: K+ b; u5 A
                  ;; world.  -1 for non-intersection patches.) }) J$ Y+ i) P5 ~( q9 {4 ~" V* u
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
, R5 d) x2 n- U4 l  auto?           ;; whether or not this intersection will switch automatically.
% j+ v  z$ Z8 g5 x& H5 n2 p                  ;; false for non-intersection patches.7 X: Z9 U6 O# G# C3 p
]& Y' I) a3 J% f. U' @
. R& s' E( b7 E) `

' K5 r7 G5 B& P( ~9 H; l;;;;;;;;;;;;;;;;;;;;;;
. E$ ]' F: f' j;; Setup Procedures ;;- A3 ^+ ?$ A% T2 M; h" z4 D2 d
;;;;;;;;;;;;;;;;;;;;;;
1 t" J  A9 G8 p2 K& s' \" Q% B
+ @2 Y/ v9 h" k5 M/ e- n2 @;; Initialize the display by giving the global and patch variables initial values.
4 f5 t/ p7 @0 h. S8 @7 U" G% V;; Create num-cars of turtles if there are enough road patches for one turtle to% B+ N, D% q' J" c
;; be created per road patch. Set up the plots.
7 t/ S: @, a' _- z- hto setup
  X1 x6 A5 x! h7 q& ]! b( ?: |6 u  ca) K" L! T5 t# t5 K3 S2 o* e
  setup-globals
- `3 G8 M* h& x& a% ?0 U- ?
* x! K5 W% Z+ c/ x  ;; First we ask the patches to draw themselves and set up a few variables
7 o% \" v3 m# M9 E4 k- K& T* }  setup-patches
: T% G( m$ t! S4 |, D& k5 Q' M- [( Z  make-current one-of intersections( l/ O2 F- ^1 \9 }" R( q, J
  label-current. f9 t" }/ N5 r, P: C* T9 L

" f- ^% \- h, R5 s  set-default-shape turtles "car"( F* b, j) _! P! B

  ]+ G8 P: R0 X% [  if (num-cars > count roads)
! p+ g8 `' n6 L3 J3 B  [2 z% q$ y/ o0 c$ Y$ \
    user-message (word "There are too many cars for the amount of "8 ?. u$ @7 s7 }( E5 J
                       "road.  Either increase the amount of roads "1 Y  }3 f! T1 D1 q8 i# d0 d
                       "by increasing the GRID-SIZE-X or "
- e' H2 f0 L7 o# x5 p" u                       "GRID-SIZE-Y sliders, or decrease the "8 ^3 z/ n7 k. |9 D4 y) S
                       "number of cars by lowering the NUMBER slider.\n"
& C/ P9 g: t! }6 n7 f% {$ A                       "The setup has stopped.")  h% o$ T2 }' {  V' e
    stop
2 W: J2 x4 C( [7 m6 {& W4 P' u  ]: p4 |) u! V# f8 X, X

2 i: [# p5 i, A2 _- V! a0 n2 T3 C. _  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color- e5 s3 u* L9 s5 t4 w+ t8 _: b
  crt num-cars# ^! W3 d: `) n- Q: g. W- D
  [
0 t. K; e: Q- w* o. X    setup-cars3 C" [( w) C& B' U6 D- p
    set-car-color0 m( C* w; q+ E
    record-data
" Z* t, x7 I' Z  Z" R9 v  ]4 o7 X+ E$ w1 s: y

1 b0 i9 F' u: l7 N, r' U  ;; give the turtles an initial speed
6 S7 K0 ^1 b5 d  y" Q% V  ask turtles [ set-car-speed ]1 K/ F" r( u3 F
/ {. g; ~& ~- g% G/ E
  reset-ticks. C! p7 r: a7 ~9 I; z; Z' K# d
end
# u) e, C; K+ _  R% k) E- ~& w
/ h* ^1 \  d  i, G4 A! e" n# C;; Initialize the global variables to appropriate values( f3 Y  s4 t6 Y; [% y
to setup-globals$ c2 ?' O& I& A: t* Y, A0 A) F$ B
  set current-light nobody ;; just for now, since there are no lights yet) E5 O" p! W2 f  c
  set phase 01 F5 y/ ^6 Z- b* [* U
  set num-cars-stopped 0
# Q/ j- W7 o: L" W/ S3 G  set grid-x-inc world-width / grid-size-x" q1 t+ I) I6 N+ k' |1 H7 M: R
  set grid-y-inc world-height / grid-size-y2 U2 `6 S  {/ o; x, }0 h

+ w; J& k5 n4 I$ b; R9 L& p' N( ]  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ l; A6 |8 p3 e: M# w2 ?7 y% s  set acceleration 0.099
" J9 G/ z- h! Z8 N9 Q, s  |end& h; S. V; g0 B0 k! s. Q
& S# ?, Z. ^2 k- W# K& ]
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. r* s# w7 `, u( I; e) q! O+ p% t
;; and initialize the traffic lights to one setting! O, ^+ y( e0 |) U8 ]7 U- S0 I
to setup-patches
+ i, @: y. y9 n, S6 A# b  ;; initialize the patch-owned variables and color the patches to a base-color3 V8 j( L! j  V6 v8 N( E- i
  ask patches
2 Z% e& P: d  ?% L  [9 |3 U. F; @0 x" W! M
    set intersection? false, r- W4 j5 _. J& i
    set auto? false
& t0 P6 M3 R. n& b    set green-light-up? true- I/ n8 j0 Z- B  f
    set my-row -1
% l' p, n) K# O    set my-column -1
& d$ R  l* e: ~: W5 Z5 ]+ K    set my-phase -15 b/ K" f" x6 }0 x, ]
    set pcolor brown + 3
. L9 l& }" e  f0 Y  {  ]
% Z$ A$ o* \0 z2 V1 ]9 e( U% e. Y
: _7 n3 K" A, _# ]# D6 o& v3 H  ;; initialize the global variables that hold patch agentsets
. f  H* M: ?( a& Y' h$ ?/ K  set roads patches with/ \& k& [, m0 k: j9 Q7 `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* Q1 A% ?/ `8 Z5 h% C3 N; H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" ?) q( U- u# `* ]2 W( c
  set intersections roads with- H. O: |$ h8 l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% V7 a9 @, {9 T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ z9 _' S% v' w4 x' G
; N0 `3 d3 L& L
  ask roads [ set pcolor white ]+ R3 e$ s! H* `# R! \* |: a: U
    setup-intersections
2 J. X8 A5 g$ o; X9 q; J4 Oend/ r7 k7 r1 i& n+ _' X' I
其中定义道路的句子,如下所示,是什么意思啊?8 J% P; }9 J- f5 [9 ]
set roads patches with8 b& p. _! g$ Z0 z  U8 r( I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ _  i: y/ W- I8 r" H" x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ `3 t! d' ^" X8 |/ K: ~9 N' p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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