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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。1 A8 V, {: [  ^, h. f  W- E' [4 i
netlogo自带的social science--traffic grid这一例子当中,
7 m7 J) i8 D4 W* N$ B- t! u" pglobals& O9 G+ P# d. D4 {2 x5 h) H- \
[
7 j- R( n! w& b2 N  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& {$ `( @& c+ j& A# c8 |  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 q  N2 p6 K/ j% k
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' t: }* i/ l: s) @( i5 ~                           ;; it is to accelerate or decelerate6 I# R. E2 C/ v9 ]3 b8 O6 X& D5 u: w
  phase                    ;; keeps track of the phase
$ h. I! Y, y: s& i  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# {. j. K: d$ h9 x  current-light            ;; the currently selected light/ X% Q9 k1 v$ Y- t1 p; n; W
6 a+ Y+ x/ F! T1 ^( \) U
  ;; patch agentsets6 J  L: R1 |  p9 ~
  intersections ;; agentset containing the patches that are intersections7 T) K2 c1 y% e
  roads         ;; agentset containing the patches that are roads. I+ W' A( P2 N' D  a
]
- L& [0 t* B2 c5 J" T1 ?8 t6 F& x" R- W# P' t0 q/ D0 }6 }3 ~
turtles-own, L) o2 h' u) _
[
6 @8 @% p0 E- E6 n/ F) m# ^  speed     ;; the speed of the turtle- v: ]! M' P; F: S4 J
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right% S, w' M8 L- }: O  p  L
  wait-time ;; the amount of time since the last time a turtle has moved
; Q9 y" a3 F3 t6 {( y! S( A: v) G]
( K; R# o! x. K
. Y4 o+ u" D& L) y3 Zpatches-own# S2 N3 `" D& D# e
[( O+ S7 P# F, V: d# S$ k2 R
  intersection?   ;; true if the patch is at the intersection of two roads) Q: ?* B5 O2 b4 R4 d) @9 n+ B/ ?! h% b
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% S3 H( o# |$ a* }& b9 _
                  ;; false for a non-intersection patches.
  F' i" l( ]- q* z3 A( H  my-row          ;; the row of the intersection counting from the upper left corner of the5 T' O( `9 O2 N$ o& ]  S
                  ;; world.  -1 for non-intersection patches.
8 t- N) v. w! x' |  my-column       ;; the column of the intersection counting from the upper left corner of the
! r8 T0 Z/ Z/ _, W                  ;; world.  -1 for non-intersection patches.* T& g) l  k4 X8 m% C
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ G+ C; O9 `" \1 A2 l* z  auto?           ;; whether or not this intersection will switch automatically.
9 n; G, _" w" J2 A+ Q8 J6 w& J                  ;; false for non-intersection patches.  `# \" i7 w  I: T+ G
]1 D+ x$ L6 W% B6 |, W

3 T* P9 u4 j+ o  D2 d; Q3 K* H# G+ a1 @
;;;;;;;;;;;;;;;;;;;;;;$ H5 l. \% e5 W- d4 d
;; Setup Procedures ;;9 K# {' S( j& h1 F1 l( |; M
;;;;;;;;;;;;;;;;;;;;;;
( j6 x/ K9 D+ I9 C, Y7 @3 v; h. @7 T0 E- T1 @# @
;; Initialize the display by giving the global and patch variables initial values.8 J: `" \2 o6 |- O$ n7 x, v* ^
;; Create num-cars of turtles if there are enough road patches for one turtle to
; x1 W: z5 M3 W5 ?" _) [: g;; be created per road patch. Set up the plots.
/ N* Y* m- a2 a% uto setup9 s) q" i8 W/ m+ m
  ca. J' J+ f' N2 O
  setup-globals! O; w  V: p/ z+ c

4 X$ a# n/ w* P6 z# O" o  ;; First we ask the patches to draw themselves and set up a few variables2 E5 W6 k$ V. R6 O8 u! S/ x
  setup-patches
) M( [8 T) P& V  make-current one-of intersections. g+ O1 O- l+ A( B; Q2 Y& c
  label-current
# I& P- V" Z( Y# N. K. K$ y9 q6 L
  set-default-shape turtles "car"
. r/ q/ `: q# d  @8 d8 t' c& `
6 A( h' z$ v- T4 Q  if (num-cars > count roads)" r" I# J4 h2 l- X5 \
  [: Y9 h2 t$ H& l5 ?
    user-message (word "There are too many cars for the amount of "- k' _+ c/ y2 l1 K- g; c
                       "road.  Either increase the amount of roads "
& ~2 Y2 S% [3 B                       "by increasing the GRID-SIZE-X or "  F  y6 l8 K& A
                       "GRID-SIZE-Y sliders, or decrease the "
- e0 Y' c4 t$ `% h6 t: k" [                       "number of cars by lowering the NUMBER slider.\n"
+ J  s' z. s6 }                       "The setup has stopped."); O+ u1 M) _" x. S9 e- |5 S
    stop
* k% j& {- {2 Q7 D* V0 J/ T6 ^* L  ]
( n: ~. w0 V& S* P5 X
( R) e2 y. ]) h) j% W  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
; r2 |; P# z( V% B) V2 |. O  crt num-cars
: t9 |+ }0 _% Z- b  [
. j+ P" m1 c, {+ Z    setup-cars
+ n6 |4 I& S* t9 _" r    set-car-color
+ @# w: h" {  q    record-data
, i9 L/ o  D. |  ], @( i$ p4 d0 i9 s: E; s2 C' L, L
1 \2 S0 E- o0 N9 v$ N+ g
  ;; give the turtles an initial speed: n) Z. i8 }, [1 L2 t" I, w" d
  ask turtles [ set-car-speed ]
; x1 S& @' z) ?, U# z0 o( {+ j3 Y1 o
  reset-ticks. o' M7 ~, I1 P0 G7 K5 M$ e
end0 {# N% ?9 h8 c& `- o7 _
0 I5 Z& q) f" P5 s
;; Initialize the global variables to appropriate values! R6 Z; Z& f1 \/ U4 D) \
to setup-globals* O" r9 Q; v6 Q8 I# q
  set current-light nobody ;; just for now, since there are no lights yet" [2 M9 c3 n' I# }' K
  set phase 0
& |' c' U# q7 X: Y- S  set num-cars-stopped 0
, f. m5 J( p( ]; A& O  set grid-x-inc world-width / grid-size-x
9 |- O4 j% y5 [6 t2 A0 }' `$ `  set grid-y-inc world-height / grid-size-y
9 r/ e& I, ~9 d# z, T' C* [9 ^; F
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( m5 ^5 e) P) M0 Q6 d  set acceleration 0.099
$ s( z/ `( o/ i- n2 \- ]7 nend% C9 p. y' p7 v  |- ], |0 m

& W: `5 s# _- a- v, o;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 {/ J' z' o5 M& F- N5 J
;; and initialize the traffic lights to one setting: e, r( F5 t0 J
to setup-patches* _- X9 D1 e1 d$ \1 i0 s' M7 e  K5 M
  ;; initialize the patch-owned variables and color the patches to a base-color
2 r. E6 q# q% e8 y! A  ask patches0 r! X* C. h( D6 R8 u
  [
$ m' W/ v0 y' ]3 Q7 c% B7 ?    set intersection? false
1 Y. e& o; U' G, [8 V    set auto? false+ Z5 ]7 g5 G6 ?/ z1 A
    set green-light-up? true
) J# J6 Z8 U5 V+ R" e    set my-row -1
6 h, Q" s# o5 r$ `6 b    set my-column -1
  p3 s5 G* B% O, `$ U$ a2 K- W    set my-phase -1
7 ]5 P9 e# U. E( \) E/ t    set pcolor brown + 3, ^9 L( @# J6 K# X$ @
  ]+ @7 l- K: z# M) P( Q, L

: T+ I% f* l, F0 V  ;; initialize the global variables that hold patch agentsets: I. i0 U- U) e0 ]# N* B. S
  set roads patches with3 q* a2 L! M# @! h1 ~# O2 X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 F( U! t- b( V" X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! f8 r# H, N% Y5 u" K6 ?) P
  set intersections roads with
" d& N# s2 h1 L4 w  K5 D' i* t2 K! H! p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& `. _! k8 G8 u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( B) G" Q7 c' M  M- N8 g7 e4 M
0 Q! _9 T8 [: F$ i) H0 t  ask roads [ set pcolor white ]
3 Z$ ?3 b3 p0 [9 g: ^    setup-intersections, D5 G) ?2 k( k) Q9 D7 {- t
end
6 W: b1 r) q7 D- p其中定义道路的句子,如下所示,是什么意思啊?/ k4 F4 Y( o. h$ G  F9 t1 z! t0 b
set roads patches with2 V- n5 R2 h8 I) V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ J  P+ _% r9 V/ ?6 y! o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 ]/ A  l+ D" ~: `6 S; Z/ K* U
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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