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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 _3 a( a. C- N2 I% u
netlogo自带的social science--traffic grid这一例子当中,0 I/ Q+ ]3 R' T) d* |+ ]
globals
( `' Z4 q1 U# T[* Z0 M7 D/ }4 `6 B
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! ^8 x/ l) u5 [  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: \' `/ K1 c5 Z  ?* g' z/ p  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 e( q" N- V1 R( @" h" `
                           ;; it is to accelerate or decelerate
1 C% U, i! t4 \! |  phase                    ;; keeps track of the phase
$ h+ B7 w: w* a7 [( v( Z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 |' k' S3 D+ a- O2 [  current-light            ;; the currently selected light$ d  ^. G+ u1 f! S" D+ U- y6 A

% a' ~! |3 R: S" _2 ]' n  ;; patch agentsets
! M) M5 F7 k% Y. i6 ]3 \) C7 c  intersections ;; agentset containing the patches that are intersections
, Z/ c( Q8 f* J* @  roads         ;; agentset containing the patches that are roads7 N5 w* g8 W' Z! m2 d- N% k
]
3 V$ d8 |& i; |2 y8 P2 q9 j4 V+ m; v7 `
turtles-own* v& I+ q% F/ b5 a0 @% X+ u
[
1 b& h7 }5 T6 R  |  speed     ;; the speed of the turtle
) R/ ~- L: W. M0 y" P  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 T# {, v$ H5 u( b, H  wait-time ;; the amount of time since the last time a turtle has moved
$ @5 j, L7 ?- p( L" o" a  d7 ?]
& n) V1 k. b; r( q7 a; [4 T0 Q2 I- H# y9 x$ y
patches-own' C$ s: ~9 W: W6 l8 i& U' N
[% O: M& f5 F( F
  intersection?   ;; true if the patch is at the intersection of two roads
" G/ U$ y$ N& v  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ h) t: L1 A9 e0 v
                  ;; false for a non-intersection patches.
, e" m$ L3 `, P9 j+ ]( ~  my-row          ;; the row of the intersection counting from the upper left corner of the
  s; R3 Y8 U7 b                  ;; world.  -1 for non-intersection patches.! d. Z8 F( \0 E$ h5 b& S
  my-column       ;; the column of the intersection counting from the upper left corner of the3 y- J. t* u7 ]9 |7 T) T5 }
                  ;; world.  -1 for non-intersection patches.* |4 w7 I/ z. D4 J5 x! ]
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.5 X6 E8 }* B% U9 [5 U! w/ K
  auto?           ;; whether or not this intersection will switch automatically.
! v! G) b$ t2 o. I                  ;; false for non-intersection patches.- L6 r. {( r! l0 ]% Q4 }
]
( G) j* p/ p7 i+ ]! _% R  ~1 z# ^4 r& J/ E& q6 ^, e
2 }: @8 Y7 y; l8 e
;;;;;;;;;;;;;;;;;;;;;;
( ]  n, a5 Y6 v- H0 ~/ u;; Setup Procedures ;;
& H  ^# \; Z& L" w% X; }5 A;;;;;;;;;;;;;;;;;;;;;;
' J2 p* z+ Z- D6 _, f& z! B; r6 k6 s9 i5 ~" X6 Q! y9 ~" Y# M4 c/ T
;; Initialize the display by giving the global and patch variables initial values.
- a3 v. T; i6 x;; Create num-cars of turtles if there are enough road patches for one turtle to+ k. r4 e( q9 s4 Y4 N, o0 V( ?
;; be created per road patch. Set up the plots.
# ~( \- F9 _# E; n  \& C+ jto setup" t' |; l* A9 N+ P6 F
  ca# N& M; W% c" n" x
  setup-globals
* m" j! \6 V# h/ I$ q$ x$ C) @2 {- Z3 k# Z
  ;; First we ask the patches to draw themselves and set up a few variables  D; m5 z2 x! I
  setup-patches7 q) d! s; a7 Y. L* T
  make-current one-of intersections) L1 y6 D2 j+ t% i3 {4 Z/ B- w
  label-current1 s; S6 B& j, k2 l, [% d

; G- I3 M) G! j. t+ z3 y: V* e& O  set-default-shape turtles "car"
" {- [2 }" |; N# l# f) N5 s
' U# E: K. P2 e. L" E4 E) E- P) A  if (num-cars > count roads)4 `% i9 q' A4 U0 X2 g8 d" T
  [) |: L# [6 f+ L+ d( J( z3 {4 ]# C. Q, a
    user-message (word "There are too many cars for the amount of "/ v* R0 C' J0 i6 I5 ~. p: F7 r( a
                       "road.  Either increase the amount of roads "
* r/ n! d9 l4 j                       "by increasing the GRID-SIZE-X or "
4 {; p! `: \5 F                       "GRID-SIZE-Y sliders, or decrease the "
" E* @$ a& L! u7 y0 D/ d) e! v- h# s                       "number of cars by lowering the NUMBER slider.\n"+ g) U, `6 L- q4 M0 ?3 ^
                       "The setup has stopped.")2 B- G$ f4 N7 d- ^4 u4 V, }) f
    stop6 r+ B' V. T. A
  ]
$ L" G$ {- t8 C/ j3 J5 H* v) y+ s# ~! v& r1 g" y
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: D- Z" q+ l5 Q, N$ y  crt num-cars
7 v; u4 G9 C; I, {  [
: q1 d$ o8 H& M2 T    setup-cars
5 q2 k) T4 h# l    set-car-color5 T$ G8 h$ @" o0 S
    record-data4 N# G5 S9 M- N& p4 T
  ]1 `* S8 c$ ?2 Z9 k% l/ b  B

5 K  M' n( ]. Y* g" r  ;; give the turtles an initial speed
, N& [* N( Z5 w) M* W  ask turtles [ set-car-speed ]
6 _0 @+ M0 N$ R+ s. o. u+ P
6 F# y/ o! X5 `8 ^  reset-ticks
2 `, s& A+ \# s: iend9 I0 h3 @: r, z" ?! \
3 v9 Z; r9 e% k4 Q: L5 X4 g
;; Initialize the global variables to appropriate values+ l) z% T0 @; m( R
to setup-globals5 N% w9 S  N2 }9 K+ q  G0 `+ y
  set current-light nobody ;; just for now, since there are no lights yet
+ V- }; \: ~9 \( d. s# U  set phase 0; a3 n7 g5 J8 h7 L! U- z
  set num-cars-stopped 0
- g# ?4 C! P2 A! ]) ^+ g  set grid-x-inc world-width / grid-size-x. V; m0 {, }( {+ s1 K
  set grid-y-inc world-height / grid-size-y
$ G) \% E. c. a; ^" n+ Y
$ m! t& t# F; Z! v4 X8 }  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 _3 i) z! A9 R  s
  set acceleration 0.099
) q' L9 b7 T) q6 V! S) Jend9 F) B& Y9 g) ^) A
! }! [- Y3 I5 K  l* L  M# I" J
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# H) x: I8 Z: r% b7 v  B  n
;; and initialize the traffic lights to one setting. N1 F' G% U0 Y
to setup-patches& x1 t( U% H% v! D% ~3 g+ v
  ;; initialize the patch-owned variables and color the patches to a base-color% ^; P: A8 D+ v1 a
  ask patches
& g5 @: g8 H$ `6 r( U  [
( ~) B& Z0 _9 n3 P% p# g5 T    set intersection? false: O( s( @3 K4 E2 n9 d( ^1 ^
    set auto? false
5 ^# u7 P* M% m/ W, a    set green-light-up? true
0 k5 Y, G" I/ z$ z    set my-row -1  }' Z$ Z% v" s$ x
    set my-column -19 ^* C' F: b7 E" a- ~
    set my-phase -1
) q2 w7 Y3 T0 x5 ?: q    set pcolor brown + 3, o' ]- [5 S8 Y) i9 z! ^7 b
  ]# P! A. U6 B6 R- y
! I" l5 H2 w' y8 E( O6 l$ E
  ;; initialize the global variables that hold patch agentsets
) E) t: I3 u# M; b; g, N/ B  set roads patches with
4 A6 }' j/ d9 N; t$ y) Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# ]0 K8 U, H- M( |' C! `4 j. N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( W/ R0 P: c3 D1 [! Y" H/ [  set intersections roads with
- K% W# T4 S0 _1 o5 d1 a6 n5 p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& F. R* r! _, L, V/ V+ ?, `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& P9 _; E% a# ]  ]8 z9 o& ?. ?' v& H
) \5 t* @; @5 V
  ask roads [ set pcolor white ]
% {1 i7 C& R) t% U    setup-intersections9 [6 d3 [& h( n8 P% m1 D
end
% V4 e4 f" C3 W& Y+ X" ?其中定义道路的句子,如下所示,是什么意思啊?
3 C# Z9 |2 Q0 K4 ?, ^" @4 J+ `# A/ J set roads patches with# R  ^$ V8 X9 X+ @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- `" `9 }/ @, t; W; Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, e6 f# v) O! c" Y# j. T5 f! W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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