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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。
- u+ w! P8 @7 l" j4 Tnetlogo自带的social science--traffic grid这一例子当中,% K+ E3 B! ~% k; ~6 m% L
globals
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/ y/ T, P4 ?  o% Z  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  s  I/ y( ~7 J3 Z  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 H% [2 u. y# m  l2 j  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ ~$ B  ^; m5 b- N                           ;; it is to accelerate or decelerate/ E4 L6 r& h- E4 \! P) q# k6 w) r+ N
  phase                    ;; keeps track of the phase# q0 x" I2 o# ?* a5 H8 S' p
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 b. [+ s2 [, e! l# M
  current-light            ;; the currently selected light9 m4 F9 g) F3 e6 c! u# X  l( e
/ e3 L9 n; r$ e+ f
  ;; patch agentsets8 b# M+ Y) F4 B: [* j7 c/ @  Y
  intersections ;; agentset containing the patches that are intersections
2 V- q) n. J2 o7 i- I3 t  roads         ;; agentset containing the patches that are roads* o. T) h4 e/ m8 R+ @/ k$ X0 t# C3 p, K! q
]
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turtles-own
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  speed     ;; the speed of the turtle' S+ k+ W/ k* `- w. `! J1 C
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  M- ^) c7 _: M/ e& _; w  wait-time ;; the amount of time since the last time a turtle has moved5 K) Q+ Q; x& {1 T' u: Z
]) b$ r4 u, A! ]* v' w3 G; f
2 n( |1 B  j0 _( c$ x
patches-own9 C0 d- J) n! x2 n# g2 W7 e5 L7 e
[
. t6 `( R: T2 H, e1 ?  {  intersection?   ;; true if the patch is at the intersection of two roads
9 ~* \! t* X% n$ Q+ T% U' H% ~5 ?  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 e6 N* F$ f5 F
                  ;; false for a non-intersection patches.
! M! Z' ~# |$ L  my-row          ;; the row of the intersection counting from the upper left corner of the
( U, H6 s7 n! k' r4 y                  ;; world.  -1 for non-intersection patches.8 ~8 @* E/ @& B! _
  my-column       ;; the column of the intersection counting from the upper left corner of the! w. b0 ^) y) ^$ b& ]
                  ;; world.  -1 for non-intersection patches.8 f+ W. L' T  K. X* M' Y5 v
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* B" A! D9 n. X4 m  auto?           ;; whether or not this intersection will switch automatically.
( N8 s/ P* z8 T& k0 K7 F' \: T4 `                  ;; false for non-intersection patches.
  G9 j! c* ^$ y* m! \8 H& J; b/ U]
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- ~% D, x6 c0 I: f6 M" u" H1 M;;;;;;;;;;;;;;;;;;;;;;, P9 f8 p' R+ ?3 P- x
;; Setup Procedures ;;
# ]2 f# W' q! k4 c;;;;;;;;;;;;;;;;;;;;;;
' s& G  s# \5 \+ J8 }* B  U" ~3 D. Y7 k4 ?% p
;; Initialize the display by giving the global and patch variables initial values.
0 l+ U- y2 e# F! \8 M9 H! `;; Create num-cars of turtles if there are enough road patches for one turtle to
& N) z7 l, i+ x;; be created per road patch. Set up the plots.( J& f4 }4 L' _& p* j1 [
to setup
! d( K8 T. Z3 ^  ca
' V# s/ X3 }6 I9 n  setup-globals
9 }, w9 `' \+ v
6 d- I7 ~4 T+ _7 {5 \3 G  ;; First we ask the patches to draw themselves and set up a few variables" d# J6 h- _$ a: n7 u) Q4 f7 Q
  setup-patches- `1 _1 }9 y( E& }
  make-current one-of intersections. n8 g- K3 ]9 C* |# B
  label-current$ K" T' ]% W& O  R4 b/ v
6 E- U: t' ~4 B: j
  set-default-shape turtles "car"- M, K8 d' S/ b+ l2 a. C

  S5 k# U& m6 R, v: i) W9 Z  L  if (num-cars > count roads)1 P" ~/ k7 d+ E+ }4 A9 X' t
  [! k. {8 T9 v' Q
    user-message (word "There are too many cars for the amount of "2 N) ^6 v4 g$ o7 |! q# C
                       "road.  Either increase the amount of roads ": J, u7 K$ V- _" I/ ^" j
                       "by increasing the GRID-SIZE-X or "
" A7 z( M3 c; _' ?                       "GRID-SIZE-Y sliders, or decrease the "
0 {2 u0 T: j0 a                       "number of cars by lowering the NUMBER slider.\n"
# Y9 n" V* K% E/ H$ n1 h                       "The setup has stopped.")5 T$ x. i3 y- g0 s, A
    stop) K9 j; `1 k% _/ f
  ]
1 {( o2 f0 w- @9 \5 P* v. m- X3 \' f/ ^: _/ k2 J9 L
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 @) q7 {8 ?* r5 u* O  crt num-cars5 @( `# g$ P8 P1 L' O( u) b) k+ K
  [  i( m% p, W% L% n" t
    setup-cars* b1 S7 f8 j: F  x( {4 c
    set-car-color
, q" ~5 |! `$ C. f    record-data
2 c! X* L% Q2 {3 f, }! @6 ]2 ~  ]
# p. v1 w0 P* a& D% L
. P6 x( s0 L9 S& H; ]  ;; give the turtles an initial speed& i9 h& ^- [: V% S1 l0 ?1 L/ l
  ask turtles [ set-car-speed ]
+ [. x% F) V; e4 N4 C# j! R7 ^% N" ?$ Q4 V2 Q" B* h5 B
  reset-ticks
0 o7 ^& C2 Y% vend  v; V; Y, Q0 P! f! ~, ~

7 {, U: Z3 m6 B; r. \;; Initialize the global variables to appropriate values# g# j: B! t' c, h( K2 s! I  \. S
to setup-globals
: i" v9 s1 K/ Y# y  set current-light nobody ;; just for now, since there are no lights yet
# m& H9 P# \6 z0 T1 o9 u# B  set phase 0
- \6 o  Q2 V1 W0 p0 |5 Y8 n9 h) T  set num-cars-stopped 0* @. W8 v; p+ O; ~) L8 X
  set grid-x-inc world-width / grid-size-x
5 Z  w  X: j6 p. i  set grid-y-inc world-height / grid-size-y, T7 ^- k8 B% S0 o# M& v
: d6 t' R5 z  R2 M& x# R
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 D8 K" Y& L$ r4 Z& [+ c) J  v7 {  set acceleration 0.099
$ C5 i) u$ u* F; fend" Z2 d8 w* _0 H5 t7 T1 ?

/ i  N& X* E' ~  E/ X;; Make the patches have appropriate colors, set up the roads and intersections agentsets,% X" A" t$ T3 ^; I. q. |" T
;; and initialize the traffic lights to one setting
' D7 ~& R/ i7 c' n3 Yto setup-patches
( O4 m8 a( d# V: D& }; \  ;; initialize the patch-owned variables and color the patches to a base-color: x( h  E! A( r8 O+ s
  ask patches) O% n6 Y# U* E$ d
  [
: s7 y- x3 ~' F    set intersection? false
' k3 j! q: ~( `; W    set auto? false
6 V. z( w7 k& \1 J9 U6 n7 }) i    set green-light-up? true
5 n* Z# v( g8 c" y' P! F2 j: D    set my-row -1
9 G' U4 W+ A5 p5 e$ t" w6 J# p    set my-column -1
! q' B/ o4 [: h8 |2 H  O    set my-phase -1
& x3 ]; V! D, S" r    set pcolor brown + 3! W% ?. i" F6 N. Y9 L
  ]4 M: s! ~9 E9 e5 z/ W6 ?

, j% ]$ y7 w6 R4 n( M  k  ;; initialize the global variables that hold patch agentsets
, q1 z# Y- w  z" N: ^5 B1 ]0 V6 P  set roads patches with+ u- `2 y( G0 O/ I8 S# A3 d: M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' ?6 M2 M) d- f: @4 ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 C, D' ~5 p/ ~7 d  set intersections roads with; d' s* h1 _, m) ^* {( k/ w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ V4 d6 ^# @6 U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" l. i. n7 a! \# G

; Y1 q1 z( P! |9 Q# A9 p# w  ask roads [ set pcolor white ]
# B0 \! f4 w( K" F; L    setup-intersections7 _4 f. b  r2 \6 v
end
5 }6 v* v" q* N* {  ~0 _1 u其中定义道路的句子,如下所示,是什么意思啊?3 v& @4 f, E" w! J2 E  y$ A
set roads patches with5 I8 C5 X9 E, o  K' J; s' p& d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& R! F: j4 a6 e) V. V' Z  z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 n, H# ~, C# 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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