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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。
, {5 z- P: ^) D: Dnetlogo自带的social science--traffic grid这一例子当中,
: w7 R% E- ^% Z$ ~: ]$ ]0 wglobals' C1 K3 p8 @( P! L
[
" \0 v. B/ I+ |* p7 q9 y& n  grid-x-inc               ;; the amount of patches in between two roads in the x direction% F6 w" \5 F3 k8 j* X$ K& `
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) ~! H+ k- `+ V& t  acceleration             ;; the constant that controls how much a car speeds up or slows down by if+ T  w2 l$ B* T1 |$ ?1 J
                           ;; it is to accelerate or decelerate, ^( k$ w" A: D) V
  phase                    ;; keeps track of the phase
+ O2 C2 f! I5 e; s' V! G- B' b  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; m+ H, C1 _$ w+ k% H  current-light            ;; the currently selected light
( ]* ]# a) ~, {4 X0 p+ E( |: B7 w! @  d+ r& _% W
  ;; patch agentsets4 V; V# l3 F3 J3 _
  intersections ;; agentset containing the patches that are intersections
8 c# P% i9 q0 J9 @* h1 |  roads         ;; agentset containing the patches that are roads
4 j3 m" `$ ^* U8 S! n0 |- i  O]
: f8 m; y; u4 ^4 F+ {" k
( Z+ Q# t: \1 a1 ~) zturtles-own
/ J6 u7 Q0 F( |3 H[  ~/ a# H8 b- P& Z3 C/ [' [3 m4 f/ n
  speed     ;; the speed of the turtle. u  h/ {9 [1 R
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- q8 P5 T3 ~& J, z- V: p- C+ O2 D
  wait-time ;; the amount of time since the last time a turtle has moved& x- b' Z0 |8 h8 ^7 ?$ z
]
9 ~0 }8 P5 V) U/ z5 l( y& U# p) C; u" C) v
patches-own& |1 l4 i( p: k3 A+ _- [
[
5 L- E8 N$ _( ^* h) b+ K0 c  intersection?   ;; true if the patch is at the intersection of two roads
7 I: R" B( M0 T- d2 @' F  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; s1 e% S" z, Y                  ;; false for a non-intersection patches.9 I' U9 t& q8 x; k! u
  my-row          ;; the row of the intersection counting from the upper left corner of the
; p* e7 r+ i7 E3 y. p3 Q                  ;; world.  -1 for non-intersection patches.- ^/ [( w/ K' ~3 s0 n: n9 z: p  u& f& d
  my-column       ;; the column of the intersection counting from the upper left corner of the
) L/ \$ R; V6 w! I. a5 x) O                  ;; world.  -1 for non-intersection patches.
5 c7 k* J! {" I- ]( r# P* E  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ C" c1 K, K. Q9 c0 P" l
  auto?           ;; whether or not this intersection will switch automatically.( t" F  Z% h9 X1 h! T
                  ;; false for non-intersection patches./ f/ D7 h% E! D$ i
]  B: a7 q3 X* r  R' ~) V
" D( p, B( v; B# _+ g  X  C9 F  G

7 H# n4 U# R* i9 a4 _;;;;;;;;;;;;;;;;;;;;;;0 ?$ F" I* q7 X" Z% V& d$ @3 v: o
;; Setup Procedures ;;
5 k' H' P: f* L;;;;;;;;;;;;;;;;;;;;;;/ I0 ?) R+ |* A3 A

. f* `5 X* V  _- L5 C7 o' I& k;; Initialize the display by giving the global and patch variables initial values.( S7 b: n+ e( u& ^* p& a4 x
;; Create num-cars of turtles if there are enough road patches for one turtle to
# j. F- w8 o8 U. V* F" I1 I8 r;; be created per road patch. Set up the plots.
6 O" z3 K; f) R6 b# Kto setup; t) c- ?" V- L( z6 Y* D4 ?
  ca& z/ P9 s, D1 @- ]7 H( n
  setup-globals1 V) R# r1 `8 ], G3 a: O. l
5 a! H% O* ~3 Y6 O' Y
  ;; First we ask the patches to draw themselves and set up a few variables4 Q5 Z! P7 v9 {: {4 Z3 T
  setup-patches! n* X3 _9 b9 q, O9 s6 p: N) {5 T8 Y
  make-current one-of intersections
7 E; F1 M# \, o1 H7 ^3 ^1 d/ b& A1 _  label-current
: h) D4 [1 w' A! D( Q1 j/ h  _  C+ W7 m
  set-default-shape turtles "car"
: D! U$ c; }6 s  ~
  C1 ^) }( D  L: |4 \* w% U$ Q) S  if (num-cars > count roads)# C) M# p$ {# r* G3 V3 ~5 F$ X% A8 X
  [
7 f' z9 V* v  y- C# d7 {% {" I1 f    user-message (word "There are too many cars for the amount of "4 B) H2 g$ h& b
                       "road.  Either increase the amount of roads "
: T6 K6 T3 [$ r9 w4 T                       "by increasing the GRID-SIZE-X or "
+ C2 R( r4 Q7 X, i3 o                       "GRID-SIZE-Y sliders, or decrease the "! I1 t9 G! d* a" d1 v" A4 K
                       "number of cars by lowering the NUMBER slider.\n"# z8 g" ?. T6 U
                       "The setup has stopped."). r5 f9 P4 \* p1 T
    stop; ^& `! ]. H2 c9 {; b' z
  ]5 @5 ], n% x1 s! [. U
9 V  s1 \! Q9 c+ }0 \1 `0 G* x
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ H( R, {% [- k0 V2 D7 @) q
  crt num-cars
4 o% z7 @  Z- q( z3 `  [
3 r0 M3 F+ x9 V- _: U7 |    setup-cars
. c/ n( h8 [' d; C# e" L    set-car-color' x4 I+ E2 J( f. ]# W/ D  O
    record-data
6 `. z4 ~! U7 F  ]% V2 }6 |% \# G2 j& x8 y7 d

6 f, C+ A; w5 j4 g, t1 S$ [  ;; give the turtles an initial speed9 j1 u: k0 r# ?$ R4 R6 @
  ask turtles [ set-car-speed ]% H5 h! q7 M6 `1 {/ Y9 ?9 {' m
; _% `  ^! ~3 k5 c9 G/ l
  reset-ticks8 A# H( O5 j# t/ F
end
4 `, w, ?" T! Z5 Z: w! r, [
( D- S6 E* t  F* y- C' n8 f;; Initialize the global variables to appropriate values" Q3 Y! v$ I7 A2 D8 J5 j. A
to setup-globals
" B7 L2 w: A# j4 e! ]9 n7 b  set current-light nobody ;; just for now, since there are no lights yet
  D& ]5 h( }8 {; T2 @  set phase 0' |( r* X3 o6 R/ G+ k$ O
  set num-cars-stopped 0
! p& Q8 U" }$ Y" [, g+ n  set grid-x-inc world-width / grid-size-x/ r7 F0 \) ^: ~0 Q' P  W
  set grid-y-inc world-height / grid-size-y6 o4 l  ]& c* r3 `$ H3 S; p

6 A/ M) s) E4 o: w+ i; T( D: S  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- Q. M3 S1 z+ n. e9 n% T6 Q
  set acceleration 0.099
" q6 J2 `1 {4 A1 l" X, E3 _- Eend* x' i* ]7 B7 `( S% e  g* C5 M
; J: B. E3 f+ @, z3 d5 B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" f  c8 n8 h( ^; f;; and initialize the traffic lights to one setting& [  F* h0 y9 y4 x
to setup-patches
3 Q) S8 g% }( ~9 F; E  ;; initialize the patch-owned variables and color the patches to a base-color
$ c" m- I* Q3 D) @1 s  ask patches
7 g6 M, T- @3 ^: x! N4 G) j  [- [* D3 ~8 r6 n2 F' ^2 D, G+ o
    set intersection? false
; b: B. S- T1 D    set auto? false/ K& F6 h' o% r; v- T1 q0 ~8 X
    set green-light-up? true
* ?8 i" P( C/ x4 m" d, S+ ?    set my-row -1: g; }1 F4 l& m1 C9 h3 `
    set my-column -12 N" c% u  M2 t, U  J7 |* G
    set my-phase -1" h' L; z* T* D1 ^6 b- g" G: e; o, I
    set pcolor brown + 3
$ y1 O8 Z" L% m1 V  ]% H0 K& z) ^( q+ u# v

. s  P" _' Z  Z9 Z1 k1 `  ;; initialize the global variables that hold patch agentsets
8 _" U) x8 W% A& c* P  set roads patches with
% ]) N- l+ {$ r. ?1 e% l+ Q/ j5 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 f: z3 r  @2 k- R1 g% Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 F; }! U: D  J3 @' X' k9 q* D' T) O' Y  set intersections roads with/ V' m, f  e* I( |. L6 W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( A9 }- ^- H7 _; G6 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 h) Q) q2 _# S! w. K/ r% ]. T% L+ Y- q5 Q" K' {. c' P! H
  ask roads [ set pcolor white ]6 _. h5 p9 r5 c  B8 K+ o9 L6 i
    setup-intersections& c+ J! D2 z4 t
end
/ w! g% o% l4 T* p; ^# ~其中定义道路的句子,如下所示,是什么意思啊?: |2 j/ \. G8 p. b# p9 Y/ r
set roads patches with3 Q3 X$ Z4 ^, @4 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 Z0 |6 A& X$ k$ E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% E: v3 o/ ^3 G( {' W! _) e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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