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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。- y9 n6 W+ L' k
netlogo自带的social science--traffic grid这一例子当中,) U5 S: d8 t. n4 M
globals3 I& g" T: b: Z/ E3 v- `
[& z2 G3 n4 m1 a5 D
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
0 ?" i$ j1 z# S) Y/ U  grid-y-inc               ;; the amount of patches in between two roads in the y direction
3 J  M. s/ F/ F8 p) @- V/ D9 Y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ p% L9 q: R& o6 D
                           ;; it is to accelerate or decelerate
7 V5 {8 y5 t7 |+ `' R( q/ t2 a  phase                    ;; keeps track of the phase8 d  ~+ N7 i% U2 l, K6 g' L
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: k) T: f: e2 Z2 U4 z
  current-light            ;; the currently selected light, z. o" i0 y7 `2 r0 w
. w7 E& h/ s3 X
  ;; patch agentsets
. V6 I% }; l/ q  intersections ;; agentset containing the patches that are intersections  n9 L  t: |- p0 W- X; {1 B
  roads         ;; agentset containing the patches that are roads: S7 F% }( S! a5 L3 b
]
% l% @+ n$ r- P  @4 W, B: L5 s- u( J" }; N+ x. c* U4 d3 t
turtles-own2 h5 ~2 A- `  @9 J- W5 m
[1 o* C" z. _" k, f2 i* }  k3 E
  speed     ;; the speed of the turtle' G6 |& |& |5 u1 ?; V( X2 O4 w( \
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. ]: Z; N% @% v! j* C8 G
  wait-time ;; the amount of time since the last time a turtle has moved
9 ?' |6 w' v5 g8 B! Z1 u]
6 X, [# w5 {: s. c8 u" E# ^
: F2 E3 W/ A7 L/ j' g% bpatches-own
5 m# L$ |  J! l! @+ K[! n: L3 L; R; F- z' y1 \1 l  Y
  intersection?   ;; true if the patch is at the intersection of two roads
. I; K7 G1 K& B& n+ z# A( C; t  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# S4 A, q: t3 P  H9 T* b8 t                  ;; false for a non-intersection patches.
' O& e* c6 F; t0 y# f+ r  my-row          ;; the row of the intersection counting from the upper left corner of the: r+ X: p, D/ g
                  ;; world.  -1 for non-intersection patches.. c! _8 S+ r6 ^! a
  my-column       ;; the column of the intersection counting from the upper left corner of the
2 j$ l( S0 c2 O% |: q                  ;; world.  -1 for non-intersection patches.5 F  K) S6 Q1 {! O8 G  v
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: \- J/ p) X# P+ o: ~7 c  auto?           ;; whether or not this intersection will switch automatically.5 z3 r% E) Q2 Y3 S% D( ]$ A3 |
                  ;; false for non-intersection patches.
  G9 q- f, S. R]) B' ^. S4 f; i& U

* x. q6 m! z8 y- W  r/ J* f* m# Q: U8 ]2 ]
;;;;;;;;;;;;;;;;;;;;;;
  C) j3 F% N8 n7 d( Z1 ~% s;; Setup Procedures ;;5 J: t+ e5 e- ~5 @$ ?! n
;;;;;;;;;;;;;;;;;;;;;;3 o  J' B# p) m5 J0 V; H

, V' W9 h: o2 V- T- c;; Initialize the display by giving the global and patch variables initial values.% O. S6 \% e4 t: x0 y& ~5 ^+ a
;; Create num-cars of turtles if there are enough road patches for one turtle to2 [* i5 _6 t5 p4 U$ |
;; be created per road patch. Set up the plots.
0 Q; z; C0 c  }/ V- }  c# g. c  b5 A: dto setup0 y' ]' v+ Y* Z  K2 D
  ca- q! c' v, I1 u: s) i
  setup-globals2 m# U' h' ^* h
7 l+ w9 x% A/ `+ p" z2 m7 f
  ;; First we ask the patches to draw themselves and set up a few variables
/ X* V. z6 c8 t  setup-patches
" E( a! r: `3 w7 ?* B7 ~  a( Q, O6 X  make-current one-of intersections4 f9 R: X# G8 T! D' N5 Z
  label-current* j6 h" p: S6 o5 z4 ?
, k* W% o. t# M- H, O: r6 l5 I
  set-default-shape turtles "car"
5 `% ]2 k, Q, h* ]7 L8 z& o5 r9 _6 c: y7 ^; G* p1 a( `0 V8 W( m
  if (num-cars > count roads)' i' d- V- j' [0 P1 w
  [
! C" b2 M$ {4 c! L: }& K% S! A! H$ N    user-message (word "There are too many cars for the amount of ": `5 d! p8 z2 S( `* E- a
                       "road.  Either increase the amount of roads "
& K' |! B6 A' r& p                       "by increasing the GRID-SIZE-X or "
$ e% @' m& Q, K# v) f0 T6 Z& ]# W6 I                       "GRID-SIZE-Y sliders, or decrease the "8 |, o9 z0 ^. V( g3 E% V3 C
                       "number of cars by lowering the NUMBER slider.\n"
' f6 `1 w: s% S3 n- D  _! f                       "The setup has stopped.")
1 I' x# ]1 ~) X' r8 A# f- F2 k    stop& g$ t8 V5 ]5 u4 _
  ]
0 Z  v" n0 o, @* {5 e: H' V: U, u. l4 L% V% K- w
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! m1 v* t/ S( A  `
  crt num-cars+ D0 O, \4 |9 G# n* J! n" q" q
  [
: a9 c' `2 I& P8 j+ s* I9 K    setup-cars1 h. i* d! q2 L% ]$ r5 o! z
    set-car-color
# h3 p3 L) h) W7 N8 [    record-data
* w, P, e. q* G4 {' d9 V8 P4 Q  ]
9 L0 r1 A0 R2 F0 z1 M* _, o* U" `4 ^  T4 \" B1 Q
  ;; give the turtles an initial speed
4 _+ ?  Q  n+ ?- g3 {( t  ask turtles [ set-car-speed ]
- ~9 G3 |& u! }7 o3 m4 _; e6 U3 T
. R" Z, _6 T" `7 I  reset-ticks
: H6 e  y) f5 {  `3 Z  mend3 [6 ~0 j' T1 `# F# `5 `- D0 v

0 N& v1 V, U5 Z$ x;; Initialize the global variables to appropriate values4 @5 q& L* V# y4 f
to setup-globals, ~1 ?+ y3 A0 Z  V
  set current-light nobody ;; just for now, since there are no lights yet
, \# A; j9 x4 ~; t' Q+ q$ L- V8 i, ~  set phase 0
( ~) Y1 j; L, \& d+ i6 Y  set num-cars-stopped 0
; K: y0 E0 F5 _" Y& H+ I  set grid-x-inc world-width / grid-size-x/ Q( T5 i0 V" V4 G$ X
  set grid-y-inc world-height / grid-size-y
4 W- G: R4 h. e& C3 I, a; {
( R$ @0 k) A( B' }8 E  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! V8 Z# H. Z6 k9 ?0 ^) u
  set acceleration 0.099/ j4 F% R% m' W" K- ]
end0 F4 a' J8 T/ K4 I5 h- ^

/ [, k: _9 f" c2 S;; Make the patches have appropriate colors, set up the roads and intersections agentsets,, B" d9 I& D. z4 @, k/ U& v9 N
;; and initialize the traffic lights to one setting3 ~+ h" E9 A" v2 B# [
to setup-patches
* M! f4 p0 A( y& @! u# d# B2 c5 _  ;; initialize the patch-owned variables and color the patches to a base-color4 q- n7 C2 b3 K) b% v" \
  ask patches
7 \! t* P& I: e5 I1 e  [$ b3 v6 ^1 ?/ u
    set intersection? false
; d! h, ]( \7 z    set auto? false
" H+ j" p: ^: Q' s( T4 {    set green-light-up? true
, D$ O$ b, D9 P0 _    set my-row -1
  t9 l6 G" Z' f- A; D    set my-column -1
* V+ u  R% u  s5 e    set my-phase -1
; {9 _7 |1 l/ K  N4 L' s    set pcolor brown + 3
( T* B% N6 x! @- h9 Y4 k1 ~4 S  ]/ p& A# q( o+ g! a: }7 e9 ^+ \
! d  x$ R! D9 X1 H+ U" I
  ;; initialize the global variables that hold patch agentsets
4 B! T- z, e. f+ E  set roads patches with& X4 G4 `4 o6 d' I! ?$ H# S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# U& I8 P: @/ F1 ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ o' r( D! i" ?2 _5 b  set intersections roads with  a9 a9 ?8 ?+ H$ g7 H" C- ]' Z+ H; e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; s- J% F$ `& `! f# }! t) ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' x' {- [& {: M# T6 S7 E6 \% @! U

9 d7 @; ]; g: c7 c( p  ^$ E  ask roads [ set pcolor white ]
! ]+ @6 |8 J! X    setup-intersections
# J, V5 B  F8 \end
' U. L% m' w/ K4 U6 e, W! @0 U其中定义道路的句子,如下所示,是什么意思啊?
% r5 E# O5 n, y; Q  q3 n set roads patches with
; X/ G5 U# ]7 y6 Y- c" u0 n* m/ z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! h7 M( ?2 M5 ^* W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: h6 s7 a9 g5 ~( d* G1 c1 U8 r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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