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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。6 G' A) _2 C9 I) J* E6 V7 ?! i
netlogo自带的social science--traffic grid这一例子当中,  A8 e4 w3 `5 N  ~, B
globals
, e/ X: H4 h; U. K[+ w8 C0 O/ g' X5 v. E$ q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% ^/ ~; @: A$ x, @  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 m" O1 O) y. m/ ^& n& Y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 d) f; K% k. k! n
                           ;; it is to accelerate or decelerate5 L9 }; ~; t$ A9 F
  phase                    ;; keeps track of the phase! \7 z; ]5 X3 y' c; l# ^+ O
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# {2 Z% ^3 Y" [; u  current-light            ;; the currently selected light
) ?2 Q! K9 `8 a4 f3 u: L+ o) N. G1 ~9 N, v
  ;; patch agentsets
2 q5 {) U: [  E3 Z- B2 |  intersections ;; agentset containing the patches that are intersections; y+ Q* |/ l* [9 t. [/ p
  roads         ;; agentset containing the patches that are roads
! J8 H6 w: q1 Z]
) K3 w1 y& }* H7 K
3 J: q4 o4 N& z' _/ |turtles-own* e3 R5 M8 N* I' z2 z
[' Y7 N- G% r: J$ d% h+ U+ J
  speed     ;; the speed of the turtle
0 y( I' c4 B( C  up-car?   ;; true if the turtle moves downwards and false if it moves to the right) N3 L  T4 ~4 ^4 \
  wait-time ;; the amount of time since the last time a turtle has moved
0 b8 V: E9 _! @; {0 G6 m]
% a6 A6 A- S* l- K+ V# d( S  Y5 D
% S8 V% T* O( b# I, M( [3 Opatches-own
- X0 Q5 t& y# A# @( v# F3 Y; m& Y[: q5 n  k2 [/ m9 E9 K
  intersection?   ;; true if the patch is at the intersection of two roads
2 K) W3 z. K5 Q2 _% |; g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( R) n2 F" o2 }4 v
                  ;; false for a non-intersection patches.
: }* A& T5 G) t  my-row          ;; the row of the intersection counting from the upper left corner of the2 L* w0 j' |2 ^  I. ~- k$ v/ G7 p
                  ;; world.  -1 for non-intersection patches./ K7 Z3 z4 r, @2 T7 }, f  A
  my-column       ;; the column of the intersection counting from the upper left corner of the1 `0 f# b" Y" V. p
                  ;; world.  -1 for non-intersection patches.
! b  }3 q' [) b8 ]- ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' G1 \' R& o- X/ ~0 F
  auto?           ;; whether or not this intersection will switch automatically.4 v/ K. G- `2 f6 m
                  ;; false for non-intersection patches.
: @! ]1 E, z% Z]; C: f! b6 i6 z. @9 q* z6 R7 u
2 G5 Z6 A! @- s
# _) i3 k+ G6 ^* f
;;;;;;;;;;;;;;;;;;;;;;
7 z/ Y  M0 m( Y6 M;; Setup Procedures ;;9 [9 V, n: Y9 ?
;;;;;;;;;;;;;;;;;;;;;;
( u- Q: e3 M/ }; k" s4 w4 C6 J0 _) x$ p- {& h0 j
;; Initialize the display by giving the global and patch variables initial values.
4 y$ q/ e4 Q6 E2 r8 e# ?;; Create num-cars of turtles if there are enough road patches for one turtle to# D9 }( o9 o* _# U( {
;; be created per road patch. Set up the plots.$ r2 O7 K  `+ ^. O! Q, _
to setup) V7 k- S: {" x+ L, @1 C& ?+ ^
  ca: Q9 U% x! U0 N6 j$ ~+ m
  setup-globals) z7 t2 _# n' F
6 z# F2 _9 B/ ~! E
  ;; First we ask the patches to draw themselves and set up a few variables
$ [$ ?& _3 T! J: I  setup-patches# ^1 A" c# [8 U$ b  i
  make-current one-of intersections
, A2 p6 ]. h& A! K  label-current  e/ \9 B7 w2 d* I; J' J; W( l% b

4 m  z' e6 _1 {  set-default-shape turtles "car"
  F1 p) P/ X8 g* C
7 L& {; I. r$ g& P( ^  if (num-cars > count roads)6 v1 ~; ], Y+ X8 }# S+ ^
  [
! u! Z; `6 X6 M) E# \" a6 G    user-message (word "There are too many cars for the amount of "
4 F3 B; g6 [9 F1 H/ G0 y- ?                       "road.  Either increase the amount of roads "
% K" {1 N3 `( S$ ]                       "by increasing the GRID-SIZE-X or "
" u9 E% b: ?; ?  j                       "GRID-SIZE-Y sliders, or decrease the "3 q. j& D8 ?5 N/ T" z
                       "number of cars by lowering the NUMBER slider.\n"0 z8 p$ }0 @* h; [0 \+ f4 E9 @) f& h
                       "The setup has stopped.")2 b0 e+ v, A9 T6 U  H9 b. c$ A$ j# e
    stop! p) ^2 [) _5 E% e; X' k, o% G
  ]
7 }0 A- ?# q  d) y* Y+ S2 r
0 D4 U9 i# Z# V! u, [- O  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& }+ I. |# E# G, X+ t( ~" {- W7 y# x
  crt num-cars# S. h0 b/ u- c' d% t+ P  C
  [
$ W6 {- D( Y1 P+ @( Y& G/ D    setup-cars4 W7 `+ `4 f+ g& q( q8 f' Q1 Z% V3 [
    set-car-color
# m- `) s+ n8 w    record-data
9 n* h4 h! y, D! Q' k  ]( j# i$ n7 j* V; `( j) e- s$ K
/ U* ]/ b: x7 Q$ x
  ;; give the turtles an initial speed
- D0 Z. L5 d6 w3 }# O, Z  ask turtles [ set-car-speed ]# N8 |0 O7 B# z* m$ L4 y

& O. q  r# d+ F  c+ r/ U  reset-ticks
! s) P# ?! o8 S' N1 S% {end
9 `7 m( e! J9 q# d3 p" ^  d: x8 M
;; Initialize the global variables to appropriate values+ e" @' G* L9 _, H
to setup-globals
, {7 d0 v. ?& O. A/ r% K* ~1 \  set current-light nobody ;; just for now, since there are no lights yet' t/ v. k" x+ J9 W+ C
  set phase 0
7 Y2 R4 f/ [9 H1 \! t  set num-cars-stopped 0% v6 T3 [' x$ N8 z8 n
  set grid-x-inc world-width / grid-size-x
* G- {1 B# Q* C7 U" N5 a4 H) b  set grid-y-inc world-height / grid-size-y' T# f  e4 R, t

- S& a# C  Z7 z7 a* f( M. A7 G4 I  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ p4 ^  P% k; F7 q, r1 o  set acceleration 0.099$ y8 @( J8 e+ F: X6 H
end
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: R$ J, x: [' C! |;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 P$ f3 |% W2 p# g; Y% J
;; and initialize the traffic lights to one setting
# J- Y1 P) \: k/ Gto setup-patches- A$ P' r( u  ^7 `1 h( H$ P
  ;; initialize the patch-owned variables and color the patches to a base-color
! U& ?( Y! s5 @- T" y7 p( O  ask patches
- a8 P) b, W+ i/ P% U- j) a  [
' `5 h1 M) X6 d1 l    set intersection? false
" k$ ^! [% b6 S5 B9 _2 t    set auto? false( X% L1 n# o9 S0 w# T( J1 {7 |
    set green-light-up? true
& `- U3 |, i) C* _1 N    set my-row -1
8 k7 {  J1 _0 t& j    set my-column -17 ^! z3 A9 V5 I  D) w( Z+ ^
    set my-phase -10 j/ K7 P) U% M2 P2 v4 y
    set pcolor brown + 3
9 i0 m4 X& i, g; b" P* D  ]
* ~* g2 p" O4 f' N8 m: Z$ R
* F4 ~. R+ D5 z/ d4 X  ;; initialize the global variables that hold patch agentsets1 g+ |/ k+ h9 \. B# N5 I1 W/ G
  set roads patches with' e0 e  Q3 D2 d0 }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 c- ?& e+ G8 [, f4 E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ j$ R) a$ r$ f5 f3 A: M  set intersections roads with
" f( ^/ R1 z% a$ g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 U% S8 n1 Q( L" ?8 h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. h- u1 [! e) i
( T: T, s- x/ w& s% i
  ask roads [ set pcolor white ]
6 N( u  H) K( w  ^7 i5 o+ L    setup-intersections5 a! E; A* I" x
end
5 L+ M- o: f2 K' Q9 ^! k  m其中定义道路的句子,如下所示,是什么意思啊?
$ T9 }# |; R. V! N set roads patches with
0 s/ n' Q2 S2 ^8 W2 N4 m4 b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 ~( d; }, _6 ^; W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 _2 H$ X" H" 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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