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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。9 E. k9 i4 w6 t
netlogo自带的social science--traffic grid这一例子当中,3 \  u$ l6 N. o% J8 Z- S% u
globals
' s( Q' f7 Q. n  V9 G  ]% @2 Q[- g) D% Y) W0 D) w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ F! |" n4 k. [: j3 q- D) W
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; g9 p  E1 q7 j+ k! b, Z" S  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  m' b/ I5 U6 h                           ;; it is to accelerate or decelerate
( e+ M2 r* k$ [$ @; @6 x4 w  phase                    ;; keeps track of the phase4 I* o" ^; T6 E& G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, M0 x+ B. U! d5 ~& o
  current-light            ;; the currently selected light
9 J$ B5 X$ S# h( P+ \- X7 p3 c! U1 z' N/ h% T8 `, W7 W# n
  ;; patch agentsets
' v3 X$ g5 m$ \# F, i  intersections ;; agentset containing the patches that are intersections  F5 `( g  d& r: Z& D7 K
  roads         ;; agentset containing the patches that are roads
) G8 g$ q2 Q! B6 \- z. \3 ?! d' L]
' S2 B( @/ @( Z7 b, c9 r
- h; _. O/ ]5 eturtles-own. A6 M& n3 o3 G- f7 u1 W
[, Q  V* x0 J# ^: @; ]4 r4 H
  speed     ;; the speed of the turtle+ l$ r* Y0 t9 F8 J% p
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 r" [: t1 H6 r+ M' r, `! h  wait-time ;; the amount of time since the last time a turtle has moved" h2 }, k7 k; q) i: E
]
8 k( V: c5 K1 t: m- y  N' k$ `5 ]8 {( S# K0 Y* V
patches-own
) l" [4 @1 Y" k0 e5 ?2 M% Q[
3 n( r! u3 E4 E% d3 t9 A  intersection?   ;; true if the patch is at the intersection of two roads  c0 n9 h, `8 Z* Y! S& o
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( q, Y; g' m- u. d! l
                  ;; false for a non-intersection patches.
" d0 F1 y1 w1 B9 U  my-row          ;; the row of the intersection counting from the upper left corner of the0 k& l9 z* R# `" T+ X
                  ;; world.  -1 for non-intersection patches.0 j8 ?4 d4 Z7 {8 w7 |
  my-column       ;; the column of the intersection counting from the upper left corner of the
! ]4 ?+ M5 }# F$ Q1 a                  ;; world.  -1 for non-intersection patches.
2 e/ N2 K, ~( I  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ ~1 B: q) x0 P4 R+ Q* C+ `6 d$ [  auto?           ;; whether or not this intersection will switch automatically.8 h" j* s- j0 O
                  ;; false for non-intersection patches.
! [6 \1 P( Y. p& ~( G% B" u$ ]% j+ D]3 f4 |2 q. a9 d; L6 N

' o; j  {( Y/ V! B- z9 ~# Q% s2 g  d9 _9 N
;;;;;;;;;;;;;;;;;;;;;;4 w2 D9 e) v0 x* v' P- f) C
;; Setup Procedures ;;
3 X  D  u& m% N# u; J# a3 U;;;;;;;;;;;;;;;;;;;;;;
+ J2 ^7 w- N* K8 Z; Z# `' X$ o2 R
* z' c9 M# V0 D3 b  W1 b;; Initialize the display by giving the global and patch variables initial values.
& {: H" R5 A$ j) {2 v8 d/ j;; Create num-cars of turtles if there are enough road patches for one turtle to
$ f. l$ q$ a8 L$ B;; be created per road patch. Set up the plots.
% H. }6 D8 ^' a1 E# G2 ato setup: r; ^' v+ J+ ^/ ^
  ca
' X  p( r2 h5 A" `: a  setup-globals" g6 }4 y# x' d3 s  L$ S6 W

, k* C! ?4 G2 A0 {8 q7 W% k  ;; First we ask the patches to draw themselves and set up a few variables% ^/ q- r; ]+ |6 N# ^# [
  setup-patches! y, P% _) x3 ~& j* H5 s4 y+ _
  make-current one-of intersections  q7 l6 B" T$ x1 f/ Q
  label-current' }: U# Z, K$ E  Y" h0 H$ g
6 p. O( G- `8 g7 \+ a( S: |0 a' g
  set-default-shape turtles "car"4 q3 i# S# |: K7 j8 x$ c$ T

/ @& }, |5 x3 ?  if (num-cars > count roads)
/ j5 M: [' Z# X3 ]% n  [, U& {3 h/ K/ b/ l, F9 @9 o
    user-message (word "There are too many cars for the amount of "1 J9 s0 S  d# m+ ~% E
                       "road.  Either increase the amount of roads "
/ C% }7 v! r+ w2 G! u                       "by increasing the GRID-SIZE-X or "
- e! P1 \, E/ X                       "GRID-SIZE-Y sliders, or decrease the "; ^5 ^8 U& ?8 \) e( A
                       "number of cars by lowering the NUMBER slider.\n"+ P- [% [6 B5 C- `/ [+ s; I$ |
                       "The setup has stopped.")/ a; _3 ~7 ^- y+ U+ D& T
    stop. ^7 L" C' Z! s* N8 w
  ]
8 h& I1 V3 P: ]$ H: }
- Q( O, S3 T3 |) ^- M2 ^  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 F, G1 L3 ?0 a9 H- @
  crt num-cars5 ^  E9 R$ r0 q: L- Y
  [
8 X4 l" e/ A6 p    setup-cars; I; i7 p( g$ @% P
    set-car-color
& z' O/ m7 l9 U# i2 I; R5 V    record-data
$ g( h( R9 D$ K  ]
' R: `- Y% X; q6 R! [, R: x
* r/ E+ J% y4 [  ;; give the turtles an initial speed0 A5 Y( G- q4 `% J# m' k8 k
  ask turtles [ set-car-speed ]4 L* e! ^/ v3 S& k2 m

( D% [+ c  ~# N* f5 V2 i  reset-ticks
8 L% a8 ~$ G1 g. yend% s" X  K' V/ y2 h. L0 Y' G! z
; T6 Q3 v  d( L: b; l! O
;; Initialize the global variables to appropriate values6 f+ V1 G! v' O5 Y$ W3 b0 D! D0 H
to setup-globals
1 ]0 k- }+ b- R' v. I  X& r- p; G  set current-light nobody ;; just for now, since there are no lights yet, J" e5 c% Z) u8 @
  set phase 0
% M9 F, B" N* o) y, P5 A  set num-cars-stopped 0" B) d! T7 P8 e+ o0 K; {
  set grid-x-inc world-width / grid-size-x
: U* D+ x- \2 f+ s  set grid-y-inc world-height / grid-size-y
+ v7 s, V9 s( b' o( X5 V$ O  i# l9 k: ?5 r
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) `* X' h) [$ |+ @
  set acceleration 0.099
# A/ c6 R+ p# ^: Dend
7 R* @2 s* r% c
( A9 j* v$ z% H/ g  ^$ \; s1 [;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 N2 @* }: ?' v$ X$ `5 l
;; and initialize the traffic lights to one setting5 _$ \& y; \6 Z) k3 ^. o
to setup-patches9 `3 N. h- X3 y% p' w' p! Z
  ;; initialize the patch-owned variables and color the patches to a base-color
. P' L/ {; a% Q* i) t6 ?9 D  ask patches
" {5 I" A5 A! `$ b  [
- Y0 K. U1 W% b+ U! A- P& {    set intersection? false: t4 x7 @8 F' h  ^8 Y
    set auto? false
# g9 o8 [+ f( M' ]    set green-light-up? true
5 W1 Q( M! L: P; ^$ s* `    set my-row -1( \' {. Q' C% Y7 D: H& J$ h
    set my-column -17 c0 D! Z* ?; \  s+ n  {+ |9 e
    set my-phase -1; r7 x. e9 g% s6 X
    set pcolor brown + 33 l" I, e4 Z+ x( f& b" _# F
  ]9 S4 l6 X0 V+ x. j: g9 C
. J# [* c4 v3 b# d4 L  |
  ;; initialize the global variables that hold patch agentsets4 l* D) q+ E6 V6 b/ v, U" R& q6 E' W: a
  set roads patches with
. H) ]. x& M% R4 r4 Z$ O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 P3 w$ i5 e9 I$ u7 h8 b% B1 T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" h" c$ n7 ]4 n7 r) }  set intersections roads with
: o( F1 @0 `$ `, ?* G9 W$ v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ b1 u1 F/ }& [4 n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' |, U/ }9 S9 L& b  k" t% x
0 w4 b" z1 j# B
  ask roads [ set pcolor white ]+ W+ q0 ?  ^4 O- U
    setup-intersections- Q% r" e' q: C! r
end5 N4 F: p( T9 K! T" g% \* K( y1 r
其中定义道路的句子,如下所示,是什么意思啊?% v, k0 y* @' o3 g/ F# c  C
set roads patches with
2 C/ b& }% p) \1 L; ?8 p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ d# p8 x1 Q. e# q/ W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 ]1 Y1 L+ O5 t' e9 H" m3 S4 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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