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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。
. U2 O, q$ ?9 M! }: q' @netlogo自带的social science--traffic grid这一例子当中,5 @$ \  x/ J- i& S8 \
globals- w% s3 W. T% g0 t
[+ A+ T! g/ f" B6 O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% N- K4 ?& [7 E' Q/ N; C' ]  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ h. _2 \, n" C7 i" V
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# X) [; x0 u9 u) w
                           ;; it is to accelerate or decelerate
8 p7 a: o4 Z. H8 g  x, o6 W, I2 l" K  phase                    ;; keeps track of the phase
1 _& J5 o( o& f8 D8 A- C; F/ I  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 l3 `* I# o) f; _
  current-light            ;; the currently selected light6 l1 B3 m- f5 W6 ^: {
; V. t7 {8 X  H7 e: j
  ;; patch agentsets( N# j' [2 {' d, k4 G5 X* c
  intersections ;; agentset containing the patches that are intersections6 a' N! [0 k( a% i
  roads         ;; agentset containing the patches that are roads
* h( `0 [/ ]/ ]& E8 o]& F1 e3 w/ q- y; v
: q3 C6 [2 ]0 R% T0 [( M; p, `1 Q
turtles-own) n" @( w& I3 u
[1 p0 r8 h8 L% _
  speed     ;; the speed of the turtle: y$ ]9 d# g, X
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* t# T& _: m4 b$ V/ |
  wait-time ;; the amount of time since the last time a turtle has moved
$ Q1 T. p: B% S4 L]
6 T, A! o; n0 R! U+ ~* }5 f) v0 ^: U
patches-own) D4 l# t; P4 |+ N$ F% `/ {
[+ b) b4 V2 m- w$ n
  intersection?   ;; true if the patch is at the intersection of two roads0 q7 x* k( V1 i' {9 L5 O: v
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ T0 P$ G# Q0 h% B6 X
                  ;; false for a non-intersection patches., l0 t- q  Q6 ~2 ^& b
  my-row          ;; the row of the intersection counting from the upper left corner of the
9 Q+ I4 r1 K. B* f1 Q                  ;; world.  -1 for non-intersection patches.+ C- j5 v) z, s- k+ S0 y7 H+ e
  my-column       ;; the column of the intersection counting from the upper left corner of the6 K7 x1 n2 s, K3 P
                  ;; world.  -1 for non-intersection patches.
9 n; t" _) j/ A" Q) o, B; D  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., ^! f6 W. w3 e9 l+ j8 P1 t& v1 U
  auto?           ;; whether or not this intersection will switch automatically.) |9 g% d& p: @0 L, o
                  ;; false for non-intersection patches.
. P# y5 ^% g; o4 @: S6 W2 T]& P- |/ G. L7 c9 q- O

6 e3 @% @- }# o1 w4 m2 t. u' W- q
# Q6 v) z/ x, z;;;;;;;;;;;;;;;;;;;;;;; M7 Z, P; d; @2 w3 y0 q% c1 v" t
;; Setup Procedures ;;
! H3 ]% V# V  N& r3 e;;;;;;;;;;;;;;;;;;;;;;
  q5 P/ _$ m$ ^) S; k3 u
4 o) _% J. O0 \3 [- m' U5 y;; Initialize the display by giving the global and patch variables initial values.
# e9 L: [' E8 S$ x3 c: O;; Create num-cars of turtles if there are enough road patches for one turtle to
5 n3 q  [( G; d8 X# M5 A1 C( C( z;; be created per road patch. Set up the plots.  X$ z$ w8 G( P) w- k: ^
to setup& g, |7 e' V: l) n
  ca
8 c* Z- X& Y6 K  N# h4 L  setup-globals* v+ i' X( K3 Z3 b" x- e

0 k0 e# n6 c: ~+ X# `  ;; First we ask the patches to draw themselves and set up a few variables- p7 U( P. W* W5 @) y( o
  setup-patches
* w; i8 Y& b& L  make-current one-of intersections
/ i; W- u2 Q' d5 ^; y, s: Z0 o  label-current2 R& j& P8 K" R3 O0 f

* X' S( c# H* p1 V* R6 U# F  set-default-shape turtles "car"
( w0 Y) V7 T4 K/ {2 P
( w4 T& F$ D7 }: F  if (num-cars > count roads)
  x* c6 w; l! X# A% b+ g+ y. f  [
" {& p$ u: B" G" J    user-message (word "There are too many cars for the amount of "4 t, c+ ~+ z# |  p
                       "road.  Either increase the amount of roads "
( C* a2 V! y% t                       "by increasing the GRID-SIZE-X or "* X; A. X6 _0 P4 c) z1 t% [
                       "GRID-SIZE-Y sliders, or decrease the "
8 q9 }: }+ Z, k, _                       "number of cars by lowering the NUMBER slider.\n"9 R* t, E2 N* k1 m2 f
                       "The setup has stopped.")" R: A4 n7 `) c& t. Z- y
    stop
8 g6 v4 L1 b1 H7 Q  ], z; R% k( V  t/ L- @* m8 L. s
4 q. p0 q- A! \8 C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 U0 Z" `% F' _4 G1 A' }2 ^) H) U
  crt num-cars
1 q6 p6 N+ i- N3 r9 w  [0 i- l* K/ ~% a9 ~) y! {1 X
    setup-cars
) U/ ?4 \. k# i8 u; c    set-car-color- R* b: P3 U3 ^1 Z/ g
    record-data1 M2 P* f6 J# D
  ]- w% s! s9 k: t0 E9 N
( e% k: Q* [, I4 t* g0 j+ _
  ;; give the turtles an initial speed6 N7 b& B  D" m  [2 i
  ask turtles [ set-car-speed ]$ ^5 p+ t' `% B% z
0 c9 Z/ \9 V. K/ @5 T  f5 ?, s) @& X
  reset-ticks
, R3 t) a" p! q) q0 f* T! uend
4 o% _3 G8 w! K9 a3 f
. z* m4 e. p) {8 U;; Initialize the global variables to appropriate values
- ~0 e* s/ D! I, ^5 {4 l" f' {to setup-globals
  l& U! W! }2 {( D2 r  r  set current-light nobody ;; just for now, since there are no lights yet3 b3 T7 Y8 ~9 ~' C* R+ |9 X' @: A
  set phase 0
- v4 J' S* S- D) _+ m0 }" L  set num-cars-stopped 0" m/ x+ w" N6 u$ s7 ]+ y# F1 m! O
  set grid-x-inc world-width / grid-size-x4 a+ B6 h, `) ]; c9 Q
  set grid-y-inc world-height / grid-size-y/ d8 r9 {* S4 c( {/ C$ J
4 `, r8 M+ w5 Y5 E6 ~
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: c7 N9 z2 \3 N9 Y8 r  set acceleration 0.0998 V- c) N: N3 \$ w% {" B: ~
end
2 V* [; d  S3 S& y6 D; U: y
- x6 C" |8 C6 g+ B& p1 n; R% v;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& c. e3 {1 G( I* M+ p$ S8 H
;; and initialize the traffic lights to one setting
& L" f) X* m6 X1 _8 ?6 cto setup-patches4 l: V% O4 ?5 Q- G# y+ Q+ Z
  ;; initialize the patch-owned variables and color the patches to a base-color
& a* J: F. S& }  d0 ?  ask patches% ?  s. k; h: J4 a/ h' a
  [
- `) G( E8 p) g    set intersection? false
1 i% k) A1 T! ~/ k8 k: C/ O    set auto? false
7 s: k- i* p( f& ~: D& N+ q: h2 X    set green-light-up? true9 h6 l5 `: j  r
    set my-row -1
- K# {- [7 `1 K' A4 R' g    set my-column -1) o& @- \/ ?& {6 Y
    set my-phase -1! K2 P; d1 e7 B: M( F. q8 ]  p
    set pcolor brown + 3% U3 ^8 w  X5 A) _/ O" ~) O, E) R
  ]; P; `5 G* C, @) b' k- Z+ Y$ c
- @* D% u* p4 h3 g7 ?4 S3 T
  ;; initialize the global variables that hold patch agentsets
( }; f- [- e8 P1 ?  set roads patches with
; t% J% A5 z! U+ F5 T* b7 N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 g3 ?+ v3 R$ o' q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# C3 i4 c9 b3 L; E7 [) A- h; I
  set intersections roads with
0 g# u# d. A7 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. O6 F: D% K# C5 x. z, k+ R4 w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- z" m6 U7 n1 A" t  ^7 H  \1 a" C2 |: X  r5 S+ m* M  h9 r
  ask roads [ set pcolor white ]
5 Y/ {/ [% j+ E2 `- @    setup-intersections" L) ]7 E' c4 l
end6 m( R9 K  }  u9 b7 _" b; N1 s
其中定义道路的句子,如下所示,是什么意思啊?3 s) Q* k# X3 r
set roads patches with
: M, J7 `, ?' T; C+ ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 F! g5 O+ Q! W: t) H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' q8 `9 B9 B2 d+ ]& o- i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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