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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。3 w3 E! T8 o9 G2 b# I" n
netlogo自带的social science--traffic grid这一例子当中,
( E1 N* P6 ?/ p) z* y. Yglobals
% w. r& S: q; p; c, ?[9 [3 _' ~# y- s$ s% |, H, J: V" m
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& A* n2 Y6 W; _. O  grid-y-inc               ;; the amount of patches in between two roads in the y direction) v5 S6 _- @, F. F4 G- T
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if4 Z" K4 [  I  N7 o
                           ;; it is to accelerate or decelerate! F& h/ w: O" F; N9 k# G( Q+ Z
  phase                    ;; keeps track of the phase' I& ]* P* s. B5 r* A9 e% C7 u
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 ]6 `. ~, s1 R+ ^6 ]; |; R
  current-light            ;; the currently selected light
9 w# a' N4 K7 {; _0 t: l3 g) O; D/ J8 A; B7 n9 w6 o
  ;; patch agentsets2 J7 G  U/ a1 S3 d8 F, a$ E  U' R
  intersections ;; agentset containing the patches that are intersections
1 g" K4 ?0 G) o6 E2 d; {$ s- F  roads         ;; agentset containing the patches that are roads) t5 A$ ~2 R2 v) g& q1 F- p+ c
]
; z6 i" H4 {, E# w( I
5 y. h% ~# N4 R( F0 T0 N' nturtles-own" Z! X  E) p: K  j3 p3 {
[
: T9 x9 g" ?5 ?6 l* A6 ~: c6 |  speed     ;; the speed of the turtle4 Y5 ]5 h- [( S, @- z) X& s: W, D
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right) O( x) ^0 t$ u2 y+ _0 Y
  wait-time ;; the amount of time since the last time a turtle has moved- h, S; D& @  D6 c
]/ p/ d, U5 X" x
& f4 m- {* [  E
patches-own/ D- B1 l3 A, \! V( F; R" J
[- R& k/ U$ i* ]4 r
  intersection?   ;; true if the patch is at the intersection of two roads
# |  S. h. V# w. e$ ~  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% W5 q; i7 R' \: I. e* r$ n" j+ c                  ;; false for a non-intersection patches.( e1 f6 B& Z% K$ m, u: F
  my-row          ;; the row of the intersection counting from the upper left corner of the! I+ F* X0 n0 ?
                  ;; world.  -1 for non-intersection patches.; \" ]+ B8 z- E! ~4 u
  my-column       ;; the column of the intersection counting from the upper left corner of the- d9 r8 X  \2 J
                  ;; world.  -1 for non-intersection patches.
8 k2 a- g( z8 b5 n1 l2 f3 A  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 j8 ^  u" l& x: o
  auto?           ;; whether or not this intersection will switch automatically.
  j+ z0 [6 Z! @2 T8 `* V                  ;; false for non-intersection patches.7 ^" l  G) q/ U9 `, V6 s- w; _
]
( z3 \7 Q( U3 N9 r" C3 ?6 J/ |, t3 T8 W- {( s
) b9 z1 n6 M5 z2 c
;;;;;;;;;;;;;;;;;;;;;;- I9 T; c4 c" h9 V
;; Setup Procedures ;;
/ m- A; Z/ {; K7 K2 ^;;;;;;;;;;;;;;;;;;;;;;0 K/ a. M/ e1 I6 ^8 v8 e; q7 o

4 [( F6 ]) V; L( b1 {9 X; v! K;; Initialize the display by giving the global and patch variables initial values.8 W* }( [) q! ]& v" r
;; Create num-cars of turtles if there are enough road patches for one turtle to
) u9 x6 G) e, a;; be created per road patch. Set up the plots.
1 c0 G: H! a# G6 p8 C, oto setup) r( A) m9 m( _
  ca, p0 z( E$ N+ h2 n# C
  setup-globals7 r3 {" `% X2 x( O, R. L! h3 a. o

% H3 g( N3 Z, r$ k5 o4 p; J3 F  ;; First we ask the patches to draw themselves and set up a few variables( _/ |* O& v, E; @$ b6 H5 Z
  setup-patches" y/ A$ c9 f* u% p
  make-current one-of intersections
9 D% `$ @3 Y9 O# D- u2 M  label-current9 z4 W3 n7 F8 X! [& s1 w
/ g" V/ u+ ?. J( N
  set-default-shape turtles "car"
7 N) V4 Y$ z6 J8 f: M- J
! k- a- Y% `. K$ W0 ]4 J  J4 W: X  if (num-cars > count roads)
! b2 m& k2 G* k" l  [
8 ]5 \7 s' [0 I% l2 e6 X" J    user-message (word "There are too many cars for the amount of "
  o, G- x4 W9 l0 N                       "road.  Either increase the amount of roads ", f& ]  r/ l% t2 S# x" d
                       "by increasing the GRID-SIZE-X or "
8 ^( z1 J: a6 F- d4 B                       "GRID-SIZE-Y sliders, or decrease the "1 C) B5 T7 A7 P+ q% w) l' h
                       "number of cars by lowering the NUMBER slider.\n"2 g" E0 Y7 q: N# A$ R/ ]& q
                       "The setup has stopped.")0 a8 w+ N5 S( |0 }# k( n5 B& G
    stop9 Z* E$ e; Z/ m5 f! @! C
  ]3 }/ |/ j$ S! N, r1 F8 C6 h

3 Q4 l1 P! n3 S% D! Y) ?4 J7 k  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* e1 l5 M$ a$ a/ d  crt num-cars
5 i1 i2 a8 j, W$ T& A3 N  [. H" r/ G; M, B7 u
    setup-cars
4 T' V% n! d* a0 n" V4 P; z/ }1 A    set-car-color
6 w) l+ @5 [! R9 M, \9 d    record-data
2 r& E6 N7 K# t/ f  ]* R' F0 i3 h5 f3 t9 @0 h! @, M
, O* E4 g" [" ?# V' ]6 Y
  ;; give the turtles an initial speed
+ C- c+ {+ G! B  ask turtles [ set-car-speed ]
1 M  h2 v6 d* O4 ]7 o+ B5 t- f1 ~6 X4 \+ _& @
  reset-ticks* g. G/ h7 Y* M; o- [* k. d6 A
end
8 n) x8 Y& ]! n& _& W6 v' {
8 k7 r! t$ j4 H;; Initialize the global variables to appropriate values
5 G. g6 Z5 y) O  Ito setup-globals
' P/ q' H" D( h9 o  set current-light nobody ;; just for now, since there are no lights yet; o  P% |) g0 T- {; R
  set phase 0
6 A( d5 w9 l9 F4 M4 H9 Z  set num-cars-stopped 0
# Q% b# `( i6 U! V( c  set grid-x-inc world-width / grid-size-x
! [5 W: c# m5 J1 b+ q  set grid-y-inc world-height / grid-size-y8 S5 l6 j4 u* P& }5 Z8 e. C
# t" W* D) d* `2 @+ J; O
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! \8 f1 y8 ]( u- o2 R4 ^, s2 r3 T
  set acceleration 0.099
  Q1 M& G0 z* B$ ?5 C( w9 u0 f" oend' e% {- |( p7 A( B' y

& N$ j$ s: p9 a; [; F& r$ e! R4 d* M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) P% m4 \6 |* ~/ ~5 g;; and initialize the traffic lights to one setting: ~& S7 _1 m- @3 N8 L* l
to setup-patches
3 P: p  n/ J: n; W  ;; initialize the patch-owned variables and color the patches to a base-color1 [6 E4 c4 k3 T- ?
  ask patches
: ~  u% |$ c9 z, N  [8 Y6 d3 I# v0 N* u
    set intersection? false
" V- [6 E2 m% q; M2 L; Z, L' T    set auto? false
; T: e. U+ W! R/ g. s    set green-light-up? true0 ^# s! j) B. [( [
    set my-row -11 U' n: p7 ~  V, ], e3 j8 n
    set my-column -1
. d6 L1 D  X! Z- L    set my-phase -1# _) |2 q' B" v" u5 F
    set pcolor brown + 3
3 T+ N0 z/ `* {( @' q8 x# N( J  ]
4 N3 }# u4 D, t6 C" s. w% |0 f, x8 V. Y/ z" B& U- K
  ;; initialize the global variables that hold patch agentsets! z% d, D& O* Z' E: \/ d, b$ \
  set roads patches with
, z# }  \  I6 W- Y" j- y6 Z( ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 J9 z+ e# ^: F  h2 L- a& K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! V% b. V& [  u4 d# u! S" o  set intersections roads with
" `* f' R6 }8 N% a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 k  A! V. l4 p) i" c" A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- h" \1 y' i) {) R9 p$ q

, ^) T6 G5 x% G  {  ask roads [ set pcolor white ]# ]/ M6 E- }! u7 @- X6 |& P9 P
    setup-intersections: p  |4 _/ _: V; k8 l$ k4 ?
end4 k8 x# S6 m6 r, r2 T3 t2 `
其中定义道路的句子,如下所示,是什么意思啊?
) ]- L1 n) K& {$ F9 x; q6 [ set roads patches with6 ^! b1 q! M/ t8 A2 W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( B/ v3 M4 [: K1 W1 h' U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ f9 H7 M* n8 h6 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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