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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。1 o7 A1 Y  y. h0 r, R/ L" D& G5 c& E
netlogo自带的social science--traffic grid这一例子当中,
$ X1 k. M, {9 n. K- Yglobals
/ z! m4 B/ d3 D3 Q  o[1 I4 u7 K% `; S. W* n: s
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 L. d0 L% l9 F% _6 c/ C! X1 L
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! O& |) E- K4 m! q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if" T- G) D7 {; R+ ?
                           ;; it is to accelerate or decelerate
1 q! b: S( i: U  U  b- {$ w; }  phase                    ;; keeps track of the phase1 k4 e& c" a- R, `$ l. S& g6 \; l. `
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 d$ x5 [/ b% {* v- F  current-light            ;; the currently selected light
* o- L' T1 W. a4 B# W( {8 a/ Q2 @  p$ z1 y4 O2 L
  ;; patch agentsets
8 z8 l' N9 i! y  intersections ;; agentset containing the patches that are intersections
/ }6 t2 D' y  Y0 K3 f, P9 R2 `  roads         ;; agentset containing the patches that are roads8 R" d/ \3 [# D3 `
]
/ {8 `# s7 B; B! }  q) b* o& x
% j9 J) {/ S- Mturtles-own
) V4 U5 M9 S+ _5 I6 R. J[$ m* z5 t9 k4 z5 K+ W  f6 |
  speed     ;; the speed of the turtle
4 v( F  k5 p# K# C3 b3 o  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 \0 ^% u4 \- \4 m; k! p* Z
  wait-time ;; the amount of time since the last time a turtle has moved5 r# V0 U* a* r. n8 J: |) D
]+ U; J  J% l* C

) \# Y$ v' P: D% `* {  a0 [patches-own
6 c! o+ j& _$ _& p+ v[
/ T! H0 \  {3 ?* ~! Q% l! v  intersection?   ;; true if the patch is at the intersection of two roads. I+ s0 L2 @& y7 T7 b3 I' K# O
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% h! f) y) c8 M/ X6 W+ e                  ;; false for a non-intersection patches.# k2 ?9 V( [) C& |' m8 F- Y
  my-row          ;; the row of the intersection counting from the upper left corner of the
+ w; ]% n2 A1 M, g+ O3 m                  ;; world.  -1 for non-intersection patches.$ u4 e8 [* `( c/ u( H
  my-column       ;; the column of the intersection counting from the upper left corner of the: G9 X; Q) C/ H0 y! b
                  ;; world.  -1 for non-intersection patches., b6 L# O$ a5 H9 X
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 u" w: D; z/ ~( I4 u
  auto?           ;; whether or not this intersection will switch automatically.
8 K- E% J4 T  ~4 }) k4 W' A8 i                  ;; false for non-intersection patches.% i4 F6 Z. b1 J6 t" e4 P( O
]. y# E+ B1 v# L4 u! k5 w2 `- \

- t" R  P/ D9 u8 K
# H, M' N9 d+ j;;;;;;;;;;;;;;;;;;;;;;
3 ~& ?) \4 w9 j' e3 Y;; Setup Procedures ;;; u7 w) F' }% k7 T
;;;;;;;;;;;;;;;;;;;;;;
1 }' h% ]$ F& c7 n7 E/ G
3 D" \3 p  Y7 j* x0 A. U;; Initialize the display by giving the global and patch variables initial values.
4 a$ Z: c- ]/ i, t! H3 p" f;; Create num-cars of turtles if there are enough road patches for one turtle to
# C! p; k9 u9 |% U# Q;; be created per road patch. Set up the plots.0 P8 E$ l- p  i6 x  {4 C" P
to setup
$ ^* m* t. X0 E9 ^- V3 y' ^3 g' p0 c; b  ca
/ _" d+ j2 ]4 h' Q$ w! y! O  setup-globals& n9 H' U8 @6 t7 L) P6 I
7 l* r& I, z( u
  ;; First we ask the patches to draw themselves and set up a few variables
* f" M* J9 w2 x8 Y5 ^6 R) I8 A  setup-patches
8 ~; h* L: f; Q% C  make-current one-of intersections6 Q* `& h6 a4 N% l' L
  label-current
5 }. K, g/ {3 [0 n7 O
4 E1 R, |) c) u& `1 p2 v2 d* A  set-default-shape turtles "car"
% F& v8 {2 l1 o$ t5 p( d; a+ K( K% d( R4 Z4 e3 r: m* N+ E9 g" M
  if (num-cars > count roads)
. f! e- U7 |( C* ?1 Y" \  [# H/ j* J# W6 O+ K7 _
    user-message (word "There are too many cars for the amount of "! a; _% \) r0 [7 @( x( O0 ?
                       "road.  Either increase the amount of roads "
  s$ j) z# E/ p+ @! w; n                       "by increasing the GRID-SIZE-X or "6 e, {& b0 M% R& S0 e% ?, `  J
                       "GRID-SIZE-Y sliders, or decrease the "& M5 u# u: W& ~
                       "number of cars by lowering the NUMBER slider.\n"
# T9 f4 s9 ~* G6 z+ x2 _4 @                       "The setup has stopped.")# f8 Y5 O! {4 N9 O4 C
    stop9 K! I5 l. Y) K
  ]
0 Z- |0 B1 @9 C* T/ v8 Y6 ]) V7 s' Y( H4 _
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ u/ F0 U, w" G, X& e' }! V  crt num-cars9 n5 }' H0 q6 G+ J/ _3 c
  [; c' ]( K3 i% z- B9 v0 v
    setup-cars+ o; n$ i# `' i, }# m6 }5 p  ~0 s% i
    set-car-color
" r4 A, ?' K: g$ ?3 D; u% K8 i7 z    record-data
: E" S! M7 w5 v. x) J- d  ]. D4 H2 C- x1 L- U- [& |
+ r  B% \6 I$ Y" C% ]4 _
  ;; give the turtles an initial speed6 Y/ ~/ m3 U8 U; k' R
  ask turtles [ set-car-speed ]
' n% e& K& k% i
& @5 O% x7 w4 a3 s' t; Z# ]  reset-ticks# A) a' T4 H2 L' r
end
8 O7 G' Q# m4 X) g! V8 v/ g6 }  {% m
+ k/ y$ [; A# d% p' G# Y2 e2 c;; Initialize the global variables to appropriate values
4 k: T5 D) B( H/ ]7 `, k; y9 ~8 a- qto setup-globals
, d* f- E+ l" w. ]- r  set current-light nobody ;; just for now, since there are no lights yet( m# Q( |! x% f: K: `4 H( u8 q
  set phase 0  V8 ?: v  j" K5 m: k2 [3 U
  set num-cars-stopped 0, O! x$ W3 L, K2 ]
  set grid-x-inc world-width / grid-size-x* ]( x1 c% K6 Y1 ^" N- B! z$ r
  set grid-y-inc world-height / grid-size-y. \# l2 z9 m7 o+ {* i
) Y. U3 `) h2 A) R6 q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% O- @3 x4 i8 ~; s# M) \
  set acceleration 0.099
* ]- u* y2 }( C8 E  E) ]  uend
! A  k; W, o& Z- `! V
; N/ p# r1 G6 B* m0 S. F1 u;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# g7 S+ x+ j6 E6 ]! G8 D# J, k6 |: \+ m
;; and initialize the traffic lights to one setting& w9 W; b) R0 H- h& w) R
to setup-patches0 g$ P7 X2 J1 s2 q8 H' }6 k9 s7 {. ?
  ;; initialize the patch-owned variables and color the patches to a base-color! B/ K; F7 C& }+ Q" C$ z
  ask patches
' J) j! p  M& h7 i  [
8 X- b9 f$ u# m; J    set intersection? false
; ?$ I7 O" l: F, X3 M0 ^    set auto? false6 N  A0 O! X* E- D8 f+ V
    set green-light-up? true+ ^6 z) }5 F1 p2 Z, E/ A. i
    set my-row -1
' X; h( }: @" Y* r8 n0 H* G    set my-column -1. Y! l  \6 E3 `" v0 Z
    set my-phase -1
7 `) ~) f1 N. f$ v! T- Z. M    set pcolor brown + 3* a; M1 O% A$ B) h1 m7 x- l
  ]
# S. b9 f% |' g; P# v# j$ v. X
# z4 g. z1 j; D5 V% i$ N  ;; initialize the global variables that hold patch agentsets# t) ?. b1 {+ t, }
  set roads patches with
: s7 P3 S: `, Z+ j) @7 ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# L% {$ d  W+ }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" G2 m; w6 Y: W- K1 v; t  M
  set intersections roads with6 J: Q) o; t3 E# a" x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; e8 m7 t8 u$ p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- e8 S9 P8 r, w7 y1 @0 j7 |- h
- U! K) k8 s- o, u  U- c  ask roads [ set pcolor white ]
0 p8 Z# N( T; I7 U, l& |    setup-intersections
9 M" U4 j# i$ _' [! F% W& g) cend. Y, m4 ]0 n% q$ H2 c! N# p- c" o2 U
其中定义道路的句子,如下所示,是什么意思啊?
- x6 j' w3 _. [- v2 ]- s" u set roads patches with7 B- }$ h+ _# E' \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ B( h8 u, F6 L9 X& o6 z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 Q6 |) c& }9 h+ p
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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