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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。# o; R7 C8 i( F$ Z' g1 [5 r+ p' T
netlogo自带的social science--traffic grid这一例子当中,
' Q! e! w! f- p" U3 E: F) vglobals
' j/ R0 o# v" P) A1 N4 n& ?[, |" w2 y# A2 D/ w- @$ D! n" z" v/ |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  z/ Q: c' a  n  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 E# ~* ^1 Q! q1 F# T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ |) s1 Z7 [- r4 x9 N' h                           ;; it is to accelerate or decelerate
* H8 q. B* p. Z! [3 z$ k  phase                    ;; keeps track of the phase1 l0 B9 J- z$ N
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. l) r" q; {2 a0 M* A# n/ \
  current-light            ;; the currently selected light
/ q! F' y" L1 d, n7 F. s( {0 B/ V
  ;; patch agentsets9 X' D; s7 `4 i' X6 P3 y4 k) h
  intersections ;; agentset containing the patches that are intersections
0 @+ V: Z# h3 ^4 |, u4 O  roads         ;; agentset containing the patches that are roads$ c/ m  V6 ^- A, L/ F
], o1 F) ?9 L# j$ k' V7 V3 c' t
9 _: R' x. w* s& s4 ?
turtles-own4 e8 ]; H  u7 v2 E( _
[* t4 g/ g- W0 z$ m
  speed     ;; the speed of the turtle* h- l6 C" g' N' D+ R* e* X
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 P. |/ t1 Q* D# v1 b0 M
  wait-time ;; the amount of time since the last time a turtle has moved
* u+ m: n* X' G. y5 }- c) {! s]
( [+ C0 _& `! Q( U+ M' M  @+ ^: I/ \2 r
patches-own
4 i+ N" L0 c& C) h* \[1 N2 B1 k3 ~' D. |" s* X4 p
  intersection?   ;; true if the patch is at the intersection of two roads
) C8 V) T8 ?% o& I- w* p  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( Z+ m: H, e# O. N, y8 N                  ;; false for a non-intersection patches.
# Y" s2 y( }  f3 g  Q6 P  my-row          ;; the row of the intersection counting from the upper left corner of the
8 w! a9 v  V' M9 r# P. |; p0 z: X                  ;; world.  -1 for non-intersection patches.- V' P- ?0 \3 C& x
  my-column       ;; the column of the intersection counting from the upper left corner of the: }0 c+ I1 q' j; d' w
                  ;; world.  -1 for non-intersection patches.
. O6 G9 R' X7 o$ W7 H# F# O1 s  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.5 c. h3 E( u$ V/ _# Z9 ]
  auto?           ;; whether or not this intersection will switch automatically.
4 E$ b0 X9 w; \" @* A& K6 g                  ;; false for non-intersection patches.
1 j& P" g" g/ K6 o: C]
4 o2 ^8 h5 {# H3 F, ?. ?# D' F' D# Q* ~9 d& Z
, k1 s& w! [* K2 [
;;;;;;;;;;;;;;;;;;;;;;
0 i6 d) ~' V3 j;; Setup Procedures ;;: B9 A4 y8 ~2 W: {: w
;;;;;;;;;;;;;;;;;;;;;;
$ N) Y. U2 P8 W8 Z  b' \( Y- P+ n% h8 r! R3 s9 s
;; Initialize the display by giving the global and patch variables initial values.
# O) r+ \* |* H;; Create num-cars of turtles if there are enough road patches for one turtle to
4 R) }3 L# K+ M- V6 e# n: T;; be created per road patch. Set up the plots.
- U' C8 _: E/ f7 A* Vto setup) i4 K+ U: \' Q4 @1 r
  ca
3 r7 H) b0 @7 u  setup-globals
7 o' W: ?# v: _( k6 j) D9 ~9 z
3 `1 z4 ~0 D: W; M  ;; First we ask the patches to draw themselves and set up a few variables
; p" `! w) d3 R' w6 Z; Q  setup-patches
' _1 r+ o+ s: ^! |- w  [/ k# ?  make-current one-of intersections
+ O- @. e" v4 G8 s  label-current
  T. b$ W0 W$ C; @
  i- C/ N/ H6 p: D  set-default-shape turtles "car"
' n9 A3 X5 x$ Y# J! v0 i. Y) |/ \2 K2 S# k0 o" |
  if (num-cars > count roads)
" E; u" D* m- A: M" J7 `  L8 S* l. v  [# @8 ~3 S, K0 z1 t  u
    user-message (word "There are too many cars for the amount of "
* g# O+ I' P1 J- G$ j                       "road.  Either increase the amount of roads "
$ C4 f! C9 P& d                       "by increasing the GRID-SIZE-X or "+ V$ R( X4 b3 ~: h  `
                       "GRID-SIZE-Y sliders, or decrease the "
, t3 Z- F% r# F2 k; P5 Y& x                       "number of cars by lowering the NUMBER slider.\n") |. ]$ U* q2 D1 L
                       "The setup has stopped.")- u/ @( s: {3 L  }! P9 O. k2 I
    stop) a8 |/ w/ M& ~2 [
  ]& \4 B# L3 I+ u+ E: g0 P

& E( |" g; L/ ]  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color4 `4 u: k+ D1 N  e. e0 O
  crt num-cars
  b* C: i! X$ v$ j# `  [6 w9 B" o; A* a. Y
    setup-cars8 Q$ v/ A( Z- P6 o0 ?/ Y4 s
    set-car-color' f' N, d% M8 X* q
    record-data
7 q/ A/ r. ?+ H) b, l  ]
, \: S2 x3 K" o) ?. y! I# J& n3 Q. f7 K* x- b
  ;; give the turtles an initial speed. Q* \& {$ i: Q% a  y* _
  ask turtles [ set-car-speed ]1 |5 n  F) @; c+ P0 X. W4 W& l

* d7 b: \) Z6 {! i2 z1 b9 ^# Q2 Y  reset-ticks# }+ {" z7 H* Q7 w
end
+ M9 \' C& `+ a6 t! ^
& y, N; E0 Q2 \& \% m- }1 L;; Initialize the global variables to appropriate values# R7 z  a7 v1 k6 F" o: o
to setup-globals
5 Z  A3 f$ w4 l2 D  set current-light nobody ;; just for now, since there are no lights yet6 k% c* t# w! ?" t$ b8 K
  set phase 0
; u5 {6 t: Z/ W7 l  set num-cars-stopped 0& z; b# J* q* J9 I
  set grid-x-inc world-width / grid-size-x3 E! Y- z0 A  A+ Y$ n) V1 E
  set grid-y-inc world-height / grid-size-y6 T! ]$ {2 w1 X' t! c
! D' P3 T2 p( t0 a5 q" A# K
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 D) A9 e+ }0 t! z% L: q3 x5 p  set acceleration 0.099
- G9 R7 E% `3 K; r% Q. Kend. D. l& s4 E" a, R

& d# g3 Z8 U% W. v3 u4 u;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ W5 }) {- o7 V: x' G! a4 d;; and initialize the traffic lights to one setting
3 W1 C: |4 b- Z, q" r; tto setup-patches* K2 ]+ q( g- \+ x
  ;; initialize the patch-owned variables and color the patches to a base-color
6 D/ y  H4 I& w) u  ask patches
8 y. }7 x2 Z7 A% A0 b, t  B& [  [2 J; x, V1 P3 q
    set intersection? false; J, ?% I1 `3 F% u0 C+ Q6 [2 W
    set auto? false$ U' y! r# l/ u1 q# d$ o
    set green-light-up? true3 ]3 A/ Y$ T, w* A
    set my-row -1
& [. W; Q5 ]4 Q1 i; `$ C4 Q    set my-column -1+ s0 P7 [/ t+ q' f
    set my-phase -1
( W- j0 C% p3 X5 q    set pcolor brown + 3
: M+ ]; B) `! j+ `" a3 [' A% P  ]
) f8 }' h- q' a( O
, w: Y% y' t$ e4 I$ W' S$ I* v  ;; initialize the global variables that hold patch agentsets
3 N& c( `1 O4 e: m  set roads patches with  A7 R- m, A# {% F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( @4 W% n- D$ U" m& p- P+ D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# Y, u3 K' _6 @; r, d  set intersections roads with
5 N% T& _: T# {2 T5 T8 i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; ?5 o- z' \0 m/ o& a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- h3 u" F4 J5 }2 M+ q
, ~. ]9 w) q9 H( m. M8 X
  ask roads [ set pcolor white ]
: D) v( G1 V. ?9 n    setup-intersections
0 `3 o$ U" @/ j' A& p% K9 pend* e  s) [0 {+ h. m' V# V
其中定义道路的句子,如下所示,是什么意思啊?$ w- b# i& E' m- |; I! Y
set roads patches with
  g/ `- M4 [8 @. Q( D# G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 u% r0 y5 h7 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& w! m0 W4 k2 m
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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