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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。, H: M' V/ |3 `( E' D
netlogo自带的social science--traffic grid这一例子当中,; B' V  v- \% [: G& C1 J" ^3 b
globals
; j# C% Q3 h9 K, ?5 G4 P7 I: J[8 D. G* h0 F' \' M2 R- I: O8 j& k
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ ?+ l2 y) E% Z4 {4 v, D  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 W  i) x+ r) d  c9 g  _; o
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: y( A) u# L. O% u% w                           ;; it is to accelerate or decelerate' C6 o/ S7 _  m; X8 J3 U; Z
  phase                    ;; keeps track of the phase8 y; j' P3 w+ |9 X8 G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 v/ J2 L$ @( h, n- j
  current-light            ;; the currently selected light
! O! L& s5 V7 d% O5 v- T( p2 B* q7 j5 x( f. ^5 I. [# j
  ;; patch agentsets
. |5 J( m" E) Z4 w4 o  intersections ;; agentset containing the patches that are intersections
) U" e: R7 y8 E$ v' N' K9 _! f  |  roads         ;; agentset containing the patches that are roads
0 W7 i3 ?9 {( B$ ~0 B$ R2 g) h/ o) e]# c/ x4 Q6 q0 H" x% M
$ u# k- t; m, F7 t2 U3 x
turtles-own! L; B* r* O0 e/ n
[/ E- s7 G& {2 k$ I- X6 q
  speed     ;; the speed of the turtle
  {) Q& c3 Z/ W, U; c  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. x8 n% i% X# p
  wait-time ;; the amount of time since the last time a turtle has moved
! z% F! I+ N  j* f1 u) |* R]6 O* [( O" o1 P1 t) R

* h4 Z- R+ m  G( t% ~( M/ Apatches-own. E* e+ ^( g, Q
[) s# M$ F# n. Q/ h: T- {: f
  intersection?   ;; true if the patch is at the intersection of two roads
* t6 B4 c4 V+ {: @  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 c: h8 H9 E* c/ u: I7 I                  ;; false for a non-intersection patches.1 S! s: ~  B8 q% @. O4 p1 y
  my-row          ;; the row of the intersection counting from the upper left corner of the; I: w9 b! ^$ R7 }
                  ;; world.  -1 for non-intersection patches.: {; e( B* O: p) d1 E3 g( A# [
  my-column       ;; the column of the intersection counting from the upper left corner of the# P. N. p. _! E
                  ;; world.  -1 for non-intersection patches.
' u4 i+ V. J" q# a  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 \) H" A& ?3 v: T
  auto?           ;; whether or not this intersection will switch automatically.: X8 O% M8 V3 A
                  ;; false for non-intersection patches.9 q* G: l1 r, L- T: J, T
]
7 _3 @$ @; x) F4 R
  t' W2 p' l: _0 H
8 T8 {! K$ d( ?" }& k# P! a;;;;;;;;;;;;;;;;;;;;;;
# A& T! Q* l; V3 i' O( Y;; Setup Procedures ;;
- G" w2 L: b) H;;;;;;;;;;;;;;;;;;;;;;7 }! |8 F6 y1 W( {/ c5 D* h$ k

; W7 K: ^2 G/ H) W;; Initialize the display by giving the global and patch variables initial values.
; _1 W  ~9 c& I;; Create num-cars of turtles if there are enough road patches for one turtle to( E, [9 K  p2 n/ Z
;; be created per road patch. Set up the plots.$ ^8 r: j( g/ Z- m2 u" ]
to setup
* ]3 R6 N- Z/ [' `/ C, a  ca
, B; O! m' v: Y, u# a  setup-globals) e$ {8 S0 z4 N# X; j, B
2 j; z9 y2 |& w$ S7 r/ y
  ;; First we ask the patches to draw themselves and set up a few variables
; l, z4 q/ q7 Z  setup-patches
' h! U/ E' j. b1 R5 C2 T& {  make-current one-of intersections
- M) a; X# \+ g- w% m  label-current
$ B& ^# u! ^- k$ M6 Q/ R- q
: r. k4 `" D0 B, g/ |  set-default-shape turtles "car"" v8 D" N  p/ ], m
! g/ O6 G, s+ z$ z  j9 U' d
  if (num-cars > count roads)
2 M/ Z" Y( ]. E: _  [& F7 S0 M9 q  q' l2 c+ z
    user-message (word "There are too many cars for the amount of "( \$ a9 g( @+ G
                       "road.  Either increase the amount of roads "
/ I& ?) f" J4 p7 x                       "by increasing the GRID-SIZE-X or "
5 z5 g, D3 z- z                       "GRID-SIZE-Y sliders, or decrease the ". H; B, H$ P' r- m. {& q
                       "number of cars by lowering the NUMBER slider.\n"9 A! m9 j1 k8 z
                       "The setup has stopped.")
- `2 u5 a' W# I' F    stop
) O+ G9 A6 C- [5 s# K# J  ]3 m' V3 X% m6 i6 m7 ^( O8 [5 @

4 Q2 Q* t, q. L  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& I: \, }2 A% U  crt num-cars+ @7 M  T7 W$ _3 r, I; a
  [
$ N8 n8 O: B8 U' @, @    setup-cars
2 L3 T+ ?4 F, o! f    set-car-color7 g; V: D2 P7 C2 g
    record-data
& j' _* y8 N% @6 J# ?( Y( G# s2 T1 j  ]
0 s, I' L  X  n) k1 T% n( X. j  K6 q" L% t
  ;; give the turtles an initial speed
! Q- M4 G9 r8 d8 T  ask turtles [ set-car-speed ]
! F5 V8 j0 v9 E9 s* u
  ~5 Z$ {9 u/ i+ Z5 z( O4 l! f  reset-ticks, T: M3 a/ K, ~) m. \& K
end3 u9 G; @, F3 O: |; q1 Z* ^

* J) }' R0 ]% g5 i+ x) ~5 j/ K6 B+ ?' T;; Initialize the global variables to appropriate values  t- ~7 y; x. c) h  M! t% ?
to setup-globals
! o1 Z* R1 H, h; q& V) K1 L8 P- Z  set current-light nobody ;; just for now, since there are no lights yet
2 V) n. S# ]  A3 O# U  set phase 0' M7 d. ^2 b% @# {3 ?% E- D; V
  set num-cars-stopped 0( W0 X7 e* B' B( m
  set grid-x-inc world-width / grid-size-x
9 g9 U0 P: S! O( v  set grid-y-inc world-height / grid-size-y: m, I) w) x0 X7 m  L8 E
( ?( F% a2 D3 c# j0 H
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" t3 B7 ]0 F1 ~' F" J  set acceleration 0.099$ }, L! J1 ~3 f- ]3 {) G! A8 C* T
end
1 t9 B0 F8 Q! }  N( a3 s7 w) O
% o. e  y3 j; M( ~2 h: s% u;; Make the patches have appropriate colors, set up the roads and intersections agentsets,; Y; x5 D; i" k& b# p
;; and initialize the traffic lights to one setting/ }' T+ q. B& g4 }1 Z4 M8 M
to setup-patches& a6 L% R& x/ x
  ;; initialize the patch-owned variables and color the patches to a base-color
% q( Y- p+ ?3 S2 ^1 d  ask patches
6 o% x3 M' T% t  [
# g" J7 v8 d- i2 L# P3 W! R: d1 B; C1 C    set intersection? false
7 X8 }3 m2 w3 O! W    set auto? false
/ f1 H7 T% c, a" g    set green-light-up? true
& g- G3 M/ q% L    set my-row -1
3 T* ^$ t! |& Z- G2 I9 ~/ |    set my-column -1
5 G; t; v( r9 Z% ~2 v, M9 H    set my-phase -1
* E& j+ I5 A( k, g& L/ a3 b    set pcolor brown + 3- @/ `- s9 T1 p$ W; |
  ]
0 b4 ^' I1 g/ t1 b  a% K
+ U5 z0 M7 c& s& \+ p  ;; initialize the global variables that hold patch agentsets& }: z1 U% P0 `, |1 i! H8 m9 W5 V
  set roads patches with
0 ]8 d1 f0 B6 ?( J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, W) j7 @' y. D: x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 R  M1 R; K6 a6 s6 ^+ e* C5 X: ~  set intersections roads with
; z$ u/ p$ U9 t8 M  S0 \! q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 h  F  M9 d4 Y# i" P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. f' m5 s8 u0 q: P

4 H2 y: Q4 @4 n* Q  ask roads [ set pcolor white ]
9 F( V/ \# R% Y" b1 B* K    setup-intersections& M; X! n: t( `0 g; P6 z
end
0 [; H/ H% b: o, Q3 H其中定义道路的句子,如下所示,是什么意思啊?; K& e6 V- ?- G& [
set roads patches with
6 j3 L/ G5 f6 a. y7 `3 x; x0 j" A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 d7 l" g4 i& F( v, g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: ?+ ^: }' f+ B6 ?" I3 d
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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