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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。
" w3 W" [4 F) a$ p' {" b  M8 Hnetlogo自带的social science--traffic grid这一例子当中,% d( S  t2 z. M) I8 L9 B: ]% p
globals
) r8 \# C, K% V[
- Z  G! t; C- R+ M$ O- w  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 c# f5 M  u2 E, J9 Y8 \  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! h* T) C1 D/ g  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: f- U1 ?$ Q5 M  \- s0 R
                           ;; it is to accelerate or decelerate
+ x' G1 R6 t- T  s1 {  phase                    ;; keeps track of the phase
1 f- d( _" d  Y7 r2 z( L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 r/ @. N9 B. j% g; X2 ]0 R! ]  U5 L/ p" l
  current-light            ;; the currently selected light1 j, i. x; P- l$ U5 V

7 z( n5 [! w4 g* N& S  ;; patch agentsets0 _+ g( I8 {/ r$ R) ~/ f
  intersections ;; agentset containing the patches that are intersections! q6 |. K" ]  W! F, G0 Y: e5 p4 I
  roads         ;; agentset containing the patches that are roads
2 |3 u9 Z, R  _4 i( t0 K8 Z]
4 i$ m. ^1 U* U  k! Z' w1 f! I. z
2 ], F. U9 o' ~' I6 }. p7 `; @6 Mturtles-own
& \2 F/ C, e. Y, d) W4 V[! l: o3 F- F8 ^9 y" q
  speed     ;; the speed of the turtle" h" x% Y5 y  b/ x# l6 I7 W3 ~
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
8 {9 r3 J/ D+ w6 d& x$ B" g0 P  wait-time ;; the amount of time since the last time a turtle has moved
) m8 L) @! C. x" _4 ^1 a]
' Q* F1 [+ i1 Z* T+ J$ K1 H: A5 x: I+ S, G9 Y; E
patches-own( g/ Y7 e+ P+ Y+ |) o: I8 q6 T0 K- c$ l
[
# F" U- p2 D6 B3 ^  intersection?   ;; true if the patch is at the intersection of two roads
, m$ {1 o4 S1 }  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 z; I) `5 I' Q                  ;; false for a non-intersection patches.
1 g+ k, r, K7 r: J  my-row          ;; the row of the intersection counting from the upper left corner of the
' H! t& E- ?8 x/ w9 [, K# u                  ;; world.  -1 for non-intersection patches.6 Q5 k5 b+ x0 G; @5 M
  my-column       ;; the column of the intersection counting from the upper left corner of the) N, E% N2 O* l) p1 A- _% ~
                  ;; world.  -1 for non-intersection patches.7 k+ d& Q1 M6 n" r/ b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ a( h% h6 R7 m" M
  auto?           ;; whether or not this intersection will switch automatically.) C# f# W; T3 _9 s  {( |% C$ G$ j
                  ;; false for non-intersection patches.3 E* k- x5 F* [
]
' E8 J# H6 `) G. Q" [. d7 r* W" G5 k+ k. J7 R5 y# s& ^
8 a' k5 T4 D. @
;;;;;;;;;;;;;;;;;;;;;;
+ `% c  F) \8 X# D1 y! w2 o1 S;; Setup Procedures ;;& ?5 I' d( N6 L/ ?2 I
;;;;;;;;;;;;;;;;;;;;;;
5 @! d8 G6 M1 P5 T* o6 G( @: ~4 f$ @5 P
;; Initialize the display by giving the global and patch variables initial values.
0 B% L- T% I: D( J7 _) R$ I& ^8 s;; Create num-cars of turtles if there are enough road patches for one turtle to
  J( |5 |$ {9 S) Y: n;; be created per road patch. Set up the plots.8 X  r* ?5 ^$ x0 R6 h0 a3 Z) O
to setup) @' t& y' d5 A: V" a9 ~  U
  ca( E7 L  U, E. N: w2 ]( D
  setup-globals
0 ~& ]) f: M0 T$ ]% U# j( J/ b" Y3 ~$ C0 H7 C" r
  ;; First we ask the patches to draw themselves and set up a few variables
( U. K: O3 n% p- a% M  setup-patches# h! Z& \5 u# G  z7 f
  make-current one-of intersections
% g+ w2 g$ p/ c% M# ]( I6 d# C  label-current
  ~, f( O/ h8 h; Z; m4 n4 ]  ~& V2 S  R: s. G5 W) P; P& _0 j
  set-default-shape turtles "car"
* R  ]' ?( j* M% O# u& \; S, O; A" D7 A# Z  N
  if (num-cars > count roads)
/ Z) ~; `" D" M. c( K1 B  [# Q: m1 D  ^  x% A4 S* i
    user-message (word "There are too many cars for the amount of "
; R1 g# u5 j$ r1 U" c2 o6 ~  ]% S                       "road.  Either increase the amount of roads "
) O( u: L0 p$ U7 Y1 G8 n% \; z5 g                       "by increasing the GRID-SIZE-X or "
/ B+ B3 c  f9 ~4 {* a5 A1 ^2 [                       "GRID-SIZE-Y sliders, or decrease the "7 G) i/ g6 O4 ]4 d3 x4 \4 c0 l
                       "number of cars by lowering the NUMBER slider.\n"
8 K- d6 q7 q7 P6 z! r8 s                       "The setup has stopped.")" q& \; S, q. p4 l6 k. b
    stop4 t/ m% Z8 }4 G. q
  ]
% h1 G7 k. N3 S' H4 ?
7 M& b: Y- @% a, |7 W  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& P* n5 p& T+ O( X; \* V; h  crt num-cars" N% K, T- ~( z+ I/ d. [, a
  [. h; o  k# A- U5 g& m* N
    setup-cars! _1 A4 k. E4 ~4 F) w  h) G
    set-car-color' f/ P- E' q- S0 ^1 d, p+ E
    record-data4 D  a9 u4 e2 E- y2 `2 S% H( U* v3 }
  ]3 K2 h/ c5 C; t, k# L! i: c4 K
8 m! T! \" O6 A. n% M
  ;; give the turtles an initial speed% R  q' ~, \% N, E; ]0 R
  ask turtles [ set-car-speed ]6 x2 i1 u$ O0 w% N" f: W$ a0 [6 U. r

; ?- |; Q2 [# e  c, P% K. ]  I' t. k/ J6 A  reset-ticks# }) e2 ]" w) @  `0 \
end
2 Q4 Z# R3 s- Q* O0 w" g7 b" u# k$ i2 W" ^# @0 a! i0 P& w
;; Initialize the global variables to appropriate values7 }# F0 l$ B9 H# g3 i# E2 H
to setup-globals
/ [" ]1 N! ~! w2 I) ~  set current-light nobody ;; just for now, since there are no lights yet
. U$ w6 q& V, M  set phase 0
# v8 J/ t- p; C0 D2 |. A  set num-cars-stopped 0- Y" b) I  Z; f7 g5 v2 o0 s
  set grid-x-inc world-width / grid-size-x
3 \: U; N2 F# z' |$ R% I! g  set grid-y-inc world-height / grid-size-y
& s8 l3 e, d1 @3 o: r& K4 B; `' f  b+ u  _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% g: W2 s" ]+ c
  set acceleration 0.0995 {! B( m9 P: j( Z
end; z/ v0 k# b4 R7 J! Z2 E+ e; ~

" X% V# W8 s/ T2 K9 X;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 I# X5 N/ o0 r& I' h" {' T% M
;; and initialize the traffic lights to one setting
8 v/ ?* u1 J! {5 a$ A8 U2 qto setup-patches5 X; r5 z) I" p) V( G$ g* h* f
  ;; initialize the patch-owned variables and color the patches to a base-color
9 U. A3 H& i2 X" X( Q/ U+ m# `  ask patches: i0 a! y/ R1 W* _8 s; l
  [; d# [5 G$ q1 ~  O
    set intersection? false
6 m6 E, b. Y( S6 ^5 E    set auto? false8 n/ ^- n* ]4 }& L3 j* `: j
    set green-light-up? true4 ~8 H9 G2 q1 _% z3 q
    set my-row -1$ s+ |, m) C: q' w. ?3 Q- M* w
    set my-column -1
7 Y4 B3 Q1 W$ U9 Z    set my-phase -1' f4 N8 Z' y! ]5 K0 e
    set pcolor brown + 33 x# Z2 \% M9 j
  ]
+ F1 o% ^5 ~3 @- Z5 A  X# I6 l4 P. {9 Q) w- S; l
  ;; initialize the global variables that hold patch agentsets9 H  C5 v" L7 {7 {( u
  set roads patches with
) u, B. ]. u# P* `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 U! F# K+ P+ A' T( ?- R$ k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ @! V" T6 v5 U. N  set intersections roads with
% y, Q( |! }# X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 h' k" s9 x5 Q& O- P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: Q( O, _& C" D! x
& p- A5 a" O8 R
  ask roads [ set pcolor white ]# ]" h8 e. J; L/ M7 i& y
    setup-intersections
5 u: t( `- d8 P8 O& g3 Hend
9 a% {4 Z. G7 K3 i3 w2 Z其中定义道路的句子,如下所示,是什么意思啊?
0 u: j/ B: m, ], P/ K. d$ N set roads patches with
  g. }* j1 h  a9 x+ B4 `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 r/ O5 |, T! ~$ J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 H* L5 x3 x. Y9 n1 o' n& v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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