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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。' K( i6 @. h, d) s" m; v) V
netlogo自带的social science--traffic grid这一例子当中,4 ]5 c# @" P( n% c0 I- \+ H
globals
) \7 _1 q7 X4 j[
( f  ?1 \4 `8 Q. I) X/ F! S  grid-x-inc               ;; the amount of patches in between two roads in the x direction: G2 N; F& k. d9 c3 ?; ?8 l
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* H8 D9 X! @+ t4 x' c  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 T: q6 r" D: Z' X+ L: u/ b, l                           ;; it is to accelerate or decelerate6 G: q  n+ o5 g) m" w
  phase                    ;; keeps track of the phase
+ ]% ~9 R1 h. _  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% {: o( I9 j3 G$ K% r3 H  current-light            ;; the currently selected light! a! D6 d9 @. h% m
/ I5 U1 X4 r& Z8 d$ e
  ;; patch agentsets5 O% j7 n% Y# |/ D1 ~% l3 y, ]
  intersections ;; agentset containing the patches that are intersections
7 Z  P- u2 b' h1 z. ^9 M6 L- B4 L  roads         ;; agentset containing the patches that are roads
) O7 x2 E0 |+ W5 o& P0 l]  Y( U0 Z2 O8 s5 P8 l
5 r' f# C5 F  o3 h( n8 {
turtles-own
2 k+ P* D8 E4 Z1 }# E8 f" D[
5 l+ X0 U/ d; h- t1 w. _  speed     ;; the speed of the turtle& g  Z: V6 u/ C4 m5 r: k" G, R2 R
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. o7 B! e( [) Q  F4 l1 e
  wait-time ;; the amount of time since the last time a turtle has moved! n0 n' z/ W8 w% c5 w/ j% j" o* ?
]4 Y* {. a+ |5 m! x" w
" y) m5 {0 {( B9 r+ a: m; V0 \" k
patches-own
# y, r- X2 S# C6 _1 K) k: m. Z[& ]5 L5 O9 P9 m  w6 ]! F
  intersection?   ;; true if the patch is at the intersection of two roads
$ a6 e; L" v4 d  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- d7 p  N& E* N+ S                  ;; false for a non-intersection patches.
% t6 w9 a; f: t: U  my-row          ;; the row of the intersection counting from the upper left corner of the
& K0 r) W; m* H                  ;; world.  -1 for non-intersection patches.
4 T; b( U+ m8 a  my-column       ;; the column of the intersection counting from the upper left corner of the
7 x9 Z/ b1 G% |# E3 w8 W9 }                  ;; world.  -1 for non-intersection patches.& @0 C# y, D$ ?3 X( O
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' R4 a* D! b6 u  auto?           ;; whether or not this intersection will switch automatically.
6 u0 k- r( b1 p  @) n- M6 r8 P1 E9 y                  ;; false for non-intersection patches.
' S2 l; z; u- s0 ]9 M1 F]
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;;;;;;;;;;;;;;;;;;;;;;: }' t7 n: c1 S- t: q. u
;; Setup Procedures ;;
" v6 X) _0 h3 \7 p+ _* ~;;;;;;;;;;;;;;;;;;;;;;
  T  W, F: `; d$ |, Z. `% q
! k* v3 A, D4 L9 ^5 y;; Initialize the display by giving the global and patch variables initial values.+ i- a8 u; e" w9 ~
;; Create num-cars of turtles if there are enough road patches for one turtle to5 j- ^7 Z- M( t0 K
;; be created per road patch. Set up the plots.
2 F" t8 P% A- Wto setup- h. A  Q3 U  y' t- c" H6 Y
  ca/ b. r2 j" V/ h9 D# Z
  setup-globals
( G$ k0 P, g- w# [+ V2 v% \5 \  K" Q4 e  K  E. y
  ;; First we ask the patches to draw themselves and set up a few variables
+ ]$ x1 g% a$ k& M; e  T: \: t  setup-patches4 q9 m# g2 ^4 b: f6 U: O1 P9 S
  make-current one-of intersections1 t% f) s+ u1 ]7 ~6 C  s
  label-current5 ^( t1 o) C. o2 B5 V

: u/ n  v4 _% F5 r' h  set-default-shape turtles "car"
$ t. I% J' r4 d% J8 ?) o! }0 s" f: V* w% u8 G
  if (num-cars > count roads)% c8 {! L0 g3 Q5 `% y
  [' @' Y2 I! |  q. E( y  m( v
    user-message (word "There are too many cars for the amount of "6 D. Y1 r5 d% ?5 Z4 A3 \# _
                       "road.  Either increase the amount of roads "
1 Z6 n9 |; v' z* T4 V                       "by increasing the GRID-SIZE-X or "
+ ^' g/ @  d* _6 D# {                       "GRID-SIZE-Y sliders, or decrease the "; A5 B8 X. T+ }9 C
                       "number of cars by lowering the NUMBER slider.\n"3 I* t. u" ]3 M4 s' n, P7 ~, ?
                       "The setup has stopped.")8 Q. ]. X( ]3 G2 S. ^) k! |
    stop1 x- T5 C/ c  |# Q7 z# j
  ]8 Y. k+ }0 U( n* B  H7 A
, ]8 P/ q6 M& h  H+ Q; q  {% C- k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
8 |/ c, F  R8 \; O- i/ `- [  crt num-cars; m& }1 x. t6 ]' M/ }, [
  [3 n5 D* B1 {, G1 m0 P! R9 ~
    setup-cars% F0 B, [& V3 I+ U) \
    set-car-color! k3 }  |( q8 U4 Q& C
    record-data
+ T1 w$ {2 S' e  ]
* D- l' C% v9 F+ l7 O' F- N
/ a7 n8 @! x! |, K& I  ;; give the turtles an initial speed
, Z- i9 w9 |* f( k! m" G3 D  ask turtles [ set-car-speed ]
+ l1 f* e, \* E( b+ D
4 o4 a" C& W% u4 j5 k* e  reset-ticks$ \! V8 F5 x$ l5 L( C
end
( }# e- ~% c- {6 r0 f! f5 G" f; X( W
;; Initialize the global variables to appropriate values5 s+ q; d* a6 H  p( ?* E! h
to setup-globals. T- w: ?9 }- X' O  r# \2 m
  set current-light nobody ;; just for now, since there are no lights yet0 _" [8 @1 D8 M: R$ u3 M
  set phase 09 k# j1 C! V+ F( f
  set num-cars-stopped 0
% P$ U. |  }% D  set grid-x-inc world-width / grid-size-x
' r/ A' }1 ^9 o% G( H( ^  set grid-y-inc world-height / grid-size-y
+ a: R% V( ]# q, Q* M( T# G2 p4 ?
: u2 n9 I: i; J9 @' Y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( ?- g$ H9 g/ u# B  set acceleration 0.099
  N0 P- Y. Z; s3 W  S( Aend% P: G, `' u+ I
) I; ?2 G. [. i& ]: O5 ], e0 p
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 d8 i; _( N) y4 o' m
;; and initialize the traffic lights to one setting% `4 W! i) ]- e/ W: W
to setup-patches
, x6 c8 Z: R, B6 T0 @$ F# R  ;; initialize the patch-owned variables and color the patches to a base-color$ N1 o( E& `+ W. B  n! F0 l
  ask patches
( }3 ]) ?% [2 |3 s7 ]/ c$ k/ L' B+ S% j  [
* _, {5 {2 X# @0 Z' h5 S    set intersection? false
$ f( e* o0 _2 {    set auto? false7 Z7 f( L9 ]. B& M$ L+ O# {
    set green-light-up? true+ D3 o  ~/ A* a1 X8 {. w2 k& {5 E* I+ S
    set my-row -1
' k6 I6 Q8 ^# ]9 l, j- U- t    set my-column -1( ?" f0 P% L+ O3 P4 O
    set my-phase -1
7 Z# @8 v0 q3 J9 U7 @* m    set pcolor brown + 31 W1 R6 G2 k2 W4 }  x
  ]. ~. ~3 N6 Q$ v+ S

2 r- v, i3 X; u$ f6 q+ b8 u  ;; initialize the global variables that hold patch agentsets
2 K0 \5 `' G6 c0 i6 H: u. a  set roads patches with* r9 h# S4 ^2 ]1 ~; o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 m8 ]1 @* p# v9 h& e  X( S7 J9 d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 C" M+ W% P+ |: B7 B  set intersections roads with
) i0 J" }/ ^4 y6 D) q6 R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) F2 `% y" u' _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" p% y/ S' ~* B% ?" |
, f7 n: \5 {; v& ^
  ask roads [ set pcolor white ]
: f( l2 L$ b( o    setup-intersections3 G& Q# l" `* w
end. A3 q2 F2 D5 H% g4 e6 z, D8 i% S5 J( k
其中定义道路的句子,如下所示,是什么意思啊?
- s2 e0 O  u* Y0 L5 J set roads patches with
: y, `  H# T/ O/ F% R7 w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 D) ^6 R/ }* y; |2 b# Z; t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ v( F, k& i8 \, {3 F7 L
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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