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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。5 [; }# s6 \. F- F7 E, k9 q4 @# L
netlogo自带的social science--traffic grid这一例子当中,
; S8 m; W& g1 `& M6 Kglobals
. E5 J. s" R' w5 A1 H1 P. M8 e[
  f3 V1 f$ Q: D9 Z  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) Q5 _$ Q( |: Z! A% Y  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 v1 q( @/ _' Q$ P5 T* {+ g( K5 V" d: l
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 P, r* u. t& S3 g
                           ;; it is to accelerate or decelerate" u% F9 V2 G' s, g2 F5 V1 h! H
  phase                    ;; keeps track of the phase
) P0 G2 N+ k& U& R+ @# x4 j  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" F' o- H( P: P& \0 k+ S/ E
  current-light            ;; the currently selected light' A3 \/ r( _2 a: d$ t% u2 E( d

: j7 g7 c: g# A1 Z% q  ;; patch agentsets
& I1 V3 E* N0 m" }: f  intersections ;; agentset containing the patches that are intersections
& \" ~" W4 d+ y5 F, k& b7 w/ N  roads         ;; agentset containing the patches that are roads% Y! g9 a" P; P% }2 ?
]
2 s! h/ n1 F' f
* ~4 W/ {- F6 ^- t9 W0 b. c8 Hturtles-own' L/ R" k! c% g2 S
[
9 E( t" A. `" ]- Q  speed     ;; the speed of the turtle) ]1 o  o2 N- {. v0 Q( J0 {; K
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! N% }, V0 Y7 e- h" [9 D  wait-time ;; the amount of time since the last time a turtle has moved
5 n0 f, e+ \2 e" @7 U]) }& [/ ^3 i1 c5 h& w$ i

. Q5 c; t, ?) W( N9 t* ?patches-own
  w3 M2 x/ g9 \7 _$ I5 m# ~: h3 g[/ c; A& V: m, Y
  intersection?   ;; true if the patch is at the intersection of two roads
, s9 I: K$ E* c0 v% T  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! g! l$ h$ G9 [* o9 _
                  ;; false for a non-intersection patches.& ]7 ~/ V/ L0 n) X' y
  my-row          ;; the row of the intersection counting from the upper left corner of the1 K" i* L+ e& w' t
                  ;; world.  -1 for non-intersection patches.
# u/ t/ M/ K% @0 m  my-column       ;; the column of the intersection counting from the upper left corner of the! T( C2 S4 R7 Q
                  ;; world.  -1 for non-intersection patches.
6 _3 ~- J; X# ?! e' K" U5 n0 W  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  }$ V7 J4 M" ^5 x% P. O# p2 o) F
  auto?           ;; whether or not this intersection will switch automatically.
6 V  p6 m9 q# A, ^* y+ }4 m8 r1 ^6 K4 P                  ;; false for non-intersection patches.
/ d2 a$ Y+ a7 ^5 E9 ?0 ^* z]
9 U0 H5 k; T3 H
; m  T- Y! @6 `# T" Q' \! A5 j2 Q0 j1 e3 j* v5 \9 Q& U
;;;;;;;;;;;;;;;;;;;;;;0 e7 A- v9 s. c) {
;; Setup Procedures ;;( D5 O4 l0 S# p: k6 X0 a
;;;;;;;;;;;;;;;;;;;;;;- K. v+ O6 b; `, T0 c
$ \/ z, K1 l, e5 d1 D* z* a1 b
;; Initialize the display by giving the global and patch variables initial values.
: _4 }' }2 k+ W# ~/ O6 @' A) p;; Create num-cars of turtles if there are enough road patches for one turtle to
' p2 \* [9 k) f  n;; be created per road patch. Set up the plots.
9 r! y  Z$ ^) A  A6 ^( v( Z/ Fto setup" M$ I1 z; _, R( n# S  R
  ca
6 R5 D2 \" A8 Q  setup-globals
7 R. F7 n9 \4 d
, X6 Z  {2 T9 q0 E  ;; First we ask the patches to draw themselves and set up a few variables. {9 |$ u; H3 X2 @
  setup-patches$ J# ^3 g! B' K( f6 {2 h6 x; q3 @
  make-current one-of intersections
" ^1 y% ]) h) t0 q9 y! Z  label-current
5 i1 y1 H+ y9 W, @# S; y8 q" q# h7 f; K- p' u
  set-default-shape turtles "car"
7 T$ `* w% n0 {0 I3 Y5 v7 n7 ]/ a9 y
8 Y# y, H# k" C" j. @3 f  if (num-cars > count roads)
/ D5 ~* n; p; r% K8 ~4 w) X4 A  [
# u0 o7 s' @- U" Z$ L4 g6 N+ p    user-message (word "There are too many cars for the amount of "
% n. I  ]1 [& D5 P6 @& E. i6 Q, f                       "road.  Either increase the amount of roads "6 K/ ^; W" _/ w: {' n( y0 M
                       "by increasing the GRID-SIZE-X or "
5 e  A* r8 {7 s& T                       "GRID-SIZE-Y sliders, or decrease the "# g2 {' a) @7 z' y: S2 u
                       "number of cars by lowering the NUMBER slider.\n"
7 d  H. c* g- F- R4 d- v$ j4 x                       "The setup has stopped.")0 ]0 d: [% A- n4 C  y+ o2 A
    stop5 J9 Y3 f7 p% u" w  ?; _4 g, l
  ]
; D! `1 v! H2 o: S
0 r3 W/ W# E$ F0 M  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 D8 _' \, L4 o" O( c: ]7 n  crt num-cars
1 n! D+ \* |# @! v6 e6 I1 P, f  d  r  [
+ b* @  U8 b8 ^    setup-cars0 Y) E0 @9 g% M& T" o: b
    set-car-color
9 [) ]: E$ u; y: ~4 u    record-data* {) Y- q$ T. J4 V
  ]
* U: c3 [. `, k2 A9 \  W
: b6 T* [0 N* B+ B! ]+ a* C* {  ;; give the turtles an initial speed- H  t& _9 F. Z$ {* |( f! C
  ask turtles [ set-car-speed ]
7 G0 P- q) w# @" E, U; }  t; k$ q+ ~3 Y  d* p+ U% ~
  reset-ticks
, I2 _$ b, J; q  v' Y7 q5 \7 `  ^end
7 i( K0 B: B) y# W0 C, ?7 T. \& N1 }, s7 h* T! x
;; Initialize the global variables to appropriate values
0 [9 P" R* z) ]5 {to setup-globals
, {+ @6 I% Y9 o; \1 n  d6 K  set current-light nobody ;; just for now, since there are no lights yet+ U# ]* G" c# r5 z, X
  set phase 0- ^; u% @& b/ C! Q
  set num-cars-stopped 0" I' Z2 M& v' w( F+ H
  set grid-x-inc world-width / grid-size-x: w) w+ [% _% X* g/ _
  set grid-y-inc world-height / grid-size-y
9 q! i7 d4 j& b7 o5 e  @' \* o& c% t+ v: V7 T6 |# o' a! ?% g7 Q; N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# U7 w: f5 A5 Y& B$ U) q" V
  set acceleration 0.099
$ A, ^9 J3 i( I# _3 ]3 Nend
% C9 _9 W8 X& l+ p" b# m& J, I5 ^, }% @( b, c4 p: N
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 E2 O; D# |4 T1 L: A5 ~;; and initialize the traffic lights to one setting
' z4 E; C& y1 |+ W+ F" @# w2 gto setup-patches: r' \0 h7 @, ^0 g  C6 `5 G% o# b6 d
  ;; initialize the patch-owned variables and color the patches to a base-color
# n8 t. }* C- S' A  \) u% ?  k  ask patches
" [% @# J& I) k% u/ e* `/ L% |  [  [4 ^6 F+ r4 x6 c: Q- A
    set intersection? false
1 f# }' s8 ~2 ^! Y+ e" E8 R    set auto? false0 A) g+ m3 f; e3 ~7 v% t
    set green-light-up? true( |0 c/ V9 g& b
    set my-row -1
  D6 ]! o# k& @, g6 v( Y, `* W    set my-column -1
& B) T7 D+ k9 {- |8 O- [    set my-phase -1
' R. T6 p1 v7 z, H9 B9 c: ~    set pcolor brown + 3
: \2 D$ y% _9 b1 J- E/ |" W" S  ]
4 _' W( t$ j2 H3 y6 ?( }% p6 N" B8 @' m
  ;; initialize the global variables that hold patch agentsets, `# }/ s+ w4 R6 [( B9 h
  set roads patches with
6 K% ?" g/ h8 P. b6 X! t$ P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& w7 v' b" e# p6 m! J5 p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# E( x: G4 Z1 H) R
  set intersections roads with
" L2 v# Y* `3 j4 y; H9 H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& B* v4 q& g0 c) a6 f: H" j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& t  [. D0 p2 W0 z- u+ t/ n$ m
4 `5 G0 t  G% L( Q/ I3 l" D  ask roads [ set pcolor white ]" A' ?0 |2 {4 T' ^1 P: |
    setup-intersections
% x6 i+ k# l; Q0 R) R7 xend! `" j, ]% o0 o0 [8 W4 i
其中定义道路的句子,如下所示,是什么意思啊?
5 z' `9 {: b8 o- c/ {# d set roads patches with! W' B% L. b5 N8 n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ {/ N5 o- q) z7 U2 K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 n9 c5 _: \$ }5 s" S0 |- J0 o
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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