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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。' E3 s1 W4 v4 `8 M4 L+ t
netlogo自带的social science--traffic grid这一例子当中,
+ J( R/ H" x+ `) B$ V* a! mglobals
( z, n) r4 \5 L1 b; e7 x* ^+ E3 t[
" N+ G) X6 G9 F$ s  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 ~+ i+ P' C; e& G" k5 W8 I( U/ a  grid-y-inc               ;; the amount of patches in between two roads in the y direction. F6 o( _! l/ N" U
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% F7 y% ?" [, V2 e1 Q
                           ;; it is to accelerate or decelerate
+ G5 _8 R& E6 w" Y* K4 u  phase                    ;; keeps track of the phase
$ K8 g; U+ T, _- L5 ]6 b- V" D3 {. A7 E  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ h8 J- M1 g6 A& O7 Z) r+ S. J  y
  current-light            ;; the currently selected light5 J4 Y* q3 u3 d) C" z7 H
1 d, Z3 K; G! \9 z4 G
  ;; patch agentsets( }. F# E* G* S
  intersections ;; agentset containing the patches that are intersections
" G( S+ n/ m' j0 y- b5 R  h# b$ L  roads         ;; agentset containing the patches that are roads: s) u0 Z; J% B' }  ~3 ]) ?
]* X, M! e- u  D: \$ X% _2 T

" j% [+ R, [- N2 y2 Q2 |turtles-own& ^' p5 s/ H: V
[
) Q. A2 G, Q& S& X" s7 g. N: v  z9 |  speed     ;; the speed of the turtle& w; ~- k- ~% O: n/ @8 [  k7 H
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* c0 ^3 B  z! |5 p  wait-time ;; the amount of time since the last time a turtle has moved
* H3 V% j9 N' `, a], G) c5 S9 |' I  J6 [

; r6 w6 o4 s- B2 Epatches-own
- [9 K. C" y, E4 o, E1 H4 ?[: q) G3 F- K: D. |$ I/ ?
  intersection?   ;; true if the patch is at the intersection of two roads
7 |; @) ^5 |  h1 t8 o, g: o( \  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! p9 @5 i- l$ W
                  ;; false for a non-intersection patches.8 G. f  ]8 J9 b! O. x( B
  my-row          ;; the row of the intersection counting from the upper left corner of the$ _! s: `5 s, `# x9 e2 F' Q2 Y! F
                  ;; world.  -1 for non-intersection patches.) B9 M; M0 {0 R/ Z+ J
  my-column       ;; the column of the intersection counting from the upper left corner of the% r! f& I8 u+ v) X
                  ;; world.  -1 for non-intersection patches., h7 H& w' Q5 ~) a3 u
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) k0 H6 m, {" L# h" c  r  auto?           ;; whether or not this intersection will switch automatically.
7 |6 T3 S- x* e2 _6 a7 Z% k& H: v. h                  ;; false for non-intersection patches.3 M4 E* c( t5 s. f
]
! \" @2 n. [8 ]! f. c8 F2 t
" u' @( k7 N! C# @4 v; B1 o" f
& b# x* G! J3 W' X;;;;;;;;;;;;;;;;;;;;;;5 @8 L4 l4 m7 x9 I, w. p
;; Setup Procedures ;;
" P) L4 A; u2 b& p* x# z1 I;;;;;;;;;;;;;;;;;;;;;;
: U- x4 C/ R7 P7 v4 e; r, f5 ]! g( C% R/ q2 u4 `% p& [
;; Initialize the display by giving the global and patch variables initial values., X' `4 D' T  F! O) B
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 x" I$ [6 W0 z1 x) P0 M;; be created per road patch. Set up the plots.6 }* X8 Y; Q$ k9 g( |2 u
to setup! H# b# A/ j- P, L
  ca( _+ E% W. X2 Y7 E& K8 o  u
  setup-globals- ]/ s8 s7 L3 ~* M' k
, D' @& \% t6 U
  ;; First we ask the patches to draw themselves and set up a few variables7 V- W9 a( ]0 Y' b, @# c2 P! \6 f
  setup-patches
/ h. K+ [( L0 M# |/ q" h" o% ?  make-current one-of intersections) R9 z4 ^6 i; }4 Y
  label-current
4 [6 m% g: M1 J( }/ }3 {/ U
% L. o4 q( o1 x* G3 H3 n  set-default-shape turtles "car"
6 m( d0 R$ R0 g# [# [/ w0 q, s! c/ F3 C, B/ A3 `& r  g
  if (num-cars > count roads)
# ~; ~# b; z! b! E5 b  [
4 x9 [" A0 R1 X5 |) B! U    user-message (word "There are too many cars for the amount of ") }7 _$ u$ H+ u
                       "road.  Either increase the amount of roads "; r$ x8 t1 O$ K2 G" b0 q
                       "by increasing the GRID-SIZE-X or "$ f# x  {- C7 }" R( i8 v1 n
                       "GRID-SIZE-Y sliders, or decrease the "& x/ H3 v( ?1 N3 t, U3 q
                       "number of cars by lowering the NUMBER slider.\n"
0 \5 ^: z; S6 o4 x1 ~' w                       "The setup has stopped.")
" i! ^3 }6 p3 m$ t* l8 \2 K3 H    stop
7 o3 B9 {8 X! \5 l  ]
6 _5 X. _, s: h- W9 p
+ s* E7 [0 C/ _" V; z( v- H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color4 n- |  B( K4 J% d. O5 A- S
  crt num-cars
) I# n/ o+ _1 Q  [8 W! s+ Q5 L4 o+ [9 k
    setup-cars8 s7 _+ A+ d& {2 C) h* Q
    set-car-color
8 B/ [' {* q& V3 |% f1 o    record-data5 ~1 J, E, f7 ~3 ~
  ]' P; ]$ r. a1 w' m/ t# I

/ X- ]  z7 c$ N4 [( G! M  ;; give the turtles an initial speed
  J6 f: d6 j( T- k) o; _! p  ask turtles [ set-car-speed ]% Q8 S- _0 W- s: b0 |/ U" f( A

9 @/ j, d  b' X8 ?6 t9 I4 k: X  reset-ticks" U6 m6 Y- [5 W( m
end
8 [% q' |3 }% u* m) `4 c/ z% L( G8 A
;; Initialize the global variables to appropriate values4 o' [1 e) `2 W, ?  l" m
to setup-globals, z* f7 R  ^/ B% I
  set current-light nobody ;; just for now, since there are no lights yet1 w0 S$ v) R0 J; t
  set phase 0
9 H9 N  x* x" m1 y  K6 W- s  set num-cars-stopped 0
; g- C* v( P2 Y6 M! _  set grid-x-inc world-width / grid-size-x
& R  g  ^# p; P& d  n' a9 d) g/ O8 c  set grid-y-inc world-height / grid-size-y
7 ^  ~3 l/ c3 R' L0 f" _& X
4 a* A8 s! F+ a7 p: J4 b" ~  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 p$ ?% t+ }( k" C6 N  set acceleration 0.099
6 C, `* l1 \; G" ]: j( H, _end
6 m' ?4 H/ T2 w
" [8 V: [  A8 L& r5 [;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 U. f1 d8 H1 r* T;; and initialize the traffic lights to one setting' v0 P; v/ s8 \8 q
to setup-patches
  ]: o1 A/ N& a1 }) d; ^, u$ \  ;; initialize the patch-owned variables and color the patches to a base-color; |5 K+ K# Q& g# c
  ask patches# E( V9 }8 X; o
  [5 R/ D5 ^& b0 P
    set intersection? false
# f' c) }! J# A  }$ \) Q    set auto? false
8 h+ \- r8 z# L  {) l7 _: ^    set green-light-up? true, Z5 ]' s& k. e) m4 P1 R) j- q+ }
    set my-row -1- Y) O, U% F# Q  D
    set my-column -17 a2 Z/ J( U! E8 C! T
    set my-phase -19 M- ?# U, R; k! Z3 b  c/ c0 F
    set pcolor brown + 3
. D) N" q; d, K( I8 @  ]6 J9 L% P8 B' L& G2 K4 `) c

% p; z8 ]0 ~+ H7 c$ G# H  ;; initialize the global variables that hold patch agentsets$ m) l0 g, R) b8 D2 Q* S+ z; u
  set roads patches with
1 U; Q: q/ n5 x- {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- y, {6 J) l; M& O8 u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 u6 U/ V$ F: N* m' v  set intersections roads with
& p2 ^6 K4 h, Z* Q" \6 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) e. e; H8 ?  n% B& Q9 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ o! T7 c, C& j1 S
; w6 [1 ?2 M' `0 t$ e* E
  ask roads [ set pcolor white ]  X/ _, h4 S  g+ d$ ^' k; _
    setup-intersections" q8 K# a+ u3 k& p& p' w- \" D
end1 t4 W' |5 x3 N" F. [
其中定义道路的句子,如下所示,是什么意思啊?% I* {/ W1 u" I3 v
set roads patches with- B& \) L0 R" j9 B7 H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 z1 E1 G! e" s/ n2 P' z7 p- R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. L% i1 s) F( H4 K" 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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