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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。2 ^* C" A; s. A5 x( L4 ?+ @
netlogo自带的social science--traffic grid这一例子当中,
# {- Q' W1 l* V' n8 Sglobals6 E# z: q/ f4 ?4 z, L
[; |, u5 D, R; y4 Z& |8 }$ F- i
  grid-x-inc               ;; the amount of patches in between two roads in the x direction" G+ a+ o- a7 B, g9 }# T4 @3 v
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' S  \$ ]; m" n) n9 m- V  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
1 U, M2 ~+ z2 R, {2 S                           ;; it is to accelerate or decelerate
$ J) m% |+ i8 u9 D7 K0 \* p  phase                    ;; keeps track of the phase: t) L  A1 O* u
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
) F: j6 @5 z( v  current-light            ;; the currently selected light3 _  x. P0 D8 F6 \% c

# c$ Z+ n; o( |  ;; patch agentsets9 t. G8 ]( u. d
  intersections ;; agentset containing the patches that are intersections
+ Z, ?  W- d6 |7 Z( D5 Y  roads         ;; agentset containing the patches that are roads+ S* e2 }" S# c
]' z) y* Q" x$ I2 m& l& Z& k* @9 N+ `

, w8 V8 {6 |) c! ~9 R. ]turtles-own
. ?9 R1 F& W$ W5 s[1 B- c' l( O2 P. q% R
  speed     ;; the speed of the turtle+ \( c) y& @3 \
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
& @1 _- k& _( N/ p, [# r+ w3 q$ O  wait-time ;; the amount of time since the last time a turtle has moved
+ s, w' D' m" P4 C( r/ V]; E2 u! ^& N: \
5 Q- t5 x9 S; R4 X
patches-own
4 L/ b% E7 F7 s1 U[
2 I9 [2 L6 T, @! s- I  intersection?   ;; true if the patch is at the intersection of two roads( A6 @; ^8 P- C2 m
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; Z3 x/ k! }; |* N                  ;; false for a non-intersection patches.
8 l% P6 z, y" h. Z# C$ q/ W" [  my-row          ;; the row of the intersection counting from the upper left corner of the! |) ?* b% J5 W/ w
                  ;; world.  -1 for non-intersection patches.7 L1 a  c+ U4 x4 j# X9 G; X
  my-column       ;; the column of the intersection counting from the upper left corner of the! x5 Y( H7 a+ V( v9 d" \
                  ;; world.  -1 for non-intersection patches., R7 U0 c. N6 ?0 m
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  U  H0 f3 Q( Q9 Q8 U4 o( ~  auto?           ;; whether or not this intersection will switch automatically.
' p: |! N3 b" L8 Y5 w" q" h                  ;; false for non-intersection patches.5 X1 o% X5 @, Q  q
]
0 J: [' r$ e  R, b9 ]+ G/ J3 R; A6 |

" |  x2 E  ^8 A, j$ n! v7 X;;;;;;;;;;;;;;;;;;;;;;
. ?8 V# B- }0 {6 ?;; Setup Procedures ;;% R/ ]7 |5 t4 B) r6 @
;;;;;;;;;;;;;;;;;;;;;;% F8 g/ L# _. Z$ H

* u+ W3 I* ], A3 X8 w$ b;; Initialize the display by giving the global and patch variables initial values.
7 J* V6 Z; }( R5 s. r7 T4 B;; Create num-cars of turtles if there are enough road patches for one turtle to1 {/ N* }2 t; v" V* ]- J& D/ X
;; be created per road patch. Set up the plots.1 ?# f- p& D( U0 v! F
to setup& p% Q# x( g  e. G
  ca+ m# i8 ?: U% |2 |2 X* F
  setup-globals5 S* D( \# p9 n6 V) O! Y

; B- L9 i& o8 g; K4 J- }5 J. Q& d$ U/ ^  ;; First we ask the patches to draw themselves and set up a few variables& }$ N5 Y- k$ ?& ~
  setup-patches# l" P5 t* K- N% N. w2 J# s
  make-current one-of intersections$ U3 n  b2 {& {4 R
  label-current
4 Q( ]% Y) f4 O1 h* I3 g2 B7 g0 v7 I1 w6 P+ w! n# e2 |' w4 I9 s
  set-default-shape turtles "car"( }' a* L) S( g# Q" a! A/ x
$ p) Z- K" j* F! Z( E: c
  if (num-cars > count roads)
1 j' U$ v3 A1 G& R' ?  [) _" I/ r9 i; L# e
    user-message (word "There are too many cars for the amount of "
& p2 h: R; N% n/ h                       "road.  Either increase the amount of roads "3 i, M6 S; b; N9 N6 R
                       "by increasing the GRID-SIZE-X or "
6 j3 M" P, M$ h% n1 n                       "GRID-SIZE-Y sliders, or decrease the "
/ Y" v: J2 o3 J+ M  p                       "number of cars by lowering the NUMBER slider.\n"
8 \9 R; Y' w" O                       "The setup has stopped.")# ?; i. J- }, W+ Q
    stop3 ~0 E# k0 F1 w6 e8 q
  ]
  I6 A1 O7 ~6 O. m1 o. v, p2 y9 i, s5 Y2 d* d0 }
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color  H6 ?0 Q  X5 f+ L: y2 V
  crt num-cars" E2 ]7 v1 Y0 L
  [' `4 d7 F! A6 a( l/ U
    setup-cars; [$ m6 S* [# w: ~2 G& N
    set-car-color  S; X; `6 g1 W
    record-data
8 R/ u/ B! J# B$ c" y& Y6 \1 i  ]
  B. t( N3 i' w/ g+ d9 g' L8 J# @' q7 T# C  v! N' h
  ;; give the turtles an initial speed: k6 F8 r6 l( P( B
  ask turtles [ set-car-speed ]
' p  q* d; d7 [" @: m+ M' O/ _+ [0 ^; ?7 l
  reset-ticks7 L2 }9 ^) {: ?0 w, O, E" S
end! i5 v! ?) Z) V5 A

% a5 a# g- j7 H: p% f, l0 T0 ]5 t;; Initialize the global variables to appropriate values8 A5 ]/ [( X* @* e* p9 V
to setup-globals5 N3 |! P- }+ ]) z, [1 Q
  set current-light nobody ;; just for now, since there are no lights yet7 j5 S: r, V, H) l- {; _
  set phase 0
$ S2 `: r9 o* t- X' p. m  set num-cars-stopped 0
6 T9 K  y& `1 D) |2 [1 t* B: ]  set grid-x-inc world-width / grid-size-x+ Y  l$ L. @( B, F* N( }+ _& I
  set grid-y-inc world-height / grid-size-y
) u/ i& v. O! }* C9 M
0 [% s( u4 E1 E( f! p  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( O) x, g3 t$ k  set acceleration 0.099
( L/ ^% X8 r. b+ C' c0 I) Qend5 ^, x0 ?2 L3 A' c+ }
4 i1 _  i, X: F2 A5 b/ ^
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 w- I+ f1 w& e! m9 M" O$ T
;; and initialize the traffic lights to one setting
; R* }5 }* Z, I. I) Tto setup-patches
2 {4 ]2 R* ^! C3 c$ z  ;; initialize the patch-owned variables and color the patches to a base-color
: [1 i* f( u1 O/ h7 Z5 B( U; S  ask patches
4 V1 [& H' `5 M: B$ h: D; H  [
) K. `4 g1 \$ d$ \- C' q/ n    set intersection? false0 B- A( P' `* ]( ?
    set auto? false
; j1 w- ~3 E7 _  H    set green-light-up? true+ O. X( T$ B5 u% e# O; M
    set my-row -1
* s7 [: L& S7 q; C0 l; }    set my-column -1! k4 }$ }5 h' R& w  e& E  d) P: p
    set my-phase -11 b3 }2 j% w* M3 `. W
    set pcolor brown + 3
; j* ^, J( _3 u! L  ]  ~3 N$ g6 s  `: Z7 J2 ^; ?
6 a6 C5 O. T" V1 L' C
  ;; initialize the global variables that hold patch agentsets
' T- L+ A6 x4 k5 k) p% q. q  set roads patches with
- F5 H% E6 b. ^7 W& f" T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' I8 h2 Y, s$ A) a% R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; Y) \1 J3 E* G6 C2 N+ c  set intersections roads with$ {+ m& j8 N* l  G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) k  f' U: [( r- v, R4 _) U9 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" _7 G0 L' ?& T, r* g

% A* [. g( r) T$ l9 x( O  ask roads [ set pcolor white ]% T* C% }" g) p- h& r% Q
    setup-intersections, P: J( u1 k6 a+ ^3 Z% h
end/ o6 t5 t- q! z
其中定义道路的句子,如下所示,是什么意思啊?" r- X) C: f+ G+ t5 ^
set roads patches with$ \" Y2 [8 p/ n. [$ ]. }& z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ g8 k5 q' f4 o" K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; O: R' @! X4 ?
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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