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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。9 g2 O1 r1 h% n! i
netlogo自带的social science--traffic grid这一例子当中,' b: W- l+ B# z8 u1 x$ _- H( Q% c
globals4 f7 U$ X( B& G! Z
[
) j6 s$ i6 W& C3 d* G3 \  grid-x-inc               ;; the amount of patches in between two roads in the x direction. l, S9 K* c9 f5 m. Z- X
  grid-y-inc               ;; the amount of patches in between two roads in the y direction! N6 w0 ^& a' ^$ h2 C
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% G# K9 B2 z2 E' ?8 z3 {' J                           ;; it is to accelerate or decelerate
& f6 t$ S  d1 @' p& q3 @; v4 Z4 q, N  phase                    ;; keeps track of the phase3 K0 u6 |& D9 V7 K* m5 k
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 \( O" e/ Y/ \8 `, Q  current-light            ;; the currently selected light
8 a# b# ]7 e4 T* g* R. T6 q. Z3 }/ z+ n* B! ~
  ;; patch agentsets& A  D% e# p2 Y0 ]& C$ M
  intersections ;; agentset containing the patches that are intersections9 w- H! }* J3 Y9 s2 Z0 v
  roads         ;; agentset containing the patches that are roads4 Y' e4 C( r9 t* G
]
3 A! g3 Y6 i' s$ z! ]  g9 ~: V- Z
5 y$ m5 v8 D+ C! Q; U; Bturtles-own
  u: g6 C# z) I! l' h6 w& X1 o  t[3 B3 D: m2 B2 m1 Z
  speed     ;; the speed of the turtle. k3 {/ `# o9 K+ }1 d
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# X, N2 c5 [5 t  wait-time ;; the amount of time since the last time a turtle has moved% r+ P! F9 r" w9 v, C
]
& E2 u$ z. _5 v. S1 \# M1 ]$ L9 T& w5 z, o% R/ T% l8 D1 G/ X/ i( q
patches-own- o$ {$ e  Y8 q1 j2 D9 ?- g4 ]; S7 H
[
% l9 y' k; K, V2 f) ]: m  intersection?   ;; true if the patch is at the intersection of two roads  E- B; D( t& e; W. s
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 m: v3 Q; l5 x
                  ;; false for a non-intersection patches." n& b7 p* M; u$ N5 O
  my-row          ;; the row of the intersection counting from the upper left corner of the
' b7 w! w; m, n3 N$ n                  ;; world.  -1 for non-intersection patches.
  F% F( Z6 r5 c7 i9 Y( K  my-column       ;; the column of the intersection counting from the upper left corner of the
5 H4 I! F( h! k# x$ s                  ;; world.  -1 for non-intersection patches.' R% F: D0 t  [; C4 v3 {
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* s4 M7 S# q! X1 J! ~! u
  auto?           ;; whether or not this intersection will switch automatically.# \9 e8 ^# o) j7 O3 ]
                  ;; false for non-intersection patches.- v, w& F% z' Z  c4 z
]( L( ?6 F1 f; Q+ f. t; J  w

9 d# _' l% Z4 W" j% Z9 h9 S9 z& {; A0 v8 k+ f" }
;;;;;;;;;;;;;;;;;;;;;;: b: ^1 V, }8 A  N4 T
;; Setup Procedures ;;6 L' N+ ?. H* i. P! g% V; |  ?
;;;;;;;;;;;;;;;;;;;;;;# _! I* @1 _5 o

( U& v" |0 Z3 D;; Initialize the display by giving the global and patch variables initial values.
3 J: u/ H: x& f* D( s! f  X) \  \;; Create num-cars of turtles if there are enough road patches for one turtle to1 Y0 a% l/ u* O( S3 r" ~  z
;; be created per road patch. Set up the plots.) \% x: ]* J/ a
to setup5 U; c! p! N% ^& e
  ca
$ ^' M( ^4 f+ K% F) T9 J  setup-globals
' n& m* D8 U- g3 `3 s' F* e: {
) E9 w" L$ Z' c8 n" a2 a' ]6 Y  ;; First we ask the patches to draw themselves and set up a few variables
: F9 T  m5 l! k+ t) p  setup-patches( i0 n+ a9 d0 }" J& g0 c2 L
  make-current one-of intersections$ |8 k( m6 X) j6 c7 ~
  label-current
& N. J% Z4 ^& T( L
1 _. D! e( B8 G5 Z" V% t7 a  set-default-shape turtles "car"
* o. Z0 c" h1 r; y
+ R3 z3 h5 Z& B3 `( e) j% `0 Y" k5 H1 w  if (num-cars > count roads)
+ F( d. b$ Y" d7 h; R' }  g( S% w  [
) Q$ m5 q; q7 V7 r: D    user-message (word "There are too many cars for the amount of "
8 v/ A* t/ x4 V- F) _: d                       "road.  Either increase the amount of roads "0 l- ~( v8 c) e1 {6 U8 t
                       "by increasing the GRID-SIZE-X or "
, Y, M1 e# D2 C( P) V# G' v4 l                       "GRID-SIZE-Y sliders, or decrease the "
3 ^" l' s" L' E                       "number of cars by lowering the NUMBER slider.\n"
* R1 d- a6 k8 C& u2 ]                       "The setup has stopped.")8 M, E# F+ U; x2 i  d! M. G
    stop
) S; l+ T) K2 f  ]
( S; s( n2 r! m& G% w( N  X7 X0 C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 D, Q) a# @' A9 V# n  crt num-cars- ~& n+ ~- n5 f2 ]
  [
" Y9 _' E: F% E    setup-cars
" r1 l0 J# V. o. V3 {; \    set-car-color
' ~/ k' I! W6 M& N; T, Y  y9 q    record-data5 y$ Y6 O) E' i
  ]2 Y  W: y, U7 G$ `$ W

5 @  [3 Q# _- ~# [  ;; give the turtles an initial speed: k0 @, I2 E* \* F
  ask turtles [ set-car-speed ]  E3 J5 I" d) }. c) n- B2 }; l

$ f1 r: u4 B3 G  reset-ticks
$ i; E# W# G. R6 j1 X- Rend
& S  f( U: _1 J! I1 |7 J4 i1 \# K5 r% m  l8 x5 k) W
;; Initialize the global variables to appropriate values+ x) H% Y+ ]! @) m  j
to setup-globals
5 D( G; ^- n7 G# {# M4 a: V+ y% `  set current-light nobody ;; just for now, since there are no lights yet! p# p  @; J0 z
  set phase 0' I& k1 a, P& j+ X9 [6 V
  set num-cars-stopped 0, ^9 o* I- E# \$ P
  set grid-x-inc world-width / grid-size-x3 F' `/ |0 l: V8 [- d1 Q
  set grid-y-inc world-height / grid-size-y
/ Z  f/ w  D& y
& I: j, D5 i$ M& n4 W  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 u6 G, s% p% s2 z
  set acceleration 0.099
4 `$ u7 e  C: X6 B8 ?. g0 N/ xend
9 B' x: R# o0 j7 j
& X2 q1 }: _! z4 C$ P% |! M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' Y! x* `; f' A6 n( C;; and initialize the traffic lights to one setting
6 O, X2 H7 b4 v$ W6 cto setup-patches
0 ?; O6 J, o! I  ;; initialize the patch-owned variables and color the patches to a base-color8 R# A5 u4 o- ]& I: n) `
  ask patches
% h5 @6 U5 I; F) P3 @  [
/ s8 g; ?5 l: e; q  ^+ ^    set intersection? false
3 _9 [2 \  E' M! V0 H9 J    set auto? false
  W3 U9 o6 f# v4 d1 i    set green-light-up? true
3 Z3 d( z0 X. k$ F1 l4 a# m    set my-row -1
$ C! c; G) M7 {1 \& x    set my-column -1
% Y9 [  V- L% _, b  O    set my-phase -1
" m% A5 K( w6 V- B" ]' K    set pcolor brown + 30 {: Y  V, |7 x0 U+ E
  ]- u& v/ k( U. v; v9 w
2 D# Z. @- y. }' R) Z2 v
  ;; initialize the global variables that hold patch agentsets
3 o7 _  Q, a1 J; Q$ g  p- L9 S  set roads patches with
- }5 X( _% O- \% Z: V$ S" m5 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 [) J. C7 r) w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ p% B$ k: M# [! y! ^* u  set intersections roads with9 k( P; W" F3 M" d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: `- M" m) E( [1 M2 x8 F; U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; {$ [1 G" }, P2 y2 d) `6 y3 S* W- Y7 F
  ask roads [ set pcolor white ]
* {+ F: c; ?" s6 i    setup-intersections, a. v. K6 q+ @
end
0 W: i* i& l9 R其中定义道路的句子,如下所示,是什么意思啊?
2 u3 s9 O) L: q2 T set roads patches with
( k$ ^& u5 C5 }& u! r9 @$ t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) _% d. d; \. I. E0 a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 d2 M5 v* t! C( o. d. d
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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