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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。0 _4 P, D: B1 c" m+ S0 Y
netlogo自带的social science--traffic grid这一例子当中,
* l) M) R) B' M$ f. v& q7 v: Lglobals
6 ^) j: Q" ^- [9 d( h' Q' d1 p[, }2 q1 ]5 _5 g! j; `2 L* M
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
( C5 ^" [, P8 P  K* u' H. }  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' a% D" a# r$ i$ m5 n: A4 e( k  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 ^" h6 o$ M: H3 J, F. ?
                           ;; it is to accelerate or decelerate" k1 `* N& P' G* \
  phase                    ;; keeps track of the phase* F# k. C: \7 P
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! \- r- A! M5 Y. ^9 K" |
  current-light            ;; the currently selected light/ N" Q! ~* K( w1 F  J
1 I7 u8 n8 R% z: `- A2 u
  ;; patch agentsets% Q3 ~# @" H9 u  U& g1 S
  intersections ;; agentset containing the patches that are intersections
* E8 y: Q, U/ z. ~" a  roads         ;; agentset containing the patches that are roads
% Z0 w. c" q' W- O]
$ k- }1 D, ^! g2 b' c/ b. m( N" n; f9 ]0 H  u9 I, `
turtles-own8 ~4 c, s+ t' [' U6 x0 d3 t" I
[
/ }) y* y( \; L/ S9 }' A  speed     ;; the speed of the turtle
+ {9 W" W* U+ n' A4 t5 W  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( o, c' X# r+ v  Q+ ^6 e8 W1 {  wait-time ;; the amount of time since the last time a turtle has moved
- |9 o" ^9 c; L6 m+ h2 d* K' ^0 x]
$ q, {- y* a2 W2 R" i5 Q4 x, m$ d/ H. |% Y) o+ D) ~
patches-own/ z' D9 g9 p( \1 ]
[$ |" A7 K( ?1 ?6 Q+ b* H/ R7 ~6 g
  intersection?   ;; true if the patch is at the intersection of two roads
/ @; J# O! i1 c7 ]7 R$ S) X  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 V( _, z; e( F1 R
                  ;; false for a non-intersection patches.
. _- i: n3 e( l# h6 Z$ R, E! U  my-row          ;; the row of the intersection counting from the upper left corner of the
$ b, m5 w; k3 W6 A8 ~  J* `                  ;; world.  -1 for non-intersection patches.2 ~% E5 I' t. i! `% b
  my-column       ;; the column of the intersection counting from the upper left corner of the; P/ [, U7 ^$ W6 f6 L- @
                  ;; world.  -1 for non-intersection patches.. k& h" c; J' X( j* \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
, h$ Y0 J( }6 j: e7 }3 n  auto?           ;; whether or not this intersection will switch automatically.
6 _# h2 _6 v6 y8 g" d                  ;; false for non-intersection patches.
; o5 x/ L4 k6 r]
2 A9 T* ]: G) n4 D. @  Z( x% ~% J0 R1 M# @

& h8 f1 \  V1 k( A2 B;;;;;;;;;;;;;;;;;;;;;;- a+ I' R! B& p" ^4 c6 v& b0 z) N. P
;; Setup Procedures ;;2 y# s, d% H. P  U6 }
;;;;;;;;;;;;;;;;;;;;;;
" f1 c% ~& c$ g' G/ @5 s3 ]3 R. T) K
;; Initialize the display by giving the global and patch variables initial values.' X& t# {8 ?" T& h
;; Create num-cars of turtles if there are enough road patches for one turtle to
* [& W  g# _+ f) p: A, [;; be created per road patch. Set up the plots.; }. R( F, T- V. G' S  `
to setup
3 u" m" z. b$ D+ c$ Q  ca
* |! v9 Q# E) \( e6 r% B4 l3 N  setup-globals
( O0 m& c" ^: M3 D3 O& x% }7 e6 p" n  \; B+ [# P
  ;; First we ask the patches to draw themselves and set up a few variables
  f- D; a+ S1 _2 ]( s+ M$ j; c  setup-patches
% r# b2 X  H% L. Q0 o! w, t  make-current one-of intersections
1 w% }+ X4 h3 h$ k" f* l4 Z  label-current
# V% k- ]; L6 _) L' F, o- F  Z& Z- x+ C+ J8 K* h3 ~
  set-default-shape turtles "car"2 r# g7 u3 v% }% O" G3 U

" q8 i; g1 u- E% A# Y$ c; f  if (num-cars > count roads)
) X) D5 @2 S: T3 A& m4 v- A  [4 B. {/ N8 ]$ o% z
    user-message (word "There are too many cars for the amount of "
  A% e, s- u/ G$ i, C                       "road.  Either increase the amount of roads "
" |" c5 A) e+ I7 w) i                       "by increasing the GRID-SIZE-X or "3 \6 \3 L. C9 l' G7 j1 S1 f; Z! c
                       "GRID-SIZE-Y sliders, or decrease the ") p0 \: Q# N. G; b
                       "number of cars by lowering the NUMBER slider.\n", a+ a* H0 J2 r% F1 J/ n  O$ C- c# Q
                       "The setup has stopped.")
! U) O9 A4 B0 }0 c9 U    stop& I- V! A1 ]1 e& l+ x, x1 _
  ]! Z& x: j0 |3 \7 |# ^
. l# T6 |/ s5 t9 N0 e+ T" {
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 m9 [* M! g# H' D4 I( t  crt num-cars. E3 J1 Z0 l* \. P+ C
  [
, F9 X% H/ M9 g$ ]    setup-cars9 T) J9 {3 G5 L9 ]& U; G4 a+ h( j# p
    set-car-color
6 Y* p* G3 L+ }' d9 a( _- e% Y; Q    record-data5 K' e" C. f0 @, h. B/ P
  ]* L+ R/ M6 u$ |

) ?1 U3 ~% X( q' b! f  ;; give the turtles an initial speed# h+ p. f/ B3 Y( b9 d
  ask turtles [ set-car-speed ]
0 X# R+ }7 B( R+ b% O; n) y& F$ z. U0 J% i7 u" _  O; r: F
  reset-ticks; z+ X" ]  B! j3 e( B
end
3 v9 `, X5 M3 Y3 A" z
0 `# S/ o* o# d7 f* T7 v* [;; Initialize the global variables to appropriate values2 o. w' n7 v/ c* z
to setup-globals$ P1 a2 E6 F, @7 g) \! y$ x
  set current-light nobody ;; just for now, since there are no lights yet
: H9 G" v% R/ u  set phase 0
/ _: T6 D( v! l; x  set num-cars-stopped 0
/ g: I% G. e6 U# X( I  set grid-x-inc world-width / grid-size-x
9 L9 L0 ^" E4 w% o; u) F  set grid-y-inc world-height / grid-size-y( I. E) S+ ^# L+ m5 E& @

: [. T' i. P1 W' m* X/ O# n4 K  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, \6 G! Z( f8 m8 D; m) F* }
  set acceleration 0.099- m. O. z3 ~0 h& c2 U5 Y8 b3 X1 H9 \
end
' ?, O/ U6 A7 m" A/ I$ n1 S& i  ^' t5 J) ^
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, u! R4 G4 a  ?6 Z/ \* o;; and initialize the traffic lights to one setting2 K' J' a5 O! `2 |+ Z
to setup-patches8 h4 F. h5 ?( Z
  ;; initialize the patch-owned variables and color the patches to a base-color
: B& m# s( B: u; o2 q) C' K  ask patches
- L! y8 o& [# c+ u8 [+ ^  [
1 q' O$ @6 o7 ]7 }; x    set intersection? false( |* ]) I) U  q0 P* X* E  q
    set auto? false
& k" [) R- _5 _' T2 U; |9 ?' P$ [    set green-light-up? true* M8 c9 e% }* e3 ?6 q$ @
    set my-row -1
, r- g/ ~4 C8 v5 N: X0 |) i, j: N    set my-column -1
$ T( h- p! X1 {) x5 Q7 b    set my-phase -1) p' K. j5 @4 J9 f3 B. d
    set pcolor brown + 3' `9 I- {! O( ~+ C2 G
  ]
# h  s  |  e% Y+ A4 j& k5 `" a1 z( y
  ;; initialize the global variables that hold patch agentsets3 C5 A0 m+ \3 ?- O/ j7 ?. h1 }
  set roads patches with( x- A; \' n) V( ?6 K, _' l/ G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* }8 _& S; r: I6 Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. }7 Q4 @7 W$ P
  set intersections roads with8 ^  Y+ V1 ~! K/ }6 d  y* x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ I5 J9 Q; V  B) H& U4 t) M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# j4 r$ C9 }( v' ~$ i- D0 Y8 C' _" ~- W+ a. ~
  ask roads [ set pcolor white ]
! \0 @" [$ r7 n1 g+ ]5 W    setup-intersections
: t+ ~% q0 w5 t3 F8 v; E3 Y: Hend7 b- Q* ^- Z* g
其中定义道路的句子,如下所示,是什么意思啊?
" e& ], T- A8 M* [& k9 I3 W set roads patches with
+ X; y/ [* L; A( f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 }* l  v- [0 R# w+ i. \- A# a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& S% B2 w4 `2 v  `2 @. p+ `
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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