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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。" J" ~8 w- A8 P* v' f
netlogo自带的social science--traffic grid这一例子当中,
3 |% Z: g1 }+ w7 n( z5 d2 Yglobals# k5 z* N0 B; i6 k6 t
[
+ {# U3 a# Q5 M, @. }  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ G* z: q/ {  j
  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 s1 p, ?# ~: s' G8 j- P5 I
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 }1 i2 }( T$ [+ j                           ;; it is to accelerate or decelerate! ]' P* S* L8 n
  phase                    ;; keeps track of the phase# E. E5 |6 A# q* U7 h6 [
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. r8 u' X8 Y! A0 E+ i, A: q
  current-light            ;; the currently selected light
% E1 P+ @1 J; O9 C& o: K. {7 p: X1 a0 o3 }9 j% N
  ;; patch agentsets
9 W0 N  c* p& K: w  intersections ;; agentset containing the patches that are intersections' p) ~8 ~) ^* X* O
  roads         ;; agentset containing the patches that are roads
: d" X% \5 u2 x4 w]( }3 Q" q9 f5 [, T7 A( ~/ {
' g7 m$ e4 `9 k* a
turtles-own* N, p. k; t$ b& o
[
' C( v8 v7 P/ b. c5 O  speed     ;; the speed of the turtle2 @5 O8 ^5 [  t4 P: O: U
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* Q6 T9 J  v. f
  wait-time ;; the amount of time since the last time a turtle has moved
* _- U1 o6 a$ E]
, x, U" ~3 q$ d! O& ?4 @) g
. S' Y9 d+ I9 ^$ jpatches-own
) C2 o: T6 y- _; c/ q[
  F7 F+ q( I+ p: T5 r( M  intersection?   ;; true if the patch is at the intersection of two roads( `, [2 Z& |/ P0 x1 p% l2 Y$ e
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* W. h* {0 J. [9 ^
                  ;; false for a non-intersection patches.: {+ x4 \- Q* H9 C7 Y" ]! A( l) E
  my-row          ;; the row of the intersection counting from the upper left corner of the: T/ z5 ~7 z( b+ F. D+ E/ }
                  ;; world.  -1 for non-intersection patches.9 ?  I1 Q0 o) J& y8 w% k" h' l
  my-column       ;; the column of the intersection counting from the upper left corner of the: l% z: ^3 @: @0 g8 m/ r
                  ;; world.  -1 for non-intersection patches.- C, M; h3 s% H8 E
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' a9 j4 s- D- {1 ?- g4 j, g+ \  auto?           ;; whether or not this intersection will switch automatically.- t* ^& A% u2 J1 r8 q) R, M% R
                  ;; false for non-intersection patches., b  }/ i5 e$ i$ z1 F  |& r
]
  p& A. e/ n% F) p, u, f
5 l- X! D5 F# a7 Y2 m  X0 r+ [. s3 E7 _
;;;;;;;;;;;;;;;;;;;;;;1 _* l1 H3 u% w, v& W
;; Setup Procedures ;;, k: x8 U5 K5 T; o, A
;;;;;;;;;;;;;;;;;;;;;;% U6 v/ M- P* h& Z! g! Q
  N9 p' ^' o7 x* c, h- i$ i
;; Initialize the display by giving the global and patch variables initial values.2 J* E4 J8 ~5 E: e: o
;; Create num-cars of turtles if there are enough road patches for one turtle to
1 n& L* F2 R- ]- `;; be created per road patch. Set up the plots.
' |! ~+ J  E0 \* ]# p( Oto setup
' P( \" ]7 l( p) \& N* v2 G5 }  ca
0 b: e; \. I8 c! H2 r& \0 _6 ~7 L  setup-globals- J9 n. ~  M/ \

0 E5 N# j2 U9 Q- u9 ~  f2 Q  ;; First we ask the patches to draw themselves and set up a few variables
# O+ @/ ^: [3 k  u* m  setup-patches
3 m/ {  Y3 b( v$ P& b  make-current one-of intersections: _% r3 \8 n9 p7 Y
  label-current; }- n8 K) w8 C/ ?4 d/ m
+ {# r7 H0 {3 }7 A5 g
  set-default-shape turtles "car"
2 v' v+ p. `7 u& k( N# u9 l/ Y; F% w  p* y( z" r) P
  if (num-cars > count roads)
  G2 h8 L: d; D9 s  [& E; X( [9 g5 |1 {
    user-message (word "There are too many cars for the amount of "
! c' b& @9 o0 i$ R                       "road.  Either increase the amount of roads "
( y! q. T5 r# I" v6 x                       "by increasing the GRID-SIZE-X or "% D+ U" d% Y6 h
                       "GRID-SIZE-Y sliders, or decrease the "& [- t( W8 S- ~6 C1 @, A" C
                       "number of cars by lowering the NUMBER slider.\n"
1 O  H0 T. F1 M                       "The setup has stopped.")5 E4 u1 e7 i4 J7 P$ z+ N3 `) k" t
    stop
) O6 N0 V( h& S9 j( J  ]: ?2 Q: Y! D, }; ]. d1 C

$ p2 }: J6 S- t# P6 F; B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. Q7 H& K% K9 k4 E
  crt num-cars9 }) q. @; s8 B/ j
  [' P, r) b! v  n: h5 \. ^, k
    setup-cars
! r- R: m4 l" I    set-car-color
0 `) p3 s* I, J# o- q    record-data& g9 L$ r! l0 u9 ?, V
  ]# q5 |( u, W: s: q9 r

7 I4 _: E! j! N7 ^, H' f  ;; give the turtles an initial speed2 U) c' q5 c% Z- j
  ask turtles [ set-car-speed ]
- y" S; O) ?% I( W4 _8 K
8 V2 B+ c" ~7 N2 y9 X# g3 f  reset-ticks/ a2 T2 D/ L8 a5 V1 f3 V" Y
end
% V) v" ^  S9 @" I/ `- l5 ^- J6 s3 Z
2 o+ A; w, G  h1 N$ L;; Initialize the global variables to appropriate values8 \6 O! d( h( \. G" }2 j" i
to setup-globals
9 \9 Q8 B, j5 I4 h* m! |4 F  set current-light nobody ;; just for now, since there are no lights yet
& ^$ ?+ B* G6 {7 Y  set phase 05 J# ?! A8 z' j+ T8 e9 u9 _
  set num-cars-stopped 0
5 k& F; V) A8 x6 ?+ n  set grid-x-inc world-width / grid-size-x- ^8 z: y1 ]$ U. o; ?1 N/ ~
  set grid-y-inc world-height / grid-size-y2 H* \- c8 s5 T+ z/ K& _

8 J6 U( I( I/ b( {9 a- P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 q7 q0 ~  K' @+ }) z! ?/ c
  set acceleration 0.099
! K, K* z( g0 q' s$ Uend
/ H# k* [! [7 X2 Y
, b# q# o, S+ Y, l  f8 v;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ U/ u9 o9 X, h0 R0 m& w+ ]* f;; and initialize the traffic lights to one setting
% B7 k, \, N0 ]( Qto setup-patches0 _' ?0 d7 {4 l5 J
  ;; initialize the patch-owned variables and color the patches to a base-color
; U( a$ Y$ m% `3 |0 y  ask patches) z3 y! m9 ]% g" B: f$ f
  [- V+ w" Z: Y6 A. U: v9 n+ S
    set intersection? false
$ Y/ Z  x/ g2 i5 N4 M: U9 G% ]    set auto? false/ b! _' J9 n, }# W
    set green-light-up? true
+ q8 c' k7 `6 Q, \3 a    set my-row -18 d) U; T& H. w2 }
    set my-column -1/ b1 |* A5 ?( m- {: ], ]0 _3 w
    set my-phase -1
3 |) y! S5 X6 r7 Y+ L4 f    set pcolor brown + 3; [9 n; {& \) ~9 X0 w1 W
  ]
$ T# X) i& n9 j* A1 C* K$ A9 g. A; u; V1 E
  ;; initialize the global variables that hold patch agentsets
1 o5 n: w0 B, l) e; x( a5 w. h8 ]  set roads patches with; H* `+ R: d. y3 L% |* k& {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. ^; }; R1 v* g3 i& {/ P* ]+ R3 N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 {/ L- X1 Y; N/ H
  set intersections roads with
2 e0 ~+ @5 t( G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* m, j# a- P/ t# M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- m- I1 ?/ g# O* k& [& j+ t( z
  Q( `0 _- q, k" t1 e  ask roads [ set pcolor white ]
: v3 a7 }) h$ y2 `, H1 s    setup-intersections4 H" B, p2 W, X* k" k
end) s! e6 a! _3 t3 s/ J
其中定义道路的句子,如下所示,是什么意思啊?) K% R+ E6 u* S  K* R/ [
set roads patches with
: c. [' R+ B0 _' r. m1 W8 l( Q1 P4 g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" t" @/ L2 X) J2 Y( o; j0 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% \: F1 e. I! {4 d: C: {/ I
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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