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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。
' ~( z4 q4 w. L2 r! P. Nnetlogo自带的social science--traffic grid这一例子当中,- e: Q! w6 y5 i! u( }
globals
3 G/ {" q% Y- ?8 x- R7 [[) k" b! }1 v0 T- |. a! W
  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 H- Y" l# f3 B. ], z4 l
  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 j+ F: d* y( O; x3 b6 M. f
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% x$ d, `0 n9 Q' q7 B+ S# \/ Q
                           ;; it is to accelerate or decelerate: r) z. ~' ]& N' r- O$ n" f5 v
  phase                    ;; keeps track of the phase
/ \0 x, H1 d1 T  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 O0 t7 C2 l+ ?9 d4 Z  {# r) X  current-light            ;; the currently selected light- H0 E9 b% d2 c) k5 L
8 h  O6 E$ W+ {- |# Y# I6 p: Z
  ;; patch agentsets
$ w$ \( v  z: @3 o' \  intersections ;; agentset containing the patches that are intersections
. J4 s& r# a( }! C4 Y8 t) X  roads         ;; agentset containing the patches that are roads
1 O& f8 w' ^) Y6 ]+ D$ z]# v# N% P' H% S5 k% q4 ?

% c8 g+ b- O% \  E& D2 Xturtles-own
4 q6 w& J, G* G4 I" V" ]- y' H[
* C0 g& [+ e6 a  speed     ;; the speed of the turtle
0 E- N* e5 F2 r0 h  o  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; e1 C; Y$ k! I/ }3 `4 @: c
  wait-time ;; the amount of time since the last time a turtle has moved* {- ^, Q$ U, ~& r; v9 @4 v( U
]2 E! A+ b6 S5 F7 H
3 i. @1 s2 |7 q* J* R
patches-own
3 }' ?$ g2 D) ?& B! o) m( f7 H[( ?  e7 A5 y, E! j2 |9 `$ Q
  intersection?   ;; true if the patch is at the intersection of two roads
% _8 I+ G1 i0 N& @4 m  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 J' @/ v0 s- X7 P+ H' G5 \/ R$ E
                  ;; false for a non-intersection patches.' }0 A1 g0 |  l9 }& {! H" o
  my-row          ;; the row of the intersection counting from the upper left corner of the
& R  I9 I0 S! d; C                  ;; world.  -1 for non-intersection patches.
* I% L3 v+ z4 N  my-column       ;; the column of the intersection counting from the upper left corner of the
( K; j, p6 l& }                  ;; world.  -1 for non-intersection patches.
6 c2 J- H% _4 v9 L! P' z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* v4 Z( ~8 ^) i% f" i  auto?           ;; whether or not this intersection will switch automatically.. Z/ r' P- X/ k7 A/ v! K
                  ;; false for non-intersection patches.6 P6 ~- P# F$ |' n: B
]
9 n2 _# j# u% J# j+ I
; z  w, k9 @' C4 M- H& I. w
; y  q, q8 z. [6 l2 R;;;;;;;;;;;;;;;;;;;;;;
! O5 o/ E! n' S2 f;; Setup Procedures ;;
2 P$ N7 D) G# w( U1 ?2 d. S;;;;;;;;;;;;;;;;;;;;;;0 \" G% [, d0 |7 a
: }* t/ g( j6 j
;; Initialize the display by giving the global and patch variables initial values.2 m4 g, d' m/ p
;; Create num-cars of turtles if there are enough road patches for one turtle to
& V, w( b7 D) E( G' Z$ c' _, s7 @  r;; be created per road patch. Set up the plots.( _* {" f. E' J" I/ Z  r1 y, P6 S
to setup$ H( k, `6 S# d/ m
  ca
8 k- q$ \3 W2 f0 f0 [% N  setup-globals2 [+ @/ c; L+ a

# Y3 F- j) s0 y" c% n4 ^  ;; First we ask the patches to draw themselves and set up a few variables
6 ?7 z+ Q; L, a  setup-patches
: T! l" F. M, i4 N+ W# g  make-current one-of intersections
, O$ t; ~0 q- [9 O# q) y& ?, [" l  label-current2 {2 r& |$ c+ w; d: Y; s! Z# L
" ~4 c' {  t8 b, T' j
  set-default-shape turtles "car"0 h% F1 a: d2 ^+ E' X+ r

9 g- q' @; Y% x( M. e( v8 q  if (num-cars > count roads)
8 c% G  a( J6 u  [
8 e) j8 _+ |6 X8 l    user-message (word "There are too many cars for the amount of "
. L; b4 P% Y& N                       "road.  Either increase the amount of roads "9 g. [( \4 u$ H1 P0 Q7 y
                       "by increasing the GRID-SIZE-X or ": L9 G# t- c! p* m7 y' s
                       "GRID-SIZE-Y sliders, or decrease the "9 |  u# g: n9 X3 @. x( \4 t% O2 L: V
                       "number of cars by lowering the NUMBER slider.\n"
" T6 A% G3 w; L! t1 s. Q                       "The setup has stopped.")1 s) C4 B$ D& G
    stop
; o1 m3 F7 ]* Q9 f2 n8 E  ]6 K! ~* W! g. f4 Y" }' U4 n
/ k4 H) Y6 v# P# Q- L; I& a0 Q( y
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( l6 W, I# {8 c* U! N' m7 B
  crt num-cars' S3 \5 h5 B1 b; l, _% o
  [
7 k2 X# Y+ j) e9 v3 x' W; }( O    setup-cars# w4 L% k8 O6 C8 X. }
    set-car-color8 f# e1 i- J! e$ G# ^* Q
    record-data/ ~9 X2 u5 F/ S# d
  ]5 q3 r2 q" w: \1 `7 N
& ^6 L1 Q+ z# a& F+ P8 a5 v
  ;; give the turtles an initial speed
( d$ w& _& t" P( i# D  ask turtles [ set-car-speed ]
8 T: d9 h# N7 g& h# J/ Q/ `. C- w5 G0 q& Z& q9 E
  reset-ticks
3 {4 y& P, H  N( N) Kend
6 k; I; H; Y+ n* T4 Y
1 \5 i$ o# K, f/ l) R, C* w6 j;; Initialize the global variables to appropriate values
3 S4 ]# ]- c& K$ @  dto setup-globals
) x9 ]* h, G& Q3 G; f* I  set current-light nobody ;; just for now, since there are no lights yet
. G0 V4 H: Y" K8 k  set phase 02 }7 m( ~6 i3 @7 u$ T6 B
  set num-cars-stopped 08 f8 J" p% d0 @# ^3 v; W8 B
  set grid-x-inc world-width / grid-size-x+ |) M' v9 A5 n
  set grid-y-inc world-height / grid-size-y
0 X; Z6 f9 `# b) \4 b( S7 P$ f
6 x8 e) R/ X. c& s9 r8 c0 C% N  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary* d# B; `! ?) U6 S7 \- e1 G
  set acceleration 0.099
" l( R) w- c- gend
* d$ {/ ^% R' X4 K( L9 T* z
, c. @8 g! G) k8 q( W5 z+ B3 P  k$ l;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 \/ `7 G8 T2 e$ Y
;; and initialize the traffic lights to one setting# x5 @8 L% O7 u
to setup-patches
5 A/ d) q# ?0 t- ?  U+ o/ r, r  ;; initialize the patch-owned variables and color the patches to a base-color
* t% J: S, H, C3 }" O1 s; S  ask patches
& x  k* ^- P% S$ {! f  [8 ?0 W8 l7 p" h" B  `4 V
    set intersection? false
5 ^! z9 G% p- X& A3 I5 B    set auto? false/ `$ H0 z9 y% a8 L6 `: u9 m+ y
    set green-light-up? true
0 {" o. |3 G0 x# u) v( O' B    set my-row -1
4 w+ `+ d, V, c8 H) F    set my-column -1  q: X) P: A5 \) K* _
    set my-phase -14 a- K5 h  S1 r( u- N* X' H
    set pcolor brown + 3
* }) t, E2 z3 j1 X$ A  ]
+ f5 B3 d. k3 g! {* ?6 m; u
) c  n( E( D. i$ J( m' a/ l3 n9 ?  ;; initialize the global variables that hold patch agentsets4 A& l9 R- f5 w) s5 y" O: m8 e
  set roads patches with
3 |( ?$ S/ T, \+ x) E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ @( j* p, p; H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& v2 s. Y' L, q3 a  set intersections roads with- R3 g1 j9 t8 Y( N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and# d( b2 q5 z4 L2 N: E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 C. i/ d( B) D( u

( S4 N! h- L! o, H% Y( \: x  ask roads [ set pcolor white ]" ~: v4 m# o- B% x' Q  ~
    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?
3 \$ f0 `/ k! t0 [" h. T set roads patches with9 E: P& [+ }0 o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& f/ K% [  R8 }/ F  j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ I% q7 c0 ^3 [7 Z5 A
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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