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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。( q$ |- Q" L9 V3 I$ f  x" p) e
netlogo自带的social science--traffic grid这一例子当中,# o; [7 f7 P, j
globals
3 c! M5 E! d# v3 i; ?3 f8 P" _- }  A[3 k' V+ o2 W* _8 t( K: g' W
  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 E3 r$ D: z  G" I7 V! Z. F9 C# v- ^' \
  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 k8 [" X7 q. M% Z7 c5 m6 u3 i
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 H1 d- e7 i- A) N$ l                           ;; it is to accelerate or decelerate, J2 o+ P- v& i! [
  phase                    ;; keeps track of the phase
! o$ i$ `* Z6 D" u1 r7 w/ b  p; o1 N0 z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 I5 R! q* S+ @; o! {
  current-light            ;; the currently selected light
- h* H5 Y$ D9 k/ e5 O+ \! a; l' J  u7 p
  ;; patch agentsets4 x- |. s& [! P/ a7 ^" u# a
  intersections ;; agentset containing the patches that are intersections
0 h3 ]9 l& x/ R7 u1 j0 r  roads         ;; agentset containing the patches that are roads+ L' B. B- r! l
]
) s3 x: o- H/ Z+ {7 v: E
& n  h1 c3 b, X: i9 M6 lturtles-own8 b; v/ g6 J4 P7 T% p: g
[! H3 Q0 Q) Q4 @; p; H; Z# ~  q6 |
  speed     ;; the speed of the turtle( p# i" P2 E" ^9 ~$ r% Z4 K! |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: f' P5 l( x+ s
  wait-time ;; the amount of time since the last time a turtle has moved
& Q3 z1 ~- Z) T1 b7 X]
0 s; I9 D  i% ?: M, M/ t( x; c
. b1 O- G% c9 O- i- s) C8 ?patches-own0 C: Z9 s0 Y) ~, e4 ?
[  _% o$ y3 q. M9 s, O5 Y
  intersection?   ;; true if the patch is at the intersection of two roads
& {- n; c! k; {6 P4 I- ]  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  c1 B, J7 m* k+ d, I                  ;; false for a non-intersection patches.
/ @' N" U7 C2 K( r, P8 ^6 N4 ~/ O  my-row          ;; the row of the intersection counting from the upper left corner of the8 ~! o5 T6 Y; ^2 D8 i/ k
                  ;; world.  -1 for non-intersection patches.) a# \/ b8 G4 x9 Y) V
  my-column       ;; the column of the intersection counting from the upper left corner of the
) f. ]9 M4 c& |( ?; C3 m                  ;; world.  -1 for non-intersection patches.  C& h  h9 o5 P+ ^$ F
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.; R/ s) [. Q' ^1 t8 o
  auto?           ;; whether or not this intersection will switch automatically.6 H' t# q7 E$ D, ~. a2 Q
                  ;; false for non-intersection patches.6 E. Z3 f- O* H) P
]1 b* t6 ]0 {" L1 l) a
! j0 [+ [' H6 c/ N- M

+ C( a3 n( c5 A. [;;;;;;;;;;;;;;;;;;;;;;
2 S  Y8 S, G7 D# n# S;; Setup Procedures ;;
+ E+ ^+ e: l# A1 {6 t( Y;;;;;;;;;;;;;;;;;;;;;;
; V" _" o7 |; F  ~( l0 W7 ]. O& t# r
;; Initialize the display by giving the global and patch variables initial values.
* {3 o/ @* {+ }& f9 W  I' M; r;; Create num-cars of turtles if there are enough road patches for one turtle to7 b; a* {& _# G$ N5 ^5 n# J
;; be created per road patch. Set up the plots.
$ A0 M7 {5 ~4 l. W! hto setup
4 E5 t( g# f$ g1 o, n  O. O: Y  ca
* h. z- `0 ~" a; w$ c* ~  setup-globals# S/ b. V7 C( B. y

0 |. n# q, A+ N3 N  ;; First we ask the patches to draw themselves and set up a few variables
: t/ d! \$ A% X0 X1 z# l" t  setup-patches8 k" m. K: R/ v0 C# S" l* r5 I
  make-current one-of intersections+ ]; C- [. B( L$ W, k
  label-current; _4 t& ?  j" ^& ~9 k0 Z  O" \0 K

* V  O3 M3 D/ X/ a  set-default-shape turtles "car"' C: B* n0 E* Q9 u

" t. S! z4 R% \1 L3 w6 L  if (num-cars > count roads)0 ~& R& }; O; x% J$ J" U8 _
  [
* ?0 j$ V# h1 l' q& {- k    user-message (word "There are too many cars for the amount of "6 z2 ]. _2 ~* j6 j; _% V
                       "road.  Either increase the amount of roads "
( b% C& t! K$ j, Q9 e% p. A                       "by increasing the GRID-SIZE-X or "
2 W% C7 Z: ?: U6 ^8 F( F$ A( R                       "GRID-SIZE-Y sliders, or decrease the "+ L. ^' S7 d5 Y0 t# c  @$ m
                       "number of cars by lowering the NUMBER slider.\n"
7 o3 ~- P( R& ~0 T* `+ M                       "The setup has stopped.")3 f. m) U# q0 l
    stop
0 I4 `* J' A+ {' S. m8 Q/ f4 C5 i  ]( A6 K$ I; P6 B  C' N4 n

0 k- U* [9 H! H9 q" ?% B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 ?6 N7 |- {2 I* o! N$ k
  crt num-cars8 o& L) @0 u+ o% g2 b4 |
  [
3 C  l$ Z3 H, e, J, y+ Y* v, c6 ?    setup-cars+ P8 L5 S3 r5 B, H6 j4 p
    set-car-color( i0 e) y. G- e6 w/ U* z' @
    record-data
+ i# f. _4 |9 q$ a: f& x5 Q. f, U  ]
. I4 ~3 D% T5 z7 p2 t5 L4 Z9 S. K, x
  ;; give the turtles an initial speed
8 P6 V! O3 Z3 X4 l  ask turtles [ set-car-speed ]  }; L4 W: h- ^, [

6 ^5 j. N" V' j2 S% Y6 v  reset-ticks
& S* Z) [. d+ X! H. J% _end
# C% i0 b& k6 |3 X4 O( b6 J$ t/ M
# a3 ]5 j/ h; };; Initialize the global variables to appropriate values
5 N, k0 Q7 q, A% L( U6 gto setup-globals" c1 x: B- S. y/ t) G1 E
  set current-light nobody ;; just for now, since there are no lights yet5 i8 O( T* S& S8 h9 h  _+ h& D
  set phase 0
: M9 r) d1 c1 V1 e% v3 n  set num-cars-stopped 0
% z  o$ A  J+ X: |3 B  set grid-x-inc world-width / grid-size-x
9 z: g4 W) Q, M2 t% i# ^( D  set grid-y-inc world-height / grid-size-y0 Y7 O$ q3 p3 w$ N. j* l

( Q: ^$ q: H; e. E  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, S/ e: O" K+ m& p  set acceleration 0.099
/ N& j5 o, X# W. Hend
( s: s6 M' t& `) e+ H
  V  ^' S9 i  w! \;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 `0 R$ Z4 {2 [( q+ a;; and initialize the traffic lights to one setting* Z0 N; @8 b& Z! [- Z7 ]$ I
to setup-patches
( E) e5 D- o( f9 P9 K- \  ;; initialize the patch-owned variables and color the patches to a base-color1 M& f- ^1 \% _. p7 w" k
  ask patches  l7 U4 v# L. Q8 ~6 `: L
  [
) c( v% F: s6 s' ~3 _' A# ^    set intersection? false
' D4 `: G; @/ M& Y" B. O; q: I$ }7 m    set auto? false
& e5 [( l: H: Y7 t* W& C; y- P    set green-light-up? true# I+ R' N/ \7 r" o/ b. {! b
    set my-row -1; C9 L# i7 N$ g( D+ |
    set my-column -1
( p/ w& p+ x$ P% D9 R$ `    set my-phase -19 o. ^1 x- d: F' B! T# H! W: N
    set pcolor brown + 3
( |: @; s( w+ \) v8 d  ]* M' x( T3 d" u4 D2 u& B

% a! j7 ]1 H+ y+ K  ;; initialize the global variables that hold patch agentsets' D- Z/ n& Z8 q: [# C! k; ]
  set roads patches with
3 Z& D! r$ [6 o4 N7 s: X1 l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, c% w" O0 M) \- @4 i6 ]5 m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], T8 m" V( O% m4 }1 n
  set intersections roads with
& ?$ s2 D! [# b- a2 [& z- g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' Y6 y6 [0 W+ p4 }6 O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* Y. J9 s' {$ |3 c: i! i  j
4 p8 X/ }/ N8 y3 V- [4 _' L  ask roads [ set pcolor white ]
2 J; _; v- [& U    setup-intersections+ B6 i6 \7 @& `3 G1 s2 H$ b
end  z/ v# a! T. {. J
其中定义道路的句子,如下所示,是什么意思啊?; K! v9 F/ Q& I
set roads patches with. T+ ]/ k/ Z; P% g! ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. a7 I5 @0 t. s2 q# j2 e8 I1 ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 Q0 a. Z' b% n: [" R1 l$ [
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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