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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。* ^/ V" ?( t4 e% P- y4 `: @3 J: p
netlogo自带的social science--traffic grid这一例子当中,5 H1 P' r) m+ c5 [: [* \5 Y, r
globals
# y# P+ y. d% k3 \: o. m[
$ M; v9 u0 p( |0 Z6 m/ d/ B* t  grid-x-inc               ;; the amount of patches in between two roads in the x direction
; M7 B9 V$ c, B2 k8 Z% w+ g' h, X  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 e0 \" `( I; v# i! x  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: j! J" e0 O# a0 j. O0 P
                           ;; it is to accelerate or decelerate. w3 k1 i5 u1 B
  phase                    ;; keeps track of the phase
) y3 ^3 S' a6 C% R  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
0 r( O, i6 F" u" @/ r7 E  current-light            ;; the currently selected light
# x5 f3 L/ w2 a4 {
4 X* V; r7 }1 l3 t  ;; patch agentsets2 y7 N7 Q; ]4 b
  intersections ;; agentset containing the patches that are intersections6 k6 F1 X! ]0 L, o$ A' k1 X% ]
  roads         ;; agentset containing the patches that are roads
1 [2 _7 o3 @! t$ u) A( T]
, V- C! h5 ?! ~2 r# C+ y' g
5 v) n5 {& h/ N5 lturtles-own5 i9 p. K0 J# W' h% Q; t( y
[
5 R8 v* p- D+ ~. D5 v" y  speed     ;; the speed of the turtle; d7 m+ Y9 o: S. Q4 j
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 P* l% E4 ~, D2 z
  wait-time ;; the amount of time since the last time a turtle has moved  M, i" X5 }) k; N8 C
]; P4 `$ r2 Q3 U. v1 X! o* j
* e) Z. j' @  u% g
patches-own
2 i) S( p. U# P9 K9 N[% S7 U9 P) e" p0 C
  intersection?   ;; true if the patch is at the intersection of two roads
% B' N5 R5 T6 A; ?! K; @' d. r  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 I* I9 O3 z4 {! p$ h8 Y                  ;; false for a non-intersection patches.
" U) _& m0 n7 _! Y7 p3 ]  my-row          ;; the row of the intersection counting from the upper left corner of the
0 h- H" A+ Q8 D0 P                  ;; world.  -1 for non-intersection patches.' U  Z# m4 v4 P! ?
  my-column       ;; the column of the intersection counting from the upper left corner of the# E$ m; i6 u: N7 S8 r
                  ;; world.  -1 for non-intersection patches.
  D5 t) h: O* w7 v" P* Q  o  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 q) M1 `' ?1 a; p6 }' r! ^
  auto?           ;; whether or not this intersection will switch automatically.
" h( ?( v  {3 q# @: R9 d/ W                  ;; false for non-intersection patches.  H2 G- z6 M* t% z7 |% Z
]7 v5 Z- z& x0 z+ p

/ c  `" b) X) ^; t' u' j' M4 M( N# Z! X
;;;;;;;;;;;;;;;;;;;;;;
, z) y5 a! h8 j4 Y- r. P7 Z. A;; Setup Procedures ;;( e, s: `4 d& b, [
;;;;;;;;;;;;;;;;;;;;;;
, W: a3 w4 z0 s: f) h' s. i, q* `1 ]+ S
;; Initialize the display by giving the global and patch variables initial values.
4 N# o  w6 R* d+ d! K; S;; Create num-cars of turtles if there are enough road patches for one turtle to" O5 W% r% c7 Z7 v& w: H9 H
;; be created per road patch. Set up the plots.4 `( S+ H  }' E% E% `
to setup
, q& A, m5 L) z+ s+ D  ca
3 q6 F' k/ ?( I( J/ d6 X- s" U% C  setup-globals
- W, R8 I. V) l$ x! X% @# ~9 i6 O7 y  ~
  ;; First we ask the patches to draw themselves and set up a few variables9 t7 J7 |# e, A
  setup-patches
7 C5 F* b4 e. f! m  make-current one-of intersections$ V" b  E* L9 f+ D4 I/ ~+ l# r' ~9 D
  label-current
8 z6 O8 Y# H  c7 K8 y+ A
$ `& x1 @+ _8 M2 H  ?! g4 F  set-default-shape turtles "car"
; {2 ?2 f- R% {* l7 r
6 m( M. E3 |5 W0 u; R  z4 w2 t  if (num-cars > count roads)$ I; d2 |( ]7 H9 p( L$ l
  [
' a6 y$ y. D- F# }. w    user-message (word "There are too many cars for the amount of "
3 Z  d: U. x( o, c4 H, {                       "road.  Either increase the amount of roads "
$ S4 Q- o+ D4 ^3 D5 C; m2 j                       "by increasing the GRID-SIZE-X or "0 X$ Z* k# Z- ]( I: @5 q) b
                       "GRID-SIZE-Y sliders, or decrease the "& x- {7 A: A0 O& e6 O
                       "number of cars by lowering the NUMBER slider.\n"
8 V6 W+ u# q5 t+ I! Q0 `                       "The setup has stopped.")  I3 e, J( G% F2 R5 L0 D" y# A6 x1 r
    stop$ Z5 S3 B# M+ G6 N
  ]
; V% L4 T$ [  `$ x0 G) E
4 w- P8 T1 z- |6 F" j0 J1 a  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# U! v% X" x# b* L
  crt num-cars+ ?% ^" O0 l0 ~# l1 S
  [
  p- ?, m' u. Y8 o    setup-cars6 u1 [- v9 M5 ~
    set-car-color
$ K! U- h! O8 T" j    record-data4 `5 {# X" c; x; U! g: y1 |
  ]
/ d" E" C9 T1 b1 `8 q
3 k. d7 h; I6 b- s0 B# l6 n' r$ x  ;; give the turtles an initial speed1 B' m4 A" _& @- E( p
  ask turtles [ set-car-speed ]5 U; z/ A# K2 j1 y% A8 i# S( p) A
+ ]6 ~7 z* m8 Z( B) \
  reset-ticks
" m0 u, g! [* h2 r$ i  J: \/ tend  V- W2 N/ i3 C0 _5 j
1 F: p$ E) u' r& Y& B& ~; ?
;; Initialize the global variables to appropriate values
8 o8 T4 n) |6 a# n" ~& kto setup-globals
9 O* X+ e4 Y$ J' ^$ B) ]' J5 J  set current-light nobody ;; just for now, since there are no lights yet9 g& D. x0 A  K
  set phase 0, R/ z: l3 j& o) L1 H+ x
  set num-cars-stopped 0
' x4 L7 ?4 a6 j  set grid-x-inc world-width / grid-size-x7 S# g0 M/ M+ m) I# f
  set grid-y-inc world-height / grid-size-y
" b/ w1 D# @& `% }+ m5 B9 ~) Z1 H. J0 a: y& M: g/ O
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 ?5 H% ]% g' c, @" x  set acceleration 0.099' r8 P  P2 T1 A9 q5 v. F
end+ f5 h( S) @" t. E; s

# Z3 `; {- p0 E5 ]* K;; Make the patches have appropriate colors, set up the roads and intersections agentsets,, i8 Q% Y+ [3 \1 z
;; and initialize the traffic lights to one setting
6 T) v# L" r8 k  }- fto setup-patches
: Y3 S3 X  e3 f- J9 E  ;; initialize the patch-owned variables and color the patches to a base-color
/ S4 i! U4 @7 R: |$ S; R# f7 K  ask patches5 d. |0 }; h7 D* a
  [/ c1 ?* ]8 l& C7 l2 S" u  Z
    set intersection? false+ x- T/ j. e) N7 r- o$ \
    set auto? false
; _. b7 i2 x- b& [9 B0 f    set green-light-up? true' O- c; G" U8 ^  c
    set my-row -1
0 j+ N* I9 |) V) _! k    set my-column -1
1 z9 }) E9 @0 h0 `1 B    set my-phase -1
: t5 P' D+ H- u- \    set pcolor brown + 3
6 {3 ^$ i1 W* s( @9 M" Q  s  ]8 b2 C; f( _4 q3 V8 N  z
% T( x1 i7 F# J, K  L4 z
  ;; initialize the global variables that hold patch agentsets
! V; p& l- i& N( L  set roads patches with
6 V( d' _2 k8 w8 t* F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, T! ]: }0 c2 m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; t+ K/ U3 l" `# f: V7 Z# @
  set intersections roads with+ O7 d' ~" ]; n1 s' M' V# b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- k+ Y% ~& z) P7 \6 r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% t' a2 K* z7 J1 t
2 F8 y- f3 \) d6 U  ask roads [ set pcolor white ]2 {. o3 B! p# k: a
    setup-intersections
- I# ~" ~9 v8 K/ w; `9 r0 A5 i! Uend$ Y, s+ ^0 S2 ?! v* k
其中定义道路的句子,如下所示,是什么意思啊?
5 Z! V: S1 w- y8 Y4 _5 V5 _0 _ set roads patches with
( p8 o* m" a, r" n1 N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 t5 z/ q# e. t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 G  H& u2 l/ `% ^  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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