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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。& v8 k( Z1 o3 f" D" L: k- r! ^, x
netlogo自带的social science--traffic grid这一例子当中,6 \3 m  ?% `  u7 L: f) S
globals9 U- }2 j' W* d) Z
[( I% r7 j9 p+ V: t9 X
  grid-x-inc               ;; the amount of patches in between two roads in the x direction, t* v  `& N  [# K; Y# f
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ q7 i" Q' N( @) u
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 O& p4 r. A1 M                           ;; it is to accelerate or decelerate
/ c  l. \: N' l, E  phase                    ;; keeps track of the phase
6 i4 r1 ^; S: d: t/ e) A! C  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% D0 L$ t0 w6 d! M! F. [- k  current-light            ;; the currently selected light3 S  c- o9 E) |) ^8 w4 G

9 s  B! R1 |' r4 b6 y2 X! Y( }# L% w  ;; patch agentsets
2 [8 @  ]* ]8 |) J0 ]' t" b. g  intersections ;; agentset containing the patches that are intersections2 c5 }1 ]5 U0 y! u) x! R* W
  roads         ;; agentset containing the patches that are roads
3 B* i( Q9 G: `3 i! F! k! z]' R7 W! I1 p( }; K# r, E
! F) h. c4 n$ A( X
turtles-own
- ~3 r, b" P' \7 q[1 a8 m6 ~4 l, Z
  speed     ;; the speed of the turtle
- b; v; X4 N" |6 z0 O$ L3 I! |8 f  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 m3 P( w( V. R2 X  wait-time ;; the amount of time since the last time a turtle has moved
# x$ W; {; d# f]. A) b0 R% I. t& Q$ S# g
; X: ]( x( f: c. X% ~) t
patches-own5 V3 g* J3 i! R
[
  c5 T' a7 e. d5 w  intersection?   ;; true if the patch is at the intersection of two roads$ t0 o4 O3 k# M- {  c
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: J& n7 M9 u8 ^/ O& Z6 S5 R! U
                  ;; false for a non-intersection patches.4 g) h: f' p) [, g" J3 K$ f
  my-row          ;; the row of the intersection counting from the upper left corner of the
4 N! x6 e- W" V, `, R                  ;; world.  -1 for non-intersection patches.
# F* \; f( v1 l2 L+ c  my-column       ;; the column of the intersection counting from the upper left corner of the/ u/ c0 R. Q7 u( e1 k3 a% Y6 _
                  ;; world.  -1 for non-intersection patches.
% C2 a/ ^9 e" w% l1 I3 P  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., q  ~9 l' I5 X
  auto?           ;; whether or not this intersection will switch automatically.
+ n& Q1 S8 P7 ]                  ;; false for non-intersection patches.) t( s' }7 H- M' A. Z& _
]
7 \( [8 D$ U' I! e/ y! u0 k9 Q. w* Y/ b: E* h, c
" j6 S; r8 m2 O1 z- c  s
;;;;;;;;;;;;;;;;;;;;;;" E4 o  {7 M3 L3 \
;; Setup Procedures ;;
- H: B3 u' e6 [; F; P7 M7 |: s8 o  f;;;;;;;;;;;;;;;;;;;;;;
+ L, U+ V1 U5 {& ]# ~( {
$ y- w/ G$ N! x" j4 ^. D4 F;; Initialize the display by giving the global and patch variables initial values.
+ y7 Y' O& x" G( Y7 C;; Create num-cars of turtles if there are enough road patches for one turtle to
; w8 @2 Z* O; k% E* Q- A;; be created per road patch. Set up the plots.
1 o% }* Y5 Z% {$ x- N0 b6 eto setup" h8 w; k0 C3 L# v! A) P
  ca  b4 Z4 a! e' c/ W
  setup-globals  C, d$ [' _4 ~8 t2 x7 y
% o: A! j1 n6 `
  ;; First we ask the patches to draw themselves and set up a few variables( S" I# M0 s: \. e
  setup-patches
0 }; ]) A1 W' H2 R  make-current one-of intersections
% m0 y7 z, X4 u  label-current
: V- ?. f; Y) B/ _1 w3 Q; h+ Y/ g) {# O- t7 C
  set-default-shape turtles "car", Y; `% K% Y2 {# ^$ ^2 Y
0 |) A. N* |* @7 ~) y
  if (num-cars > count roads)" s2 }6 A7 S3 b- {7 A
  [  I" h6 O" s4 F1 w1 L2 b. t
    user-message (word "There are too many cars for the amount of "( e! G, X; \7 G. _
                       "road.  Either increase the amount of roads "- g: E. \! G0 W! u
                       "by increasing the GRID-SIZE-X or "2 G9 Y" s# l- V
                       "GRID-SIZE-Y sliders, or decrease the ". ?1 k  h7 T  ]" i  m# f, E( t4 ]& U
                       "number of cars by lowering the NUMBER slider.\n"
6 j+ K( K5 `6 U                       "The setup has stopped.")! [* K+ b1 d4 k. [+ M/ g
    stop8 }. I* ~5 F0 a+ a: J8 e
  ]  Y0 U3 E& O- X* N6 D8 m2 W

+ c' c  P' p& l+ _4 r& m. b  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) ?5 H- B: q0 O. L( @2 ?  crt num-cars+ D* ^7 _7 U- `3 q
  [3 V4 j1 j1 o0 ]7 M
    setup-cars8 t4 l- T4 p7 v  Z1 b& _5 ^
    set-car-color' F1 P+ ~) x: q8 W
    record-data
7 }' Y7 u- b" ?2 Q4 o+ m  ]
, J( f- m% i# A
/ b2 j: S3 O6 R  ;; give the turtles an initial speed% \) N' q1 ]+ {) g
  ask turtles [ set-car-speed ]
* k2 c* I+ ?1 J, G7 X$ v1 ^) ^$ A0 s6 }' P5 `. ~$ Y! I& f
  reset-ticks4 Y4 U0 r& @$ z5 ~& k2 n
end
$ p) O9 {7 Z1 \$ L" \% i; \. _* n) E& F! [! a
;; Initialize the global variables to appropriate values
% ~4 k9 ~* `( _/ j+ |* ato setup-globals+ g  ~3 Y4 p6 N3 K8 b4 v
  set current-light nobody ;; just for now, since there are no lights yet
0 A/ Q! M+ P; X1 {4 C  set phase 0
" j7 Z: e9 o$ o6 N+ }; W* |  set num-cars-stopped 0  D' G. e, U! |
  set grid-x-inc world-width / grid-size-x/ A, N5 ^$ m- z( x5 {, L
  set grid-y-inc world-height / grid-size-y; c4 S& D+ k( k  i4 N
6 U$ h9 _$ d8 B
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: f" L% [4 P0 h' y4 _" I6 u; ~  set acceleration 0.099
1 t) Y# E8 z& u: r/ a2 H5 d$ Qend
& ]0 F  Q1 ]. J& N% N4 \7 k
' e6 G* U0 a+ Z2 k' Z8 H# I2 f- i;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; s9 x' v4 K: y- |( k;; and initialize the traffic lights to one setting
* }' Q7 a2 f' j- W5 B, xto setup-patches/ ^- w: b: A* ~0 i- @
  ;; initialize the patch-owned variables and color the patches to a base-color: `8 y6 H* v9 I) G
  ask patches
0 n, L' S/ w- P1 F7 a5 U, F  [* U! {( Y9 i, E- ?
    set intersection? false
8 G* L% P( l) I2 a( A! `0 F9 ~. V    set auto? false6 P% c3 v# B( ]4 ~  q" E% B9 f* N
    set green-light-up? true
# B5 P9 p$ H* p    set my-row -11 [" F1 r8 b4 t
    set my-column -1
' k: b0 ~. f, @    set my-phase -1. ~- a: b+ i3 D1 @/ C% F
    set pcolor brown + 34 o5 a! d5 A4 O6 g! B  \* u  U
  ]
+ E: i, l4 ^" w" q1 L) a' k# S" }% T  J% p# f9 l
  ;; initialize the global variables that hold patch agentsets
) l. r: d; `* P6 C7 X: i" n% w/ e  set roads patches with; W8 {% o/ Q) j% h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 B4 c) w% [$ I- P7 H6 O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# a' R% r6 X- i6 f6 B0 |
  set intersections roads with9 h  Z1 q) B% {8 D9 Q6 q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ i+ ^% D2 b" f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ B5 m% U! f! @# Z) d$ J
" v, B% L4 z  j  ask roads [ set pcolor white ]
9 N5 ]7 M* }- t* l4 v5 P, ~0 p    setup-intersections
7 U4 n- J" b" Z6 Eend
  M* @0 x* V9 ^) K4 d其中定义道路的句子,如下所示,是什么意思啊?
4 J- F) x7 d5 g set roads patches with( Q8 R$ j9 w6 W! o- G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, m6 o8 x0 O/ }- N$ q3 r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' J/ P  x9 h/ R4 ^6 l% t
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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