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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。
9 ?0 c/ h% m4 P0 s/ D4 ~netlogo自带的social science--traffic grid这一例子当中,# [4 T- F8 b" Y  i% I) |$ v; Z
globals9 Z1 k' @' o- E/ D
[* e/ O. d0 n- O. g
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
# Z+ a6 t! C* h) Q1 c/ v6 T  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 z) S: a7 l# W4 G% J  Y, W' U  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; C' B8 p9 b; a  k0 @
                           ;; it is to accelerate or decelerate- L% H' I5 F% m" v% F. D/ L
  phase                    ;; keeps track of the phase
) n% {  w- R% r0 V) H  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
7 H' O; w3 U! h4 f$ X  current-light            ;; the currently selected light
3 f* `# s$ w  h
/ H. w' `, q# x  ;; patch agentsets5 C" o3 g9 k  f- _( B& ~" P' U: b  V
  intersections ;; agentset containing the patches that are intersections
1 B5 o. j0 }* ~7 j3 J1 Y* \5 x  roads         ;; agentset containing the patches that are roads: n# K9 A, k7 A' \; g
]* N8 |  u/ P  U) J& \' ^4 ]2 [

4 n3 w/ R4 J: Q  Q. Rturtles-own% C" U( }3 A, l4 U
[
  `! P3 o; m9 T  speed     ;; the speed of the turtle) S! ]: g7 r$ _, M- M
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 S$ D; h/ p2 f$ d; B4 n! n
  wait-time ;; the amount of time since the last time a turtle has moved# P8 M+ Q4 E/ L1 `6 p2 n" h5 {
]
& E" u. [% E  w) ?6 f7 W1 P3 Y4 S) ?! I
patches-own
% |+ ?; j# d( p0 w2 u/ ^8 m! j  W2 H7 }[: }" s- M# X: t8 y8 X' c
  intersection?   ;; true if the patch is at the intersection of two roads# e, M* L0 p% q) b/ A) S) U! _
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 j+ \2 h6 O7 V# M* w) Q
                  ;; false for a non-intersection patches./ H: h8 D+ @. J8 X0 m
  my-row          ;; the row of the intersection counting from the upper left corner of the
, e4 c7 x* n' i, K                  ;; world.  -1 for non-intersection patches.2 A/ N. u! E# p# `
  my-column       ;; the column of the intersection counting from the upper left corner of the/ S4 E0 I' e2 {( C
                  ;; world.  -1 for non-intersection patches.
: j# Z" X, _- Y6 K1 L  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) O1 {* v! B( T2 [$ V
  auto?           ;; whether or not this intersection will switch automatically.
: E+ X+ Q2 U0 S1 `. v/ L                  ;; false for non-intersection patches.
6 ?( K+ |+ \; G, `; q, Z* X]! i+ t* k; S/ }7 `3 \" n
: t/ y2 S8 u4 Y2 e
$ X+ M- X# x/ u8 c
;;;;;;;;;;;;;;;;;;;;;;
8 R1 ^$ ~. i8 B' O0 L5 p  r;; Setup Procedures ;;
/ s6 U' P& @6 X% O2 p+ s" X  i* N7 Y;;;;;;;;;;;;;;;;;;;;;;2 ^* g2 |4 E' O; _8 q2 ?
4 B8 V2 f& }# P( j. N
;; Initialize the display by giving the global and patch variables initial values.
) a/ j5 ~+ m) [$ x4 B;; Create num-cars of turtles if there are enough road patches for one turtle to
/ h6 z! m+ ^" {6 W7 v! T' ~1 h;; be created per road patch. Set up the plots.  E+ r/ x# l! J" |2 g! ]$ s; Y
to setup7 ]) a4 q4 a" o! D
  ca
- }) @  O; D8 n' `! |6 }! [$ K3 D  setup-globals
! J* N9 O) d& w4 I) A1 H- O( b4 f  S- R
  ;; First we ask the patches to draw themselves and set up a few variables
. q7 _' n% h, \& M% Q2 d  setup-patches0 ?. x% g% ^, ]% }: R
  make-current one-of intersections5 S" `3 Q  s  ]7 e3 j8 V
  label-current
0 s1 Y1 b& ~. |$ u/ b
" \+ r9 S( |$ S  T. L' A  set-default-shape turtles "car"
% r; Q7 {" d% h" X" ?% s) E$ C
2 o' ]8 |, \1 g; l& U  if (num-cars > count roads)
% I( L  I# O+ o  [
# a* j7 t/ ^5 r( {4 y& B% b    user-message (word "There are too many cars for the amount of "
0 ^; K1 Y7 X3 p) ?9 A; k                       "road.  Either increase the amount of roads "
% t5 U: T6 O' k" u' J) Y, G                       "by increasing the GRID-SIZE-X or "
9 X( V& J! T; F$ K6 x0 o                       "GRID-SIZE-Y sliders, or decrease the "
9 G4 x! }  G' |: B$ u) N6 Z& o0 O                       "number of cars by lowering the NUMBER slider.\n"
& e/ A' R0 D4 b- C4 X7 ~- c( @1 }                       "The setup has stopped.")
$ M' j6 Y  Y7 D6 r1 f    stop) T: u* ~3 r: @$ Q0 O9 Z! u9 R# m
  ], u# W* E# X, V; f3 h

: c/ _' B# b( [) y2 B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% a% R2 N" b! g2 n- v+ Z  crt num-cars& N" P$ H* |! `2 {& c4 l. Y
  [4 M- h  d% J) `) `# g
    setup-cars
0 X% e! H6 U0 i5 s7 b6 i    set-car-color* n- U0 J& N- L. X  B5 H! P+ U1 a
    record-data
& w# s4 U8 l2 l- G% [; i  ]
6 ^9 R) i' e" T1 t, O7 o
, Q+ S( x# B2 L# a8 H! ]3 E  ;; give the turtles an initial speed
2 A( [0 U5 U& Y* d4 f3 _& [  ask turtles [ set-car-speed ]
, [% ]: a! ?3 }/ f
2 l0 A* [% j5 _2 `- K" l  reset-ticks1 J3 L8 i' C, M
end
, x8 p, `. M+ h  i# [( R
7 ?7 l# j" |5 Y' f) X;; Initialize the global variables to appropriate values- E+ w/ T% `9 @9 ]. `
to setup-globals
3 @; o, I& o  v0 J- V1 P# t& r  set current-light nobody ;; just for now, since there are no lights yet
/ \, d: G4 p: k5 t% a# _: Y  set phase 0' b# U. i5 U" a* `' |( e) a
  set num-cars-stopped 0" |7 i, s- M+ Z% L$ M
  set grid-x-inc world-width / grid-size-x# ~& @- F- ~. N9 ^
  set grid-y-inc world-height / grid-size-y. t. m3 `6 u4 e
+ h5 b- ~! G2 q8 H
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ P+ j8 ?6 ^1 ~  set acceleration 0.099  `) ?- g- A$ p% |1 B- [* N
end% Z  Y0 ]. |# U& }+ [- ~$ K1 ^. V
8 t7 Q7 |5 x' W
;; Make the patches have appropriate colors, set up the roads and intersections agentsets," S. _! J8 m, `( ~
;; and initialize the traffic lights to one setting; G* e) [5 E  ]- Y' }
to setup-patches
' D; C) w. U( {8 n  ;; initialize the patch-owned variables and color the patches to a base-color
: ?1 ~& `% ~) Q% G% [5 A) B  ask patches) c/ [/ T6 x9 t! T# _8 m2 q8 C
  [% f) y" F3 W/ {% f7 T+ p" k4 c
    set intersection? false
0 v' A" I/ Q% A/ y! D3 E+ H- s    set auto? false! R+ w: u% n! m: J% Y2 o8 K/ ~  \
    set green-light-up? true1 I& p& U, C# V" A' e5 N% F3 Z
    set my-row -1/ H  j% ~5 L  f1 H+ X5 ^, b# q
    set my-column -1
! D; X9 a: r* Q    set my-phase -1
+ t; I' Q, o( z; X' _' D1 H9 Q    set pcolor brown + 3
9 p9 `' {/ _. Z1 Y5 ]  ]$ m1 O. T+ F0 u! B. r+ g

  O. L6 X5 E2 P  ;; initialize the global variables that hold patch agentsets6 L8 q' J2 @3 c+ R4 t- B
  set roads patches with
6 b  r3 u1 I1 i% X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! {  T/ F/ ~: }0 Z$ u; y5 W, A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! Y6 A! a" ]" K  set intersections roads with
# ^: o4 n' D: W1 h9 S8 ]. c  ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% C2 K1 q2 i8 Y9 g3 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 g5 W5 g1 J3 M( d5 n9 V7 i5 l8 X1 C
+ s9 V+ m; k0 ~' ?6 J  ask roads [ set pcolor white ]$ h  p9 w6 w" D' r: W# o
    setup-intersections5 l6 q. V* l% l8 Q$ u: d' X
end; Z# w- c* V2 j- h. ^. C, I
其中定义道路的句子,如下所示,是什么意思啊?
5 i7 r- _0 h* d# @" A8 p( c' x set roads patches with! X# u. {1 b  M/ s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! F. ^5 ~( |0 J3 h5 z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 d0 X: t' Q! r; [
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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