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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。
+ q7 R. L, j8 L( Y* \netlogo自带的social science--traffic grid这一例子当中,
# D2 ]/ K* \7 d0 q) y& I2 b3 v) w1 Cglobals
* D- g% ]& b0 e7 H& w" [  v[: ~. o( }; y; c  O" t
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 p# \, B" E* j; {& B7 B; X
  grid-y-inc               ;; the amount of patches in between two roads in the y direction' ^5 ~" F+ E+ \3 B6 s
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ f1 ?0 V5 k7 l- y                           ;; it is to accelerate or decelerate
, s5 g7 p3 ^: \" F- `6 f9 [  phase                    ;; keeps track of the phase
0 Q/ k# U7 K2 |7 k1 v  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 I6 u8 U" T5 h( `! m  current-light            ;; the currently selected light
( a. Z, o& V2 G
9 ^% W8 ]8 P& V/ W  ;; patch agentsets
9 z/ M  E: b3 r8 s  intersections ;; agentset containing the patches that are intersections) Y" ^0 S5 P' L4 Q9 y8 E
  roads         ;; agentset containing the patches that are roads
* b" J; @- ?8 {& K+ c" Y+ y5 |]
/ o& o1 t6 E2 Y
! u  K" x, P! b3 t% U: X# hturtles-own
! Z7 u4 F# W3 j3 M! a# e% h" `[, _1 }/ l. V; G" d7 N/ u
  speed     ;; the speed of the turtle
) Q6 Y0 j  Q. x4 `6 q3 f7 _  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 A6 X# W: c" }0 y9 n8 C) m( H2 e* q
  wait-time ;; the amount of time since the last time a turtle has moved; _- R+ A+ E3 o5 \7 i* f
]4 O7 z/ E5 p9 V% l7 X

4 Y! W/ ?2 e% }  Cpatches-own2 E8 ^2 q9 f& l) A
[
; E' N1 `- P  L5 t4 G: o  intersection?   ;; true if the patch is at the intersection of two roads
  }: z# c1 o8 [3 D: w3 X' w* ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 G: H5 C7 ]1 M+ L2 _! s" t                  ;; false for a non-intersection patches.& N5 @4 }! c3 L" C! @! U' h; E
  my-row          ;; the row of the intersection counting from the upper left corner of the5 X; h6 s; [, g
                  ;; world.  -1 for non-intersection patches., e2 P/ d, s4 {9 s: C
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 Q9 A% D; f6 M                  ;; world.  -1 for non-intersection patches.6 r$ V) [3 j# I& p  N6 o) T
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* q2 o9 s$ d9 s1 P$ S5 ^
  auto?           ;; whether or not this intersection will switch automatically.3 l, U5 [9 U( E6 U7 M9 X8 r, R+ ~4 @
                  ;; false for non-intersection patches.5 L3 j9 a5 p  o: [+ T9 g6 F% [% {0 K
]1 ?( N8 g+ _+ H2 z' H/ }6 z8 M, Y

8 v1 Y9 }1 J/ O& d( B5 t% _$ }7 Y4 |( W* O/ O
;;;;;;;;;;;;;;;;;;;;;;/ S2 v' [7 E7 o  ?5 N
;; Setup Procedures ;;3 K. r# d5 L: W+ h% U: k: B
;;;;;;;;;;;;;;;;;;;;;;
1 B( i: B0 o. p1 n& d8 S
7 X4 O4 O6 u1 y7 U1 \: ^$ h;; Initialize the display by giving the global and patch variables initial values.' |( |3 E  i# z! j! P+ \- w
;; Create num-cars of turtles if there are enough road patches for one turtle to8 l8 t5 E) U4 H+ @0 e& }; u
;; be created per road patch. Set up the plots.
# a. e/ D0 `7 D! K5 Tto setup
0 P) h' t1 E4 g  ca. g) `& m- M$ s
  setup-globals! B5 v* S  b: V" A

% N2 q4 b. M/ q4 A  ;; First we ask the patches to draw themselves and set up a few variables
8 }# L, B2 z$ C7 K, S4 h& N( }  setup-patches
  S: f% a6 M2 ~8 k; N  make-current one-of intersections" v4 Y0 [9 t: I, W+ d6 J
  label-current  C8 B+ M6 r1 I% k
5 A. J0 I4 |: E; O3 d
  set-default-shape turtles "car", e& O: k: A* P# ^. j$ G

+ ^7 {0 y- d1 D& v  if (num-cars > count roads)
+ q8 R& e8 T3 g9 i+ f) k  [
0 e1 Z; i8 W; x% z8 a# \% ~; x2 Q    user-message (word "There are too many cars for the amount of "
% m  a. h% f" J1 o- _& c, H5 C                       "road.  Either increase the amount of roads "6 Z: U: f1 [! u, y
                       "by increasing the GRID-SIZE-X or "
1 E4 n1 ~; g3 ~: }                       "GRID-SIZE-Y sliders, or decrease the "/ t) i" S" ^! y0 l+ h* i
                       "number of cars by lowering the NUMBER slider.\n"
5 `3 Z* C9 \8 @8 Y+ E, |* w                       "The setup has stopped.")& f% S1 z1 {" Q
    stop
8 e' z" ?( f1 k. v3 u. \# S  ]
+ q6 Z: l) O6 h6 v" h# r8 v* ]7 g  I$ ]
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 |) W" l% c# H; P: C  crt num-cars
7 r9 R: q% L" ]2 X1 G! O( s- t  [
& q1 h! `- `( h    setup-cars6 u" [, q  U+ Y
    set-car-color6 h" O: Q* |! f: e
    record-data
3 y6 ^" J) D- [5 Q9 u9 E  ]
0 U- v7 h$ }8 A' @. P- c; ^6 I9 M- t9 ]
  ;; give the turtles an initial speed
" G1 I  i' X( M" d5 h3 V# p  ask turtles [ set-car-speed ]
$ O; A. A' e) f0 [0 q/ c
4 Q* W+ k8 g3 D& v: t( q( }  reset-ticks0 U9 z* V% p. L! Y
end
  N1 h! D* ]6 e! Y0 l& N8 r; L% T/ }8 }7 e
;; Initialize the global variables to appropriate values1 ~7 W. \/ j/ V% @: Y# h
to setup-globals
& Q& H. j1 v" Y7 g; s0 e: B8 ]" l  set current-light nobody ;; just for now, since there are no lights yet
0 D! w4 q* b' X! }7 D5 h* ]  set phase 0- N2 T2 b+ A: ^- H
  set num-cars-stopped 0, J8 {3 X' ]( Q4 Z  v# ?/ V3 h5 o0 q
  set grid-x-inc world-width / grid-size-x+ {9 P+ V5 f  _; a5 ?( a. n2 {0 q7 }
  set grid-y-inc world-height / grid-size-y
/ ~7 [4 g2 d/ C5 N8 T: e- b# z& Z5 h' C7 U5 s! W. H! h7 [
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; S9 g; A' S; P  s+ F8 Q
  set acceleration 0.099
# C  {5 ?1 s& N; a0 [4 Mend) X: o5 ~# m8 W

6 R" Z/ b7 g* M4 k8 E9 \;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 L6 ?! Q7 d. _
;; and initialize the traffic lights to one setting
1 |) [& T2 K( P9 l4 ~3 ato setup-patches
/ m  g1 G* S1 ^$ y  ;; initialize the patch-owned variables and color the patches to a base-color; R- O; L( E7 u; ]* E; |
  ask patches
$ d( D; P5 Q  ]1 R' P  [
% |, L; ], f2 y4 x* F5 e. H) u) v: W    set intersection? false
( @. c! q" b$ ^- i    set auto? false7 l; ]; r' j7 d" d: x0 c" Q
    set green-light-up? true
2 X: g5 z- ?6 |9 D    set my-row -1
' ^8 z4 }3 `' q: u    set my-column -12 w* k7 @7 y9 X7 K5 ?* \% n
    set my-phase -1! R/ J/ T& ^- D+ `
    set pcolor brown + 3
, \$ f& [4 c4 x# F9 M9 X$ o  ]
- r- O  N! R9 x$ p" L+ ~8 }
' T& x& N% R- y1 H& u% G! j$ @  ;; initialize the global variables that hold patch agentsets
8 R% s! {+ d1 h) X) C( H  set roads patches with' z7 C6 k3 k# ]0 U' v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( ?7 O2 A% }3 t& C% ^0 r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( a6 C/ R+ P3 ?+ @  p  set intersections roads with' U0 {8 c! x( w6 B8 n; U+ H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: {( C5 w5 n4 r6 Y; h2 B! F2 _, t: u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% e/ C, x- F! o% H+ ]/ ?& o1 t$ ~
7 h! D1 U8 t0 s1 G  z- x: d  ask roads [ set pcolor white ]: ^$ X: o1 h; B. j* K
    setup-intersections
' `3 r' x! ?4 D5 h* i. O. D; T, J. iend2 j: k% t+ c3 Q2 V7 a! v) D
其中定义道路的句子,如下所示,是什么意思啊?
% R' D+ Y1 n  X* y; A6 h& N$ x1 c2 R set roads patches with
, J$ A) J+ N1 Y' i; r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, g  q6 |. P1 E- h2 {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 i/ T0 C# ?+ \0 o9 O9 U' F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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