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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。* S' d  ]$ t9 Z' F' \0 D
netlogo自带的social science--traffic grid这一例子当中,3 I! R1 F- x# b- S
globals
$ o0 b3 R  Q2 l1 S[
+ u" A2 v/ \# k' b! n: x  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 a, ]7 n' N" w
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
9 b/ w: B+ {0 N0 E  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: H) D7 e! k% |2 d6 N5 Q1 w
                           ;; it is to accelerate or decelerate
9 G$ l- c+ C9 U- k# J  phase                    ;; keeps track of the phase1 c( |/ m* v& d  }: O! T
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 _& a* p* }! N" H( Y" W$ ?
  current-light            ;; the currently selected light& |% d6 ]% _5 q6 M
* v( ?$ d8 k  F6 U' M+ A5 q3 `" I7 n
  ;; patch agentsets: v* D' k1 P$ v
  intersections ;; agentset containing the patches that are intersections+ s+ Q$ G. r$ E9 y
  roads         ;; agentset containing the patches that are roads
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. ?2 S* q. E: j' N& x6 K5 V) @+ G; O4 f! G
turtles-own9 M1 L, A$ q+ ~8 P& d
[4 V6 h, m" a2 V2 T% b
  speed     ;; the speed of the turtle* H: C6 E. k' f( W: e2 [
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: i6 a5 t5 l: j* A4 ?/ {
  wait-time ;; the amount of time since the last time a turtle has moved
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" ]" ]9 ^8 t! Y1 J( s' v6 J; `( }2 J+ G7 e" T
patches-own/ h( ~" e2 M" U6 \+ A! N8 U
[
$ e6 p- C# K0 N2 X/ k5 I  intersection?   ;; true if the patch is at the intersection of two roads
7 e) Q, F/ ]. f$ f! i2 z  K  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ ?; p) ]  f* C9 `$ q# o7 K                  ;; false for a non-intersection patches.9 M7 b9 H& e4 W( [! Y8 |+ n& M
  my-row          ;; the row of the intersection counting from the upper left corner of the" I8 Z# X( O  z7 e- ^, {
                  ;; world.  -1 for non-intersection patches.
+ l: F; M- B3 Y( w+ i  my-column       ;; the column of the intersection counting from the upper left corner of the& H) D! g4 W# U% ?" f
                  ;; world.  -1 for non-intersection patches.
7 h- V9 T% F' D* N( e  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 h( d- \' x2 X- h
  auto?           ;; whether or not this intersection will switch automatically.  _" ]+ x' r8 S9 o, _; t
                  ;; false for non-intersection patches.1 W$ B' z- e4 _' _: _6 p2 _
]
% H- u1 L. i+ t
; G0 c! D. `4 O% O1 ^* y
' k3 P( _5 b3 t0 X3 K0 `;;;;;;;;;;;;;;;;;;;;;;* y6 n6 {- y; M. `9 H  ^! l4 B
;; Setup Procedures ;;
8 ?; q7 ?) s# x" _( f;;;;;;;;;;;;;;;;;;;;;;1 l# e: I6 S+ B$ y9 o3 E

5 j: K4 N/ O8 }; d;; Initialize the display by giving the global and patch variables initial values.
2 r; Z+ y6 x5 ]5 {! t" Q6 b+ r;; Create num-cars of turtles if there are enough road patches for one turtle to
7 o- _% r/ A. v, `;; be created per road patch. Set up the plots.+ M8 n& K. D7 `
to setup
% V# z% l9 A* _0 {8 X9 {- U4 U  ca
& d0 l9 Z: B2 Y  setup-globals0 i% n( L1 J$ w7 @7 H

; b, N8 Q0 h# j( `1 O0 y  ;; First we ask the patches to draw themselves and set up a few variables. l8 b& n/ a5 q* j; K- ]9 M
  setup-patches
; k9 u3 `) R( {" m' E  make-current one-of intersections
1 A" A' f$ [) d' c9 R' N' e) t5 z  label-current
: f+ f& M. F# p8 e) [  q8 ?' n! M, {- y+ j) p+ J9 r5 |$ O
  set-default-shape turtles "car"
, }2 x- Q: S* s9 S7 `/ f1 f) _& _
# w; o3 }, l3 F. X: S; @  if (num-cars > count roads)  O( }6 u2 V5 O" w
  [
1 D! c% g; A! Z    user-message (word "There are too many cars for the amount of "
; M! }" j8 y6 M/ \9 S                       "road.  Either increase the amount of roads "
: g% h6 ^9 i! \+ m4 i8 x                       "by increasing the GRID-SIZE-X or "
; A5 p8 w6 P) T$ c                       "GRID-SIZE-Y sliders, or decrease the "
# y3 f8 r) U( G0 h; {' S2 Z                       "number of cars by lowering the NUMBER slider.\n"8 b0 D) S  S2 u/ Z4 ^; B0 p
                       "The setup has stopped.")2 G$ b7 ^2 K$ o( @( c: X! [
    stop
# R. o6 M2 ~! n# j; T8 y5 S  ]
0 l0 x, n# j  ]* E4 c1 o
  u% d7 D- N+ v9 q; v7 b  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 P- A, \) w/ ?0 _  H# j1 c  crt num-cars
% b. B1 e, I, O  [7 A% F; Z8 S1 ^9 i6 U
    setup-cars" p* D- F$ q0 S7 C) e- k6 S4 T
    set-car-color6 J; z8 A) R! d1 p
    record-data
5 Q2 ?0 I" @0 B% c( L# m  ]
' g6 d4 i, u: t$ B$ k" d0 g) E
7 m7 ~2 N, t3 P- W0 H/ x  ;; give the turtles an initial speed5 T+ {( ~, h6 W$ ]2 V' p9 Y, R) }
  ask turtles [ set-car-speed ]
: E$ P' J( m; G/ |
! t7 H. s" k) g! p  reset-ticks
' b0 T/ F: w5 C. [1 u) rend
8 C' l' z0 b4 ?% G4 B& K  H/ U; o: }6 r8 y& U, F3 L
;; Initialize the global variables to appropriate values
* u! c; [1 Y2 y( [7 i5 F6 yto setup-globals3 i' g! ?  t, k- S3 p
  set current-light nobody ;; just for now, since there are no lights yet
- ]  z" v' s7 u  set phase 0
  ^) ~# _9 E. H5 D' A  set num-cars-stopped 02 J# c' K7 J# \7 L. q5 D' o
  set grid-x-inc world-width / grid-size-x% G! ?+ ^: q/ z, N/ \
  set grid-y-inc world-height / grid-size-y
) O. O/ L1 }/ }' G* h) ^; |
. K/ g# D) l' A  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; s7 G5 M* D, D* \& s  set acceleration 0.099
; S( g& B9 A' e0 ^4 zend$ w- z6 N, C& o9 P5 U' W
' N1 U. F% o9 x5 X; e5 b1 L+ g( I
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* D; R, A6 T: I* D0 T+ c
;; and initialize the traffic lights to one setting9 s7 `! Y: R: l4 Z
to setup-patches4 \% Z8 l6 _7 c& ^! B
  ;; initialize the patch-owned variables and color the patches to a base-color
# S0 |/ p  [1 L( x8 P6 S  ask patches. u8 ], a6 `: f4 @
  [$ b7 y% ~, U4 w9 m; J
    set intersection? false8 f' L# o8 ~0 T) |/ B1 I
    set auto? false% ?$ r& m" N( E1 Y) R
    set green-light-up? true1 \) ]9 t  d! R0 E9 u: N# E
    set my-row -1
1 u/ ?- _5 \' L- _* u    set my-column -17 H0 A6 Y8 v, B) y% k, D
    set my-phase -1' e- m4 p, S# w# x/ o! J- R* f
    set pcolor brown + 33 @0 n' z1 L6 o( t3 @  p% p
  ]
* M4 ^5 x) W$ i1 ~, Z. k( H1 M5 d& B% w- f
  ;; initialize the global variables that hold patch agentsets
" M  r/ L+ o; ?5 U5 V  set roads patches with; ^  a+ U. ]+ J4 L# T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ P1 R8 r0 l+ V; V4 H" M2 y+ ?/ G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( M; b% x; l' u6 r/ d  set intersections roads with
9 D5 G( E% u2 T4 i% h! u$ F/ j9 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ O% m9 U- I/ p4 G; ?- \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! E; p" V+ Y) }3 z
& l  X: n$ P8 K* C/ i! a  ask roads [ set pcolor white ]
& @2 c* M+ L3 }. W    setup-intersections. W1 h/ h) Z( Q+ k0 g, _' F! q' @- h
end" ~6 I" [8 I+ x0 w
其中定义道路的句子,如下所示,是什么意思啊?' S+ D, c  i) q4 z8 U0 Y6 c
set roads patches with5 P  [) X1 R  p$ p
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! i+ b) N( K* H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( u5 O3 K: x/ f+ p3 ]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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