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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。! `) J( L  k9 [! k3 `
netlogo自带的social science--traffic grid这一例子当中,
' g! ]7 B/ v" m; E9 ~' Nglobals. }# i/ u3 l7 D# H2 v
[
2 D3 B* |! Y8 t( Q  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 @% j' B4 h% o- u: z' z; x( x
  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 Z; q/ P% y, X
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, c3 E3 d% s3 \2 g8 _. e) z                           ;; it is to accelerate or decelerate7 F' u4 |( C8 v4 {
  phase                    ;; keeps track of the phase
) o9 F5 J8 m0 M$ y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 {2 f  f1 e$ C) u4 f
  current-light            ;; the currently selected light9 m, u, \- G3 \. ]- o
/ u5 r+ l7 s6 o6 G# r* P
  ;; patch agentsets  ~5 [$ j5 O6 r# d9 d
  intersections ;; agentset containing the patches that are intersections
( O! N1 T7 I! }4 L  {$ h  roads         ;; agentset containing the patches that are roads& O  A/ o- @0 n% Q' a2 N) y) Z* x
]
$ @, X2 L8 ]9 m$ O1 @! Z1 c+ ~, y6 [- \1 y; ], k, d
turtles-own
  e: ], [$ ?& I. J+ _0 B[
8 m) t2 d4 e- f0 H, H3 t  speed     ;; the speed of the turtle
0 J0 M6 d) a3 t: h0 Y- ]  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, J/ ~- `" @5 ~) x
  wait-time ;; the amount of time since the last time a turtle has moved2 Q$ g& L4 a+ k6 I- y$ D
]
2 b$ y5 Z; c. z+ M( Z- D1 n
+ h& h- ]4 K( ~9 x$ P, ~" Opatches-own
* r$ N- [/ L( c7 X[
' Y0 a! k# w( _- K  intersection?   ;; true if the patch is at the intersection of two roads7 I/ ^4 `8 ^% c: n& p  ~
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. |. V" n3 P  ~4 m$ `( t                  ;; false for a non-intersection patches.% @% m( l. v! z+ M
  my-row          ;; the row of the intersection counting from the upper left corner of the
- x; d3 L6 }$ T7 O                  ;; world.  -1 for non-intersection patches.
/ I, `- }! i) B. v  my-column       ;; the column of the intersection counting from the upper left corner of the3 Z2 h# t8 ]. N) y
                  ;; world.  -1 for non-intersection patches.
  Y( d6 S4 p# G) t7 B  o+ N  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* }, N1 A, L, P: }* H! Q0 T5 b+ l
  auto?           ;; whether or not this intersection will switch automatically.
7 G7 q5 ^; H% n, _                  ;; false for non-intersection patches.2 _, L. e/ ^+ t/ ?" w6 H
]2 E* s3 y1 |+ G

% a  j$ _; W; {' N5 G1 r! h2 ^5 ?- Q, A& |5 z" Y) M. C" X0 q
;;;;;;;;;;;;;;;;;;;;;;! b3 S: e* R6 k$ b" y% h1 Z0 A$ h
;; Setup Procedures ;;
! V- K: @" L6 `8 ?  T7 [/ f& k9 K;;;;;;;;;;;;;;;;;;;;;;
; m0 C. }$ U0 Q
, F1 o8 K4 ]0 }4 A3 y;; Initialize the display by giving the global and patch variables initial values./ d& {1 ~1 ~6 y0 F
;; Create num-cars of turtles if there are enough road patches for one turtle to
- G$ i  f8 K: V;; be created per road patch. Set up the plots.
) Z" S( ^2 V3 Z9 c! P! H7 ~4 k0 U5 V) _to setup
0 ^; |  f# }( }% K6 Z  ca1 d5 u' }9 c+ @$ ?0 ]3 Z
  setup-globals, i& ?7 u9 }: @9 ?# d
8 [- F4 j+ M3 B+ }
  ;; First we ask the patches to draw themselves and set up a few variables
6 j4 K$ n9 ]% f  setup-patches. u, m# H' Q! h: }( p  l
  make-current one-of intersections! t% }! J# c5 X; W
  label-current3 g# |$ @, c9 K8 `- @

) [1 u/ x1 Q* c$ f1 h  set-default-shape turtles "car"- u2 ^, z+ J! N" X9 F
% p5 x2 c: F. ^7 X3 [
  if (num-cars > count roads)
, Z) l. L7 F9 `6 j) x8 F' w  [5 f, a* U8 t4 p1 A3 k
    user-message (word "There are too many cars for the amount of ", y9 R+ r6 B; s
                       "road.  Either increase the amount of roads "
3 r# z, q) X& F9 s: l                       "by increasing the GRID-SIZE-X or "5 w2 }) G9 V3 p& x
                       "GRID-SIZE-Y sliders, or decrease the "
  P( `" `4 }+ ^" K' S# K                       "number of cars by lowering the NUMBER slider.\n", [2 r3 b" {& p+ N' z
                       "The setup has stopped.")
/ P5 P# W9 R( _- {% z9 J8 J; a    stop. E, h, R3 C, R9 W% F
  ]% ]4 n; V) Z' K+ ^* j0 x- J! G

# f3 M) I5 N1 m8 N1 U# D0 w% B/ h  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 k8 t! `1 C. ^% e& i  crt num-cars
* e9 H" q0 D& Y3 I  [
0 b( O% J2 b  M7 A- ~4 O! K    setup-cars
0 k6 R. ~# j& Q    set-car-color
) t4 X: w6 O: h4 v    record-data& F! o0 j6 ~- Z4 N. m, F
  ]
/ L: q2 u' S# @: J+ o
; H6 w& w1 p" |. S- L! w' \; N  ;; give the turtles an initial speed
+ `6 O3 k% q; ?9 l3 x$ ?: T  ask turtles [ set-car-speed ]
0 L; [" p; }0 T
( D$ C( L: Q: S  reset-ticks9 M# r, r' _- W9 G9 I
end
2 h$ w9 f* O" T; d- m5 S, _  U/ |' ^1 G- X0 ~- L' a, E; U
;; Initialize the global variables to appropriate values
, X4 t( ~: N0 hto setup-globals
8 m) w4 i3 F. a- q/ ~  set current-light nobody ;; just for now, since there are no lights yet% I, r; C2 m* S" _6 o- s. E* H
  set phase 0
% x7 I; V' z5 F  set num-cars-stopped 06 u! [: @5 ]( u( p) A. b
  set grid-x-inc world-width / grid-size-x
' t6 h4 Q( z% B  `! Q  set grid-y-inc world-height / grid-size-y
8 b" V+ ^- C9 ~3 I2 q1 K. a$ ?7 x: k, i, v3 V/ U* g
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; s, X3 D. X2 F2 N  C
  set acceleration 0.099# H( {8 n6 Y' \: j3 d# s% n
end9 q  Y  m# s( M" F

) W6 Q( S# N1 r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# t/ ^0 y) J2 |: E2 z, I+ I6 Z0 V
;; and initialize the traffic lights to one setting
+ Y& g' V" F1 {8 z. \to setup-patches
- n8 L! j% @4 _  ;; initialize the patch-owned variables and color the patches to a base-color
$ z9 z! M+ g/ \% |" o' F  ask patches3 j. }: O8 Q# C
  [
- S  ]/ O! b$ K: [/ U% q# t5 k: ]& l    set intersection? false
2 n6 V) f  D% X    set auto? false
7 a- i1 r% |2 |( E    set green-light-up? true
0 s& a4 j/ W) ^3 [    set my-row -1' [+ {$ f! B( h/ x
    set my-column -15 X6 ^6 ~: W; E+ q
    set my-phase -10 B: }( i7 r$ [( L" c
    set pcolor brown + 3
$ J. @& `' j: \  ]  i8 R/ T4 ?2 r/ f; L
  q( f; |7 ^% \* P$ I
  ;; initialize the global variables that hold patch agentsets
- f/ p1 q" J, [8 [! V  set roads patches with
: h. Z1 F; f: y. H# Y& }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ ?4 _7 [/ e& S! Y' Y: y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  x3 A) O4 N% r/ J3 [7 k8 S# r  set intersections roads with
$ O' v/ h, R2 l* p0 O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% Q1 G' G' V1 R& g* Z7 H- Q  P' d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ P6 e& P2 R2 y0 \/ E# B
+ S# f4 t& U8 U) Y* j  ask roads [ set pcolor white ]
' t3 z% K/ K2 c. l. `3 p7 t: Q2 T    setup-intersections& M/ k! B1 A9 J* ]% b
end- y) }0 _/ T" j
其中定义道路的句子,如下所示,是什么意思啊?
! z' @) h: K, O set roads patches with
% G) K. E% V/ ~' P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. q( r8 b( Q) @9 Z5 a$ \8 f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 J9 b- L! U9 w, {3 q+ k; O3 M
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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