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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。
5 v  s: r  q# f# X3 ]7 Enetlogo自带的social science--traffic grid这一例子当中,
, z1 p5 F4 U. S! Y  x" ?globals
5 o& @- t% t; u9 x6 N[
$ f0 m( [8 y3 Z/ u  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 D( c6 O) T2 X, z
  grid-y-inc               ;; the amount of patches in between two roads in the y direction# c1 S2 j2 B" }+ |& y- \
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
1 D9 z, b0 O$ ]/ W9 W                           ;; it is to accelerate or decelerate
2 u& c% F/ K6 p: I& E1 X  phase                    ;; keeps track of the phase0 X9 Y/ }# l; H0 P8 L5 T( a- d
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" F# s; O8 e8 d  {9 {
  current-light            ;; the currently selected light1 e4 ~. p0 C/ U
) c9 W  u5 `2 |! R+ b5 t7 T
  ;; patch agentsets
! Z* m  f9 U! Y6 u  s+ O  intersections ;; agentset containing the patches that are intersections
& L! T' g9 A. K- e, ?  roads         ;; agentset containing the patches that are roads! `' F2 c7 s" Q$ X4 L
]
/ ~( e3 a' D+ t# W, a" o" K/ |2 T5 e
turtles-own
: i. ^9 i$ {$ |3 ^, S[
! [. G& \/ m- |) T" l  speed     ;; the speed of the turtle. w; D) m9 S: q, U$ U6 F5 K$ X
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
8 ?  n* w( B- X9 |2 p  wait-time ;; the amount of time since the last time a turtle has moved
# f( }  ]0 R: ^- m) L6 |]) R6 x# C! L7 I. a' w! x7 ]
3 B, x& H/ Y& H! Q1 Q: e3 _
patches-own
3 }" K5 i5 ?9 j% b  S) }[
5 [2 L( m7 w6 l8 g" v. C8 u" [  intersection?   ;; true if the patch is at the intersection of two roads
3 Z7 b" h4 k5 f$ H( m5 K  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.& ^& T- i5 Z2 [6 L! q
                  ;; false for a non-intersection patches.8 w" s3 U7 ]6 h; ?+ q
  my-row          ;; the row of the intersection counting from the upper left corner of the
( \$ s! w; }+ X                  ;; world.  -1 for non-intersection patches.
7 A& Q' h0 A" K+ P/ u+ a- J/ S6 L: P  my-column       ;; the column of the intersection counting from the upper left corner of the
- I1 U* ^( A2 c# S3 v                  ;; world.  -1 for non-intersection patches.
; ?: t% }- w4 p8 S3 t  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ x3 q) L# y1 z0 f  auto?           ;; whether or not this intersection will switch automatically.. C  q1 B/ N6 i- F8 e
                  ;; false for non-intersection patches.
  @4 p/ j& q" G" o7 _9 H" ]" X]3 L) [5 U" e# v( n5 _1 y

0 b! a! p1 q# E# u* C9 ]4 w( \5 N, K! e8 y/ @
;;;;;;;;;;;;;;;;;;;;;;
( J  D$ G7 [& d) Z' }- S6 o  M' C;; Setup Procedures ;;1 Z# [6 u7 e( G
;;;;;;;;;;;;;;;;;;;;;;
- N/ y, v3 m  w* d; G0 O6 L6 Y
6 d" v+ B5 y6 S: ^1 E;; Initialize the display by giving the global and patch variables initial values.
+ e; `% \3 X( n) {. v! [5 m5 E;; Create num-cars of turtles if there are enough road patches for one turtle to
: [; q+ q8 H' N" B: _& W. N;; be created per road patch. Set up the plots.: O- Z9 o6 `0 Q* F' [
to setup5 Y2 {+ M9 k2 Z8 u
  ca
$ h( H' b5 P  f  setup-globals# v" {  R3 b' z# ~
5 s' b5 j* f0 D$ t" y5 B/ V
  ;; First we ask the patches to draw themselves and set up a few variables
) V% T: }; B! S, r7 A! I3 ]" {1 A' ]  setup-patches
( x7 j& f/ Z! {  o! V: y! [) r$ j' m  make-current one-of intersections1 V6 F- e9 _5 ~3 j6 z" W" k
  label-current& m/ U9 s- Z$ a
6 g1 i, D6 g2 u, m8 |4 O
  set-default-shape turtles "car"
4 _8 S6 I: s- h/ h" k- A
& O" K) y6 h7 @  if (num-cars > count roads)4 C* U- B) }. ?3 r" d' D
  [
! U: n9 X+ r. z! F$ W! O: f2 T    user-message (word "There are too many cars for the amount of "
; w5 y5 k% ]" x) B( g                       "road.  Either increase the amount of roads "
- l4 t& [4 D8 m7 A! l                       "by increasing the GRID-SIZE-X or "
' _: d3 _2 K7 E, _! B0 q                       "GRID-SIZE-Y sliders, or decrease the "
0 v# ]8 @7 j& E1 a, c( b                       "number of cars by lowering the NUMBER slider.\n"5 x: O) |/ X3 }3 u3 [5 N1 ]2 z* R
                       "The setup has stopped.")7 M+ H( T! N2 W" ?- T  H
    stop
2 G& _2 a6 [+ Z- M: L2 Z  ]
/ ~8 N1 x& @6 z
' P$ q8 G5 A. Z7 S  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 A7 D) y& m9 J+ b$ ?+ X
  crt num-cars0 R' B0 J7 V3 @+ e) }6 ~% M
  [
* k% K% H% _+ ]& T  z  v* N9 B    setup-cars% ~% f) r: E% b2 ?8 d, k
    set-car-color# h0 V- W* s8 o2 D& E  I( b1 r
    record-data
3 a3 D+ H' i& f# J  ]. p/ W+ Y3 _) z; Y; Q

8 B2 W' a7 R1 l. s2 r1 `5 f  ;; give the turtles an initial speed$ j1 L& x; ^; o1 b' E7 r
  ask turtles [ set-car-speed ]
% E& m$ m: N% f, x( T! F/ Q: k! P. ?4 x
  reset-ticks- d  C& b; k! u+ v- j1 M
end. y5 P. e! d% r0 d7 e

0 d( N* g$ C7 A;; Initialize the global variables to appropriate values
1 e, U- L# m2 k" c( k1 h% ]to setup-globals$ I, L7 ?5 }. m4 h8 Q+ u! g
  set current-light nobody ;; just for now, since there are no lights yet4 O. ]3 }3 U' ?4 a* w1 J4 p
  set phase 0
4 ~! F# b) }$ X& E2 w/ j. p/ R* s1 z  set num-cars-stopped 0
5 Y- O: J& h$ X1 V5 F  set grid-x-inc world-width / grid-size-x4 H: V8 Q  y' R* g2 b( s
  set grid-y-inc world-height / grid-size-y
5 a3 @( w. s3 g: [* Z; u2 n. L1 o% N/ r" V0 d
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 v- r! h# [# k0 V2 E( e( ~
  set acceleration 0.0995 f# Q% f% {6 O- ~, T
end3 Q  m! G& R' S6 x* Z
& R5 A& C5 A* d" F* ?
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 p5 }( t6 y$ t7 |% n, R- t2 Y
;; and initialize the traffic lights to one setting# R% y3 k' M% P0 h2 |
to setup-patches
- `6 F" l$ T7 |" u  ;; initialize the patch-owned variables and color the patches to a base-color
2 K7 s& v, }" z/ D8 C  ask patches
7 x. s# U2 G. p  [2 ?: `; l3 V4 v* V
    set intersection? false- K# v5 ]: M. E; J6 c! b
    set auto? false
. }/ o, I/ P% c/ h4 R* d    set green-light-up? true! I) C& K* ?+ s7 H9 e
    set my-row -1
- [, c  H8 {, Z- }6 G9 L1 b    set my-column -1
9 b1 X8 s7 G5 m8 K/ d    set my-phase -18 S* y, [, h4 f* @7 n
    set pcolor brown + 34 d+ m7 O% G! O6 B+ u* b
  ]
/ l0 f% m$ D4 b" c" N
  O! K3 |+ `3 w$ B! Z  ;; initialize the global variables that hold patch agentsets
$ {! F) f. `0 H  C  set roads patches with
6 }/ I7 p& M  D0 J5 l2 E, `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ n, d. z$ V  |# T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ }& c' x; T' F  s. u$ K- T7 j
  set intersections roads with: C$ f, P  p! s* v, b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- a  i' j$ I  m+ H' E* Z* c# _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 B* W6 M6 J7 Y+ j: ]- d- h# e
& x% a# K4 S; z& ^. y  ask roads [ set pcolor white ]- u# f* C* ]9 j* P
    setup-intersections3 h/ f4 c% p. P5 e
end; j$ A& {+ J- B+ ~
其中定义道路的句子,如下所示,是什么意思啊?9 t( y9 N* R" q' b+ o, S
set roads patches with/ P0 u9 |! Q: E! h, \+ \5 N6 l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# m0 O/ C! q% e4 x5 N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' d" t" t& X. E/ y- T: x
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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