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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。
7 ^7 J' N* \0 Y; x2 \- ~netlogo自带的social science--traffic grid这一例子当中,# d5 q% q" n" P& i% z0 V2 _  B
globals# A6 K% R: [- x" Z8 v# J7 p
[2 r% m- U3 i) z4 L& w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction; g* q0 f7 X- F8 c
  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 j9 E% b% I) j
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
) ~& ~, ~% h7 I/ ?9 a                           ;; it is to accelerate or decelerate7 ^5 @# _) g! k" A
  phase                    ;; keeps track of the phase
* U" |8 U% X' y8 ~) C) d  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 T+ ~9 o' f( Y5 e, a8 P
  current-light            ;; the currently selected light
3 q! ~5 U1 U* ^. R% R: \( a) W9 b
6 e" {0 a% {  K# |  ;; patch agentsets9 a1 l$ p' n# H  o) D4 J
  intersections ;; agentset containing the patches that are intersections* {" _8 y: \" u8 v7 n
  roads         ;; agentset containing the patches that are roads! G0 O6 b: X7 y. ]' {
]. n% m0 q" T3 [' F# D6 |9 i
* z6 g6 K$ z+ `4 B# Y3 M; [. G
turtles-own
( l) L, l" w( [6 w" v8 H[% z( h7 V9 `6 Z! c0 k
  speed     ;; the speed of the turtle
; |1 m/ E6 ~2 ]7 h  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! o2 h" \1 p' L  wait-time ;; the amount of time since the last time a turtle has moved
4 E# a1 E4 R! P]" I% h, d  q3 _# ^+ Z, ^
' j% `& V. @5 z7 f0 f
patches-own
& a5 _/ h+ B0 L$ ?[
# \0 [6 O; G6 o, l. h  intersection?   ;; true if the patch is at the intersection of two roads. a9 V0 a* P  [. o) J
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- Q( b+ w9 ~3 W8 T
                  ;; false for a non-intersection patches.. r. Q. W/ E' c$ ?  i; M' P
  my-row          ;; the row of the intersection counting from the upper left corner of the+ Q. k' z7 b$ S
                  ;; world.  -1 for non-intersection patches.; g" f" _; U- P" F& }  p/ z6 k
  my-column       ;; the column of the intersection counting from the upper left corner of the* S1 K1 i: z6 l9 Q$ ~
                  ;; world.  -1 for non-intersection patches.; H6 _! p) ?8 l* c
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 s/ r' e4 N1 Z" p1 Y
  auto?           ;; whether or not this intersection will switch automatically.& |2 {: N/ ~( _9 n" _9 f
                  ;; false for non-intersection patches.
1 j, B8 }5 ~3 c, c+ D]( \3 D6 g" R) H/ D; \4 Q. I
2 F- q7 T3 e7 r& r4 P

2 W9 k' r; h5 T$ }; G;;;;;;;;;;;;;;;;;;;;;;
( b2 k1 B; s; K; {. l3 t* t;; Setup Procedures ;;
; q2 d/ b) m( m7 e;;;;;;;;;;;;;;;;;;;;;;8 V2 D; [( ]( J$ ]
7 c: |9 c/ A: Q' k0 [( ^* m- A! `
;; Initialize the display by giving the global and patch variables initial values.
" m% `. H4 s' x3 k& G3 q! ~- l;; Create num-cars of turtles if there are enough road patches for one turtle to. p+ [0 ?7 {* e5 b
;; be created per road patch. Set up the plots.
: L  U. H7 X  Z$ N( [' w+ z) q, O3 |6 dto setup
9 X1 \$ i+ b" y7 r# p3 m1 N7 f  ca; e, x1 Z5 Y5 S: j& i5 n- O
  setup-globals
; k; v& t' d+ i0 B' S) \; E  E6 Q" C& W
  ;; First we ask the patches to draw themselves and set up a few variables$ t  i  C8 P! K! C! w
  setup-patches- j# X! I! y+ d; R* ~) Z& y" w( _* k
  make-current one-of intersections& q% P4 e# L2 F: @
  label-current( M4 M$ Y$ m- J) Y
; m0 @# u2 A8 R" n
  set-default-shape turtles "car") ^3 e" H, ]" _8 d$ H5 q9 v/ X

+ R  a1 @$ @6 j5 m  if (num-cars > count roads)
8 U% z* C" E% ~- W1 P# R9 k  [
( K4 B/ [7 G2 ^% y9 |    user-message (word "There are too many cars for the amount of "4 J3 a- {/ k6 R
                       "road.  Either increase the amount of roads "$ g$ a. n( f! U+ a: G
                       "by increasing the GRID-SIZE-X or "; b- O( I% @* m' k
                       "GRID-SIZE-Y sliders, or decrease the "
6 J: h* h  _5 j4 v, I: \9 l) o                       "number of cars by lowering the NUMBER slider.\n"
+ u8 n, L: v2 p+ R, X, t; e0 [0 r( P0 c                       "The setup has stopped.")# m# G  n$ y" n8 J3 C' \* e# ]  g
    stop% E* m1 I4 F" ^! s" O! B1 q# W
  ]
8 v! P- n, X6 @* y' R8 `3 }
( x4 ]5 R; r: p, l( U$ X  ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( J; g0 f( c& V" j
  crt num-cars/ b, \& [5 l) c6 B. s5 [+ u
  [4 f1 O' ], d/ P% K$ U- _/ V( A
    setup-cars
* U. n$ y2 s. o, ]    set-car-color# ?9 S) O8 ?) b+ c) n2 o* K: G/ h# I
    record-data
$ |+ q4 D* m! A4 r" W6 {: Z0 b$ u( N  ]* g$ N; Q- O$ V  N; m3 _
; w' J2 V/ O0 f7 R0 @# Z
  ;; give the turtles an initial speed& {' G6 [* J  L
  ask turtles [ set-car-speed ]2 L7 A# r/ ]5 H) R+ C3 o* _/ O) H
* h6 {- X0 m5 u6 u0 [7 F
  reset-ticks* \" i5 l# P( y8 p, @, ~, A
end
/ Y/ |/ I5 d( X# h# P6 Y- {! u4 S* k. q& }) C& ]: e9 ^2 q
;; Initialize the global variables to appropriate values
/ h/ H- w. g* Z( q5 z* P, Hto setup-globals
' l$ y' @6 c! U- X  set current-light nobody ;; just for now, since there are no lights yet5 }# j8 ^; e+ h" E! d& T+ U" K
  set phase 0
* O3 }& W; @8 H; y6 [% @  set num-cars-stopped 0
4 c0 {  T; r; O+ q% y2 |1 `6 K  set grid-x-inc world-width / grid-size-x
& R6 q  ], b9 x  set grid-y-inc world-height / grid-size-y4 z# O6 `& H) X$ \

( o& f: r( E8 s" Z4 C$ p0 G  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 O* X# s! |$ A3 e  u. [# D: R  set acceleration 0.0999 ^* E- N8 {! f
end  b4 [( p. j; q9 B# u* m( {* l! Z" E
- t) l/ H+ k9 u) t  p/ f" l2 Y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,3 ?0 o. Q7 c8 R8 f2 m( h5 y
;; and initialize the traffic lights to one setting
. u7 Q8 m& T' x! S1 Hto setup-patches# b) F* k* }! V4 }# z
  ;; initialize the patch-owned variables and color the patches to a base-color" L# j* _% V9 j/ P% h1 J: n; b
  ask patches, {' n' j& W8 ]- H0 p% a
  [, T) S0 d% @& {$ I  ?9 d& @/ |
    set intersection? false
, X- [: w7 D, U2 \0 Q1 @8 e4 c5 y    set auto? false( F: d: a) q# `
    set green-light-up? true+ s8 U& E6 g) c1 b) {0 Y
    set my-row -1
1 z$ u7 T$ z& B9 ?& M    set my-column -1" h' }  N. v0 C. j
    set my-phase -1
2 Y9 ~  _: M9 p1 R5 ^1 n    set pcolor brown + 3
* X* Y! b7 q6 n7 V1 u) n  ]4 z; \: s3 |- x. A' T6 p" m! C4 z

9 u+ ?7 F- O( f% ]4 c! I# b  ;; initialize the global variables that hold patch agentsets6 x+ t1 {/ C  y8 G
  set roads patches with' ~1 `9 O+ X- d* W9 v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' U# e* a/ h! t7 L2 u- v' X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" i" W3 a8 U! P
  set intersections roads with
! z- ~5 j2 {. D- i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. [( S+ t" v2 i. i; m& ?& q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 N% ^1 h2 ]/ l8 Z4 }8 ~

2 d$ m' J% S" S  ask roads [ set pcolor white ]; E! S$ U: P& K% r, m& {
    setup-intersections
2 A; n. x/ N5 D$ pend/ U# _5 l' C, F
其中定义道路的句子,如下所示,是什么意思啊?. y6 f% d5 y; N3 i
set roads patches with
2 G, T' x! K; v% D    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: M& O2 w$ k6 j; N1 S2 D) ]$ p; R1 J! N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% k& K2 H( T+ d4 c
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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